This study represents the first community-based prevalence data in Karen refugees in Australia and the largest cohort of Karen refugees in the Australian literature.
Nutritional deficiencies and infectious diseases were common in Karen refugees. Anaemia and microcytosis were common, particularly in young children, where iron deficiency was prominent. Haemoglobinopathies 
and lead toxicity 
are further possible causes/contributors to microcytosis in Karen refugee children, although testing for these conditions is not part of current Australian screening protocols.
Vitamin D deficiency is now well described in African refugee cohorts in Australia, and is reported in over 85% of African children 
, and adults 
in Melbourne. An unexpectedly high prevalence of vitamin D deficiency was found in Karen refugees, particularly in females, and hypocalcaemia was common. Despite these findings, the proportion with an elevated ALP (suggesting increased bone turnover) was relatively constant in those with low vitamin D (compared to those with normal levels) and in the different age groups, without an increase in the youngest and adolescent age groups, as might be expected during periods of rapid growth. Most people in the Karen community are Fitzpatrick skin type III–IV, do not wear covering clothing, and in this cohort, had recently arrived from areas with high incident sunlight exposure. There were no other obvious contributors to low vitamin D levels; obesity or use of medications affecting vitamin D metabolism were both extremely uncommon. Although dietary intake of calcium was typically low, and hypocalcaemia can drive conversion of 25-OHD to active 1,25-(OH)2
D via parathyroid hormone (PTH), a raised ALP would be expected in response to elevated PTH and an increase in 1,25-(OH)2
D. Higher levels of 24, 25-hydroxylase (which degrades both 25-OHD and 1,25-(OH)2
D) are reported in South Asians 
, which is another possible mechanism for reduced 25-OHD levels in this group. Low vitamin D has adverse effects on bone health, and there is an emerging body of evidence that it is associated with other effects on health 
. Current Australian refugee screening protocols were developed in response to a wave of African migration, and include vitamin D screening based on the risk factors of this group. Given the high prevalence of vitamin D deficiency in Karen refugees, it is difficult to cease vitamin D screening at this point, although it will be important to establish whether low vitamin D remains a problem for Karen refugees after settlement, and to monitor for adverse effects on health.
Hepatitis B virus (HBV) infection was common, with an overall prevalence of 9.7%, and an age-related gradient, reaching a prevalence of 13.7% in adults. These figures compare to prevalence estimates of 0.5–0.9% for Australia 
, and 6–16% 
in African refugee cohorts in Australia. Younger children were nearly all immune due to vaccination, likely reflecting camp immunisation programs, whereas in adolescents and adults, immunity generally reflected exposure to infection. There was a relatively high number of people with isolated positive cAb serology, which requires additional follow-up. Isolated cAb positive may represent the window phase of acute hepatitis B, a false positive result (more common in people from low prevalence areas), or, more commonly in people from high prevalence areas, immunity after previous infection with waning HBsAb, or chronic HBV infection 
Hepatitis B population prevalence is classified as low (<2%), intermediate (2–7%) and high (≥8%) 
; high prevalence is usually associated with sAb prevalence of 60–80%. In this cohort, although the prevalence of sAg positive was high, over half the cohort was sAb negative, and remained susceptible to HBV. This is important from a public health perspective, as the combination of high disease prevalence and lower than expected seroprotection will facilitate disease transmission. Horizontal transmission is of particular concern within households and in young children, and is reported in other Asian refugee cohorts after settlement 
. Household composition is often fluid in the early stages of refugee settlement, and many families stay in shared accommodation. In Australia, Hepatitis B immunisation is funded during early childhood, for sexual partners and household contacts of people with hepatitis B, and there is a catch-up program for year seven students that will cease in 2012. Hepatitis B vaccine is not funded for refugees except by these criteria. It may be prudent to assume household contact is the norm rather than the exception, and to extend funding in order to prevent transmission within the community.
The prevalence of malaria was low, likely due to the epidemiology of malaria in the area of origin, and well established local control programs. Although malaria is prevalent in the area, with 60–190 cases of malaria reported weekly in Mae La camp over the study period 
; the endemicity is low, and populations do not acquire significant protective immunity, meaning infections are generally symptomatic (and treatment is available). This is in contrast to African refugee cohorts (from hyper-endemic areas) arriving in Australia prior to the introduction of pre-departure health screening; where asymptomatic parasitaemia and waning immunity post-migration were a significant concern 
The prevalence of STIs was low, with similar findings in studies in Mae La camp 
and Karen refugees in the United States 
. The low rates in Mae La camp have been attributed to geographic isolation, religious faith, and camp governance, with defined consequences for pregnancy or pre-marital sexual relations (including forced marriage and restricting school access) 
infection has not been reported previously in Burma 
. The prevalence of Strongyloides
infection was higher than the prevalence seen in African refugees in Australia 
. Pathogenic faecal parasites were more common in the younger age groups, and Giardia intestinalis
was common in all age groups, despite pre-departure Albendazole, which has also been observed in other refugee cohorts 
One of the most important findings of this study was inadequate immunity to vaccine-preventable diseases, supporting the need for targeted and accessible immunisation in the early stages of settlement. The prevalence of serological immunity to rubella was low, despite PDMS immunisation with MMR vaccine, although no data were available on the timing of vaccination compared to the timing of health screening. Susceptibility to rubella and increased incidence of congenital rubella syndrome have previously been reported in South Asian cohorts 
, and this represents an important target for catch-up immunisation. Serology to detect existing immunity to vaccine-preventable diseases is not recommended in Australian refugee guidelines (except hepatitis B) 
, although serology for rubella immunity should be considered for women of childbearing age. This study highlights some of the issues with vaccination serology. Although the prevalence of seroimmunity to measles and mumps was relatively high, nearly half of those tested for all three vaccine components remained susceptible to at least one, and combination MMR vaccine is the only option available for catch-up. Similar issues occur for any combination vaccine. Almost all adults had seroimmunity to hepatitis A, suggesting routine screening is unnecessary, although targeted screening in those with liver pathology due to other causes such as hepatitis B or C is still recommended.
A coincidence of time and settlement patterns allowed the collection of these data in a community sample of Karen refugees, who currently comprise over one quarter of Australia's current offshore Humanitarian program intake. Only one other Australian study provides information on health issues in Burmese refugees 
, although this is a cohort of 156 adults referred to a specialist refugee clinic after initial health screening, representing significant referral bias. Three other studies report on smaller cohorts (31–113 people) of refugees from a mixture of Asian source countries, without breakdown by country of origin 
. In the international literature, only two studies are identified on the prevalence of health issues in refugees from Burma, a small study from Canada 
and a larger Karen cohort from Minnesota 
. In the cohort of 1728 Karen from Minnesota, limited data are reported, although available prevalence figures are similar, including hepatitis B sAg (10%), pathogenic intestinal parasites (15%), and no sexually transmitted infections (STI) in a smaller cohort of 170 adult patients. The current study expands this literature and provides an overview of health issues affecting Karen refugees in Australia, relevant for policy makers and clinicians working in refugee health. The findings support using most tests included in current Australian refugee protocols for screening in Karen refugees, with the exception of malaria and STI testing, where targeted screening is not clinically unreasonable.
Limitations of this study include its retrospective nature, incomplete screening leading to selection bias, and possible ascertainment bias. The figures in this study reflect real life practice, and the difficulty in ordering and obtaining multiple test specimens in primary care in a complex patient group. Screening tests were not applied to all patients in a systematic manner. Protocols and testing arrangements varied over time, leading to an apparent reduction in coverage, although tests were applied to consecutive primary care arrivals. There is also the potential for ascertainment bias arising from the use of Schistosoma
serology as an identifier (refugees not having this screening test would be missed), however this test was part of refugee health screening throughout the study period. Further, clinic attendance was voluntary, however the unusual situation of a single streamlined referral pathway to a single local CHC, with a mandated referral process, and the high attendance and follow-up seen in this cohort, led to high rates of screening uptake. The number of Karen refugees who underwent screening (1136) was slightly higher than the number settling in the local Government area over the study period (1039) 
. This discrepancy most likely represents secondary migration, but these figures suggest that this study is likely to have captured the vast majority of new Karen refugee arrivals to the area.
Finally, it is important to note, these data are cross-sectional and do not provide information on the longer term health issues in this group, or health issues arising as a result of settlement. Initial refugee health screening is essentially a form of preventative health care to prevent complications from parasite infections, provide treatment for latent tuberculosis infection and detect hepatitis for monitoring and treatment if necessary. There is limited longitudinal information on the health of refugee cohorts in Australia. In the CHC where this study was located, obesity and type 2 Diabetes Mellitus are emerging health issues in the years after settlement.
Priorities for Australian refugee health care in the future include the need for more rapidly responsive epidemiology for new cohorts, but also developing systems to monitor longitudinal outcomes, and providing an approach to preventive health care in the initial refugee health assessment that extends beyond infectious diseases.