Human fascioliasis infection: gender differences within school-age children from endemic areas of the Nile Delta, Egypt

Several studies have reported a higher prevalence of infection for human fascioliasis among girls than among boys. To investigate this aspect further a sufficiently large data set was assembled comprising of 21 477 subjects with 932 positive cases. Subjects were primary school children covered by a control programme implemented by the Egyptian Ministry of Health and Population in the Nile Delta from 1988 to 2002. Stool analyses were performed by the Kato-Katz thick smear technique for a quantitative diagnosis on the intensity of infection. Both prevalence and intensity of infection, indirectly measured as mean number of eggs per gram of faeces, were significantly higher among girls than boys. The higher level of infection in girls was consistent across different years and in different survey areas. Co-infection with Schistosoma mansoni was present and associated with fascioliasis, but schistosomiasis was significantly more prevalent among boys. In Egypt rural girls are often involved in household and farm work and are exposed more than boys to infected foci. The lower school attendance for girls in rural areas appears to be an important factor increasing risk of infection. The precise mode of transmission and behavioural risk factors for human infection need to be investigated further to identify those related to gender.