In MalariaWorld this week there is an interesting article. ‘Malaria incidence rose following the introduction of neonicotinoid-based IRS in selected districts in northern Ghana: An observational analysis’ by Coleman et al described how there was a significant increase in the occurrence of malaria (26%) when nicotinamide insecticides replaced organophosphates in IRS programmes in Ghana from 2015-2022.
A decrease had been seen earlier when pyrethroids were replaced with organophosphates and in one district the incidence decreased again when organophosphates were reintroduced instead of neonicotinoids. The reason given for the changes to the insecticide used was Ghana’s insecticide resistance management plan, which promotes the rotation of insecticides with different modes of action to slow the development of resistance.
The paper contains no data on the effect on mosquito populations as a result of these changes. Clearly, the assumption based on the hypothesis that mosquitos spread malaria is that the increase when the neonicotinoid were introduced was due to reduced effectiveness at eliminating mosquitos. However, at the time of introduction to IRS programme neonicotinoids were already in widespread use for agriculture so they must be effective. The authors opine that the widespread use has caused resistance in Anopheles mosquitos. However, they also report that testing in 2017 found that Anopheles mosquitos were susceptible to Clothianidin, one of the commonly used neonicotinoids, in high usage cotton producing areas.
Clearly, there are health risks as a result of spraying potent toxins indoors. And a study ‘Effects of Neonicotinoid Pesticide Exposure on Human Health: A Systematic Review’ by Cimino et al found chronic neonic exposure and adverse developmental or neurological outcomes, including tetralogy of Fallot, anencephaly, autism spectrum disorder, and a symptom cluster including memory loss and finger tremor.
Perhaps instead malaria is an illness of poverty exacerbated by exposure to toxins. Perhaps what this study shows is that neonicotinoids are more harmful to human health than the other insecticide used.