As one of Maryland’s rainiest summers comes to a close, the state has seen a corresponding spike in cases of West Nile virus.

So far this year, 38 Marylanders have been infected with West Nile, which mosquitoes get from birds and pass on to humans or animals after biting them. That’s seven times higher than in 2017, which saw five cases. There were six cases in 2016, but Maryland saw another high number, 46 cases, in 2015.

The state health department does not release details about victims because of privacy laws.

Most people with the disease show no symptoms, but in severe cases West Nile can attack the central nervous system.

There is no vaccine to treat West Nile. Pain killers can help with some symptoms, but some people may need to be hospitalized and given intravenous fluids.