The phenomenon of diminishing –returns in the use of bed nets and indoor house spraying and the emerging place of antimalarial medicines in the control of malaria in Ugand

Background The mosquito net existed long before it was known that mosquitoes transmitted malaria. Therefore it was not intended for malaria control.
Objectives:To scrutinise the patterns of prevalence and identify any hitherto unknown factors that could explain the findings.
Methods:Retrieval of records on malaria prevalence. Findings:Households sprayed in the previous 12 months or owning at least one ITN: 77.8% and IRS: 31.6% in mid-northern districts. Paradoxically, this was the highest malaria prevalence at 80.1%, hence the phenomenon of diminishing-returns. The urban children (28.6%), those of post-secondary education mothers (14.3%) and in the highest wealth quintile (33.3%) had a lower malaria prevalence than those without education (55.8%) and the less wealthy (67.6%), (p < 0.001). In all, the connection was that the urban (77.4%) and the wealthy (63.8%) sought health care first from hospitals, for proper treatment. Hence the low prevalence is most likely to be due to anti-malarial medicines and not to bed-nets and IRS, since the other findings of the survey show that there are no significant differences in bed nets ownership and usage and IRS in both groups.
Recommendation:Antimalarial medicines should therefore be used to control malaria instead of the nets and IRS.