Two articles in Malaria World this week describing research in East Africa provide more evidence suggesting that the main factor correlated with malaria is poverty.
‘Household practices and infrastructure associated with high Plasmodium falciparum infection rates among children under five years old in Northern Uganda’ by Echodu et al found housing structures, particularly mud/clay walls and grass-thatched roofs, were significantly associated with higher malaria prevalence (p < 0.001). Children living in houses with cement walls and iron sheet roofs were much less likely to have malaria.
Naturally, the authors linked their findings to hypothesised mosquito transmission by stating that individuals living in houses with intact, plastered walls are less likely to contract malaria compared to those in homes with holes in the walls.
However, the second article, ‘A household randomized-control trial of insecticide-treated screening for malaria control in unimproved houses in Tanzania’ by Odufuwa et al casts doubt on this. In their research, which reminded me a lot of Grassi’s railway study, described in my translation of ‘Studies of a Zoologist about Malaria’, the researchers compared houses with holes fitted with screens to patch holes and those without.
In Chalinze district, Tanzania, 421 households were randomized into two arms. In June-July 2021, one group of households’ houses was fitted with ITS (insecticide treated nets with deltamethrin and piperonyl butoxide) on eaves, windows, and wall holes, while the second group did not receive screening (see picture). After installation, consenting household members (aged ≥ 6 months) were tested for malaria infection using quantitative polymerase chain reaction after the long rainy season (June/July 2022, primary outcome) and the short rainy season (January/February 2022, secondary outcome).
The results were not significant either in occurrence of malaria (as measured with PCR) or even in the number of mosquitos trapped. The authors suggest this could be due to the study design, intervention insecticidal properties and residuality, and the high number of withdrawals of participants from the study. There was a slight reduction in detection of plasmodia using PCR in the improved houses that was significant for school aged children. However, these relatively insignificant benefits are likely due to the unblinded nature of the study.
So what is the real benefit of living in a better house on occurrence of malaria? It is another clue that clearly links the prevalence of malaria to poverty. Those who can afford a better house can also afford better food, more frequent cleaning and better water and sanitation. Until researchers properly consider these factors, there will not find the real causes and cures of the scourge of malaria.