Individual, host-vector interactions and environmental risk factors for Plasmodium knowlesi malaria among at-risk communities in Peninsular Malaysia: A case-control study

Abstract

The uncertainties surrounding P. knowlesi’s ability to be zoonotic have caused it to be “left out”. Highlighting the individual, host-vector interactions and environmental risk factors for this disease were consequential towards more focused and effective prevention and control strategies. This study aims to identify the individual, host-vector interactions, and environmental risk factors for P. knowlesi malaria among at-risk communities in Peninsular Malaysia. A case-control study was conducted involving laboratory-confirmed cases of Plasmodium knowlesi malaria, registered and notified to the online vector disease reporting system, Vekpro Online System, and primarily resided in the study areas for a minimum of three weeks. A locality-matched individual with no history of fever and tested negative for malaria through blood slide and polymerase chain reaction, PCR of the same duration was taken as control. Univariate and multiple logistic regression was applied to evaluate the potential individual, host-vector interactions, and environmental risk factors for knowlesi malaria among respondents using the IBM SPSS Statistics for Windows, Version 26.0. Results showed notably higher cases among males as compared to females (76.1% versus 23.9%). Multiple logistics regression analysis showed being male is 3.51 higher risk (p values < 0.001) to become a case. Respondents whose place of work or study is near the forest edge have 44.0% lower risk (p = 0.030), while those living in the Orang Asli village was 56.0% lower risk as compared to the organized village to become a case (p-value 0.035). These findings demonstrated that gender emerges as an independent individual risk factor, while residing near a forest edge, living in an Orang Asli village, or occupying a brick or wooden workers' longhouse situated in hilly areas reduces the interactions between hosts and vectors, thereby lowering the environmental risk. These attested to different views and approaches aimed at mitigating the risk of knowlesi malaria within this specific population. Thus, all relevant agencies must consider alternative directions in addressing the known risk factors associated with this type of malaria by acknowledging that a one-size-fits-all approach cannot be universally applied, but rather the design of prevention and control programs should be tailored to the unique characteristics of each population.