A virus once thought to affect only aquatic animals may be linked to the development of eye disease in humans. The pathogen in question is covert mortality nodavirus (CMNV), which has been drawing increasing attention from researchers.
Scientists became interested after observing a rise in cases of persistent ocular hypertension, known as viral anterior uveitis (POH-VAU), in China. This condition involves inflammation in the front part of the eye and a significant increase in intraocular pressure. At the same time, standard laboratory tests failed to detect common viral causes, including herpesviruses.
In the study, researchers reviewed data from 70 patients treated between 2022 and 2025. During surgical procedures, eye tissue samples were collected and examined using electron microscopy. The team found viral particles approximately 25 nanometers in size, with a shape consistent with CMNV. No similar structures were detected in samples from healthy volunteers.
To confirm the identification, the scientists used antibodies specific to CMNV. Genetic testing showed a near-complete match—98.96%—with strains previously found in marine organisms.
The researchers also tested whether the virus could cause disease. Experiments in cell cultures and laboratory mice showed that infection produced symptoms similar to those seen in humans, including elevated intraocular pressure.
An analysis of possible risk factors suggested that about 75% of patients had contact with raw seafood—either through unprotected handling at work or by eating it raw.
The authors say this is the first evidence of a potential link between a waterborne virus and a specific eye disorder in humans. CMNV has already been detected in dozens of marine species worldwide, from Asia to Antarctica, indicating it may be widely distributed in aquatic environments.