A retrospective analysis of human cystic echinococcosis in Hamedan province, an endemic region of Iran

Abstract

In a retrospective investigation, the medical files of the patients who, between 1992 and 2006, underwent surgery for the treatment of cystic echinococcosis (CE) in one of the three university hospitals in Hamedan province, in western Iran, were explored. Of the 179 patients involved, 44.1% were male and 55.9% female, giving a male/ female ratio of 0.79. The mean annual surgical incidence of CE in the catchment areas of the study hospitals was estimated to be 1.33 cases/100,000. Although most of Hamedan's population is urban (53.02% at the last census, in 1997), most (57.5%) of the patients lived in rural areas (P<0.05). Among the CE cases, housewives (47.3%), farmers (16.6%) and labourers (16.0%) were over-represented compared with the frequencies of these occupations in the general population of the region (P<0.05 for each). Most of the CE cases were aged 20-39 years (35.8%) or 40-59 years (29.0%) and most had liver cysts, either alone (60.9%) or with cysts in other sites (9.5%), although 19.6% of the cases appeared only to have lung cysts. Overall, 90.5% of the cases showed single-organ involvement. Liver involvement was 3.3-fold more common than lung involvement, the ratio between cases with liver cysts and those with lung cysts generally increasing with age (from 1.6 for the cases aged <20 years to 5.6 among the cases aged 40-59 years). The most common clinical symptoms were abdominal pain and/or a sensation of abdominal mass in those with hepatic CE, and chest pain, cough, dyspnoea and/or haemoptysis in those with pulmonary CE. Although 72% of the cases each had a single cyst, 19.6% had two cysts each and 8.4% each had at least three cysts. Only three (1.7%) of the cases had had previous surgery for CE. Diagnosis of CE in Hamedan province is largely dependent on ultrasonography and computed tomography. Together, these results confirm that CE is endemic in the province and indicate that certain occupations (housewife, farmer and labourer) and/or rural life are risk factors.