A new scientific study has revealed that Bornean orangutans (Pongo pygmaeus) can be infected with malaria.
The research, published in the Malaria Journal (2025), successfully mapped the complete mitochondrial genome of Plasmodium pitheci — a malaria parasite that lives in the blood of orangutans in Borneo.
The study, conducted by an international team of scientists, involved collecting blood samples from wild and semi-wild orangutans in West, Central, and East Kalimantan (Indonesia), as well as Sabah (Malaysia).
Through advanced genetic sequencing, the researchers identified a 5,871 base pair mitochondrial genome that closely resembles the structure of Plasmodium species known to infect both humans and other primates in Southeast Asia.
“This mitochondrial genome helps clarify the evolutionary relationship between Plasmodium pitheci and other primate malaria parasites in the region,” the authors wrote in their report.
A Close Relative of Human Malaria
The study found that Plasmodium pitheci infects the red blood cells of orangutans and is transmitted through mosquito bites, much like human malaria.
Genetic analysis revealed that this parasite forms a distinct, monophyletic clade, sharing an evolutionary lineage with other primate Plasmodium species.
Out of 48 DNA sequences examined, the scientists identified 27 different haplotypes — an indication of high genetic diversity but low nucleotide variation. This suggests that P. pitheci has long been co-evolving with its orangutan hosts.
Although no evidence shows that this parasite can infect humans, researchers emphasize the need for cross-species disease surveillance, especially in areas where humans and orangutans live in close proximity, such as in logging zones or rehabilitation centers across Borneo.
A Hidden Threat to Conservation
The discovery adds a new layer of concern to the conservation of Bornean orangutans, already classified as critically endangered due to deforestation, habitat fragmentation, and poaching.
Malaria infection could weaken orangutans’ health, potentially reducing their chances of survival in the wild or during rehabilitation.
In primates, Plasmodium infection can cause anemia, fatigue, and immune suppression. These conditions could compromise the success of reintroduction programs and increase mortality among rehabilitated individuals.
“Such infections may undermine conservation efforts, particularly in centers where animal density is high,” the study noted.
Early Detection for Malaria in Orangutans
By decoding the full mitochondrial genome of Plasmodium pitheci, scientists now have the foundation to develop species-specific molecular diagnostic tools. These tools can help detect infection earlier and more accurately, supporting wildlife health monitoring across orangutan habitats.
The study also highlights the need for broader research on malaria parasites in Southeast Asian primates. Compared with Africa, data on Asian primate malaria remains scarce, even though the region hosts diverse species that could act as natural reservoirs for parasite evolution.
While no cases of P. pitheci transmission to humans have been reported, the researchers warn that zoonotic risks should not be ignored. Previous studies have shown that Plasmodium knowlesi — a malaria parasite once thought to infect only macaques — has crossed over to humans in Malaysia and other parts of Southeast Asia.
With humans and orangutans increasingly sharing fragmented forests, scientists stress the importance of integrating wildlife disease monitoring with public health systems to prevent future outbreaks of zoonotic malaria.
The findings affirm that malaria is not unique to humans — it can also affect one of our closest relatives in the animal kingdom. Beyond its implications for orangutan conservation, this discovery deepens scientific understanding of the complex relationship between disease ecology, wildlife, and humans in tropical rainforests. (Wage Erlangga)
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