United States: In November 2017, a rubber plantation worker in the Southern Thailand got sick with fever, chills, and headaches just right after camping in a forest with wild macaques. He went to a malaria clinic, where the present doctors found parasites in his blood that really looked like Plasmodium vivax, which can really causes malaria in Southeast Asia.
Yet, something wasn’t right. Normally, blood cells infected with these parasites are bigger-than these were of the normal size. Subsequent analysis showed that the man was suffering from a different species of Plasmodium which known as P knowlesi which is common in non-human primates and rarely transmitted to human.
As reported by the Gavi.org, while P. knowlesi malaria was not thought to occur in Thailand during that period, he was not the only case. It was only in the subsequent months that the country recorded this unusual increase of infections and possessed 23 cases within one single financial year from October 2017 to September 2018.
Reporting from Bangkok, the Mahidol University researchers looked into half a dozen cases in the Songkhla and Narathiwat provinces and found that all the patients had been to areas where monkeys lived in the wild. “Such cases suggest the possibility of a new menace of P. knowlesi in the southernmost of Thailand,” they added.
After that, human infections in Thailand are still on the rise with over 200 recorded cases of human infected during the first half of the year 2023.
Zoonotic malaria
Malaria is an illness which is caused by minute Plasmodium parasites that are communicated to man through the bite of an infected mosquito. While hundreds of species have been identified in different kinds of animals, only five species that are capable of diseases to human are known and out of these five, P. falciparum and P. vivax are most dangerous to people all over the world.
These are further believed to have initially evolved for infecting humans only after they changed from great apes in Africa tens of thousands of years ago.
Of the 13 species of Plasmodium vectors recorded across Southeast Asia that can infect non-human primates, only two; P. knowlesi and P. cynomolgus, naturally infect humans.
P. knowlesi is the largest concern. While it is widely considered to cause mild to moderate disease in humans, preliminary data from patients admitted to health care facilities in Malaysia indicate that severe disease was present in 6-9% of adults.