By Phil London
The Massachusetts Department of Public Health announced two additional human cases of the West Nile Virus in the state Tuesday, following their Sept. 10 raising of Boston’s risk level to “high.”
The newest cases included a woman in her 70s exposed in Essex County and in Middlesex candy where a man in his 60s was exposed. This brings the total number of West Nile virus cases in the state to six, with one animal case reported.
“There are large numbers of mosquitoes carrying West Nile virus right now in parts of Massachusetts due to a nearly perfect combination of periodic rain and warm temperatures,” Acting Public Health Commissioner Margret Cooke said in a Sept. 14 press release.
Boxford, Essex, Georgetown, Hamilton, Ipswich, Manchester, Newbury, Rowley and Topsfield — towns in Essex County — were raised to “moderate” risk after the two new cases were found.
The DPH raised the risk level of 27 communities in the state from moderate to high because of “the occurrence of both animal and human cases, above-average populations of the Culex mosquitoes that carry West Nile Virus, recent rainfall and continued weather favorable for mosquito activity,” according to a separate press release issued last Friday.
According to that release, towns in Essex County, Norfolk County, Middlesex County and Suffolk County were raised to high risk. For Suffolk County, Boston, Chelsea, Revere and Winthrop are affected.
“September is the month when we are most likely to see people get infected with West Nile virus,” Cooke said in the release.
The virus is usually transmitted to humans through the bite of an infected mosquito.
“It is also important to know that as overnight temperatures get cooler, mosquito activity right around dusk and dawn may be more intense,” Cooke said in the Sept. 10 release.
Paul Beninger, associate professor of public health and community medicine at Tufts University, said the West Nile virus has “gone from non-existent to being the most common” virus within the past two decades.
“It has a natural cycle,” Beninger said. “It starts to become common in the summer, and then it drops off in the mid-to-late fall, and then it disappears with the first frost … and then the cycle starts again in late spring.”
Laura Corlin, assistant professor of public health and community medicine at Tufts University School of Medicine, wrote in an email that there are several ways in which Bostonians can protect themselves from contracting the West Nile Virus.
“We can wear long-sleeved shirts and pants and use insect repellent with DEET,” Corlin wrote. “We can protect ourselves by ensuring roof gutters are cleared of debris and by ensuring screens on windows and doors do not have holes.”
Other prevention methods include removing standing water and replacing the water in birdbaths and other containers every few days, Corlin added in the email.
While the West Nile virus can infect people of all ages, people over the age of 50 are at higher risk for severe disease.
“While we advise everyone to take steps to avoid mosquito bites, this is especially important if you are over the age of 50 or have an immune-compromised condition,” Cooke said in the press release from last Friday.
Although most people infected have no symptoms, when present, Beninger said symptoms might include headache and minimal chills. According to the DPH, symptoms also tend to include fever and flu-like illness.
“One in five people develop any symptoms, and they are usually very mild,” Beninger said.
Compared to COVID-19, Beninger said the West Nile Virus is a much milder disease.
“COVID is going to be [transmitted] from person to person,” Beninger said. “With the West Nile Virus, it’s only communicated by mosquitoes … The exposure risk is much, much smaller, and then the disease itself is much milder.”
Beninger said the West Nile Virus was not present in the United States until 1999 in New York City, which led to a “massive, really almost hysterical response” from the public.
Since there is not a lot of natural balance to contain the population of mosquitos that carry the West Nile Virus, he said it has spread rapidly throughout the country.
The DPH advises people to be aware of peak mosquito hours and protect their animals with vaccinations or veterinarian-approved repellent.
“People have an important role to play in protecting themselves and their loved ones from illnesses caused by mosquitoes,” according to the release.