The epidemiology of schistosomiasis in Egypt: Gharbia Governorate

Health questionnaires and parasitologic examinations of urine and stool wer e performed upon a stratified random sample of 14,344 individuals from 1,95 2 households in 34 rural communities in Gharbia Governorate of Egypt to inv estigate the prevalence of, risk factors for, and changing pattern of infec tion with Schistosoma sp. A subset, every fifth household, of 1,973 subject s had physical and ultrasound examinations to investigate prevalence of and risk factors for morbidity. Community prevalence of Schistosoma mansoni ra nged from 17.9% to 79.5% and averaged 37.7%. The geometric mean egg count ( GMEC) was 78.9 eggs/gram of feces. The prevalence and intensity of infectio n was 40-50% and 70-100 eggs/gram of feces in those greater than or equal t o 10 years of age. Schistosoma haematobium was detected in 5 of the 34 comm unities. The maximum infection rate was 2.8% and mean GMEC in the five comm unities was 2.1/10 ml of urine. The overall prevalence of S. haematobium in the governorate was 0.3%. Risk factors for infection with S. mansoni were male gender, an age >10 years, living in smaller communities, exposures to canal water, prior therapy for schistosomiasis, or blood in the stool (in c hildren only). Morbidity detected by physical examination or ultrasonograph y did not correlate with S. mansoni infection in individuals with the excep tion of periportal fibrosis (PPF, odds ratio [OR] = 1.25). Periportal fibro sis was detected in more than half of the subjects by ultrasonography; 5.3% had grade II lesions and 1.0% had the most severe grade III changes. Risk factors for morbidity as manifested by ultrasonographically detected PPF we re similar to those for infection. Periportal fibrosis had a negative relat ionship with abdominal pain (OR = 0.45) and hepatomegaly detected by physic al examination and ultrasonography (ORs = 0.72 and 0.68), but it was associ ated with splenomegaly (ORs = 4.14 and 3.55). The prevalence of PPF, hepato megaly, and splenomegaly increased with age. There was no relationship betw een community burden of schistosomiasis mansoni and any measurements of mor bidity with the exception of splenomegaly detected by physical examination (r = 0.40). Schistosoma mansoni has almost completely replaced S. haematobi um in Gharbia, which has a high prevalence and moderate intensity of S. man soni infection. Periportal fibrosis was detected by ultrasonography in more than half of the subjects, and 1 in 16 had grade II and III lesions. The o nly relationship between PPF and other morbidity findings was its positive relationship with splenomegaly and negative association with hepatomegaly. Hepatic morbidity is common in communities in Gharbia but the role of schis tosomiasis mansoni in this is uncertain.