Recent Incidence of Human Malaria Caused by Plasmodium knowlesi in the Villages in Kudat Peninsula, Sabah, Malaysia: Mapping of The Infection Risk Using Remote Sensing Data

Abstract

Plasmodium knowlesi (Pk) is a malaria parasite that naturally infects macaque monkeys in Southeast Asia. Pk malaria, the zoonosis transmitted from the infected monkeys to the humans by Anopheles mosquito vectors, is now a serious health problem in Malaysian Borneo. To create a strategic plan to control Pk malaria, it is important to estimate the occurrence of the disease correctly. The rise of Pk malaria has been explained as being due to ecological changes, especially deforestation. In this research, we analysed the time-series satellite images of MODIS (MODerate-resolution Imaging Spectroradiometer) of the Kudat Peninsula in Sabah and created the “Pk risk map” on which the Land-Use and Land-Cover (LULC) information was visualised. The case number of Pk malaria of a village appeared to have a correlation with the quantity of two specific LULC classes, the mosaic landscape of oil palm groves and the nearby land-use patches of dense forest, surrounding the village. Applying a Poisson multivariate regression with a generalised linear mixture model (GLMM), the occurrence of Pk malaria cases was estimated from the population and the quantified LULC distribution on the map. The obtained estimations explained the real case numbers well, when the contribution of another risk factor, possibly the occupation of the villagers, is considered. This implies that the occurrence of the Pk malaria cases of a village can be predictable from the population of the village and the LULC distribution shown around it on the map. The Pk risk map will help to assess the Pk malaria risk distributions quantitatively and to discover the hidden key factors behind the spread of this zoonosis.

Proposed Integrated Control of Zoonotic Plasmodium knowlesi in Southeast Asia Using Themes of One Health

“…Assessment of human and environmental factors associated with knowlesi -malaria risk found that interactions and sighting of macaque species, predominantly Mf , was associated with an increased risk of acquiring P. knowlesi infection [ 66 ]. The findings also support a consistent risk factor profile for knowlesi -malaria with men working as subsistence farmers, especially those who work in palm-oil plantations, with the highest individual transmission risk occurring at the forest fringe [ 19 , 61 , 66 , 77 ]. Investigations into peri-domestic transmission and exposure to P. knowelsi in Sabah, Malaysia, found that the primary vector, An.…”

“…At a local scale in Malaysian Borneo, ~80% of the forest landscape has undergone deforestation or agriculture expansion between 1990 and 2009, leaving only 3–8% of protected forests intact [ 60 ]. Deforestation in this region is typically attributable to the rapid development of industrial plantations [ 61 ], with this trend likely to continue [ 62 ]. When considering these factors, it highlights the potential consequences of decimating ecosystems and the increased threat of zoonotic disease outbreaks [ 58 ].…”

Emerging zoonotic diseases originating in mammals: a systematic review of effects of anthropogenic land‐use change

“…monkeys (Moyes et al 2016). This is a particular problem in Malaysian Borneo, where a risk map was developed to visualise land use and assess malaria risk distributions (Sato et al 2019). Such mapping approaches can help determine the risk factor for vector‐spread protozoa under LUC, enabling people to predict and mitigate outbreaks.…”

“…Viruses of notable concern include henipaviruses in Africa (Pernet et al 2014), Hendra virus in Australia (Wild 2009), and Nipah virus in Malaysia (Field 2009). Likewise, non‐human primates show an increase in zoonotic parasites with fragmentation of forests (Gillespie 2006); parasites include plasmodium (Moyes et al 2016, Sato et al 2019) and a range of helminth species (Klaus et al 2017). In Sri Lanka, habitat fragmentation from deforestation has led to wild animals roaming in nearby neighbourhoods, increasing the exposure of residents to ticks and the risk of tick‐borne infections (Liyanaarachchi et al 2015).…”

“…Our review highlights new emerging approaches to the study of effects of LUC on the spread of mammalian zoonotic diseases, such as risk maps developed for malaria (Sato et al 2019). Similarly, modelling approaches are promising tools for identifying general trends and predicting future consequences, yet we found that they are underutilised.…”