Five-Year Follow-Up on the Prevalence and Intensity of Infections of Schistosoma mansoni in a Hard-to-Reach District of Madagascar

• Published in: The American journal of tropical medicine and hygiene 2021-03, Vol.104 (5), p.1841-1850
• Main Authors: Spencer, Stephen A, Linder, Cortland, Penney, James M StJ, Russell, Hannah J, Hyde, Kate, Sheehy, Caitlin, Reid, Alice, Andriamasy, Emmanuel H, Raderalazasoa, Gina U, Rakotomampianina, Daniel A L, Nandimbiniaina, Anjara M, Ranaivoson, Tahiry N, Andrianiaina, Antsa, Cruickshank, Sheena M, Bustinduy, Amaya L, Stothard, J Russell, Edosoa, Glenn T, Rahetilahy, Alain M
• Format: Article
• Language: English
• Subjects: Adolescent; Animals; Anthelmintics - administration & dosage; Anthelmintics - therapeutic use; Child; Child, Preschool; Chronic Disease; Female; Health education; Humans; Infections; Madagascar - epidemiology; Male; Mass Drug Administration; Praziquantel - administration & dosage; Praziquantel - therapeutic use; Prevalence; Public health; Schistosoma mansoni - physiology; Schistosomiasis mansoni - drug therapy; Schistosomiasis mansoni - epidemiology; Schistosomiasis mansoni - pathology
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.20-1433

Schistosomiasis is a major public health problem in Madagascar. The WHO recommends preventive chemotherapy by mass drug administration (MDA) with praziquantel as the primary approach to control Schistosoma mansoni-related morbidity in endemic populations, alongside complementary interventions such as health education. The impact of annual MDA and health education programs was assessed in the hard-to-reach Marolambo district of eastern Madagascar, an area endemic for S. mansoni. Repeated cross-sectional studies undertaken 2015-2019 examined between 300 and 381 school-aged children (aged 5-14 years) annually. The prevalence and infection intensity of S. mansoni were assessed by urine-circulating cathodic antigen (CCA) dipsticks and coproscopy using Kato-Katz (KK) methodologies. After four rounds of annual MDA, a reduction in S. mansoni prevalence was seen in CCA (93.9% in year 1-87.7% in year 5; P = 0.007) and KK (73.9% in year 1-59.4% in year 5; P < 0.0001). The prevalence of heavy-intensity infections roughly halved from 23.7% to 10.1% (P < 0.0001), and the mean intensity of infection fell by 55.0% (480.2-216.3 eggs per gram of feces). A malacological survey found Biomphalaria pfeifferi snail intermediate hosts in multiple water contact sites including rice paddies, streams, and Nosivolo River. Despite reductions in infection prevalence and intensity, schistosomiasis still poses a significant public health challenge in Marolambo district. Twice yearly MDA cycles and/or community-wide MDA are suggested to better reduce infections. Expanding health education, improving standards of water, sanitation and hygiene, and attention on snail-related control will also be important, especially in rice paddy irrigated areas.