The variant of the virus that has already caused three deaths on the MV Hondius cruise ship has the ability to cause infections with human-to-human contagion: it can therefore be transmitted from person to person.
The National Institute for Communicable Diseases South African today issued a statement declaring that “the virus isolated from patients on board the MV Hondius cruise ship, currently off the coast of the Canary Islands, is a Andes virus(i.e. “the strain of the Andes”, ed.) whose capacity has been known for years cause infections that can spread between humans via the respiratory route”. Unfortunately, the ability of the virus to transmit from person to person is therefore confirmed. Meanwhile the ship will arrive on Saturday at Tenerifeand there we will provide assistance to the passengers, making them disembark: while the evacuation from the ship has already been carried out of two sick crew members, transferred to specialized European hospitals. According to the Bild newspaper, too a German citizen who tested positive she will soon be transferred to Düsseldorf for treatment, while the on-board doctor is also said to be in very serious conditions. The hantavirus they constitute a family known to virology for decades. I am RNA viruses belonging to the family Hantaviridae and are transmitted to humans mainly through inhalation of aerosols contaminated with urine, saliva or feces of infected rodents. International scientific literature has long described a fundamental fact: in most cases it is zoonotic infections, i.e. acquired from the environment and not through sustained chains of transmission between humans. Clinical manifestations vary according to the viral strain and geographical area. In Europe and Asia it prevails hemorrhagic fever with renal syndrome; in the Americas it is better known hantavirus pulmonary syndromecharacterized by acute respiratory failure, pulmonary edema and possible rapid clinical worsening. Precisely this second form is the one recalled in the news of the last few hours.
The Andes strain is the most delicate point: person-to-person transmission
THE’Andes virus (for which there are currently no treatments – other than symptomatic ones, nor vaccines) was identified in the nineties in Argentina and Chile. It is one of the few hantaviruses for which international literature has documented episodes of person-to-person transmissiongenerally in contexts of close, prolonged and close contact. One of the most cited studies is the one relating to the outbreak that occurred in the province of Chubut between 2018 and 2019. The epidemiological investigation, published in The New England Journal of Medicinereconstructed a transmission chain compatible with human-to-human contagion, with family clusters and close contacts. The Andes exception does not change the general rule, but imposes caution whenever a cluster appears in confined environments, with people who share spacescabins, ventilation systems and close contacts. This is precisely the element that makes a ship a peculiar epidemiological setting. Closed environments, prolonged cohabitation, exposure times and the complexity of reconstructing contacts make it more difficult to precisely distinguish the primary origin of the infection. In fact, the scientific question is not simply “has there been human contagion?”, but rather: Did the initial exposure occur from a common environmental source, or did subsequent human-to-human transmission occur? So far, the available information does not allow definitive conclusions. Sequencing, contact tracing, temporal reconstruction of exposures and detailed clinical-epidemiological analyzes are needed. There is also concern because the passenger from Johannesburg apparently traveled on a scheduled flight after contracting the virus, therefore coming into contact with passengers outside the cruise ship. This makes everything more complicated, as there is a need to trace all contacts and initiate quarantine periods.
Because this episode is mostly about global surveillance
The case of MV Hondius does not indicate, at the state of knowledge, a generalized health emergency for the European population. But it tells precisely how much the geography of infectious diseases has changed. “Regarding the Hantavirus cases reported on a cruise ship,” he notes Enrico Di Rosa, president of Italian Society of Hygiene, Preventive Medicine and Public Health “It is useful to remember that the virus is transmitted mainly through contact with infected rodents or with their excrement. Infections can cause even serious syndromes, but remain rare events in European countries. At the moment there are no reasons for particular concern for the general population: human-to-human transmission is extremely rare. However, episodes like this remind us of how essential it is to maintain high health vigilance”. This is probably the most important point: emerging diseases today do not only travel along traditional ecological corridors. They travel with global mobility: international tourism, cruises, logistics chains, air traffic, rapid transfers between continents. The problem is not the inevitability of new pathogens, but the speed with which they can appear in unexpected contexts. The answer, as Di Rosa underlines again, comes from effective health surveillance systems, early diagnosis, international cooperation And timely exchange of scientific data.
