What to know about the Hantavirus outbreak aboard Canary Islands-bound ship

The hantavirus cases on the ship created a global concern, though the WHO said that at this stage the “overall public health risk remains low”. Here is what to know.

What is hantavirus?

Named after the Hantan River in South Korea, hantavirus is a family of rodent-borne viruses that can cause serious illness and death in humans. However, the virus-carrying rats and other rodents do not fall ill to the virus.

Human infection primarily occurs through contact with the urine, faeces, or saliva of infected rodents or by touching contaminated surfaces. It is also possible to get the infection by breathing air that contains viral particles stirred up from these droppings, according to the US Centers for Disease Control and Prevention (CDC).

These viruses are generally not known to spread between people. However, some human transmission was recorded for the Andes strain, found in Argentina and Chile. The people on the ship are suspected to have been infected by the Andes hantavirus.

The type of virus varies depending on the region, and each hantavirus is specific to a different rodent host.

Hantavirus pulmonary syndrome (HPS) is endemic to the Western Hemisphere and caused by New World hantaviruses. These are the deadlier of the two variants, killing a third of those who develop respiratory symptoms. The disease progresses from flu symptoms and fatigue to diarrhoea, vomiting and severe respiratory issues.

Haemorrhagic fever with renal syndrome (HFRS) is another group of illnesses caused by so-called Old World hantaviruses, found primarily in Europe, Africa and Asia. HFRS is known to affect around 150,000 people annually, killing between one and 15% of the infected. Among these, the Hantaan and the Dobrava strains cause the most severe impact, while the impacts of Seoul, Saaremaa, and Puumala virus infections are comparatively moderate.

Is it similar to Covid?

Hantavirus and coronavirus are both zoonotic, meaning they are transferred from animals to humans, the mode of transmission, and subsequent spread, is different. Hantavirus rarely transmits from one person to another, which means in most cases infected persons have individually come in contact with the urine, faeces, or saliva of infected rodents or by touching contaminated surfaces. This is different from the coronaviruses which, after having jumped from bats to humans, freely and efficiently spread between human beings.

Both hantaviruses and the coronavirus that caused Covid19 result in serious respiratory illnesses. In the case of hantavirus, the spread is relatively slow and limited, but the fatality is high. According to the WHO, hantavirus infections are associated fatality ratio of up to 50 per cent in the Americas. In Asia and Europe, the fatality rate is less than 15 per cent.

Covid had spread at a much faster rate and had infected hundreds of millions of people worldwide. But its fatality rate was relatively low. Just about 1-2 per cent of the infected people, probably lower, died due to the disease, many of them because of lack of adequate and timely medical care.

Covid primarily affects the respiratory system, progressing to multi-organ failures in extreme cases.

“The pandemic potential of this infection (hantavirus) is low, considering that patients may start experiencing symptoms or die before they pass it on to others,” said Dr Ekta Gupta, virologist from the Institute of Liver and Biliary Sciences and a part of the Covid-19 consortium INSACOG. She adds, though, that she does not work with this type of virus.

Have there been Hantavirus cases in India?

Sporadic hantavirus cases have been reported from India since the early 2000s. There were at least 28 cases reported in a multi-institutional study from 2008 among patients with chronic kidney disease, warehouse workers, and those from the Irula tribe in Tamil Nadu known for catching snakes and rats.

“The presence of hantavirus in India has been speculated for several decades. This is the first time that evidence of its presence has been documented. It is a classic case of ‘you look for more and you will find more’,” Deepak Gadkari, former director of National Institute of Virology wrote in a paper in 2005 in the Indian Journal of Medical Research.

What are the symptoms of hantavirus?

In the case of HPS, flu-like symptoms present within one to eight weeks after exposure, and may include fatigue, fever, and muscle aches early on. As the disease advances, the affected person may experience respiratory difficulties such as shortness of breath and chest tightness as the lungs fill with fluid. The CDC estimates that 38% of people who develop respiratory symptoms may die from the disease.

Symptoms of HFRS appear within one to six weeks of exposure to infected rodents, progressing from sudden fever with intense headaches and nausea. The disease progresses in phases, with low blood pressure, renal failure and internal bleeding becoming increasingly likely.

Is there a cure for a hantavirus infection?

There is no known cure or treatment for HPS, and early detection and treatment are crucial, but some antivirals have helped manage the symptoms. Patients with severe breathing difficulties may need respiratory support like a breathing tube, while dialysis may become necessary as the disease advances.

What precautions can one take?

In regions where hantavirus is prevalent, people need to be especially careful to avoid contact with rodent fluids, droppings and nesting materials. It is advised to clean areas where rats are known to inhibit.

The WHO has advised the passengers and crew aboard the MV Hondius to practise frequent hand hygiene, remain vigilant of the hantavirus symptoms and actively monitor their symptoms for 45 days. The crew is also advised to clean the environment regularly and ensure proper ventilation on the ship, while those experiencing symptoms are advised to inform medical professionals on board and self-isolate, practising respiratory etiquette and masking up.