Amebiasis in schistosomiasis endemic and non-endemic areas in Egypt.
Stool and blood specimens were collected from each of 404 and 576 individuals at Sindbis village (Qualiubia Governorate) in the Nile Delta where schistosomiasis is endemic and El-Rashda village (New Valley Governorate) in the Western Desert of Egypt where there is no schistosomiasis; respectively. Based on the microscopical examination of stool specimens, the prevalence of infection with Entamoeba (E. histolytica and/or E. dispar which are morphologically indistinguishable) was higher at Sindbis than at El Rashda village (29.3% and 20%, respectively). At Sindbis, the prevalence of Entamoeba (both species) was 35.2% (50/142) in S. mansoni infected individuals versus 26.3% (69/262) in S. mansoni negative individuals. Serum antibodies develop only against E. histolytica but not against E. dispar infection. When serological results were considered, the prevalence of E. histolytica was 4.7% in Sindbis and 3.4% at El Rashda based on those who were positive microscopically and serologically in the two villages, respectively. In other words, only 16-17% of those who were positive microscopically can be considered infected with E. histolytica as determined serologically. However, the prevalence of E. histolytica (present or past) based on those who were positive serologically whether positive or negative microscopically was 13.4% and 12.7% at the two villages, respectively. At Sindbis, the prevalence of E. histolytica infection was lower in S. mansoni negative (8.5%) than in S. mansoni positive (16.0%) individuals. These epidemiologic data suggest that: (1) S. mansoni infection may suppress the immune response of the host and therefore, the prevalence of E. histolytica based on serological testing is probably underestimated in the S. mansoni infected people and it may be higher than in the S. mansoni negative people. (2) Serological examinations can be used in determining the true prevalence of E. histolytica (present or past infections) until a routine test for detecting E. histolytica specific antigen in stool becomes available to differentiate E. histolytica from E. dispar infections.
Mansour
N S
NS
U.S. Naval Medical Research Unit No. 3, Cairo, Egypt.
Youssef
F G
FG
Mikhail
E M
EM
Mohareb
E W
EW
D000818:Animals; D004534:Egypt / Q000453:epidemiology; D004747:Entamoeba / Q000302:isolation & purification; D004748:Entamoeba histolytica / Q000302:isolation & purification; D004749:Entamoebiasis / Q000097:blood / Q000150:complications / Q000453:epidemiology*; D005243:Feces / Q000469:parasitology; D006801:Humans; D015995:Prevalence; D012550:Schistosoma mansoni / Q000302:isolation & purification; D012555:Schistosomiasis mansoni / Q000097:blood / Q000150:complications / Q000453:epidemiology