Human cystic echinococcosis in Kyrgystan: an epidemiological study

Human cystic echinococcosis (CE), caused by Echinococcus granulosus, is an emerging disease in central Asia. This study examined official data on the incidence of CE between 1991 and 2000 and studied routine hospital records in the main surgical hospitals in Bishkek, Kyrgystan, between 1990 and 2000. In addition, a cross-sectional ultrasound study of a rural population was undertaken in northern Kyrgystan. The results of this study have indicated that the annual incidence of CE over the whole of Kyrgystan has increased from 5.4 cases per 100 000 in 1991 to 18 cases per 100 000 in 2000. Likewise, hospital admissions in Bishkek, due to CE, have increased from an estimated 21 cases in 1990 to approximately 127 and 124 in 1998 and 1999, respectively. Similarly, paediatric cases have increased from 2 in 1990 to 82 in 2000. There was no obvious association with occupation of affected adults although a disproportionate number of hospital cases were registered as unemployed compared to the general population. Whilst there was no gender difference in hospital admissions amongst children, men were more likely to undergo hospital treatment than women. Fifty percent of cysts were recorded as hepatic cysts with forty seven percent recorded as pulmonary cysts. Analysis of the data suggests that the likelihood of an affected patient having a hepatic cyst decreased with age. The results of the cross-sectional study indicated that 20 of 1486 subjects (1.35%) examined by ultrasound had an abdominal hydatid cyst. By extrapolating the ratio of pulmonary to hepatic cysts recorded in the hospital population and adjusting for age it is possible that as much as 3.4% of the rural population may have sub-clinical CE. Analysis of the possible risk factors in the cross-sectional study revealed that subjects who had CE were less likely to use well water as their water supply than non-infected subjects.