Human hydatidosis in Tehran, Iran: a retrospective epidemiological study of surgical cases between 1999 and 2009 at two university medical centers.

This study was conducted to evaluate retrospectively 203 patients diagnosed with hydatid cyst disease and treated surgically at two university medical centers between 1999 and 2009 in Tehran, the capital of Iran. Cystic echinococcosis (CE) affected more females 117 (57.6%) than males 86 (42.4%). A remarkable gender difference skewed towards females was observed, and the male/female ratio among CE cases ≤20 and ≥61 years old was 1.18 and 0.52, respectively. The age of the patients ranged from 8 to 82 years, and the age group 21-40 years (42.8%) was the most affected. A significantly higher number of hydatid cysts were recorded in the liver than in other sites (P<0.001), and more females had higher hepatic cysts (48.8%) than males (35.0%). The ratio of hepatic hydatidosis to pulmonary hydatidosis was about 11. There was a relative direct relationship between the ratio of liver to lung cases and age, and this ratio was significantly (P<0.01) higher in individuals >40 years of age (liver/lung ratio ≥43) than in those <40 years of age (liver/lung ratio 2.8-7.6). Unusual cyst locations in kidneys, brain and pelvic area, followed by spleen and spine was also observed. Single organ involvement was found in 95% of the patients, and was more common in females (55.2%) than in males (39.9%). Housewives had the highest rate of infection (53.5%) followed by labourers with 14.8%, which showed a significant difference (P<0.001). Similarly, urban dwellers was also over-represented among the cases (87% urban vs. 13% rural; P<0.001). In 69.5% of cases there was only one cyst, 16.3% had two cysts, 4.7% with three cysts, and 9.5% had four cysts or more. The results showed that further studies are needed to determine the prevalence, economic impact and risk factors of the disease in the area.