KOTA KINABALU: There is no evidence that mosquitoes are spreading monkey malaria from humans to humans, but there are challenges in preventing its spread as there are many animal hosts in Malaysia, according to a scientific report on the disease.
This view was reported in a study published by researchers from Universiti Malaysia Sabah (UMS), the Health Ministry, the London School of Hygiene and Tropical Medicine, the National University of Singapore, and Imperial College London.
The experts conducted a mathematical analysis of malaria cases reported in Malaysia from 2012 to 2020.
According to the research, the study was conducted due to the growing concerns of this virus which is spreading from people to mosquitoes and being passed to other back to humans as there was a rise in the cases of P. knowlesi in the country.
The study, however, showed that the increase in cases of Plasmodium knowlesi (monkey malaria) was likely driven by spillover from macaques to mosquitoes and then to people.
P. knowlesi parasite is usually carried by macaques and spreads to people when a mosquito bites an infected macaque and then bites a person.
Prof Kamruddin Ahmed from UMS, a co-author of this study, said this analysis showed that the spatial and temporal patterns of P. knowlesi cases were still consistent with spillover from macaques and there was no evidence of sustained human-mosquito-human transmission.
“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,” he said.
“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 be severe or fatal and remains a critical public health threat,” he said.
Kamruddin said previous evidence shows that this increase in P. knowlesi risks is linked to deforestation, with people working in logging camps or plantations at forest fringes most at risk.
Dr Kimberly Fornace, from London School of Hygiene and Tropical Medicine and the National University of Singapore, said this poses major challenges for malaria control in this region.
She said many of the existing malaria control measures, such as sleeping under bed nets 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,” she added.
The dean of UMS’ Faculty of Medicine and Health Sciences, Prof Dr Mohammad Saffree Jeffree said human cases of P. knowlesi have been identified across Southeast Asia and parts of South Asia.
He said 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.
He said new surveillance and control strategies are urgently needed to address this public health threat and called on the scientific community to continue to conduct rigorous research on malaria in efforts towards the elimination of the disease.
Meanwhile, other co-authors of the study included Hillary Topazian (Imperial College London), Isobel Routledge (Imperial College London), Syafie Asyraf (UMS), Jenarun Jelip (Ministry of Health Malaysia), Kimberly Lindblade (World Health Organization), 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).
The research was funded by the World Health Organization and the Wellcome Trust.