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Cambridge Resident Diagnosed with West Nile Virus

Risk level remains "high" in Cambridge

September 29, 2020

The Massachusetts Department of Public Health announced on Sept. 24 that a Middlesex County man in his 40s was diagnosed with West Nile virus.  
The individual, a Cambridge resident, became ill in early September and was never hospitalized.
The resident is the eighth human case of West Nile virus reported in Massachusetts this year and the first Cambridge case.
On Sept. 10, the Massachusetts Department of Public Health raised the risk of West Nile virus infection to “high” in Cambridge, Newton, Somerville, and Watertown. Of the eight human cases reported this year, seven were exposed or live in Middlesex County, including the Cambridge resident.
Most West Nile virus activity this season has occurred in an area around Boston and includes parts of Norfolk, Middlesex, and Essex counties, according to state health officials. Positive mosquito samples were first reported in Cambridge on September 3.

"In Massachusetts, the vast majority of West Nile virus infections happen in August and September when a higher proportion of mosquitoes are carrying the virus," said Claude A. Jacob, Chief Public Health Officer and director of the Cambridge Public Health Department. “Residents should continue to use mosquito repellant and wear long sleeves, pants, and socks when outside in the evening and early morning hours.”
The risk of mosquito-borne disease remains until the first hard frost, which occurs when temperatures reach the upper 20s, even briefly.
Most human West Nile virus infections are mild with no symptoms, but a small number of people become very sick with encephalitis or meningitis. People over 50 and those with weakened immune systems are at greatest risk for severe illness. Symptoms include fever and flu-like illness. More severe symptoms include headache, high fever, neck stiffness, stupor, tremors, muscle weakness, and paralysis.
If you think you have symptoms of West Nile virus, contact your doctor or nurse.
The easiest and best way to prevent mosquito-borne disease is to avoid mosquito bites. Some tips:
  • Apply insect repellent when outdoors. Use insect repellent containing DEET, picaridin, oil of lemon eucalyptus, or IR3535. Follow the directions on the package. DEET products should not be used on infants under two months of age and should be used in concentrations of 30% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.
  • Be aware of peak mosquito hours. The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during evening or early morning.
  • Clothing can help reduce mosquito bites. Wearing long-sleeves, long pants, and socks when outdoors will help keep mosquitoes away from your skin.
  • Get rid of mosquito breeding sites in your yard. Mosquitoes lay their eggs in still water. Empty standing water from flower pots, buckets, barrels, and children’s pools. Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings so water drains out.
  • Make sure that window and door screens fit tightly and are in good condition.
To find out the risk of West Nile virus in individual Massachusetts cities and towns, see: mass.gov/info-details/massachusetts-arbovirus-daily-update.
Additional information about mosquito-borne disease can be found on the state health department website at mass.gov/mosquito-borne-diseases.
For local West Nile virus updates and prevention tips, call the Cambridge Public Health Department at 617-665-3838 or visit the department's West Nile virus web page.

Suzy Feinberg, MPH
Public Information Officer

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