The impact of a small-scale irrigation scheme on malaria transmission in Ziway area, Central Ethiopia

Abstract

Summaryobjective To assess the impact of a small-scale irrigation scheme in Ziway area, a semi-arid area in the Central Ethiopian Rift Valley, on malaria transmission.method Parasitological, entomological and socio-economic studies were conducted in a village with and a village without irrigation. Blood smear samples were taken from individuals during the dry and wet seasons of 2005 ⁄ 2006. Socio-economic data were collected from household heads and key agricultural and health informants through interviews and questionnaires. Larval and adult mosquitoes were sampled during the dry and short wet seasons of 2006. Female anopheline mosquitoes were tested by enzyme-linked immunosorbent assay for blood meal sources and sporozoite infections.results Malaria prevalence was higher in the irrigated village (19%, P < 0.05) than the non-irrigated village (16%). In the irrigated village, malaria prevalence was higher in the dry season than in the wet season while the reverse occurred in the non-irrigated village. Households with access to irrigation had larger farm land sizes and higher incomes, but also higher prevalence of malaria. Larval and adult abundance of the malaria vectors, Anopheles arabiensis and Anopheles pharoensis, was higher in the irrigated than in the non-irrigated village throughout the study period. Furthermore, the abundance of An. pharoensis was significantly higher than that of An. arabiensis during the dry irrigated period of the year. Canal leakage pools, irrigated fields and irrigation canals were the major breeding habitats of the two vector mosquitoes. Plasmodium falciparum sporozoite infection rates of 1.18% and 0.66% were determined for An. arabiensis and An. pharoensis in the irrigated village. Peak biting activities of the vectors occurred before 22:00 h, which is a source of concern that the effectiveness of ITNs may be compromised as the mosquitoes feed on blood before people go to bed.conclusion Irrigation schemes along the Ethiopian Rift Valley may intensify malaria by increasing the level of prevalence during the dry season. To reduce the intensity of malaria transmission in the smallscale irrigation schemes currently in operation in Ethiopia, year-round source reduction by using proper irrigation water management, coupled with health education, needs to be incorporated into the existing malaria control strategies.

Occupational Activities Associated with a Reported History of Malaria among Women Working in Small-Scale Agriculture in South Africa

“…This finding differs from that of a study in Ethiopia by Kibret and others, in which Table 2 Crude prevalence ratios of demographics, agricultural activities, and crops produced with reported history of malaria among women working in small-scale agricultural on the Makhatini Flats, South Africa, by location (n = 644) * they found a higher prevalence of malaria, in particular during the dry season in a village with an irrigation scheme than in a village that was not irrigated. 7 However, in our study, women on the drylands were more involved in agricultural activities than women in the irrigation scheme and this factor may have contributed to the higher number of malaria cases among women on the drylands. The malaria vectors Anopheles arabiensis and An.…”

“…5 Rural agricultural communities in malaria-endemic areas tend to be most at risk for malaria infection, particularly in the presence of intensive irrigation, which provides an ideal breeding ground for the Anopheles mosquito, the vector responsible for malaria transmission. 6,7 Environmental factors such as the distance a person lived from a water source, house typology, and living in a house for more than four years have been associated with an increased risk of developing malaria. [8][9][10] Agricultural activities including land clearing for crop production, which enables surface water pooling suitable for vector breeding, have been associated with an increased incidence of malaria.…”

Do Long Lasting Insecticidal Treated Nets Alone and Long Lasting Insecticidal Treated Nets plus Indoor Residual Spraying combination have an effects on Anopheles arabiensis Patton (Diptera: Culicidae) population densities, biting cycle, biting places and biting rate; A randomised Control Trial in central and eastern, Sudan.

“…[30] Another recent study has also reported early biting cycles in Anopheles arabiensis, Anopheles pharoensis and Anopheles coustani in Ziway in central Ethiopia. [31] In this study the man biting rate (MBR) recorded for indoors was significantly higher compared to outdoors man biting rate. In this study indirect calculation of the man-biting from the spray sheet collection was used, the man-biting rate (per night) is obtained by dividing the total number of fed mosquitoes by the total number of individual occupant the houses.…”

The Practice of Jhum Cultivation and its Relationship to Plasmodium falciparum Infection in the Chittagong Hill Districts of Bangladesh

“…Agricultural practices have been previously implicated as an occupational risk factor for malaria infection in other settings, including palm oil plantations in Papua New Guinea, irrigated rice paddies in Ethiopia and Cote d'Ivoire, and forest settings in Vietnam. [14][15][16][17] In one study, agricultural irrigation was associated with greater abundance of anopheline vectors in rural Tanzania. 18 In contrast, one study in Peru found that agricultural practices were statistically associated with lower malaria incidence rates.…”