PETALING JAYA: A new study published in Nature Communications shows that increases in cases of Plasmodium knowlesi (malaria monyet) in Malaysia is likely to be driven by spill over from macaques to mosquitoes to people.
Researchers at the Universiti Malaysia Sabah (UMS), Ministry of Health Malaysia, London School of Hygiene and Tropical Medicine, National University of Singapore and Imperial College London conducted a mathematical analysis of malaria cases reported in Malaysia from 2012 – 2020.
P. knowlesi is usually carried by macaques and spread to people when a mosquito bites an infected macaque and then bites a person.
However, the large increase in human P. knowlesi cases in Malaysia prompted concerns that this parasite may be adapting to spread from people to mosquitoes to people. This analysis showed the spatial and temporal patterns of P. knowlesi cases is still consistent with spill over from macaques and there is no evidence of sustained human-mosquito-human transmission.
Prof. Kamruddin Ahmed from the Universiti Malaysia Sabah and a co-author of this study said: “Malaysia through its comprehensive surveillance system, reports the highest number of P. knowlesi cases globally, with Sabah reporting the highest number of cases in Malaysia.
“While other types of human malaria have been eliminated from Malaysia, thousands of cases of P. knowlesi are reported every year in Sabah. This can cause severe or fatal disease and remains a critical public health threat.”
Previous evidence shows that this increase in P. knowlesi risks is strongly linked to deforestation, with people working in logging camps or plantations at forest fringes most at risk.
“This poses major challenges for malaria control in this region. Many of the existing malaria control measures, such as sleeping under bednets and frequent testing for malaria, are not effective when there is a wildlife host. This poses a major barrier for malaria elimination in Malaysia and the region” said Dr. Kimberly Fornace from London School of Hygiene and Tropical Medicine and the National University of Singapore.
Human cases of P. knowlesi have been identified across Southeast Asia and parts of South Asia. While this study demonstrates there is no evidence of P. knowlesi currently spreading between humans, it may be possible for this to change in the future. New surveillance and control strategies are urgently needed to address this public health threat.
The Dean of the Faculty of Medicine and Health Sciences UMS, Professor Dr Mohammad Saffree Jeffree, urges our scientific community to always continue to support and conduct rigorous research on malaria in efforts towards malaria elimination.
Additionally, co-authors of this study also included Hillary Topazian (Imperial College London), Isobel Routledge (Imperial College London), Syafie Asyraf (Universiti Malaysia Sabah), Jenarun Jelip (Ministry of Health Malaysia), Kimberly Lindblade (WHO), Pablo Ruiz Cuenca (London School of Hygiene and Tropical Medicine), Samir Bhatt (Imperial College London), Azra Ghani (Imperial College London) and Chris Drakeley (London School of Hygiene and Tropical Medicine).
This research was funded by the World Health Organization and the Wellcome Trust.
