Human infections with Plasmodium knowlesi--zoonotic malaria

Area of Science:

• Zoonotic diseases
• Malaria epidemiology
• Parasitology

Background:

• Plasmodium knowlesi, a simian malaria parasite, has emerged as a major public health issue in humans in Sarawak, Malaysian Borneo, since 2004.
• Transmission occurs through the Anopheles leucosphyrus mosquito group, primarily in jungle environments, posing risks to humans entering these areas.
• P. knowlesi is now the most common indigenous malaria in Malaysia, affecting both local populations and travelers.

Purpose of the Study:

• To review the current literature on Plasmodium knowlesi, encompassing its epidemiology, hosts, vectors, pathogenesis, clinical presentation, treatment, and diagnosis.
• To identify knowledge gaps in understanding P. knowlesi infections.
• To propose future research directions for developing effective control measures against this emerging zoonotic malaria.

Main Methods:

• Comprehensive literature review of existing studies on Plasmodium knowlesi.
• Analysis of epidemiological data, host-vector interactions, and clinical case reports.
• Identification of research gaps and formulation of recommendations for future studies.

Main Results:

• Plasmodium knowlesi malaria is continuously reported in Malaysia, with infections ranging from uncomplicated to severe forms.
• At least 10% of P. knowlesi cases present with severe malaria, and 1-2% result in fatalities.
• Parasitemia levels are directly correlated with clinical and laboratory indicators of severe malaria.

Conclusions:

• Plasmodium knowlesi represents a significant and persistent zoonotic threat to human health in Southeast Asia.
• Despite its prevalence, substantial gaps remain in our understanding of P. knowlesi.
• Further research is crucial to implement preemptive strategies and prevent the widespread emergence of this parasite in the human population.