The death toll from the West Nile virus in New Jersey now stands at four, with fatalities recorded in Burlington, Gloucester, Ocean and Passaic counties.

Justin Sullivan, Getty Images

State health officials say 42 cases of the mosquito-borne illness had been reported around the state as of Friday.Mosquitoes get the virus from feeding on infected birds and then spread it to people they bite.

The elderly and those with weakened immune systems are most at risk of serious health complications.

Cases typically peak in late summer or early fall.

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