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1.  Epidemiological study of farmer's lung in five districts of the French Doubs province. 
Thorax  1988;43(6):429-435.
The prevalence of farmer's lung was studied in five districts of the French Doubs province (Rougemont, Clerval, Levier, Montbenoît, Mouthe) on the basis of a medical and occupational questionnaire and serological studies for precipitins. Of the 1763 active farmers (response rate 69%) who participated in the study, 270 were suspected of having farmer's lung and divided, on the basis of clinical and serological criteria, into probable and possible farmer's lung groups. This subgroup of 270 patients was examined in more detail with physical examination, chest radiographs, and pulmonary function tests. Probable farmer's lung was diagnosed in 77 cases (53 men and 24 women, mean age 51.7 years), a prevalence of 43.7/1000. Possible farmer's lung was present in a further 193 subjects. Fever was the most specific symptom. In the group with probable farmer's lung the frequency of crepitations, restrictive ventilatory defect, and radiological interstitial abnormalities was 21.5%, 9.5%, and 9.2% at the time of the study. Farmer's lung was more common in the middle tablelands than in the plain or mountain areas (p less than 0.01). The difference in prevalence of farmer's lung between the Mouthe mountain and Levier middle tableland districts (25.2/1000 and 60.8/1000) raises the possibility that cold may protect against the disease. Farmer's lung was more frequent in men and in the age group 51-55 years. Among possible occupational factors, only regular work connected with feeding animals was associated with a significant risk (odds ratio 2.55 with a 95% confidence interval of 1.09-5.93). The frequency of chronic bronchitis in the population studied was 14.8%. There was a close link between farmer's lung and chronic bronchitis, 50.6% of patients with probable farmer's lung having it but only 8.6% of patients without farmer's lung (p less than 0.001). In patients with probable farmer's lung chronic bronchitis was independent of smoking and age. There were fewer smokers in the probable farmer's lung than in the non-farmer's lung group (p less than 0.05).
PMCID: PMC461305  PMID: 3420554
2.  Farmer's lung in a group of Scottish dairy farms 
ABSTRACT The microbiology of the air of byres and bruising sheds and of hay, grain and dust from bruising machines was studied in 12 dairy farms in Ayrshire and one in Perthshire. Seven farms (FLD) had a known case of farmer's lung disease and five farms (non-FLD) were free from the disease. Concentrations of mesophilic organisms and of thermotolerant and thermophilic fungi did not vary significantly between the two types of farm but the concentrations of thermophilic actinomycetes and bacteria, notably Micropolyspora faeni, were higher in general on FLD farms. Culture filtrate and mycelial extracts of the most commonly isolated organisms were tested against three groups of sera (11 from patients with farmer's lung disease, 14 from healthy personnel on FLD farms and 13 from personnel without farmer's lung disease on non-FLD farms). Only extracts from a Penicillium sp. and a Streptomyces sp. precipitated with a number of sera, when extracts from the 12 most commonly isolated fungi, from six thermophilic actinomycetes other than M. faeni and Thermoactinomyces vulgaris, and from two thermophilic bacteria were tested. There was no correlation between disease and seropositivity. All sera reacted to at least one of 60 carbol-saline and trichloracetic acid extracts from 30 samples of hay, grain and dust. Although sera from personnel on both FLD and non-FLD farms precipitated with 16% and 19% of these extracts respectively, reactivity to extracts from FLD farms was greater on average than to those from non-FLD farms. When tested by several serological methods against extracts of a type culture of M. faeni and by double diffusion against farmer's lung hay (FLH) and extracts of local isolates of M. faeni, 91% of all clinical cases of farmer's lung were serologically positive but no one test was adequate for determining sensitisation. Fifty-four per cent of sera from FLD and also from non-FLD farms were positive in at least one test. Sixty-nine per cent of seropositive personnel on FLD farms were also symptomatic. The occurrence of symptoms apparently correlated with the higher concentrations of M. faeni encountered on FLD farms.
PMCID: PMC1008229  PMID: 911689
3.  Factors influencing the development of serum precipitins to farmer's lung antigen in Quebec dairy farmers. 
Thorax  1985;40(2):138-142.
A total of 888 randomly selected dairy farmers participated in an epidemiological study to evaluate the prevalence of precipitins to farmer's lung antigens, and the socioeconomic factors associated with their presence. Precipitins were present in 75 farmers (8.4%) (65 to Micropolyspora faeni, seven to Aspergillus spp, two to both Aspergillus and Micropolyspora faeni, and one to Aspergillus and Thermoactinomyces vulgaris). The titres ranged from a dilution of 1/32 to a concentration of X 2 (Ouchterlony's double diffusion method). In the study population there were 544 who had never smoked, 146 ex-smokers, and 198 smokers. Sixty nine precipitin positive subjects were either never smokers or ex-smokers; only six were smokers. The negative relationship between cigarette smoking and precipitins was highly significant (p = 0.004). Factors positively associated with positive precipitin reactions were: size of farm, time spent in the barn, and the presence of a family member previously diagnosed as having farmer's lung disease. Interestingly, positive precipitin reactions were not associated with any of the following: use of silos, hay conditioners, or hay dryers; the presence or quantity of mouldy hay; or the presence of respiratory symptoms. It is concluded that precipitin analysis is not useful as a screening method for farmer's lung, though it can be of diagnostic value in acute farmer's lung disease.
PMCID: PMC460004  PMID: 4038823
4.  Prevalence of Farmer's Lung in Scotland: A Pilot Survey 
British Medical Journal  1972;1(5799):530-534.
In a survey of the farming population of Orkney, Ayrshire, and East Lothian the prevalence of farmer's lung was estimated at 86 per 1,000 in both Orkney and Ayrshire and 23 per 1,000 in East Lothian. If cases with a negative farmer's lung hay (F.L.H.) precipitin test are excluded these figures are reduced to 43, 36, and nil respectively, but those for Orkney and Ayrshire are still about 20 times higher than any figure previously reported for the prevalence of farmer's lung in Britain.
Regional variations in prevalence are probably related both to climatic conditions and to differences in agricultural methods, the latter often being dictated by economic circumstances. Nevertheless the prevalence of farmer's lung could be reduced considerably by the energetic application of preventive measures, backed by financial incentives. The most important of these are efficient drying of hay and cereals before storage, more extensive use of silage, better ventilation of farm buildings, and the introduction of mechanical feeding systems. Individual farmworkers could be taught how to recognize the early symptoms of the disease and encouraged to wear respirators when handling mouldy fodder.
PMCID: PMC1787415  PMID: 4501939
5.  Farmer's lung in Devon. 
Thorax  1975;30(2):197-203.
Farmer's lung is a cause of disability to agricultural workers in Devon and there is no evidence that the incidence is falling. A survey of known cases was made to assess the degree of disability in relation to the clinical history, the presence of farmer's lung precipitins, tests of lung function, and radiographic changes. Information was obtained about 200 patients diagnosed between 1939 and 1971. A survey of 148 of these patients showed that the disease was most commonly diagnosed in men aged 40 to 50 years and the most important symptom at diagnosis was dyspnoea related to occupational exposure to hay or grain. The onset was often insidious and only 67 patients (45%) were diagnosed during the first year of the disorder. Disability was severe in about one-third of the cases. The degree of disability did not seem to be related to the serological changes recorded either at diagnosis or at the time of our survey. Disability was commonly associated with restriction and reduced gas transfer factor and with airways obstruction in more severe cases. Many individuals reporting significant disability had only slightly abnormal ventilatory function tests at rest. Radiographic changes were found at survey in about one-third of the subjects reporting disability. Many farmers had not used an efficient mask. Treatment is unsatisfactory but steroid therapy is effective in acute episodes.
PMCID: PMC470267  PMID: 1179317
6.  Chest symptoms and farmer's lung: a community survey 
Morgan, D. C., Smyth, J. T., Lister, R. W., and Pethybridge, R. J. (1973).British Journal of Industrial Medicine,30, 259-265. Chest symptoms and farmer's lung: a community survey. Farmer's lung is one of the commonest causes of extrinsic allergic alveolitis, but there have been few studies of representative samples of farmers. A survey was carried out in Devon among 91 farmers and their families in order to estimate the prevalence of respiratory symptoms and of positive precipitin reactions to thermophilic fungi. Answers to a questionnaire about respiratory symptoms and smoking habits revealed among the men a prevalence of symptoms comparable with that found in other surveys of agricultural populations in the United Kingdom but with a lower proportion of smokers. A positive answer to a question about attacks of breathlessness associated with fever or shivering appeared to differentiate people suffering from farmer's lung. Twenty-three per cent of the population had precipitins to Micropolyspora faeni and two of these individuals also had precipitins to other fungi. There were statistically significant differences in the proportions of positive precipitin tests found in smokers, ex-smokers, and non-smokers. Six known cases of farmer's lung were included in the sample and all had positive precipitins.
PMCID: PMC1009521  PMID: 4723788
7.  Chest symptoms in farming communities with special reference to farmer's lung. 
Surveys were carried out on random samples of the farming population in Devon and Wales in order to estimate the prevalence of respiratory symptoms and of positive precipitin reactions to thermophilic fungi. Bronchitis, as defined, was common among the Welsh hill farmers, and the proportion of positive serological tests was higher in both the areas surveyed in Wales as compared with Devon. All three surveys confirmed a previous finding that the proportion of positive precipitin tests was higher among non-smokers than smokers. Although the numbers were small there was some indication that measurement of peak expiratory flow showed different relationships with age in non-smokers according to the presence or absence of positive precipitin tests. The difficulty of determining prevalence rates for farmer's lung is discussed, but the results suggest a rate not dissimilar to those found in two areas of Scotland which were more than 20 times higher than any figure previously reported in Britain.
PMCID: PMC1008064  PMID: 1156571
8.  Lung function and bronchial reactivity in farmers. 
Thorax  1989;44(8):645-649.
The purpose of this study was to evaluate the prevalence and type of lung function disorders in Danish farmers. Three samples of farmers were drawn from a group of unselected farmers who had participated in an epidemiological study. Group I (47 persons) was a sample of the 8% of all farmers who had reported that they had asthma; group II (63 persons) was a sample of the 28% of farmers who had had wheezing, shortness of breath, or cough without phlegm; and group III (34 persons) a sample of the farmers (64% of the total) who had no asthma and no respiratory symptoms. The farmers with symptoms (groups I and II) had low mean levels of FEV1 and high values for residual volume, whereas the symptomless farmers had normal lung function and no airways obstruction. The proportion of farmers with an FEV1 below the 95% confidence limit for predicted values was 43% in group I and 23% in group II; there were none in group III. Bronchial hyperreactivity to histamine occurred in 96% of asthmatic farmers, 67% of farmers with wheezing or shortness of breath, and 59% of symptomless farmers. A low level of FEV1 was associated with the number of years in pig farming and bronchial hyperreactivity in group II but not group I or III. Most of the bronchial hyperreactivity was explained in the multiple regression analysis by a low FEV1, though this was significant only for farmers in group II. Thus farmers who reported asthma, wheezing, shortness of breath, or a dry cough in general had airways obstruction with an increased residual volume, whereas symptomless farmers had normal lung function. Severe bronchial hyperreactivity was mostly explained by a diagnosis of asthma and poor lung function, though some farmers with normal lung function and no respiratory symptoms had increased bronchial reactivity.
PMCID: PMC461996  PMID: 2799744
9.  The fluctuant nature of precipitating antibodies in dairy farmers. 
Thorax  1989;44(6):469-473.
Four hundred and forty five of 888 dairy farmers studied in an epidemiological survey four years previously were restudied to determine change in precipitins and in clinical features. Subjects answered the same questionnaire, which was filled in by the same nurse in the same winter months, and had blood withdrawn for precipitin analysis (double diffusion technique). Of the 445 subjects retested, 48 (10.8%) had been precipitin positive at the first study; of these, 34 remained positive four years later and 14 had reverted to negative. Twenty eight subjects previously negative for precipitins had become positive, so that 62 subjects in all were precipitin positive when restudied (13.9%). Of the 445 farmers, 369 were precipitin negative at both studies. The prevalence of symptoms, including cough, sputum production, wheezing, dyspnoea, and fever and chills, was similar for subjects who were consistently negative for precipitins and consistently positive and for those who changed from one to the other. Only one subject developed farmer's lung; he had precipitins in both studies. This study shows a fluctuation in the precipitin state of dairy farmers, suggesting that more farmers have precipitins at least once in their lifetime than are identified by screening at a single point in time. Relatively few develop farmer's lung or other respiratory symptoms. The presence of precipitins in a symptomless farmer appears to have no clinical importance.
PMCID: PMC1020806  PMID: 2763256
10.  Budgerigar-fancier's lung: the commonest variety of allergic alveolitis in Britain. 
British Medical Journal  1978;2(6130):81-84.
A questionnaire survey of 1005 consecutive attenders at four outpatient clinics yielded 117 (12%) budgerigar fanciers (exposed to budgerigars- known in North America as parakeets-for at least three months) and 296 (29%) former fanciers. Twnety had precipitins to budgerigar serum or droppings or both, and 10 of these together with 39 precipitin-negative patients reported undue breathlessness on exertion during exposure to buderigars. These 59 patients were investigated further, seven completing a series of inhalation provocation tests with budgerigar antigens designed to confirm or exclude budgerigar-fancier's lung (BrFL). Typical positive responses were obtained from four current and one former fancier. The prevalence of confirmed BrFL among the 11n current budgerigar fanciers was 3.4% (four cases). This was biased, however, by the inclusion of one patient whose attendance at the surveyed clinic was attributable to the disease. With the exclusion of this patient, confidence limits suggested that the true prevalence of BrFL among current budgerigar fanciers in the general population lies between 0.5% and 7.5%, which is similar to the prevalence of farmer's lung in farm workers. In view of the enormous population at risk, however, this implies that BrFL rather than farmer's lung is by far the commonest type of allergic alveolitis in Britain.
PMCID: PMC1605890  PMID: 566603
11.  The use of antibiotics on small dairy farms in rural Peru 
Preventive veterinary medicine  2013;113(1):88-95.
Very little is known about the use of antibiotics on small dairy farms in lower/middle-income countries. The use of these drugs can have profound impacts on animal health, farmer income and public health. A survey of 156 farmers was conducted in Cajamarca, a major dairy-producing center in the highlands of Peru characterized by small farms (<15 cows) to assess patterns and determinants of antibiotic use and farmers’ knowledge of antibiotics. The reported incidence of disease on these farms was relatively low (0.571 episodes of disease per cow-year), but more than 83% of the reported episodes were treated with antibiotics. The most commonly used antibiotics were oxytetracycline, penicillin and trimethoprim-sulfamethoxazole drugs; antiparasitic drugs were also used to treat what were likely bacterial infections. An increased incidence of treated disease was significantly associated with smaller farm size, lower farmer income, the previous use of the Californian Mastitis test on the farm and antibiotic knowledge. Farmers’ knowledge of antibiotics was assessed with a series of questions on antibiotics, resulting in a “knowledge score”. Increased knowledge was significantly associated with the use of antibiotics for preventative reasons, the purchase of antibiotics from feed-stores, the experience of complications in animals after having administered antibiotics, the number of workers on the farm and the educational level of the farmer. Overall, antibiotics appeared to be used infrequently, most likely because therapeutic interventions were sought only when the animal had reached an advanced stage of clinical disease. Few farmers were able to define an antibiotic, but many farmers understood that the use of antibiotics carried inherent risks to their animals and potentially to the consumers of dairy products from treated animals. The results of this study are useful for understanding the patterns of antibiotic use and associated management, demographic and knowledge factors of farmers on small dairy farms in rural Peru.
doi:10.1016/j.prevetmed.2013.10.012
PMCID: PMC4197910  PMID: 24188819
Antibiotic use; Dairy Farms; Lower-Middle Income Countries
12.  Farmer's lung 
Thorax  1968;23(5):451-468.
In assessing patients suffering from farmer's lung, the acute stage must be distinguished from the chronic stage of the disease. The conspicuous radiographic signs in the acute farmer's lung episode and the often dramatic clearing make an important contribution to the diagnosis. The radiographic changes in chronic farmer's lung are not specific and cover a wide range of appearances. Even minor nodular changes are significant. Farmer's lung, acute and chronic, is not a disease predominantly characterized by a defect in gas exchange. During the acute illness the reduction in diffusing capacity is often accompanied by a decrease in lung volumes; the pulmonary function profile of the chronic stage is variable. In only a relatively small proportion of chronic farmer's lung patients does a defect in gas exchange predominate, and in some it may be manifest only during exercise. Airway obstruction is a feature of chronic farmer's lung. In chronic farmer's lung patients discrepancies between the severity of complaints and results of pulmonary function tests are not infrequent. In some patients with considerable disability conventional pulmonary function studies may demonstrate little or no impairment of the functions measured. In patients suffering from an acute farmer's lung episode, serological tests should be positive, possibly in high titre. In the chronic stage of the disease the chance of finding positive serology in a patient diminishes with the length of time elapsed since the last acute episode. The period of serological transition appears to be the third year.
Images
PMCID: PMC471821  PMID: 4971361
13.  Suicide in the farming community: methods used and contact with health services 
Farmers have a high rate of suicide (1% of suicides in England and Wales). This study sought to test whether farmers would be less likely to have been in contact with primary or mental health services before death due to their reluctance to seek help. The study also sought to identify other characteristics that differentiated suicide among male farmers from other professional groups. A retrospective case-control design was used comparing male farmers with an age and sex matched control group. Cases were all members of the farming community within the Exeter Health District on whom suicide or open verdict had been recorded between 1979 and 1994. 63 Cases were identified and entered into the study. Controls were non-farmers with the same verdict who were matched for age (5 year age bands) sex and social class. Farmers were significantly more likely to use firearms to kill themselves (42% of farmers v 11% controls). They were less likely to use a car exhaust or to die by poisoning (9% farmers v 50% controls). Farmers were significantly less likely to leave a suicide note (21% farmers v 41% controls). There was no significant difference between farmers and controls for numbers in contact with their general practitioner or mental health services in the 3 months before death. There may be some differences in help seeking behaviour between farmers and the general population as over 30% of farmers presented with exclusively physical symptoms. General practitioners should consider depressive and suicidal intention in farmers presenting with physical problems. When depression is diagnosed consideration should be given to the temporary removal of firearms as the high rate of suicide in the farming community may be strongly influenced by access to means.


Keywords: farmers; suicide
doi:10.1136/oem.57.9.642
PMCID: PMC1740021  PMID: 10935946
14.  Estimated rate of agricultural injury: the Korean Farmers’ Occupational Disease and Injury Survey 
Objectives
This study estimated the rate of agricultural injury using a nationwide survey and identified factors associated with these injuries.
Methods
The first Korean Farmers’ Occupational Disease and Injury Survey (KFODIS) was conducted by the Rural Development Administration in 2009. Data from 9,630 adults were collected through a household survey about agricultural injuries suffered in 2008. We estimated the injury rates among those whose injury required an absence of more than 4 days. Logistic regression was performed to identify the relationship between the prevalence of agricultural injuries and the general characteristics of the study population.
Results
We estimated that 3.2% (±0.00) of Korean farmers suffered agricultural injuries that required an absence of more than 4 days. The injury rates among orchard farmers (5.4 ± 0.00) were higher those of all non-orchard farmers. The odds ratio (OR) for agricultural injuries was significantly lower in females (OR: 0.45, 95% CI = 0.45–0.45) compared to males. However, the odds of injury among farmers aged 50–59 (OR: 1.53, 95% CI = 1.46–1.60), 60–69 (OR: 1.45, 95% CI = 1.39–1.51), and ≥70 (OR: 1.94, 95% CI = 1.86–2.02) were significantly higher compared to those younger than 50. In addition, the total number of years farmed, average number of months per year of farming, and average hours per day of farming were significantly associated with agricultural injuries.
Conclusions
Agricultural injury rates in this study were higher than rates reported by the existing compensation insurance data. Males and older farmers were at a greater risk of agriculture injuries; therefore, the prevention and management of agricultural injuries in this population is required.
doi:10.1186/2052-4374-26-8
PMCID: PMC4012551  PMID: 24808945
Agriculture; Farmer; Occupational injury; Disease; Accident; Statistics; Injury rate
15.  Prevalence and individual risk factors associated with clinical lumbar instability in rice farmers with low back pain 
Introduction
Clinical lumbar instability (CLI) is one of the subgroups of chronic non-specific low back pain. Thai rice farmers often have poor sustained postures during a rice planting process and start their farming at an early age. However, individual associated factors of CLI are not known and have rarely been diagnosed in low back pain. This study aimed to determine the prevalence and individual associated factors of CLI in Thai rice farmers.
Methods
A cross-sectional survey was conducted among 323 Thai rice farmers in a rural area of Khon Kaen province, Thailand. Face-to-face interviews were conducted using the 13-item Delphi criteria questionnaire, after which an objective examination was performed using aberrant movement sign, painful catch sign, and prone instability test to obtain information. Individual factors such as sex, body mass index, waist-hip ratio, smoking, and number of years of farming experience, were recorded during the face-to-face interview.
Results
The prevalence of CLI in Thai rice farmers calculated by the method described in this study was 13% (age 44±10 years). Number of years of farming experience was found to be significantly correlated with the prevalence of CLI (adjusted odds ratio =2.02, 95% confidence interval =1.03–3.98, P<0.05).
Conclusion
This study provides prevalence of CLI in Thai rice farmers. Those with long-term farming experience of at least 30 years have a greater risk of CLI.
doi:10.2147/PPA.S73412
PMCID: PMC4274132  PMID: 25565778
Delphi study; aberrant movement sign; painful catch sign; prone instability test
16.  Evaluation of farmers’ diagnostic performance for detection of diarrhoea in nursery pigs using digital pictures of faecal pools 
Background
Overconsumption of antibiotics in the pig industry is of concern in relation to antimicrobial resistance. False positive disease diagnosis may result in the treatment of healthy animals. In Denmark, diarrhoea is the most common cause of antibiotic treatment in pigs. Farm personnel are not professional clinicians, which could result in inappropriate antibiotic treatments of diarrhoea.
The primary objectives of this pilot study using digital pictures of faecal pools was to evaluate farmers’ diagnostic performance in the assessment of faecal consistency in nursery pigs and to investigate the effect of different co-variables, including practical experience. A secondary objective was to compare the diagnostic performance of farmers with that of veterinarians.
At a pig congress, observers (farm personnel and veterinarians) working professionally with pigs participated in a faecal consistency test consisting of 16 pictures of faecal pools (eight diarrhoeic and eight non-diarrhoeic). The faecal pools had previously been collected and subjected to faecal dry matter determination. The true status of the faecal pools was determined by the faecal dry matter content (diarrhoea: faecal dry matter ≤ 18%). The true status was used to evaluate the farmers’ and veterinarians’ diagnostic performance.
Results
A total of 119 farmers and 18 veterinarians were included in the statistical analysis. For the farmers, the mean proportion of faecal pools assessed as diarrhoeic was 0.48, the mean proportion of correctly classified faecal pools was 0.84, the mean diagnostic sensitivity was 0.83 and the mean diagnostic specificity was 0.86. Farmers with less than four years of practical experience detected clinical diarrhoea more accurately than farmers with more than four years of practical experience (p < 0.05). No significantly differences between farmers and veterinarians was observed (p > 0.20).
Conclusions
The results, using digital pictures of faecal pools, suggest that farmers and veterinarians have similar diagnostic performance in relation to diarrhoea. False positive classification of non-diarrhoeic pigs appears to be a larger problem than false negative classification of diarrhoeic pigs under Danish conditions. If these results can be confirmed under practical conditions, training in, and validation of, clinical diagnoses may be an important factor in reducing antibiotic consumption in the pig industry.
doi:10.1186/1751-0147-55-72
PMCID: PMC3819656  PMID: 24138810
Clinical signs; Diagnostic performance; Farmers; Faecal consistency; Diarrhoea; Pigs
17.  Improved diagnosis of farmer's lung using the fluorescent antibody technique 
Thorax  1974;29(4):417-420.
Boyd, G. and Parratt, D. (1974).Thorax, 29, 417-420. Improved diagnosis of farmer's lung using the fluorescent antibody technique. In the west of Scotland 20 of 40 farmers surveyed had symptoms of farmer's lung. Ten of this group (50%) gave positive precipitin reactions to Micropolyspora faeni. The fluorescent antibody test was positive in all those with symptoms and also in one who had no clinical evidence of farmer's lung. There was a close relationship between evidence of sensitization to M. faeni in the serum, demonstrated by the fluorescent antibody test, and the presence of symptoms compatible with farmer's lung. This test may detect the disease in milder form than is possible by conventional precipitin tests and this study confirms the value of this more sensitive technique as a screening procedure.
PMCID: PMC470173  PMID: 4277527
18.  Respiratory disorders are not more common in farmers. Results from a study on Icelandic animal farmers 
Respiratory medicine  2008;102(12):1839-1843.
Rationale
Respiratory disorders are more common among farmers than in other populations, despite less atopy and a lower prevalence of smoking; this is likely due to environmental exposure to organic dust and irritants. The current prevalence of respiratory disorders and atopy in Icelandic farmers is unknown, but a significantly greater rate of respiratory symptoms than the general population has been reported in the past. Modern farming practices, which effectively decrease the generation of respirable dust, have been implemented in Iceland in the past decade.
Objective
The aim of this study was to estimate the prevalence of respiratory disorders in a nationwide study of Icelandic farmers, and to identify any environmental or occupational associations with these disorders.
Methods
We conducted a questionnaire-based study of all Icelandic farmers with an age-matched comparison group randomly selected from the national citizen registry of Iceland. The questionnaire included items regarding respiratory symptoms and working environment.
Results
Out of 2042 farmers invited to participate, 1108 responded (54%), as did 689 of 1500 controls (46%). Farmers were slightly older and more likely to be male (77% vs. 47%). Smoking rates were significantly lower among farmers than among controls. The prevalence of asthma was not significantly different between the two groups, with a lifetime prevalence of 9.4% (n=104) among farmers compared to 10.2% (n=70) among controls. Medication use for asthma did not significantly differ between the farmer (6.5%) and control (4.8%) groups. The prevalence of self-reported, physician-diagnosed chronic bronchitis and emphysema likewise did not significantly differ between the groups, but self-reported “hay fever” was significantly more prevalent among farmers.
Conclusion
Concomitant with changes in farming practices the prevalence of respiratory disorders among Icelandic farmers has decreased. This suggests that modernization of the agricultural environment has a positive effect on workers health.
doi:10.1016/j.rmed.2008.07.006
PMCID: PMC3573701  PMID: 18715772
agriculture; respiratory disorders; farming
19.  Clinical Utility of Serologic Testing for Celiac Disease in Ontario 
Executive Summary
Objective of Analysis
The objective of this evidence-based evaluation is to assess the accuracy of serologic tests in the diagnosis of celiac disease in subjects with symptoms consistent with this disease. Furthermore the impact of these tests in the diagnostic pathway of the disease and decision making was also evaluated.
Celiac Disease
Celiac disease is an autoimmune disease that develops in genetically predisposed individuals. The immunological response is triggered by ingestion of gluten, a protein that is present in wheat, rye, and barley. The treatment consists of strict lifelong adherence to a gluten-free diet (GFD).
Patients with celiac disease may present with a myriad of symptoms such as diarrhea, abdominal pain, weight loss, iron deficiency anemia, dermatitis herpetiformis, among others.
Serologic Testing in the Diagnosis Celiac Disease
There are a number of serologic tests used in the diagnosis of celiac disease.
Anti-gliadin antibody (AGA)
Anti-endomysial antibody (EMA)
Anti-tissue transglutaminase antibody (tTG)
Anti-deamidated gliadin peptides antibodies (DGP)
Serologic tests are automated with the exception of the EMA test, which is more time-consuming and operator-dependent than the other tests. For each serologic test, both immunoglobulin A (IgA) or G (IgG) can be measured, however, IgA measurement is the standard antibody measured in celiac disease.
Diagnosis of Celiac Disease
According to celiac disease guidelines, the diagnosis of celiac disease is established by small bowel biopsy. Serologic tests are used to initially detect and to support the diagnosis of celiac disease. A small bowel biopsy is indicated in individuals with a positive serologic test. In some cases an endoscopy and small bowel biopsy may be required even with a negative serologic test. The diagnosis of celiac disease must be performed on a gluten-containing diet since the small intestine abnormalities and the serologic antibody levels may resolve or improve on a GFD.
Since IgA measurement is the standard for the serologic celiac disease tests, false negatives may occur in IgA-deficient individuals.
Incidence and Prevalence of Celiac Disease
The incidence and prevalence of celiac disease in the general population and in subjects with symptoms consistent with or at higher risk of celiac disease based on systematic reviews published in 2004 and 2009 are summarized below.
Incidence of Celiac Disease in the General Population
Adults or mixed population: 1 to 17/100,000/year
Children: 2 to 51/100,000/year
In one of the studies, a stratified analysis showed that there was a higher incidence of celiac disease in younger children compared to older children, i.e., 51 cases/100,000/year in 0 to 2 year-olds, 33/100,000/year in 2 to 5 year-olds, and 10/100,000/year in children 5 to 15 years old.
Prevalence of Celiac Disease in the General Population
The prevalence of celiac disease reported in population-based studies identified in the 2004 systematic review varied between 0.14% and 1.87% (median: 0.47%, interquartile range: 0.25%, 0.71%). According to the authors of the review, the prevalence did not vary by age group, i.e., adults and children.
Prevalence of Celiac Disease in High Risk Subjects
Type 1 diabetes (adults and children): 1 to 11%
Autoimmune thyroid disease: 2.9 to 3.3%
First degree relatives of patients with celiac disease: 2 to 20%
Prevalence of Celiac Disease in Subjects with Symptoms Consistent with the Disease
The prevalence of celiac disease in subjects with symptoms consistent with the disease varied widely among studies, i.e., 1.5% to 50% in adult studies, and 1.1% to 17% in pediatric studies. Differences in prevalence may be related to the referral pattern as the authors of a systematic review noted that the prevalence tended to be higher in studies whose population originated from tertiary referral centres compared to general practice.
Research Questions
What is the sensitivity and specificity of serologic tests in the diagnosis celiac disease?
What is the clinical validity of serologic tests in the diagnosis of celiac disease? The clinical validity was defined as the ability of the test to change diagnosis.
What is the clinical utility of serologic tests in the diagnosis of celiac disease? The clinical utility was defined as the impact of the test on decision making.
What is the budget impact of serologic tests in the diagnosis of celiac disease?
What is the cost-effectiveness of serologic tests in the diagnosis of celiac disease?
Methods
Literature Search
A literature search was performed on November 13th, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1st 2003 and November 13th 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Studies that evaluated diagnostic accuracy, i.e., both sensitivity and specificity of serology tests in the diagnosis of celiac disease.
Study population consisted of untreated patients with symptoms consistent with celiac disease.
Studies in which both serologic celiac disease tests and small bowel biopsy (gold standard) were used in all subjects.
Systematic reviews, meta-analyses, randomized controlled trials, prospective observational studies, and retrospective cohort studies.
At least 20 subjects included in the celiac disease group.
English language.
Human studies.
Studies published from 2000 on.
Clearly defined cut-off value for the serology test. If more than one test was evaluated, only those tests for which a cut-off was provided were included.
Description of small bowel biopsy procedure clearly outlined (location, number of biopsies per patient), unless if specified that celiac disease diagnosis guidelines were followed.
Patients in the treatment group had untreated CD.
Studies on screening of the general asymptomatic population.
Studies that evaluated rapid diagnostic kits for use either at home or in physician’s offices.
Studies that evaluated diagnostic modalities other than serologic tests such as capsule endoscopy, push enteroscopy, or genetic testing.
Cut-off for serologic tests defined based on controls included in the study.
Study population defined based on positive serology or subjects pre-screened by serology tests.
Celiac disease status known before study enrolment.
Sensitivity or specificity estimates based on repeated testing for the same subject.
Non-peer-reviewed literature such as editorials and letters to the editor.
Population
The population consisted of adults and children with untreated, undiagnosed celiac disease with symptoms consistent with the disease.
Serologic Celiac Disease Tests Evaluated
Anti-gliadin antibody (AGA)
Anti-endomysial antibody (EMA)
Anti-tissue transglutaminase antibody (tTG)
Anti-deamidated gliadin peptides antibody (DGP)
Combinations of some of the serologic tests listed above were evaluated in some studies
Both IgA and IgG antibodies were evaluated for the serologic tests listed above.
Outcomes of Interest
Sensitivity
Specificity
Positive and negative likelihood ratios
Diagnostic odds ratio (OR)
Area under the sROC curve (AUC)
Small bowel biopsy was used as the gold standard in order to estimate the sensitivity and specificity of each serologic test.
Statistical Analysis
Pooled estimates of sensitivity, specificity and diagnostic odds ratios (DORs) for the different serologic tests were calculated using a bivariate, binomial generalized linear mixed model. Statistical significance for differences in sensitivity and specificity between serologic tests was defined by P values less than 0.05, where “false discovery rate” adjustments were made for multiple hypothesis testing. The bivariate regression analyses were performed using SAS version 9.2 (SAS Institute Inc.; Cary, NC, USA). Using the bivariate model parameters, summary receiver operating characteristic (sROC) curves were produced using Review Manager 5.0.22 (The Nordiac Cochrane Centre, The Cochrane Collaboration, 2008). The area under the sROC curve (AUC) was estimated by bivariate mixed-efects binary regression modeling framework. Model specification, estimation and prediction are carried out with xtmelogit in Stata release 10 (Statacorp, 2007). Statistical tests for the differences in AUC estimates could not be carried out.
The study results were stratified according to patient or disease characteristics such as age, severity of Marsh grade abnormalities, among others, if reported in the studies. The literature indicates that the diagnostic accuracy of serologic tests for celiac disease may be affected in patients with chronic liver disease, therefore, the studies identified through the systematic literature review that evaluated the diagnostic accuracy of serologic tests for celiac disease in patients with chronic liver disease were summarized. The effect of the GFD in patiens diagnosed with celiac disease was also summarized if reported in the studies eligible for the analysis.
Summary of Findings
Published Systematic Reviews
Five systematic reviews of studies that evaluated the diagnostic accuracy of serologic celiac disease tests were identified through our literature search. Seventeen individual studies identified in adults and children were eligible for this evaluation.
In general, the studies included evaluated the sensitivity and specificity of at least one serologic test in subjects with symptoms consistent with celiac disease. The gold standard used to confirm the celiac disease diagnosis was small bowel biopsy. Serologic tests evaluated included tTG, EMA, AGA, and DGP, using either IgA or IgG antibodies. Indirect immunoflurorescence was used for the EMA serologic tests whereas enzyme-linked immunosorbent assay (ELISA) was used for the other serologic tests.
Common symptoms described in the studies were chronic diarrhea, abdominal pain, bloating, unexplained weight loss, unexplained anemia, and dermatitis herpetiformis.
The main conclusions of the published systematic reviews are summarized below.
IgA tTG and/or IgA EMA have a high accuracy (pooled sensitivity: 90% to 98%, pooled specificity: 95% to 99% depending on the pooled analysis).
Most reviews found that AGA (IgA or IgG) are not as accurate as IgA tTG and/or EMA tests.
A 2009 systematic review concluded that DGP (IgA or IgG) seems to have a similar accuracy compared to tTG, however, since only 2 studies identified evaluated its accuracy, the authors believe that additional data is required to draw firm conclusions.
Two systematic reviews also concluded that combining two serologic celiac disease tests has little contribution to the accuracy of the diagnosis.
MAS Analysis
Sensitivity
The pooled analysis performed by MAS showed that IgA tTG has a sensitivity of 92.1% [95% confidence interval (CI) 88.0, 96.3], compared to 89.2% (83.3, 95.1, p=0.12) for IgA DGP, 85.1% (79.5, 94.4, p=0.07) for IgA EMA, and 74.9% (63.6, 86.2, p=0.0003) for IgA AGA. Among the IgG-based tests, the results suggest that IgG DGP has a sensitivity of 88.4% (95% CI: 82.1, 94.6), 44.7% (30.3, 59.2) for tTG, and 69.1% (56.0, 82.2) for AGA. The difference was significant when IgG DGP was compared to IgG tTG but not IgG AGA. Combining serologic celiac disease tests yielded a slightly higher sensitivity compared to individual IgA-based serologic tests.
IgA deficiency
The prevalence of total or severe IgA deficiency was low in the studies identified varying between 0 and 1.7% as reported in 3 studies in which IgA deficiency was not used as a referral indication for celiac disease serologic testing. The results of IgG-based serologic tests were positive in all patients with IgA deficiency in which celiac disease was confirmed by small bowel biopsy as reported in four studies.
Specificity
The MAS pooled analysis indicates a high specificity across the different serologic tests including the combination strategy, pooled estimates ranged from 90.1% to 98.7% depending on the test.
Likelihood Ratios
According to the likelihood ratio estimates, both IgA tTG and serologic test combinationa were considered very useful tests (positive likelihood ratio above ten and the negative likelihood ratio below 0.1).
Moderately useful tests included IgA EMA, IgA DGP, and IgG DGP (positive likelihood ratio between five and ten and the negative likelihood ratio between 0.1 and 0.2).
Somewhat useful tests: IgA AGA, IgG AGA, generating small but sometimes important changes from pre- to post-test probability (positive LR between 2 and 5 and negative LR between 0.2 and 0.5)
Not Useful: IgG tTG, altering pre- to post-test probability to a small and rarely important degree (positive LR between 1 and 2 and negative LR between 0.5 and 1).
Diagnostic Odds Ratios (DOR)
Among the individual serologic tests, IgA tTG had the highest DOR, 136.5 (95% CI: 51.9, 221.2). The statistical significance of the difference in DORs among tests was not calculated, however, considering the wide confidence intervals obtained, the differences may not be statistically significant.
Area Under the sROC Curve (AUC)
The sROC AUCs obtained ranged between 0.93 and 0.99 for most IgA-based tests with the exception of IgA AGA, with an AUC of 0.89.
Sensitivity and Specificity of Serologic Tests According to Age Groups
Serologic test accuracy did not seem to vary according to age (adults or children).
Sensitivity and Specificity of Serologic Tests According to Marsh Criteria
Four studies observed a trend towards a higher sensitivity of serologic celiac disease tests when Marsh 3c grade abnormalities were found in the small bowel biopsy compared to Marsh 3a or 3b (statistical significance not reported). The sensitivity of serologic tests was much lower when Marsh 1 grade abnormalities were found in small bowel biopsy compared to Marsh 3 grade abnormalities. The statistical significance of these findings were not reported in the studies.
Diagnostic Accuracy of Serologic Celiac Disease Tests in Subjects with Chronic Liver Disease
A total of 14 observational studies that evaluated the specificity of serologic celiac disease tests in subjects with chronic liver disease were identified. All studies evaluated the frequency of false positive results (1-specificity) of IgA tTG, however, IgA tTG test kits using different substrates were used, i.e., human recombinant, human, and guinea-pig substrates. The gold standard, small bowel biopsy, was used to confirm the result of the serologic tests in only 5 studies. The studies do not seem to have been designed or powered to compare the diagnostic accuracy among different serologic celiac disease tests.
The results of the studies identified in the systematic literature review suggest that there is a trend towards a lower frequency of false positive results if the IgA tTG test using human recombinant substrate is used compared to the guinea pig substrate in subjects with chronic liver disease. However, the statistical significance of the difference was not reported in the studies. When IgA tTG with human recombinant substrate was used, the number of false positives seems to be similar to what was estimated in the MAS pooled analysis for IgA-based serologic tests in a general population of patients. These results should be interpreted with caution since most studies did not use the gold standard, small bowel biopsy, to confirm or exclude the diagnosis of celiac disease, and since the studies were not designed to compare the diagnostic accuracy among different serologic tests. The sensitivity of the different serologic tests in patients with chronic liver disease was not evaluated in the studies identified.
Effects of a Gluten-Free Diet (GFD) in Patients Diagnosed with Celiac Disease
Six studies identified evaluated the effects of GFD on clinical, histological, or serologic improvement in patients diagnosed with celiac disease. Improvement was observed in 51% to 95% of the patients included in the studies.
Grading of Evidence
Overall, the quality of the evidence ranged from moderate to very low depending on the serologic celiac disease test. Reasons to downgrade the quality of the evidence included the use of a surrogate endpoint (diagnostic accuracy) since none of the studies evaluated clinical outcomes, inconsistencies among study results, imprecise estimates, and sparse data. The quality of the evidence was considered moderate for IgA tTg and IgA EMA, low for IgA DGP, and serologic test combinations, and very low for IgA AGA.
Clinical Validity and Clinical Utility of Serologic Testing in the Diagnosis of Celiac Disease
The clinical validity of serologic tests in the diagnosis of celiac disease was considered high in subjects with symptoms consistent with this disease due to
High accuracy of some serologic tests.
Serologic tests detect possible celiac disease cases and avoid unnecessary small bowel biopsy if the test result is negative, unless an endoscopy/ small bowel biopsy is necessary due to the clinical presentation.
Serologic tests support the results of small bowel biopsy.
The clinical utility of serologic tests for the diagnosis of celiac disease, as defined by its impact in decision making was also considered high in subjects with symptoms consistent with this disease given the considerations listed above and since celiac disease diagnosis leads to treatment with a gluten-free diet.
Economic Analysis
A decision analysis was constructed to compare costs and outcomes between the tests based on the sensitivity, specificity and prevalence summary estimates from the MAS Evidence-Based Analysis (EBA). A budget impact was then calculated by multiplying the expected costs and volumes in Ontario. The outcome of the analysis was expected costs and false negatives (FN). Costs were reported in 2010 CAD$. All analyses were performed using TreeAge Pro Suite 2009.
Four strategies made up the efficiency frontier; IgG tTG, IgA tTG, EMA and small bowel biopsy. All other strategies were dominated. IgG tTG was the least costly and least effective strategy ($178.95, FN avoided=0). Small bowel biopsy was the most costly and most effective strategy ($396.60, FN avoided =0.1553). The cost per FN avoided were $293, $369, $1,401 for EMA, IgATTG and small bowel biopsy respectively. One-way sensitivity analyses did not change the ranking of strategies.
All testing strategies with small bowel biopsy are cheaper than biopsy alone however they also result in more FNs. The most cost-effective strategy will depend on the decision makers’ willingness to pay. Findings suggest that IgA tTG was the most cost-effective and feasible strategy based on its Incremental Cost-Effectiveness Ratio (ICER) and convenience to conduct the test. The potential impact of IgA tTG test in the province of Ontario would be $10.4M, $11.0M and $11.7M respectively in the following three years based on past volumes and trends in the province and basecase expected costs.
The panel of tests is the commonly used strategy in the province of Ontario therefore the impact to the system would be $13.6M, $14.5M and $15.3M respectively in the next three years based on past volumes and trends in the province and basecase expected costs.
Conclusions
The clinical validity and clinical utility of serologic tests for celiac disease was considered high in subjects with symptoms consistent with this disease as they aid in the diagnosis of celiac disease and some tests present a high accuracy.
The study findings suggest that IgA tTG is the most accurate and the most cost-effective test.
AGA test (IgA) has a lower accuracy compared to other IgA-based tests
Serologic test combinations appear to be more costly with little gain in accuracy. In addition there may be problems with generalizability of the results of the studies included in this review if different test combinations are used in clinical practice.
IgA deficiency seems to be uncommon in patients diagnosed with celiac disease.
The generalizability of study results is contingent on performing both the serologic test and small bowel biopsy in subjects on a gluten-containing diet as was the case in the studies identified, since the avoidance of gluten may affect test results.
PMCID: PMC3377499  PMID: 23074399
20.  Relationships between radiographic change, pulmonary function, and bronchoalveolar lavage fluid lymphocytes in farmer's lung disease. 
Thorax  1986;41(1):28-33.
Ninety four dairy farmers were investigated by chest radiography, pulmonary function tests, and bronchoalveolar lavage. They were divided into five groups--1: 11 subjects with acute farmer's lung; 2: 25 subjects with previously diagnosed farmer's lung who had stayed on their farm; 3: 15 farmers with previously diagnosed farmer's lung who had left the farm; 4: 23 precipitin positive symptomless farmers; 5: 20 precipitin negative symptomless farmers. The study evaluated the relationships between radiographic changes measured with a scoring system derived from the International Labour Office (ILO) classification, the results of pulmonary function tests, and bronchoalveolar lavage fluid. Thirty eight subjects had radiographic evidence of interstitial pulmonary infiltrates. Group 1 had the highest percentage of lymphocytes recovered by bronchoalveolar lavage (mean 66.3 (SD 19.2]. For all subjects carbon monoxide transfer factor (TLCO) and total lung capacity were negatively correlated with radiographic changes (r = -0.45 and -0.30; p less than 0.001 and less than 0.01 respectively). TLCO was also negatively correlated with radiographic change in group 2 (r = -0.59, p less than 0.005). The percentage of lavage lymphocytes was correlated with radiographic changes for all subjects (r = 0.36, p less than 0.001), but this correlation was not seen within groups. This study shows good correlation between radiographic abnormalities, pulmonary function changes and the cellular composition of bronchoalveolar lavage fluid.
PMCID: PMC460248  PMID: 3704964
21.  Cancer risk among Danish and Italian farmers. 
Cancer risk for farmers in Denmark and Italy was studied by linking occupational census data with incidence of cancer in Denmark and with cancer mortality in Italy. Farmers in the two countries had a consistent risk reduction for cancer of the lung, bladder, small intestine, colon, rectum, and prostate. No excess of stomach cancer was found among farmers in the two countries, which is in agreement with the most recent data from other surveys. The risk of oesophageal cancer was reduced among the Danish and increased among the Italian male farmers. This can probably be explained by differences in alcohol consumption between the Danish and Italian farmers compared with the general population. The risk of brain cancer was significantly reduced among Italian farmers. There was a significant risk reduction for Hodgkin's disease and no excess for non-Hodgkin's lymphoma in Denmark, whereas in Italy a statistically significant excess risk was found for the first and a slight excess risk for the second of these diseases. The per capita consumption of phenoxy-herbicides between 1950 and 1970 was lower in Italy than in Denmark but treatments were performed mainly by professional applicators in Denmark and by the farmers themselves in Italy. Risk of leukaemia among Italian female farmers was increased. In Denmark, this increase was limited to women who were themselves owners of a farm. Specific occupations in agriculture showing a high risk for cancers of the lymphopoietic system in Denmark mostly entailed contact with animals.
PMCID: PMC1012102  PMID: 1571291
22.  Pesticides and other Agricultural Factors Associated with Self-reported Farmer's Lung among Farm Residents in the Agricultural Health Study 
Background:
Farmer's lung, or hypersensitivity pneumonitis, is an important contributor to respiratory morbidity among farmers.
Methods:
Using the 1993-7 enrollment data from the Agricultural Health Study, we conducted a cross-sectional study of occupational risk factors for farmer's lung among ∼50,000 farmers and farm spouses in Iowa and North Carolina using hierarchical logistic regression controlling for age, state, and smoking status. Participants provided information on agricultural exposures, demographic characteristics, and medical history via self-administered questionnaires. Approximately 2% of farmers (N=481) and 0.2% of spouses (N=51) reported doctor-diagnosed farmer's lung during their lifetime. We assessed farmers and spouses separately due to different information on occupational exposure history. Only pesticide exposures represented lifetime exposure history, all other farm exposures represented current activities at enrollment.
Results:
Among farmers, handling silage (OR=1.41, 95%CI=1.10,1.82), high pesticide exposure events (OR=1.75, 95%CI=1.39,2.21), and ever use of organochlorine (OR=1.34, 95%CI=1.04,1.74) and carbamate pesticides (OR=1.32, 95%CI=1.03,1.68) were associated with farmer's lung in mutually-adjusted models. The insecticides DDT, lindane, and aldicarb were positively associated with farmer's lung among farmers. Current animal exposures, while not statistically significant, were positively associated with farmer's lung, particularly for poultry houses (OR=1.55, 95%CI=0.93, 2.58) and dairy cattle (OR=1.28, 95%CI=0.86,1.89). The occupational data were more limited for spouses; however, we saw similar associations for dairy cattle (OR=1.50, 95%CI=0.72, 3.14) and organochlorine pesticides (OR=1.29, 95%CI=0.64, 2.59).
Conclusion:
While historic farm exposures may contribute to the observed associations with pesticides, these results suggest that organochlorine and carbamate pesticides should be further evaluated as potential risk factors for farmer's lung.
doi:10.1136/oem.2006.028480
PMCID: PMC1945110  PMID: 17182642
hypersensitivity pneumonitis; occupational exposures
23.  Pesticides and other agricultural factors associated with self‐reported farmer's lung among farm residents in the Agricultural Health Study 
Background
Farmer's lung, or hypersensitivity pneumonitis, is an important contributor to respiratory morbidity among farmers.
Methods
Using the 1993–7 enrolment data from the Agricultural Health Study, we conducted a cross‐sectional study of occupational risk factors for farmer's lung among ∼50 000 farmers and farm spouses in Iowa and North Carolina using hierarchical logistic regression controlling for age, state, and smoking status. Participants provided information on agricultural exposures, demographic characteristics, and medical history via self‐administered questionnaires. Approximately 2% of farmers (n = 481) and 0.2% of spouses (n = 51) reported doctor‐diagnosed farmer's lung during their lifetime. We assessed farmers and spouses separately due to different information on occupational exposure history. Only pesticide exposures represented lifetime exposure history, all other farm exposures represented current activities at enrolment.
Results
Among farmers, handling silage (OR = 1.41, 95% CI 1.10 to 1.82), high pesticide exposure events (OR = 1.75, 95% CI 1.39 to 2.21), and ever use of organochlorine (OR = 1.34, 95% CI 1.04 to 1.74) and carbamate pesticides (OR = 1.32, 95% CI 1.03 to 1.68) were associated with farmer's lung in mutually‐adjusted models. The insecticides DDT, lindane, and aldicarb were positively associated with farmer's lung among farmers. Current animal exposures, while not statistically significant, were positively associated with farmer's lung, particularly for poultry houses (OR = 1.55, 95% CI 0.93 to 2.58) and dairy cattle (OR = 1.28, 95% CI 0.86 to 1.89). The occupational data were more limited for spouses; however, we saw similar associations for dairy cattle (OR = 1.50, 95% CI 0.72 to 3.14) and organochlorine pesticides (OR = 1.29, 95% CI 0.64 to 2.59).
Conclusion
While historic farm exposures may contribute to the observed associations with pesticides, these results suggest that organochlorine and carbamate pesticides should be further evaluated as potential risk factors for farmer's lung.
doi:10.1136/oem.2006.028480
PMCID: PMC1945110  PMID: 17182642
24.  Bronchoalveolar lavage in farmers' lung disease: diagnostic and physiological significance. 
A group of 92 farmers had clinical evaluation, pulmonary function tests, and bronchoalveolar lavage (BAL). There were 12 patients with acute farmers' lung disease (FLD) (group 1) and 37 farmers who had had acute FLD, of whom 22 were still on their farm (group 2) and 15 had ceased contact (group 3); others were normal dairy farmers, 23 serology positive to Micropolyspora faeni (group 4), 20 serology negative (group 5), and 42 normal controls (group 6). Of the 134 subjects, 59 had an increase in alveolar lymphocytes (greater than 22% lymphocytes in BAL) (12 in group 1, 19 in group 2, six in group 3, 14 in group 4, five in group 5, and three in group 6). Within each group there was no correlation between BAL lymphocytes (% and absolute number) and most pulmonary function tests. It is concluded that although an increase in BAL lymphocytes is always seen in acute FLD it may also be seen in the absence of clinically evident disease and that BAL lymphocytosis does not correlate with physiological changes in FLD.
PMCID: PMC1007671  PMID: 3426661
25.  Do farming exposures cause or prevent asthma? Results from a study of adult Norwegian farmers 
Thorax  2004;59(5):381-386.
Background: A protective effect of endotoxin exposure on atopy and asthma in farmers' children has been postulated. Studies of adult farmers have shown conflicting results but often lack exposure data. The prevalence of asthma in farmers with different exposure levels to microbial agents and irritant gases was compared.
Methods: Atopy was defined as a positive response to multiple radioallergosorbent tests (RAST) with a panel of 10 common respiratory allergens, and asthma was ascertained by a questionnaire using a stratified sample (n = 2169) of a farming population from south-eastern Norway. Exposure of farmers to total dust, fungal spores, bacteria, endotoxins, and ammonia was assessed by exposure measurements.
Results: The prevalence of asthma was 3.7% for physician diagnosed asthma and 2.7% for current asthma. The prevalence of atopy was 14%, but most asthmatic subjects were non-atopic (80%). Compared with farmers without livestock, (1) asthma was significantly higher in cattle farmers (ORadj 1.8, 95% CI 1.1 to 2.8) and pig farmers (ORadj 1.6, 95% CI 1.0 to 2.5), (2) non-atopic asthma was significantly higher in pig farmers (ORadj 2.0, 95% CI 1.2 to 3.3) and in farmers with two or more types of livestock (ORadj 1.9, 95% CI 1.1 to 3.3), and (3) atopic asthma was less common in farmers with two or more types of livestock (ORadj 0.32, 95% CI 0.11 to 0.97). Exposure to endotoxins, fungal spores, and ammonia was positively associated with non-atopic asthma and negatively associated with atopic asthma. No associations were found with atopy.
Conclusions: Exposure to endotoxins and fungal spores appears to have a protective effect on atopic asthma but may induce non-atopic asthma in farmers.
doi:10.1136/thx.2004.013326
PMCID: PMC1747014  PMID: 15115863

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