A new study, recently published in PLOS Pathogens, revealed many of the complexities behind the new emerging zoonotic malaria.
"We were very surprised
to find that knowlesi malaria is really two separate zoonoses going on
at the same time,” David Conway, senior author and professor of biology
at the London School of Hygiene & Tropical Medicine, said. “There is
a lot of genetic diversity within each of the parasite types, but the
high level of divergence between them indicates they are probably
different sub-species being transmitted separately, within the same
Two different Plasmodium knowlesi parasite subpopulations cause zoonotic malaria. Each of these parasites are related to different monkey hosts located in Malaysia. Researchers believe these clues may show how the parasite spreads and adapts to humans.
"In most places we surveyed, both parasite types coexist and infect people," Conway said. "If zoonotic transmission continues to be common, it becomes more likely that the two types may hybridize genetically, leading to new possibilities for parasite adaptation to humans or additional mosquito vectors. However, as parasite mating occurs within the mosquito, hybridization would depend on whether the same vector species is sometimes infected by both types, which needs investigation."
The zoonotic malaria parasite called Plasmodium knowlesi is found in forest-dwelling macaques. There have been rising numbers of knowlesi malaria cases in humans over the past few years. Now, the disease is the most common human malaria form found throughout Malaysia. Reports state that it has been spreading across Southeast Asia as well.
"Hybridization between species or sub-species has been seen in other parasites that are associated with the emergence of novel pathogenicity,” Paul Divis, lead author of the study from the London School of Hygiene & Tropical Medicine and UNIMAS, said. “Therefore, the transmission of two types of P. knowlesi in humans might increase the opportunity for evolution of virulence or enhanced transmission."