Estimating Geographical Variation in the Risk of Zoonotic Plasmodium knowlesi Infection in Countries Eliminating Malaria

Abstract

BackgroundInfection by the simian malaria parasite, Plasmodium knowlesi, can lead to severe and fatal disease in humans, and is the most common cause of malaria in parts of Malaysia. Despite being a serious public health concern, the geographical distribution of P. knowlesi malaria risk is poorly understood because the parasite is often misidentified as one of the human malarias. Human cases have been confirmed in at least nine Southeast Asian countries, many of which are making progress towards eliminating the human malarias. Understanding the geographical distribution of P. knowlesi is important for identifying areas where malaria transmission will continue after the human malarias have been eliminated.Methodology/Principal FindingsA total of 439 records of P. knowlesi infections in humans, macaque reservoir and vector species were collated. To predict spatial variation in disease risk, a model was fitted using records from countries where the infection data coverage is high. Predictions were then made throughout Southeast Asia, including regions where infection data are sparse. The resulting map predicts areas of high risk for P. knowlesi infection in a number of countries that are forecast to be malaria-free by 2025 (Malaysia, Cambodia, Thailand and Vietnam) as well as countries projected to be eliminating malaria (Myanmar, Laos, Indonesia and the Philippines).Conclusions/SignificanceWe have produced the first map of P. knowlesi malaria risk, at a fine-scale resolution, to identify priority areas for surveillance based on regions with sparse data and high estimated risk. Our map provides an initial evidence base to better understand the spatial distribution of this disease and its potential wider contribution to malaria incidence. Considering malaria elimination goals, areas for prioritised surveillance are identified.

Perceptions and prevention practices on malaria among the indigenous Orang Asli community in Kelantan, Peninsular Malaysia

“…The probability of introduced cases of the simian malaria parasite in areas where monkeys live near human settlements would be highly likely. As indigenous populations residing primarily within natural jungle habitats and typically practising agro-subsistence nomadic lifestyle, their communities are always at risk of persistence exposure to zoonotic malaria as they come into close contact with macaques or other monkey species, which could harbour simian Plasmodium species particularly P. knowlesi and P. cynomolgi (25)(26)(27)(28)(29)(30)(31). A recent report of P. knowlesi isolated from patients from Gua Musang showed that this parasite is genetically distinguished from those of the Malaysian Borneo, indicating different evolutionary history of this parasite (32).…”

In vitro and in vivo antimalarial activity of the volatile oil of Cyperus articulatus (Cyperaceae)

“…ovale Stephens, 1922;P. malariae Grassi & Feletti, 1889(França et al 2008 and P. knowlesi Sinton and Mulligan 1933(Rossati et al 2016, Shearer et al 2016. The transmission to humans occurs through the female bite of Anopheles Meigen 1818 mosquitoes infected with the protozoan.…”

Comparative evaluation of two commercial real-time PCR kits (QuantiFast™ and abTES™) for the detection of Plasmodium knowlesi and other Plasmodium species in Sabah, Malaysia

“…Within Malaysia, P. knowlesi is now the most common cause of malaria in humans, accounting for almost all reported malaria cases [1,3], including over 2000 noti cations in the state of Sabah in 2017 [2]. Con rmed P. knowlesi human infections have now been reported in all areas of Southeast Asia where the primary reservoir macaque hosts and Anopheles leucosphyrus group mosquitoes are present [4][5][6].…”