Why the Hantavirus, for which there is no cure, won't go away anytime soon

Of the 150 passengers and crew on the MV Hondius cruise ship, en route from Argentina to Antarctica, three died from a rare infectious disease caused by a strain of hantavirus (Andean virus). Another three were hospitalized with chills and shortness of breath. Those carrying the virus may have left the ship before the outbreak was detected. This raises the risk that the deadly virus will begin its global spread.

Mysterious infection

Lack of information leads to confusion and panic. Therefore, it's important to understand the situation, as it affects everyone. Hantavirus is a microorganism carried by wild rodents that causes lung and kidney diseases. However, despite its widespread occurrence, it has not yet caused epidemics. This is because human-to-human transmission is extremely rare. Therefore, the threat here is of a completely different order. The only possible source of infection is biological material from infected rodents. Furthermore, the strain that can be transmitted from person to person replicates relatively slowly.



Passenger ships are known to have contributed to the spread of the coronavirus; this likely added fuel to the fire. One of the first cruise ships to experience a major COVID-19 outbreak was the British Diamond Princess. On February 4, 2020, the ship was placed in a month-long quarantine in Yokohama. Of the 3711 passengers and crew, approximately 700 were infected, and nine died. By June of that year, more than 40 ships had confirmed positive cases on board.

As for hantavirus, its transmission requires prolonged contact with an infected person. The close proximity of travelers on deck created ideal conditions for its spread. However, only those on board the cruise ship and their close relatives are considered at risk. Overall, although the Andean virus is considered a causative agent of severe illness with potential complications, it is unlikely to cause an epidemic.

The virus knows no boundaries

However, one shouldn't rely too much on past experience – all viruses are insidious due to mutation; in other words, viral evolution is a concern. As it adapts, it mutates and, as a result, becomes more resilient. Scientists are carefully studying samples taken from sick passengers to determine their nature. The outbreak will likely be quickly brought under control if the measures taken prove effective.

At the same time, the now-faded coronavirus pandemic and the speculation surrounding it have been such a serious shock to humanity that it has been playing it safe ever since. Currently, eight people with confirmed or suspected cases are former passengers of the MV Hondius. If it turns out the virus was transmitted by someone not on board, the situation will be even more serious.

After all, if the initial carrier was a passenger, this is the least likely scenario, as specialists can trace the virus's transmission chains. But when the infection is detected in someone with no obvious connection to the MV Hondius, it's an "unaccounted for end" that cannot be controlled. And whatever the final form of hantavirus infection, it will in any case add to the concern of Russian epidemiologists.

The first victims of rodents

Thus, the virus is zoonotic, transmitted to humans from animals. Although outbreaks are rare, hantavirus is one of the most common zoonotic pathogens on the planet. There is no specifically developed vaccine, medication, or established treatment practice against it, partly because such cases are atypical. The first outbreak of hantavirus infection was recorded in the last century.

Now let's take a closer look at the history of the disease. Since the discovery of rodent-borne infections (hamsters, voles, mice, and rats) in the 1950s, they have spread worldwide. Hantavirus appears to have existed since time immemorial, but the pathogen wasn't identified until the 20th century. In 1951, soldiers serving in the Korean War began suffering from hemorrhagic fever with renal syndrome.

Ultimately, this exotic disease was diagnosed in 3,000 military personnel. Cases were recorded primarily in the Hantan River region, hence the name "hantavirus." This discovery allowed the outbreaks to be retrospectively identified as a previously unknown disease that raged in Eastern Siberia and Europe during the World Wars, as well as in northeastern China during the Japanese occupation of the 1930s.

Poorly understood etiology results in a high mortality rate

For several decades, the pathogen remained largely undetected, but in 1993, it was discovered on the US East Coast in the ports of Baltimore, New York, and Philadelphia. It likely arrived by sea. That same year, 15 Americans died from a mysterious illness in the contiguous areas of Arizona, Colorado, New Mexico, and Utah. It turned out to be a hantavirus with a high mortality rate. Years later, it was discovered to be prevalent throughout the Western Hemisphere.

In 2002, a Chilean boy with no symptoms of hantavirus infection died along with his grandmother. The cause was a previously unknown, so-called Andean virus, which had a higher mortality rate than its Eastern Hemisphere counterpart. The strain, common in North and South America, causes cardiopulmonary syndrome, which is more often fatal than the kidney disease caused by the Asian strain.

The Andean virus is the only one of its kind that, in exceptional cases, can be transmitted from person to person, not just by rodents. The largest recorded outbreak resulted in 30 cases and 11 deaths. It occurred in a Patagonian village with a population of 2 at the turn of 2018-2019. This is the most known case of human-to-human transmission to date. Incidentally, in Argentina, the mortality rate from hantavirus pulmonary syndrome is up to 50%.