A fourth case of West Nile Virus has been confirmed in a Boston resident, the Boston Public Health Commission announced on Thursday.

The man, an East Boston resident in his 40s, was hospitalized but has been released.

Earlier this month a woman in her 50s from Beacon Hill, a man in his 40s, from Dorchester and a man in his 50s from Boston were hospitalized with WNV and released.

Last month, the Massachusetts Department of Public Health elevated the WNV threat level for Boston and several surrounding communities after confirming other human cases of WNV in the region. In Boston, many neighborhoods have had mosquito pools test positive for the virus.

Boston public health officials continue to remind residents to take simple precautions to reduce their risk of exposure to mosquitoes. 

“Mosquitoes carrying West Nile are present in Boston, and will be until the first hard frost,” said Dr. Anita Barry, director of the Infectious Disease Bureau at the Boston Public Health Commission. “It’s vital that all residents take some simple precautions to avoid getting bitten.”

Most people infected with WNV are asymptomatic or have mild illness, according to the Boston Public Health Commission. However, in rare cases, illness can be more serious.