An Imported Case of Plasmodium knowlesi infection in Taiwan, 2025

DOI: 10.6524/EB.202608_42(16).0001

Meng-Tsen Tsai^1*, Yi-Ting Yang¹, Hsin-I Huang¹, Shih-Fen Hsu², Jen-Jen Hsu², Wan-Lin Hsu¹, Hsiao-Ping Tung¹, Fang-Tzy Wu², Shih-Hao Liu1

2026 Vol.42 NO.16

Correspondence Author： Meng-Tsen Tsai^1*

Abstract：

        Plasmodium knowlesi is the fifth malaria parasite species discovered to infect humans and is currently the only species confirmed to be naturally transmissible between humans and monkeys. Consequently, it is designated as "zoonotic malaria."  
        This report documents the second confirmed case in Taiwan, following the first imported case of P. knowlesi, which was recorded in 2005. The patient, a male foreign national in his 30s, traveled to Palawan, Philippines, from June 2 to June 19, 2025, without taking malaria prophylaxis. Before he arrived in Taiwan, he developed fever, headache, tea-colored urine, myalgia, and lethargy. On June 28, the infection was confirmed via blood smear and real-time polymerase chain reaction (RT-PCR). Following treatment, the patient’s clinical symptoms improved rapidly, and subsequent follow-up blood tests were negative for Plasmodium spp.
        This case serves as an important reminder for travelers to Palawan to strictly apply mosquito-avoidance measures. It is highly recommended that travelers seek consultation at a travel medicine clinic at least one month prior to departure, where a physician can assess individual malaria risk and determine the need for prophylactic medication. If prescribed, prophylaxis must be taken as prescribed.