Hantavirus explained: Early symptoms are mild, but organ failure follows fast

The recent conversations around hantavirus outbreaks have raised concerns worldwide, especially after clusters of infections were reported on a luxury cruise ship.

While the virus can be severe and even life-threatening in some cases, doctors say it spreads very differently from highly contagious respiratory infections like Covid-19.

According to Dr. Neha Rastogi, Senior Consultant, Infectious Disease at Fortis Memorial Research Institute, hantavirus mainly enters the body when people inhale virus particles present in the urine, saliva, or droppings of infected rodents.

Once inside the body, the virus attacks the endothelial cells, which line blood vessels. This causes the blood vessels to become unusually leaky, leading to widespread inflammation and fluid leakage into organs.

“The vascular leakage is the hallmark of hantavirus infection. Depending on the strain, the virus mainly affects either the lungs or the kidneys," Dr. Rastogi explained.

Two major forms of the disease are commonly seen:

• Hantavirus Pulmonary Syndrome (HPS), which mainly affects the lungs
• Hemorrhagic Fever with Renal Syndrome (HFRS), which primarily affects the kidneys

HOW THE DISEASE BEGINS

One of the biggest challenges with hantavirus is that the early symptoms often resemble common viral infections.

The incubation period can range from one to eight weeks after exposure. Initial symptoms usually include fever, fatigue, severe muscle pain, headache, chills, nausea, vomiting, and abdominal discomfort.

“These symptoms are very non-specific and can easily be mistaken for influenza, dengue, or other viral illnesses,” Dr. Rastogi said.

This is why doctors say a person’s exposure history becomes extremely important, especially if they have recently been in rodent-infested spaces, poorly ventilated cabins, storage rooms, sheds, or abandoned buildings.

WHY THE LUNGS AND KIDNEYS ARE VULNERABLE

Although the virus affects blood vessels throughout the body, the lungs and kidneys often become the most severely affected organs.

In HPS, fluid begins leaking into lung tissue, making it difficult for oxygen to pass into the bloodstream. Patients may develop dry cough, chest tightness, breathlessness, and rapidly falling oxygen levels.

In HFRS, the kidneys become inflamed and damaged, leading to reduced urine output, swelling, low blood pressure, bleeding tendencies, and dangerous electrolyte imbalances.

Doctors warn that once organ involvement begins, the condition can worsen very rapidly over a few days.

HOW HANTAVIRUS BECOMES DEADLY

The most dangerous stage occurs when fluid leakage becomes severe enough to trigger respiratory failure, shock, or acute kidney injury.

“In HPS, the lungs can fill with fluid very quickly, leading to critical oxygen deprivation and strain on the heart,” Dr. Rastogi explained.

Mortality rates in severe pulmonary cases can reach nearly 38%, particularly once serious breathing difficulties begin. This is why early intensive care support is considered crucial.

There is currently no specific antiviral cure for hantavirus. Treatment mainly focuses on supportive care, including oxygen therapy, ventilator support, intravenous fluids, blood pressure management, and dialysis if kidney failure develops.

Doctors diagnose the infection through blood tests that detect hantavirus antibodies or molecular tests like RT-PCR during the acute stage of illness.

HOW LONG BEFORE IT BECOMES LIFE-THREATENING?

The incubation period for hantavirus is one to six weeks, or sometimes even longer. That means someone exposed today might not show symptoms for over a month.

Once symptoms appear, things can deteriorate quickly. Early signs often resemble the flu: fever, fatigue, muscle aches. But within days, severe respiratory problems can develop, and patients may need intensive care. Without prompt medical attention, the infection can become fatal.

This long, variable incubation period is part of what makes the current outbreak tricky. Passengers left the ship at various stops over the past month, and some may not know yet whether they're infected.

HUMAN-TO-HUMAN TRANSMISSION RARE

Despite growing public anxiety, experts stress that hantavirus does not spread in the same way as airborne respiratory viruses.

Dr. Aravinda S N, Lead Consultant in Internal Medicine at Aster RV Hospital, said most hantavirus strains are not capable of sustained human-to-human transmission.

“Humans usually contract the virus through direct contact with infected rodents or by inhaling contaminated particles in enclosed spaces,” he explained.

Cleaning rodent waste using dry sweeping or vacuuming can release virus particles into the air, increasing the risk of infection.

“Hantavirus does not have the capacity to spread through large populations the way Covid-19 did,” Dr. Aravinda said.

Instead, outbreaks are often linked to environmental exposure in places with poor sanitation or rodent infestation.

HOW PEOPLE CAN PROTECT THEMSELVES

Doctors say prevention mainly depends on reducing exposure to rodents and contaminated environments.

Experts recommend:

• Keeping homes, storage areas, and workplaces clean
• Sealing holes or gaps that allow rodents indoors
• Storing food properly
• Avoiding dry sweeping of rodent droppings
• Using gloves, masks, and disinfectants while cleaning contaminated areas
• Ensuring proper ventilation in closed spaces

Doctors say awareness is important, but panic is unnecessary.

Unlike highly contagious respiratory viruses, hantavirus outbreaks are usually linked to specific environmental conditions rather than rapid person-to-person spread.

However, because the disease can become severe very quickly, early medical attention remains critical if symptoms appear after possible rodent exposure.

WHAT WE KNOW SO FAR

A suspected hantavirus outbreak aboard the expedition cruise ship MV Hondius has raised global concern after three passengers died, and several others fell ill during the voyage.

The ship, which departed from Argentina and was later anchored off Cape Verde, is now being monitored by international health authorities as contact tracing continues across multiple countries.

Hantavirus spreads mainly because of exposure to infected rodent urine, saliva, or droppings.

WHY IT'S NOT ANOTHER COVID-19

The World Health Organisation is urging calm, saying this is not a repeat of the early days of Covid-19.

WHO chief Tedros Adhanom Ghebreyesus was blunt when he said a press conference, "The risk to the rest of the world is low."

Asked whether this situation resembles the start of the Covid-19 pandemic, he simply put: "No, I don't think so."

Three passengers have died, eight cases have been recorded in total, and contact tracing is underway across Europe and Africa.

The ship, which left Argentina on April 1 for an expedition to Antarctica and remote Atlantic islands, was anchored off Cape Verde since Sunday and is now sailing towards Canary Islands, Spain.

WHAT'S HAPPENING NOW?

Three patients, a 41-year-old Dutch national, a 56-year-old British national, and a 65-year-old German national, were evacuated from the ship and have been transferred to specialised hospitals in Europe.

Two are in serious condition, the third has no symptoms but was in close contact with a German passenger who died on May 2.

The remaining passengers and crew are isolating in their cabins and are reportedly symptom-free. The ship is now heading to Spain's Canary Islands, a journey expected to take three to four days.

Meanwhile, contact tracing continues:

In South Africa, 42 of 62 people who had contact with infected passengers have tested negative, but 20 more still need to be tracked down, including flight crew and travellers who may have left the country.

In Switzerland, a former passenger who left the ship at St. Helena is being treated in Zurich. His wife is self-isolating but has no symptoms.

In South Africa, one British man remains in intensive care after testing positive for the Andes strain.

SHOULD THE PUBLIC BE WORRIED?

Maria Van Kerkhove, the WHO's top epidemic expert, stated the same message: "This is not the next Covid, but it is a serious infectious disease. Most people will never be exposed to this."

Unlike Covid-19, hantavirus doesn't spread easily between people. The Andes strain is unusual in that it can pass from person to person but only through close contact, not casual interaction or airborne transmission in the way Covid spread.

A WHO expert boarded the MV Hondius in Cabo Verde, joined by two doctors from the Netherlands and a specialist from the European Centre for Disease Prevention and Control (ECDC). “Our priorities are to ensure the affected patients receive care, that the remaining passengers on the ship are kept safe and treated with dignity, and to prevent any further spread of the virus,” Dr Tedros said.

Still, for those on the ship or in close contact with confirmed cases, access to medical care is critical. The long incubation period means monitoring will continue for weeks.