Healthcare

Wild mice chronic asymptomatic carriers of hantavirus

Rodents can also cause leptospirosis, salmonellosis and other food-borne illnesses as well as 'rat-bite fever', which is why the protection offered by public health and the Nas (National Animal Health Service) is essential in the face of their increasing prevalence in cities

by Fabrizio Pulvirenti *

5 May 2026

3' min read

Translated by AI

Versione italiana

3' min read

Translated by AI

Versione italiana

Cases of probable hantavirus infection recorded on board a cruise ship in the Atlantic understandably triggered alarm.

The name of the virus was enough to generate an uncontrolled spread of concern, even before the nature of the agent in question was fully understood.

Roders to 'watch out for'

Rodents have always been - in epidemiological reality and, if possible, even more so in the collective imagination - carriers of even devastating diseases; yet, at home, we tend as a population to forget about them.

It is worth sharing a few thoughts, not least in light of the imminent arrival of rising temperatures, which, a last year's study by Richmond University, correlates with an increase in the number of rodents in our cities where more inhabitants in urban centres means more waste left lying around.

And it is worth pointing out that they are not exclusive carriers of hantavirus.
Their dangerousness, in terms of the possibility of transmitting infections, is much broader. Rats (Rattus rattus and Rattus norvegicus) are reservoirs or vectors of numerous pathogens:
1) leptospirosis, transmitted through their contaminated urine reaching water or soil;
2) salmonellosis and other food-borne toxins, favoured by contamination of foodstuffs with their excrement;
3) rat-bite fever, caused by Streptobacillus moniliformis.

And then there is history: if the bubonic plague of the 14th century devastated Europe, it was because the rat served as a host for Xenopsylla cheopis, the flea vector of Yersinia pestis. The rodent did not kill directly, but carried those it killed.

Health protection

All this makes rodent population control a real public health issue.

The surveillance work carried out by the local health authorities and the Carabinieri's Anti-Security and Health Units in markets, food warehouses, and collective catering, is one of the least visible but most effective lines of defence at our disposal and should be strengthened, especially with a view to a fully-fledged OneHealth approach.

Our National Health Service (NHS), although in need of structural updating linked to the technological, socio-demographic, scientific and organisational changes that have taken place over almost half a century, has built up a system of preventive controls that help keep very serious dangers to our lives and public health away from us.

This is not a flu

Hantavirus does not behave like a flu. It does not circulate in the air of a crowded dining room, it does not pass through a handshake, it does not spread between passengers like a coronavirus. It belongs to the family Hantaviridae, genus Orthohantavirus, and it is a zoonosis, i.e. an animal infection that occasionally affects humans, whose natural reservoir is wild rodents, asymptomatic chronic carriers.

Contagion in humans occurs by inhalation of aerosols contaminated with infected excretions (urine, dried faeces, saliva) or, more rarely, by direct contact with biological material from the animal.

Interhuman transmission is only solidly documented for the Andes strain, circulating in South America, through a mechanism that is still not fully elucidated.

For all other strains, including European ones such as Puumala and Dobrava, it is not a relevant route of contagion.

No scaremongering

In the case of the infected persons on board the cruise ship, the incubation period is between one and eight weeks, which makes it plausible that exposure occurred before embarkation.

The limited number of cases on board, in a closed and densely populated environment, reinforces this reading, as an active inter-human transmission would have produced quite different numbers.

In the case of hantaviruses, however, the risk for those who have had no contact with infected rodents remains extremely low. What this case requires - as in any zoonosis and even more so when it directly involves humans - is a rigorous epidemiological investigation with identification of the strain, reconstruction of exposure, and definition of the time window, but certainly not alarmism.

* Director of the Infectious Diseases Unit of the Vittorio Emanuele Hospital in Gela (Caltanissetta)