The impact of irrigated rice on the transmission of schistosomiasis and geohelminthiasis in Niakaramandougou, Côte d’Ivoire

The prevalence and intensity of the infection caused by schistosomiasis and  geohelmintiasis were studied in relation to irrigated rice cultivation in Cote d’Ivoire. In a cross-sectional study conducted on schistosomiasis in Niakaramandougou, in the savannah (North) area of Cote d’Ivoire, from April to September 2001, the  potential importance of soil-transmitted helminth infections was assessed. Villages  were classified according to the surrounding inland valleys into two  agro-ecosystems: (R2) full or partial water control allowing two rice cycles per year and (R0), the absence of rice growing. Urine and stool samples were collected from children in two villages in the savannah zone. Three hundred and fifty-three (353)  children aged 4 to 15 years were examined, of whom 220 were from Kafine village  (R2) and 133 from Pekaha village (R0). The prevalence of Schistosoma  haematobium was 10%, and 2.3% in R2 and R0 respectively. S. manson i prevalence was 29.1% in R2 and 31.6% in R0. Ascariasis lumbricoides (12.3%) and Trichuris trichuira were the only species present in the two agro-ecosystems. Prevalences of S. haematobium adjusted for the effects on the villages were significantly different in the two agro-ecosystems. In savannah rice growing villages, negative binomial regression on the intensity of the infection of S. haematobium showed significant positive relations with the surface of rice cultivated inland valleys, whereas uncultivated inland valleys showed no significant relation. However, S. mansoni infection intensity showed significant negative relations with infection intensity of each agro-ecosystem. Keywords : Rice; Irrigation; Schistosomiasis; S. mansoni; S. haematobium;  Agro-ecosystem; Cote d’Ivoire.