Taiwan Centers for Disease Control (hereafter referred to as CDC) announced today (the 15th) a new domestically reported case of imported Plasmodium knowlesi malaria, a woman in her 50s of Taiwanese nationality. She traveled to tropical rainforest areas of Malaysia in late July 2026, reported having been bitten by insects, did not take malaria prophylaxis, returned to the country in mid‑August, and developed fever, chills, upper abdominal pain and other symptoms in late August. She sought medical care at a hospital, and after reporting and testing, the infection with Plasmodium knowlesi was confirmed on September 1. This is the first domestic case of imported Plasmodium knowlesi malaria in a Taiwanese national since 2005, and health authorities continue to monitor the case’s health condition.
The CDC states that malaria is a disease transmitted to humans by the bite of infected Anopheles mosquitoes. Depending on the species of Plasmodium, it can be classified as falciparum malaria, vivax malaria, ovale malaria, quartan malaria and Plasmodium knowlesi malaria; falciparum and vivax malaria are the most common, while quartan malaria, ovale malaria and Plasmodium knowlesi malaria are relatively rare. Among them, Plasmodium knowlesi malaria is endemic among long‑tailed and pig‑tailed macaques in Southeast Asia, caused by Plasmodium knowlesi and transmitted by local malaria mosquitoes. Since 2004, cases of human infection with Plasmodium knowlesi have been increasingly reported in Southeast Asian countries, including Malaysia, the Philippines, Thailand, Singapore, Vietnam, Myanmar, and Indonesia. Most infected individuals may develop symptoms within 7 to 30 days, with early symptoms similar to influenza, mainly fever, and may also experience headache, muscle aches, joint pain, nausea, vomiting, and fatigue. Without appropriate treatment, several days after onset, intermittent or periodic chills and shivering, fever, and sweating may appear. Severe cases can lead to splenomegaly, jaundice, shock, liver and kidney failure, pulmonary edema, acute encephalopathy, coma, or even death. Vivax and ovale malaria can remain dormant in the liver for weeks or even years before relapsing, so after treating the blood‑stage parasites, a course of Primaquine tablets must be taken for radical cure to prevent relapse.
CDC monitoring data show that as of September 14 this year, a total of six imported cases have been recorded, with infection sources: Ethiopia (2 cases), Pakistan, Nigeria, Malaysia, and others (multiple‑country travel history) each 1 case, ages ranging from the 20s to the 70s. The infection types include four vivax malaria cases, and one each of falciparum malaria and Plasmodium knowlesi malaria. Additionally, statistics for the past ten years (2017‑2026) show a cumulative 71 domestically diagnosed malaria cases, all imported, primarily from African countries, with the detected pathogens mainly falciparum malaria, followed by vivax malaria. Global malaria incidence has been rising in recent years, with an estimated over 200 million infections annually, causing about 600,000 deaths, largely concentrated in Africa such as Nigeria. In the Asia‑Pacific region, malaria is common in Indonesia, India, and Malaysia. Malaysia records the highest number of Plasmodium knowlesi cases in Southeast Asia, reporting about 2,000‑3,000 cases annually in recent years; as of week 12 this year, 490 cases have been reported, an increase compared with the same period in 2025. Patients are mainly distributed in Sabah and Sarawak on Borneo. Because Plasmodium knowlesi is often transmitted from macaques to humans via mosquitoes, forested areas where humans and wildlife interact closely are high‑risk zones; the province of Yogyakarta in Indonesia has seen a rise in Plasmodium knowlesi cases; Palawan in the Philippines is an endemic area, with over 1,300 cases reported in the first half of this year; several European countries have also reported imported Plasmodium knowlesi cases from Southeast Asia.
The CDC urges the public traveling to malaria‑endemic regions such as Africa, Southeast Asia, Oceania, and Central and South America to consult a travel‑medicine clinic at least one month before departure, and to follow the physician’s instructions to continuously take malaria prophylaxis before, during, and after travel. During travel, wear light‑colored long‑sleeved shirts and long pants, apply government‑approved insect repellent, and try to stay in accommodations with screened doors and windows. After returning, if any suspected symptoms appear, seek medical care promptly and inform the physician of travel history and any malaria prophylaxis taken, for diagnostic and treatment reference. For more information, please visit the CDC’s global website (https://www.cdc.gov.tw), or call the toll‑free epidemic prevention hotline 1922 (or 0800-001922) for inquiries.
Source: Centers for Disease Control
Data compiled: Infection Control Office
