What is hantavirus, and how is it transmitted? Questions and answers about the outbreak

Nine cases of hantavirus linked to the MV Hondius cruise ship outbreak have now been confirmed by the World Health Organization (WHO), which warned that more infections could still emerge because the virus can have an incubation period of up to six weeks. ADVERTISEMENT ADVERTISEMENT What is hantavirus? Hantaviruses are viruses that naturally infect rodents. The name comes from the Hantan River in South Korea, where the virus was first discovered in 1976. Although many hantavirus species have been identified worldwide, only a limited number are known to infect humans. Depending on the variant, infection can lead to hantavirus cardiopulmonary syndrome (HCPS), a rapidly progressive condition affecting the lungs and heart; haemorrhagic fever with renal syndrome (HFRS), or nephropathia epidemica, a condition affecting the kidneys. Hantaviruses in North, Central, and South America are known to cause HCPS, whereas those found in Europe and Asia can cause HFRS. What is the Andes strain of hantavirus? The Andes virus is part of the hantavirus family and is the only known variant to cause limited human-to-human transmission through close, prolonged contact. There have been no transmissions among humans documented in other kinds of hantavirus, including those found in Europe and Asia. How is hantavirus transmitted? Humans can become infected with hantavirus through contact with contaminated urine, droppings, or the saliva of infected rodents. Activities that involve contact with rodents, such as cleaning enclosed or poorly ventilated spaces, farming, forestry work, and sleeping in rodent-infested environments, increase the risk. Human-to-human transmission is rare and has been documented among household members or intimate partners, according to the World Health Organization. The agency also notes that transmission among people appears most likely during the early phase of illness, when the virus is more transmissible. What is the risk for the general population? Since the beginning of the outbreak, both the WHO and the European Centre for Disease Prevention and Control have considered the transmission to be “very low” for the general population. According to the ECDC, passengers and crew who have symptoms require immediate medical isolation, testing, and medical care, while those who do not have symptoms are asked to quarantine and monitor for symptoms for up to six weeks, the agency said on Monday. The ECDC added that recent genetic sequencing of the virus strongly suggests that the confirmed tested passenger samples are linked to the same source of infection, and that it is not a new variant. “There is currently no evidence that this variant spreads more easily or causes more severe disease than other Andes viruses,” they said. How deadly is it? According to the WHO, hantavirus infections are relatively uncommon worldwide. There is no specific treatment or cure, and care usually focuses on managing symptoms. The case fatality rate is less than 1–15% in Asia and Europe and up to 50% in the Americas. What are the symptoms? In humans, symptoms usually begin between one and eight weeks after exposure, depending on the type of virus. They typically include fever, headache, muscle aches, and gastrointestinal symptoms such as abdominal pain, nausea, or vomiting. How common is hantavirus in Europe? Hantavirus infections are uncommon in Europe. In 2023, the ECDC registered 1,885, down from 2,185 in 2022. Globally, the WHO estimates approximately 10,000 to over 100,000 infections annually, with the largest burden in Asia and Europe. Have there been other outbreaks? One of the most notable reports of a hantavirus outbreak happened in Argentina in 2018-2019. Between 28 October 2018 and 20 January 2019, a total of 34 confirmed infections, including 11 deaths, were reported in Epuyén, Chubut Province. In that outbreak, three symptomatic people attended crowded social events, from which further transmission spread. Once 18 cases had been confirmed, public health officials enforced isolation of those with confirmed cases and self-quarantine of possible contacts.