Taiwan reports 1st imported case of P. knowlesi malaria in 20 years

Taipei, July 2 (CNA) Taiwan has reported a new imported malaria case, marking the first case in 20 years of Plasmodium knowlesi malaria, a zoonotic disease primarily found in Southeast Asia, the Centers for Disease Control (CDC) said Wednesday.

The case involves a foreign man in his 30s who developed symptoms such as fever and dark-colored urine after traveling to Palawan Island in the Philippines in early June.

The man did not take malaria prophylaxis and was bitten by mosquitoes during eco-tourism activities in Palawan Island, CDC spokesman Lo Yi-chun (羅一鈞) said in a media briefing.

Lo said that the patient began experiencing symptoms such as headache, fever, dark urine, muscle pain and drowsiness before entering Taiwan on June 19. As the symptoms persisted, he sought medical attention on June 25.

On June 27, due to breathing difficulties, dizziness and reduced urination, he visited the hospital again and was diagnosed with malaria. He is currently hospitalized, Lo said.

The new case has prompted the CDC to lift the travel alert for the Philippines to Level 1 (Watch) for malaria.

Malaria is a mosquito-borne disease caused by parasites belonging to the genus Plasmodium, transmitted through the bite of infected Anopheles mosquitoes.

It is categorized into several types: Plasmodium falciparum, vivax, ovale, malariae and knowlesi.

Taiwan has not seen any imported P. knowlesi malaria cases in 20 years. The last case was in 2005, involving a Taiwanese man in his 60s who also contracted the disease while engaging in eco-tourism in Palawan.

Wednesday's announcement marks only the second imported case of P. knowlesi malaria in Taiwan on record, according to Lo.

Lo explained that P. knowlesi is a type of malaria that circulates among long-tailed and pig-tailed macaques in Southeast Asia and is transmitted by local Anopheles mosquitoes.

Since 2004, human infections of P. knowlesi have been increasingly reported in countries such as Malaysia, the Philippines, Thailand, Singapore, Vietnam, Myanmar and Indonesia.

Lo added that the only species of Anopheles mosquito still found in Taiwan is Anopheles minimus, mainly present in mountain stream areas in the south and at low density.

Taiwan has had no locally transmitted P. knowlesi malaria cases for several decades due to the absence of animal hosts and Southeast Asian Anopheles mosquitoes. As a result, the risk of local P. knowlesi transmission in Taiwan is considered extremely low.

According to CDC data, as of July 1, Taiwan has recorded a total of 12 imported malaria cases in 2025, the highest for the same period since 2007.