A virus that typically affects marine animals has caused glaucoma-like symptoms and even irreversible vision loss in a small but growing group of people in China.
It is the first time that a virus originating in aquatic animals has been recorded to have infected humans and caused a disease.
The cases are thought to have arisen after the consumption of raw seafood and the handling of aquatic animals, but there are also signs of possible transmission between people.
“The fact that this virus can infect invertebrates, fish and mammals It’s quite remarkable,” he says. Edward Holmesfrom the University of Sydney, Australia, cited by . “I can’t think of any virus with such a wide host range.”
The cases of the call viral anterior uveitis with persistent ocular hypertension (POH-VAU) have been increasing in China, without a clear cause. The disease is characterized by inflammation and high pressure inside the eyesimilar to glaucoma, which damages the optic nerve and can cause vision loss.
To understand why cases are rising, a team of researchers, including scientists from the Chinese Academy of Fisheries Sciences in Qingdao, recruited 70 people in China who were diagnosed with the condition between January 2022 and April 2025.
Researchers tested this group for the virus CMV (covert mortality nodavirus), which infects a variety of marine animals, and all 70 tests came back positive.
“To date, no viruses originating from aquatic animals had demonstrated infect humans and cause disease directly”, write the researchers in their presentation of the results, recently published in Nature Microbiology.
Patients received medication to relieve swellingo, but about 1/3 still ended up require surgeryand one person developed irreversible vision loss.
To better understand the virus, researchers infected micewho developed “evident pathological changes in the corneain the iris and retina” within a month. They also observed that mice sharing the same water were able to transmit the virus between each other.
Of the 70 people studied, more than half treated aquatic animals in a domestic environment, which may have been the origin of infections. But the team emphasizes that around 16% were consumers of raw aquatic products or had close contact with high-risk groups.
There is no direct proof of person-to-person infection. Still, when researchers conducted an epidemiological study, they identified “a distinct subgroup of urban POH-VAU patients” who had neither had contact with aquatic animals nor had other risk factors beyond close contact with family members.
These family members were allegedly at high risk of contracting CMNV and presented hand wounds at the time when they handled aquatic animals. This suggests that the virus can spread within familiesfor example through sharing utensilssay researchers.
Holmes finds it plausible that the pathogen be more prevalent than you think. “I think it is very likely that the virus is present in other species that we have not yet analyzed,” he says. “It also cannot be completely excluded that there passed first by another speciesmaybe even another mammal.”
The researchers argue that this passage of CMNV from marine animals to humans represents a new risk to biosafety. Still, Holmes points out that there is no clear evidence of transmission between people.
“It’s not an epidemic”, he states.
