cyhalothrin and Parasitemia

The Government of Tanzania introduced indoor residual spraying (IRS) in Muleba district in north-western Tanzania after frequent malaria epidemics. Malaria parasitological baseline and two cross-sectional follow-up surveys were conducted in villages under the IRS program and those not under IRS to assess the impact of IRS intervention. After two rounds of IRS intervention there was a significant reduction of malaria parasitological indices in both two villages. In IRS villages overall, parasitemia prevalence was reduced by 67.2%, splenomegaly was reduced by 75.8%, whereas anemia was reduced by 50.5%. There was also a decline of malaria parasite density from 896.4 at baseline to 128.8 at second follow-up survey. Similarly, there was also a reduction of malaria parasitological indices in non-IRS villages; however, parasitological indices in IRS villages remained far below the levels in non-IRS villages. The reduction of malaria parasitological indices in non-IRS villages might have been contributed by interventions other than IRS.

Topics: Adolescent; Adult; Anemia; Animals; Anopheles; Child; Child, Preschool; Epidemics; Female; Humans; Infant; Insect Vectors; Insecticides; Malaria; Mosquito Control; Nitriles; Parasitemia; Prevalence; Pyrethrins; Tanzania; Young Adult

Little is known about the impact of indoor residual spraying (IRS) in areas with intense malaria transmission such as sub-Saharan Africa. In Malawi, IRS with lambda-cyhalothrin has been applied annually in an area of intense year-long transmission since 2007. We evaluated the impact of IRS on parasitemia and anemia prevalence in children less than five years of age by using a cross-sectional household survey conducted in 2009, six months after the second IRS spray round. We measured malaria parasitemia and anemia (hemoglobin level < 11 g/dL) in 899 children less than five years of age and used binomial regression to assess the impact of IRS by comparing children living in a household sprayed with IRS (direct IRS) with those in a household not sprayed with IRS, but in an IRS area (indirect IRS) and those living in a household not sprayed with IRS and not in an IRS area (no IRS). In the IRS area, 77% of households reported receiving IRS. Adjusting for bed net use, house construction, and socioeconomic status, we found that receiving direct IRS and indirect IRS were significantly associated with a 33% (95% confidence interval [CI] = 1-54%) and 46% (95% CI = 20-64%) reduction in parasitemia and a 21% (95% CI = 4-34%) and 30% (95% CI = 12-45%) reduction in anemia prevalence, respectively.

Topics: Anemia; Child, Preschool; Cross-Sectional Studies; Family Characteristics; Humans; Insecticides; Malaria; Malawi; Mosquito Control; Nitriles; Parasitemia; Prevalence; Pyrethrins