This is the first community-based surveillance of diarrhoea in Jakarta and our findings underscore its public health significance especially amongst children less than 60 months of age. By utilizing passive surveillance, that is detecting patients coming to health centres for treatment, we found an annual incidence of diarrhoea requiring medical attention of 349 per 1 000 children and 759 per 1000 infants.
The study was designed in preparation of vaccine trials trying to find an appropriate population for the evaluation of vaccine candidates. The residents of two kecamatans, Tanjung Priok and Koja were selected as study population for the study based on their accessibility and the relative high incidence of the target diseases. We have found that in this population only 39% of diarrhea episodes overall would trigger a visit to a health care centre. Taking into account the lack of sensitivity of the classic culture methods used in the study it is reasonable to assume that the true disease incidence could be several fold higher than our estimates. Our study population is likely to be representative of the less affluent segment of the population of Jakarta which depends on the public health care system. However the study population was not chosen because it is representative for the population of Jakarta. More affluent households in North Jakarta may prefer to make use of the private sector and were not captured by the study. The incidence of the target diseases estimated by our study may differ in the more affluent population.
The incidence of shigellosis was highest in children between 1 and 2 years of age, consistent with previous data indicating that maternal antibodies and breast-feeding may protect newborns and infants [21
]. We found increasing rates of shigellosis in those 70 years of age and older, which could be related to waning of immunity. S. flexneri
was the most frequently detected Shigella species and four S. flexneri
serotypes (2a, 3a, 1b, 1c) made up 74% of the S. flexneri
isolates. This finding is consistent with those from a previous report that suggested that the most frequent S. flexneri
serotypes are 2a, 1b, and 3b [24
The highest number of diarrhea cases was detected each year during the rainy season between January and April when North Jakarta is particularly flood prone. The number of detected cholera cases peaked each year in January. Relatively few V. parahaemolyticus strains were detected during the first year of the study which became the dominant Vibrio species towards the end of the study. The increase in V. parahaemolyticus detection may well have been related to the pandemic spread of the V. parahaemolyticus serovar O3:K6 though the serovar of the strains has yet to be determined. The detection of all Shigella strains coincided with the rainy season (January through April) and had a distinct peak in April of the first year of surveillance.
The greatest burden of cholera was in children during the first year of life. Previously, cholera was believed to occur infrequently below 2 years of age [25
] but more recent studies have found cholera to be a significant problem in young children [26
]. We found significant numbers of diarrhoea cases due to other Vibrio
species. These diarrhoea episodes were more likely to occur in adults than in children as previously reported [8
]. V. parahaemolyticus
infections are transmitted through unsafe foods, such as raw or undercooked seafood, which are more likely to be consumed by adults [8
]. V. cholerae
non-O1 and V. parahaemolyticus
were associated with milder illness than V. cholerae
The large majority of study patients received rehydration fluids (mostly orally) in accord with international guidelines. Only 4% of diarrhoea patients reported taking antibiotics prior to presentation which is surprising considering the ubiquitous presence of drug vendors in the study area. Resistance of Shigella to quinolones is not yet a major problem in the area but resistance to the more commonly used first-line antimicrobials is disturbing. Ampicillin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole are of little use for treatment of S. flexneri in the study area. Antimicrobial resistance of V. cholerae is not yet a major problem in Jakarta. However the surprisingly high percentage of diarrhea patients who were prescribed antibiotics is worrying as the drug pressure is likely to select resistant strains and is unlikely to benefit many the patients.