Deadly tropical sandfly behind fatal fever cases in Thailand (2025)

A rare but potentially deadly disease spread by a common sandfly has claimed two lives in Thailand this year, as health chiefs warn locals and travellers to slap on the bug spray and stay alert.

Thailand has recorded over 40 cases of Leishmaniasis, a tropical disease transmitted by sandflies, with two deaths confirmed so far in 2025 – one in Bangkok and the other in Songkhla, according to the Department of Disease Control.

Dr Jurai Wongsawat, a senior medical specialist and spokesperson for the ministry, revealed yesterday, April 24, that the latest patient was a foreign traveller arriving from the Middle East. She explained that although rare, Leishmaniasis has existed in Thailand since 1996, and poses a serious health risk if left untreated.

“Leishmaniasis is a zoonotic disease transmitted by sandflies, not through skin contact. It’s similar to dengue fever in terms of prevention, people must protect themselves from bites.”

The disease comes in two forms, mild and severe. Mild symptoms include small raised bumps on the skin or face which can be treated with medication. But in more serious cases, the parasite can invade internal organs, leading to chronic fever, pale skin, an enlarged spleen, and potentially death, Dr Jurai said.

“The incubation period can be difficult to predict. If symptoms appear, people should get tested and treated immediately.”

With Thailand’s warm climate creating a paradise for insect-borne nasties, health officials are urging the public to wear long sleeves, apply insect repellent, and keep their homes and surroundings clean to avoid bites, KhaoSod reported.

Dr Jurai stressed that while dengue fever often takes centre stage, Leishmaniasis is another vector-borne villain people can’t afford to ignore.

“Protecting yourself from insect bites is essential, no matter how rare the disease might seem.”

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