Malaria burden in Nchelenge: Are control interventions failing?

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Findings of an ongoing international centres of excellence in malaria research (ICEMR) study being done by TDRC scientists entitled ‘’Malaria transmission and the impact of control efforts in Nchelenge’’ have showed that there has been no significant change in the incidence of malaria in Nchelenge from May 2012 (when the project begun) to June 2015. This is despite the various control interventions being implemented in the district. This study is funded by the National Institutes of Health (NIH) in collaboration with Johns Hopkins University, School of Public Health.
The first mosquito surveys carried out in Nchelenge in March 2012 revealed high rates of insecticide resistance mainly to the major insecticides used in vector control in Zambia namely, DDT, carbamates and pyrethroids. Subsequent studies conducted in 2012, 2013 and 2014, confirmed the initial findings and raised questions about the continued use of bed nets treated with pyrethroids. The TDRC and partners recommended a new long-lasting formulation of an insecticide called pirimiphos-methyl (Actellic CS), an organophosphate, for use in the National Malaria Control Programme.
In 2014 the Africa Indoor Residual Spraying (AIRS) project, funded by the President’s Malaria Initiative (PMI) carried out indoor residual spraying using the recommended insecticide, Actellic CS. This insecticide was subjected to a six-month evaluation to determine its impact on the prevalence of malaria and mosquito population densities. The findings of the evaluation showed no difference in terms of malaria prevalence and vector population densities between sprayed and unsprayed areas.
Dr. Tamaki Kobayashi, a researcher from the Johns Hopkins Malaria Research Institute in her presentation on the findings of the study, indicated that the insignificant difference simply shows that the control interventions being implemented haven’t been working as expected. “This calls for a deeper understanding of the causes of this failure. We need to investigate why is it that we are not getting the desired results.” said Dr. Kobayashi.
There are a number of factors that perhaps could be partly attributed to the failure. One of them could be that the IRS activities had not been concentrated in areas where high population densities of the mosquitoes were found including the limited number of sprays per year. According to Mr. Mbanga Muleba, the study entomologist IRS activities should be concentrated in areas where much of the mosquitoes are present and probably to be sprayed twice every year. He has also suggested that the Nchelenge communities should be encouraged to continue using LLINs which would still provide a barrier and hence protect them from mosquito bites. The scientists also pointed out other factors that were threats to malaria control in the district which included insecticide resistance, widespread mosquito distribution, human population movement leading to cross-border malaria transmission with the Democratic Republic of Congo (DRC).
It has also been shown that malaria parasites in the district found concentrated mainly in among school going children who are also not normally included in the activities of the malaria control programme. Dr. Modest Mulenga, the director of TDRC who is also the study principal investigator, has suggested to study the effect of routine screening and treatment of asymptomatic cases in primary schools on the prevalence of malaria in the district.
These findings were shared with the Nchelenge community during a dissemination meeting organized by TDRC held on 10th February 2016 in Nchelenge. The meeting was officiated by the Nchelenge District Commissioner was attended by different stakeholders including the Provincial Medical Officer for Luapula Province, the local Chief Kambwali’s representatives, the District Medical Officer and other Heads of Government departments in Nchelenge district and other people from within and outside Nchelenge district