For the first time, a marine virus has been transferred to humans

A pathogen previously known only in aquatic animals has made the famous "species leap", infecting a human being and causing a serious eye infection with permanent loss of sight.

These are the findings of a study published in Nature Microbiology, cited by infectiologist Matteo Bassetti.

The virus in question is called Covert Mortality Nodavirus, and was previously thought to infect only invertebrates and fish - shrimps, crustaceans - with no risk to humans.

The study published in Nature Microbiology is the first systematic attempt to link Covert Mortality Nodavirus (CMNV) to a human pathology. The researchers identified the virus in the ocular tissues of the patients analyzed, but spoke of an "association with an emerging disease" rather than a definitively demonstrated causal link.

In humans, CMNV causes a condition known as persistent hypertensive viral anterior uveitis: severe inflammation accompanied by a dangerous rise in intraocular pressure, with symptoms similar to those of glaucoma. Left untreated, it can lead to irreversible visual damage and blindness.

Although the clinical picture is now well described, it remains to be determined whether the virus is a direct cause of the pathology or a cofactor involved in predisposing conditions. This is a crucial step: in scientific literature, distinguishing the simple presence of a pathogen from its causal responsibility requires further confirmation.

Transmission seems to occur mainly through direct contact with raw seafood or prolonged handling of aquatic species. Documented cases mainly concern people who work in close contact with marine animals on a daily basis. But the most striking fact goes beyond the isolated clinical case.

The possible passage of a virus typical of invertebrates and fish to humans is part of a wider context of transformation of marine ecosystems, increasingly influenced by climate change, intensification of aquaculture and increased human exposure. In this scenario, even pathogens hitherto considered confined to very specific ecological niches may find new opportunities for adaptation.

What worries researchers most is the exceptional adaptability of the virus, capable of infecting invertebrates, fish and mammals.

The oceans now represent a new frontier for infectious diseases likely to have a direct impact on human health, warns Bassetti, emphasizing that this event marks an unprecedented precedent.

More than a "first time" in the strict sense of the word - species hopping has been known for decades - this is one of the first documented cases involving a virus typically associated with the marine environment and invertebrates.

At this stage, there is no evidence of human-to-human transmission or widespread risk to the population. The case does, however, open up a new front for research: the oceans, increasingly interconnected with human activities, could become a new emerging frontier for infectious diseases.
 

(©GreenMe.it 2026 / Managing Editor: Malvina Parker - The Global Nature / Pic: ©Unsplash)