A virus affecting shrimp and other seafood may also be linked to a newly identified eye disease in humans, which can lead to permanent blindness, according to recent studies.
Researchers in China have found a connection between the covert mortality nodavirus (CMNV) and a condition called persistent ocular hypertension viral anterior uveitis, or POH-VAU. Evidence of the virus was discovered in the eye tissues of patients with POH-VAU, many of whom had recently come into contact with raw seafood or marine animals. Furthermore, CMNV induced similar eye symptoms in infected mice. If these findings are validated, CMNV could become the first virus originating in marine life associated with an eye condition in humans, which could raise health concerns, the researchers suggest.
“This study reveals that an aquatic animal virus is associated with an emerging human disease,” they noted in their paper, published last month in Nature Microbiology.
Marine blindness
POH-VAU is a newly recognized eye condition that involves elevated intraocular pressure and inflammation of the uvea, the eye’s middle layer. Chronic or recurrent cases of viral anterior uveitis, typically caused by certain herpesviruses like the herpes simplex virus, have seen an uptick in POH-VAU cases in China that aren’t linked to these common viruses.
Earlier studies indicated that some POH-VAU patients had viral particles resembling CMNV, a recently identified virus posing significant threats to shrimp farming in Asia and Australia. This prompted the researchers to investigate whether CMNV was indeed responsible for POH-VAU.
They examined 70 patients diagnosed with POH-VAU from January 2022 to April 2025, comparing them with healthy individuals. They again found viral particles in the eye tissues of patients undergoing surgical treatment, similar in shape and size to CMNV, but not in the control group. All patients tested positive for CMNV antibodies, and genetic testing revealed that the virus isolated from humans had a 98.96% match with CMNV samples from aquatic animals. Additionally, when mice were infected with CMNV, they exhibited symptoms akin to those seen in human POH-VAU cases.
How worried should we be?
Of course, more studies are essential to definitively determine the role of CMNV in POH-VAU and assess the likelihood of it causing illness in humans. However, the implications of this discovery, if substantiated, could be concerning.
First, it would indicate that emerging zoonotic diseases—those that transfer from animals to humans—can arise not just on land, but also from the ocean. Additionally, while most cases (around 71%) were linked to direct contact with raw seafood, some cases lacked such clear connections. This raises the possibility that CMNV and POH-VAU might be transmissible between humans, although this remains unverified.
Even if this disease is solely associated with seafood, the risk might be increasing. The researchers also highlighted data that shows CMNV has been identified in 49 aquatic species across various global waters, including those in the Americas and Europe.
