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International attention is growing on the Andes hantavirus after the cases recorded on board the Mv Hondius ship. According to the World Health Organization, there are currently 11 cases reported among passengers and crew: nine confirmed and two considered probable. The provisional toll also includes three deaths.
Among the people who were on the ship, four are now under observation in Italy, precisely in Veneto, Tuscany, Campania and Calabria.
The WHO invited all countries involved to maintain high health surveillance, recommending a 42-day quarantine for passengers and crew members starting from the date of disembarkation. “We expect further cases, given the dynamics of spread on a ship and the incubation period of the virus,” warns the UN agency. At the same time, however, the organization specifies that “there are currently no indications of the start of a larger outbreak”.
What is the Andes hantavirus and why does it worry experts
The Andes hantavirus belongs to the family of so-called “New World” hantaviruses, widespread mainly in South America. Unlike many other hantaviruses, transmitted almost exclusively from animals to humans, the Andes virus has a characteristic that has worried the scientific community for years: the possible human-to-human transmission. According to data from the international platform HantavirusLive, 338 cases of hantavirus have been documented worldwide, with 145 people currently under observation in 70 countries. The data, however, does not include China, where these infections have historically been widespread. The Rare Diseases Observatory of the Istituto Superiore di Sanità recalls that in East Asia, particularly between China and South Korea, the forms of haemorrhagic fever associated with hantaviruses continue to cause thousands of cases every year, although with progressively decreasing numbers.
The testing crux: few tools and almost none certified
One of the main problems concerns the diagnosis of the Andes virus. The laboratories can count on a few specific tests and almost all of them are classified as “Research Use Only” (Ruo), therefore authorized exclusively for research activities and not for clinical use. A situation that complicates the work of the regional health structures called to organize surveillance following the indications of the Ministry of Health. “We are entering a phase of active screening, i.e. the identification of people who have come into contact with confirmed cases”, explains to ANSA the clinical microbiologist Francesco Broccolo, from the University of Salento and head of the University Microbiology and Virology UOSD of the PO Vito Fazzi. According to the expert, limiting checks only to symptomatic subjects would be a mistake: “Even those without symptoms could be infectious.”
Asymptomatic transmission and the fears of the scientific community
One of the aspects that most alarms scholars concerns the possibility that the virus can also be transmitted by asymptomatic or pre-symptomatic people. The hypothesis is also supported by the International Society for Hantavirus Research and was documented by a study published in 2023 by the Robert Koch Institute in Berlin in the journal Emerging Infectious Diseases. Research has shown that the Andes virus can be eliminated as early as the first day after infection through the oral mucosa and urine. An element that reinforces the importance of preventive surveillance. “Focusing only on manifest cases means ignoring the hidden part of transmission,” observes Broccolo. “In the initial phase, between the third and tenth day after infection, the virus is already present and the molecular test represents the most sensitive tool for identifying cases”.
The virus changes little: the genetic sequence reassures experts
News considered partially reassuring comes from the genetic analysis of the virus isolated in the patient hospitalized in Zurich. The sequence, made public by the international scientific community, shows a 99% similarity with a strain identified in Argentina in 2018. According to experts, the data suggests that the virus has maintained considerable genetic stability, without accumulating significant mutations in recent years. An important element also on the diagnostic front. “This means that the experimental kits developed on the Argentine strains could also work effectively on the virus currently circulating,” underlines Broccolo. “It is a significant margin of reliability pending specific certified tests”.
Active surveillance and controls: the objective is to avoid new outbreaks
International health authorities are now focusing efforts on contact tracing and monitoring possible secondary cases. The objective, the experts explain, is to quickly identify any positive cases before the symptoms appear, avoiding the creation of new international clusters linked to travel on the Mv Hondius. For this reason, the WHO continues to recommend rigorous monitoring of passengers and crew members in their respective countries of return, while European laboratories work to strengthen diagnostic capacity and surveillance systems.