A New Focus of Schistosoma Mansoni in Yoro Village, Mbam and Inoubou Division, Cameroon

Abstract

Investigations on intestinal schistosomiasis were carried out in Yoro, a small village located in the transitional zone between forest and savannah, in the Mbam and Inoubou Division of Cameroon. Four human-water contact points were identified in the village and sampled for snails, and the inhabitants underwent parasitologic and clinical surveys to search for signs and symptoms of intestinal schistosomiasis. The results indicated the presence of two freshwater snails, both potential intermediate hosts of Schistosoma sp: Biomphalaria pfeifferi and Bulinus forskalii. However, only the former species was incriminated in the transmission of the disease, with the prevalence of snail infection being 10% (1 of 10) and 14.3% (2 of 14), respectively, during surveys 1 (in the dry season) and 2 (in the rainy season). The overall prevalence of Schistosoma mansoni eggs in stool samples was 54.4% (98 of 180). The mean ± SD intensity of infection was 100.3 ± 114.7 eggs per gram of stool. Eggs of S. intercalatum were not detected during parasitologic examination of stool specimens. In Cameroon, it appears that unlike the distribution of S. mansoni, which usually follows that of B. pfeifferi, B. forskalii is commonly found where S. intercalatum does not exist due to competitive exclusion through introgressive hybridization. Of the 180 people included in the study, 52.3% reported abdominal pain and 37.5% had bloody stools. Splenomegaly and hepatomegaly were noted in 11.7% and 3.9%, respectively, of the subjects examined. Three foci of S. mansoni were previously described in the Mbam and Inoubou Division, including Bafia town, Makenene, and Kinding Djabi villages. With the present focus in Yoro, the Mbam and Inoubou Division appears to be the most important endemic zone of S. mansoni in southern Cameroon.

Schistosomiasis Burden and Its Association With Lower Measles Vaccine Responses in School Children From Rural Cameroon

“…Our study further characterizes the burden of schistosomiasis in rural Cameroon, particularly in the S. haematobium infested area of Barombi Kotto ( 1 , 23 , 24 ) and the S. mansoni infested area of Yoro ( 3 ). Our investigations focused predominantly on affected schoolchildren in the areas and report on the infection burdens, the risks of infection, the tissue morbidity profiles and the effect of infection on measles vaccine-elicited serum antibody responses.…”

“…A subsample of the enrolled children, which came back for ultrasonography (70 from BK and 83 from Y), was further screened for bladder morbidity in Barombi Kotto and liver morbidity in Yoro. The details on the study areas have been previously described ( 1 , 3 , 23 , 24 ).…”

“…In Yoro, feces samples were collected from each participant for microscopic analysis (single stool sample per child). Per feces sample, two Kato-Katz slides of 25 mg fecal material each were prepared and microscopically examined for S. mansoni species as previously described ( 3 ).…”

“…Annual mass drug administration (MDA) of praziquantel to schoolchildren in endemic areas represents the country primary control strategy against the disease ( 2 ). The country is home to S. mansoni ( 3 – 7 ) and S. haematobium ( 1 , 3 , 4 , 8 ) causing the hepatointestinal and urogenital forms of the disease respectively.…”

“…In Cameroon, measles vaccination coverage is still at a sub-standard level with an overall 80% coverage rate. Several measles outbreaks have been reported in 2015 (Center, Far North and North-West regions particularly) and in 2016 (Adamawa, Far North, North and South-West regions) ( 22 ) which are all schistosomiasis-diseased areas ( 1 , 2 , 3 , 5 – 7 , 23 ). Intriguingly, a recent study in western Kenya elegantly described a crippling effect of mothers diseased with schistosomiasis during pregnancy on their children responsiveness to measles vaccination ( 19 ).…”