SAUGUS — The state Department of Public Health notified the town that another mosquito infected with West Nile virus has been found in Saugus.

“This was a mosquito that bites birds, not humans, but it underscores the need for continued vigilance to keep friends and family members safe,” the town posted on its website.

Prior to this detection, the first sample of West Nile virus in Saugus was found on July 29 and a second was found in mid-August.

The department raised the town’s risk level to moderate, the Saugus Board of Health announced on the town’s website. It is one of 47 municipalities in the state to have their West Nile virus risk levels elevated to moderate.

The DPH also announced two additional human cases of West Nile virus in Massachusetts, bringing the total number of human cases this year to four, the town stated on its website.

The risk levels of Cambridge, Everett, Medford, Newton, Somerville, and Watertown have all been raised to high risk for the virus, according to the town.

The town encouraged residents to protect themselves from mosquito bites, especially during the peak hours of the early morning and dusk.

In line with DPH recommendations, the town advised its residents to use insect repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), IR3535, or oil of lemon eucalyptus (p-methane 3, 8-diol [PMD]); wear clothing with long sleeves, long pants, and socks when outdoors to protect one’s skin; and avoid being outside from dusk to dawn, when mosquitoes are most active.

The Boston Public Health Commission reported its first human case of West Nile virus on Aug. 28.

According to the Commonwealth’s website, approximately 80% of people who are infected with the virus do not show symptoms. Approximately 20% show symptoms such as “fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands,” and can also develop a skin rash on their chest, stomach, and back.

Less than 1% of people infected with West Niles virus develop severe illness, including encephalitis or meningitis, the Commonwealth reported. People older than 50 have a higher risk of developing severe illness.