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Citation Information

Type Journal Article - Malawi Medical Journal
Title Indoor residual spraying (irs) impact after 4 years on Malaria indicators in Nkhoma health delivery area
Volume 25
Issue 4
Publication (Day/Month/Year) 2013
Page numbers 125-186
URL http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4052233/

The Malawi Malaria indicator survey indicated a reduction from 50% to 34% from 2010 to 2012 in the central region. This study was to assess the impact of IRS in 2012 on malaria transmission in Nkhoma after 4 consecutive years of spraying.


Rapid Diagnostic tests (SD Bioline) as well as fever and anemia (using Hemocue Hb 201+ Analyzer) to monitor malaria was used. The study used purposive sampling of clusters where villages were cluster units targeting children aged below five years with no recent malaria. A complete listing of households was done for the study in 2010. The list of households and its population served as a sampling frame. The sample size was calculated at approximately 194 under five children (N=10283) from the study area (p=0.05). The assumption was made that all factors before insecticide spraying were similar in the villages.


The malaria antibody tests data indicated that in the valley (800–1000m above sea level) the malaria prevalence reduction was from 75 to 39%, in the plain villages(1050m) 70% to 10% and the upland (1100–1200m) a reduction from 63% to 2%. The average prevalence in villages used for monitoring is at 15 % as compared to 68% before IRS. This represents a 53 percent reduction in P. falciparum infection in children. The insecticides used in Nkhoma IRS program are pyrethroid. After 2012–2013 spraying round, sensitivity test was carried out. The knock down rate for both Fendona and Icon insecticides used is still above the desired 80 %.

Conclusions and Recommendations

IRS has a dramatic impact on the malaria prevalence but more marked in the areas above 1100m above sea level. IRS should be considered in other districts of Malawi not adherent to the lake as a way to reduce the burden of disease and possibly eradicate malaria in higher altitudes.

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