Hantavirus in focus: what Thailand knows so far after cruise ship cluster abroad

A hantavirus cluster on an international cruise ship, with reported illnesses and deaths, has raised global concern about the risk of a wider outbreak. In an update dated May 4, 2026, the World Health Organization (WHO) said it currently assesses the risk to the global population as low, while continuing to monitor the situation and update its assessment as more information becomes available.

Two main clinical syndromes

Medical experts generally group hantavirus disease into two major syndromes:

1) HFRS (haemorrhagic fever with renal syndrome)

The Medical Genome Center at the Faculty of Medicine, Ramathibodi Hospital, Mahidol University, notes that hantavirus strains found in Europe and Asia are commonly linked to HFRS, a severe illness in which the kidneys can be significantly affected. Reported case fatality rates are typically in the low-to-mid range, often cited at around 1-15%. Importantly, these European/Asian strains have not been recorded as spreading from person to person in the general way people associate with large respiratory outbreaks.

2) HPS (hantavirus pulmonary syndrome)

In the Americas, hantaviruses are associated with HPS, which can progress rapidly to severe respiratory illness. WHO notes that hantavirus infections can have a high case fatality rate in the Americas, and highlights the Andes virus as the best-known example where limited person-to-person transmission has been reported, typically in close and prolonged contact settings.

Researchers stress that confirming the exact strain involved in the cruise ship cluster is critical to understanding the risk profile, and WHO said laboratory investigations, including sequencing, are ongoing.

What is known about hantavirus in Thailand

Thailand has previously documented hantavirus circulation in rodent reservoirs, including strains associated with bandicoot rats (Bandicota), which are considered an important reservoir species.

Past Thai research has also reported evidence of hantavirus-like exposure in humans in earlier decades, consistent with spillover risk from animals to people.

However, HPS has not been reported in Thailand, and a senior official from the Department of Disease Control’s Epidemiology Division was quoted as saying Thailand has not detected any domestic infections or confirmed cases at present, while agencies are working with Chulalongkorn University and the Department of Livestock Development on continued animal surveillance.

Border screening remains the key frontline measure

Because there is currently no known domestic outbreak, officials said Thailand’s main exposure risk is importation from overseas. They said screening and monitoring at international entry and exit points remains the first line of defence, particularly for travellers arriving from higher-risk areas.

The Department of Disease Control advises basic precautions focused on reducing exposure to rodent excreta and contaminated dust, including:

• Clean areas where rodents may live, using wet-cleaning methods rather than dry sweeping
• Wear gloves and a mask while cleaning
• Use disinfectant on floors and surfaces to reduce contamination risk
• Use traps or bait to control rodents around the home
• Store animal feed and food in sealed containers to avoid attracting rodents

Officials said Thailand’s surveillance system remains active and will continue to track developments closely as more confirmed information emerges from the international investigation.