Which Plasmodium species was originally described in macaques and is now recognized as infecting humans?

Which Plasmodium species was originally described in macaques and is now recognized as infecting humans?

• A. Plasmodium vivax
• B. Plasmodium knowlesi
• C. Plasmodium ovale
• D. Plasmodium malariae

Answer: (B)

This item tests how malaria parasites can originate in non-human primates and later infect people. Plasmodium knowlesi was first described in macaques and is now recognized as a human pathogen, especially in Southeast Asia. Humans acquire it through the same mosquito bites that transmit simian malaria, and its blood-stage form can resemble P. malariae under the microscope, which is why molecular methods are often needed for accurate identification. In contrast, the other species—P. vivax, P. ovale, and P. malariae—are traditionally described as human parasites with no primary macaque origin.

This item tests how malaria parasites can originate in non-human primates and later infect people. Plasmodium knowlesi was first described in macaques and is now recognized as a human pathogen, especially in Southeast Asia. Humans acquire it through the same mosquito bites that transmit simian malaria, and its blood-stage form can resemble P. malariae under the microscope, which is why molecular methods are often needed for accurate identification. In contrast, the other species—P. vivax, P. ovale, and P. malariae—are traditionally described as human parasites with no primary macaque origin.