State Health Officials Announce First Three Human Cases and One Horse Case of West Nile Virus

Residents urged to take precautions to avoid mosquito bites...

BOSTON - The Massachusetts Department of Public Health (DPH) today announced the first three human cases of West Nile virus (WNV) in the state this year. One is a woman in her 70s from Worcester County who was hospitalized but has since been discharged. The second is a woman in her 60s from Middlesex County who was not hospitalized during her illness. The third is a woman in her 50s from Suffolk County who was hospitalized but has been discharged. A horse, stabled in Hampshire County, also was infected, became severely ill and had to be euthanized.

On Tuesday, DPH raised the risk level for West Nile virus from low to moderate in every Massachusetts city and town. It was only the second time since WNV was first detected in the commonwealth in 2000 that public health officials have raised the risk level statewide.

“There has been an increase in WNV-infected mosquitoes identified this year throughout the state, an indication that the risk is widespread and ongoing,” said Public Health Commissioner Monica Bharel, MD, MPH. “That means that this year, it is extremely important for people to take steps to avoid mosquito bites including using repellents, wearing clothing to reduce exposed skin, dumping standing water, and moving indoors when you notice mosquitoes biting you.”

“August and September are the months when we typically see more human cases because it is the beginning of the peak season for possible West Nile virus human infections,” said DPH State Epidemiologist Dr. Catherine Brown. “These new human cases illustrate why we informed people about the increased risk for human infections earlier this week.”

In 2017, there were 6 human cases of WNV infection identified in Massachusetts.

WNV is usually transmitted to humans through the bite of an infected mosquito. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. Most people infected with WNV will have no symptoms. When present, WNV symptoms tend to include fever and flu-like illness. In rare cases, more severe illness can occur.

People can take steps to protect themselves and their loved ones from illnesses caused by mosquitoes.

Avoid Mosquito Bites

Apply Insect Repellent when Outdoors. Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)], or IR3535 according to the instructions on the product label. 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. Wear long-sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Mosquito-Proof Your Home

Drain Standing Water. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Check rain gutters and drains. Empty any unused flowerpots and wading pools, and change the water in birdbaths frequently.

Install or Repair Screens. Keep mosquitoes outside by having tightly-fitting screens on all of your windows and doors.

Protect Your Animals

Animal owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools – especially after heavy rains. Water troughs provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas. Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. Owners should also speak with their veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent WNV and EEE. If an animal is diagnosed with WNV or EEE, owners are required to report to DAR, Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) by calling 617-983-6800.

More information, including all WNV and EEE positive results, can be found on the Arbovirus Surveillance Information web page at www.mass.gov/dph/mosquito or by calling the DPH Epidemiology Program at 617-983-6800.


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