Thailand steps up mpox watch as Clade Ib cases rise

Thailand's Department of Disease Control has stepped up mpox surveillance after cases continued to rise, with the Clade Ib strain now accounting for most infections reported this year.

Dr Montien Kanasawat, director-general of the Department of Disease Control, said on 2 September that 254 confirmed mpox cases had been reported in Thailand between 1 January and 23 August 2026. The total is higher than during the same period last year.

Of those cases, 193 were Clade I infections, all identified as the Clade Ib sub-lineage. A further 58 cases were Clade II, while three were awaiting confirmation of their sub-lineage.

Clade Ib overtakes previous dominant strain

Dr Montien said the overall situation remained under control, but the figures showed a significant change from recent years: Clade Ib infections have overtaken Clade II cases.

The Clade Ib strain is associated with more severe symptoms and lesions, particularly among people with weakened immune systems, he said. The shift has led health officials to call for more intensive monitoring.

Most patients have been found in Bangkok, surrounding provinces, major cities and tourist provinces. The principal risk factors remain close contact connected with sexual activity, and visiting enclosed or crowded venues.

Symptoms can emerge up to 21 days after exposure

Mpox can spread through close contact with an infected person, including direct contact with rashes, blisters or bodily fluids, or through prolonged close proximity.

The department advised people to maintain good personal hygiene and monitor themselves carefully after a possible exposure. Symptoms can include fever, headache, body aches, swollen lymph nodes, rashes and blisters.

Anyone who develops such symptoms, especially within five to 21 days of a risk exposure, should go to a nearby medical facility and give medical staff a detailed account of the possible exposure.

Clinics and hospitals linked into response

The Department of Disease Control said it had coordinated with health facilities nationwide to strengthen screening and contact tracing. Its response also links sexually transmitted infection and HIV clinics, alongside infection-control measures in healthcare settings.

The department has urged the public to understand the risks and avoid behaviour that could lead to infection.

People seeking further information or advice can contact the Department of Disease Control hotline on 1422.

Join the discussion?

3 September 2026

View full article