Low Malaria Transmission in Rosso, an Irrigated Rice-Growing Area in Mauritania

The construction of dams along the Senegal River resulted in an increase in irrigated land areas and changes in the epidemiology and transmission of water-related diseases. The objective of this study was to update epidemiological data on malaria in Rosso, one of the major Mauritanian cities along the Senegal River. Febrile patients (n = 318) were screened for malaria using a rapid diagnostic test (RDT) for malaria and microscopic examination of blood smears. Diagnosis was later confirmed by polymerase chain reaction (PCR). The mean age of 318 febrile patients was 25.1 (range 1–80 years). Only 7 (2.2%) and 2 (0.6%) had a positive RDT and thick smear, respectively. PCR confirmed the diagnosis in two Plasmodium vivax-infected patients. Most participants (198/318, 62.3%) had no recent travel history outside Rosso. The majority of the febrile patients (90%, 284/311) owned at least one insecticide-treated net (ITN). The frequency of the use of ITNs was not significantly associated with season (rainy vs. dry seasons; p = 0.9) or with the number of ITNs per household (rs = 0.07; n = 285; p = 0.19). Of 285 individuals with ITNs, only two (0.7%) with no travel history were PCR-positive for malaria. Despite the presence of mosquito breeding sites related to rice irrigation, malaria transmission in Rosso remained very low, possibly due to the high coverage and frequent use of bed nets. Regular entomological surveillance for possible changes in the prevalence of Anopheles mosquito species and their behavioural aspects should be implemented.