A recent study in mice completed by French researchers suggest that some individuals might be genetically predisposed to have a deadly reaction to West Nile virus (WNV).

The study was published in this week’s issue of the Proceedings of the National Academy of Sciences. A Reuters report explained that the researchers bred a strain of mice that quickly developed encephalitis (brain inflammation), after infection with WNV.

A group of researchers from the Institut Pasteur in Paris found that inbred mice had a mutation in a section of genes coding for production of enzymes that are typically involved in fighting viral infections. This mutation shortened one version of the enzyme, making it less effective. People who contract WNV might have a similar mutation, reported the scientists.

West Nile virus is a neurological disease that is harbored by birds and spread to horses and humans via the bite of an infected mosquito