Earlier this month, the World Health Organisation notified the public about an outbreak of hantavirus infection following reports of a cluster of passengers with severe respiratory illness aboard a cruise ship carrying 147 passengers and crew members.

According to the Organization, hantavirus is a group of viruses that can cause severe respiratory or kidney diseases in humans. Because the early symptoms often mimic common illnesses like the flu, public awareness of its origins, symptoms, and prevention is critical.

As at May 4, 2026, seven cases, including two laboratory-confirmed cases and five suspected cases of hantavirus had been identified. The outbreak also recorded three deaths, one critically ill patient, and three individuals with mild symptoms.

According to the WHO, illness onset occurred between April 6 and April 28, 2026, and was characterized by fever, gastrointestinal symptoms, rapid progression to pneumonia, acute respiratory distress syndrome, and shock.

While the outbreak is currently being managed through a coordinated international response involving in-depth investigations, case isolation and care, medical evacuation, and laboratory testing, here is what you need to know about the virus.

What is Hantavirus?

Hantaviruses are zoonotic viruses, meaning they are naturally maintained in animal populations and can occasionally spread to humans.

They belong to the Hantaviridae family and were first widely recognized during the Korean War in the early 1950s, although the virus itself was formally isolated later.

Like Lassa fever, the virus is primarily linked to specific rodent hosts such as the deer mouse, rice rat, or cotton rat. While the virus can persist in these rodents for long periods, it does not make the animals appear sick.

According to WHO, geographical location often determines the type of disease caused. Hantaviruses in the Americas generally cause Hantavirus Cardiopulmonary Syndrome (HCPS), while those found in Europe and Asia are more associated with Haemorrhagic Fever with Renal Syndrome (HFRS).

While hantavirus infections are relatively uncommon globally, they are linked to case fatality rates ranging from less than 1% to 15% in Asia and Europe, and up to 50% in the Americas. Worldwide, an estimated 10,000 to more than 100,000 infections are recorded annually, with the highest burden occurring in Asia and Europe.

Can it be transmitted?

Transmission primarily occurs when humans come into contact with the urine, droppings, or saliva of infected rodents.

The most common route of transmission is inhalation. When rodent waste is disturbed, the virus can become airborne, allowing humans to breathe in contaminated particles.

Transmission may also occur through direct contact with broken skin or mucous membranes, and in some cases through rodent bites.

Regarding human-to-human transmission, WHO states that it is extremely rare. To date, only the Andes virus in South America has shown limited evidence of spreading between people, usually through close and prolonged contact, such as among household members.

Symptoms of Hantavirus

According to WHO, symptoms usually begin to appear between one and eight weeks after exposure.

The clinical presentation varies depending on the syndrome developed by the patient, but the early stage is often similar.

• Early phase: Patients typically experience fever, fatigue, and muscle aches, particularly in large muscle groups such as the thighs, hips, and back.
• Respiratory progression (HCPS): In severe cases in the Americas, the disease may rapidly progress to shortness of breath and fluid accumulation in the lungs, leading to respiratory failure.
• Renal progression (HFRS): In Europe and Asia, symptoms may progress to include severe headaches, blurred vision, and acute kidney failure.

Over all, the disease often starts with flu-like symptoms such as fever, fatigue, headache, muscle aches, and, in some cases, gastrointestinal symptoms including nausea, vomiting, diarrhoea, and abdominal pain.

While symptoms appear within two to four weeks after exposure, the incubation period can range from one to eight weeks.

Prevention

Because there is currently no specific vaccine or antiviral treatment licensed for Hantavirus, rodent control remains the primary strategy for prevention.

The WHO emphasizes reducing contact between people and rodent habitats.

Preventive measures include:

• Closing holes and gaps in homes or workplaces to prevent rodents from entering.
• Keeping homes and workplaces clean.
• Avoiding dry sweeping or vacuuming rodent droppings.
• Storing food properly in tightly sealed containers.
• Washing hands regularly.
• Avoiding dry cleaning methods such as sweeping or vacuuming in areas contaminated with rodent droppings, as these actions can release the virus into the air. Instead, wet the area with disinfectant or bleach before cleaning.

Should Nigerians be worried?

Meanwhile, an epidemiologist, Shakir Balogun, clarified that there is currently no cause for panic in Nigeria, noting that the outbreak is linked to a cruise ship cluster.

He explained that the outbreak occurred on a cruise ship travelling near the South Atlantic, and that Nigerians are geographically far removed from the affected area.

Shakir noted that hantavirus is mainly transmitted from rodents to humans, not from person to person, usually through inhalation of air contaminated with rodent urine, droppings, or saliva.

According to him, the risk of a COVID-like global spread is very low, and the World Health Organization has also assessed the risk to the general public as low.

“The risk of a COVID-like pandemic is very remote. No need to panic or be alarmed. According to the WHO, the risk to the general public is low.”

He further advised that prevention should focus on basic hygiene and avoiding contact with rodents, including properly sealing food storage, wearing protective gear when cleaning areas that may contain rodent droppings, washing fruits and vegetables thoroughly, maintaining regular hand hygiene, and avoiding open defecation.

The epidemiologist urged travellers to pay attention to health advisories from the Nigeria Centre for Disease Control and the World Health Organization, especially when visiting or transiting through affected regions.

He confirmed that no cases have been reported in Nigeria, and that the outbreak remains limited to those on the cruise ship.