Epidemiological Study and Evolution of Monospecific and Low Transmission Schistosomiasis Guineensis Foci in Absence of Praziquantel Chemoprevention: Edea and Eseka in Cameroon

Implementation of chemoprevention with praziquantel against schistosomiasis significantly decreased prevalence and intensities of infection in moderate to heavy transmission settings. However, evolution of schistosomiasis transmission pattern in previously known low transmission areas remains of concern. This study aimed to evaluate prevalence and intensities of infection of human Schistosoma infection and specific snail intermediate hosts cercaria shedding in Edea and Eseka, two previously known monospecific hypoendemic Schistosoma guineensis transmission foci in Cameroon, then compare data to previous epidemiological surveys. This community-based cross-sectional study was undergone in 2024 in Edea and Eseka by collecting socio-demographic data, stool and urine samples from consenting dwellers. Stool and urine samples were processed using Kato-Katz and urine centrifugation techniques respectively to count Schistosoma eggs under microscope. Parasitic loads and intensities of infection were determined. Schistosoma intermediate hosts were collected in waterbodies at human-water contact sites, identified using shell morphology specific identification keys, then tested for cercarial shedding. Data were compared to previous epidemiological reports in 1969 and 1981. Data were statistically analyzed considering a p-value S. guineensis eggs were detected in humans with a prevalence of 0% (0/215) and 1.7% (4/229) at Edea and Eseka respectively. Being adolescent (p=0.008) and attending waterbodies for bathing and fishing or laundry (p=0.02) were associated to S. guineensis infection. Only Bulinus forskalii were harvested in the two areas. Of the 43 alive B. forskalii collected, the prevalence cercariae shedding was 0%. Compared to epidemiological data gathered 45 years ago, the prevalence of S. guineensis infections has decreased significantly in the two sites. Prevalence of schistosomiasis has decreased in Edea and Eseka, S. guineensis remaining the only specie. Infected subjects harbor low to moderate intensities of infection. Bulinus forskalii were cercariae free.