State Health Officials Announce Four More Human West Nile Virus Cases
On Sept. 7, the Massachusetts Department of Public Health (DPH) announced four additional human cases of West Nile virus (WNV) in Massachusetts residents, one of which has resulted in a death, along with the detection of heightened WNV-positive mosquito activity in several areas of the state. On a separate note, health officials have also confirmed the diagnosis of Eastern Equine Encephalitis (EEE) in a horse and completed the case investigation of a Middlesex County resident who died of EEE earlier in August. Based on the totality of these results, DPH has raised the WNV and EEE threat level designations in every Massachusetts city and town to “Moderate” unless already designated at a higher level, and reminds residents everywhere to continue taking precautions against mosquito bites.
“Taken together, all of these findings point to the fact that the threat of mosquito-borne illness is very real in Massachusetts no matter where you live,” said DPH State Epidemiologist Dr. Al DeMaria. “Keep using insect repellant and avoid outdoor activities at dusk and after nightfall until the first hard frost, when we can be sure that the threat of mosquitoes has passed.”
The latest WNV human cases include:
- A Worcester resident in his 60s with severe underlying medical conditions was diagnosed with WNV in mid-August and has since died of the illness. This is the first WNV death in Massachusetts this year; the most recent WNV death here was in 2005. Based on this finding, the WNV threat level has been raised to “High” in Worcester and Auburn. “Our thoughts and prayers are with the family and friends of this gentleman during this difficult time,” stated Worcester Division of Public Health Acting Commissioner Dr. Michael Hirsh. “While we have been fortunate that we have seen a very low number of human West Nile cases, on rare occasion WNV can be very serious. Today’s announcement should not stir a sense of panic in our community, yet stands as a reminder to residents to be cognitive of the preventative measures recommended to avoid infection.”
- A Middlesex County resident in her 60s has been confirmed with WNV and is recovering. The case investigation is still ongoing and her likely place of exposure is still unclear, so changes to WNV threat levels in the area are pending those findings.
- Two human cases of WNV have been identified in residents of Greater Boston, a woman in her 70s and another woman in her 50s, both of whom are recovering. These cases will not result in any changes to current WNV threat levels in the affected area.
Health officials have also detected multiple WNV-positive mosquito pools in Methuen. Based on these results, the WNV threat level has been raised to “High” in Methuen.
DPH is also announcing several findings related to EEE surveillance and case investigations:
Based on further epidemiological review, DPH has determined that the Middlesex County resident who was announced yesterday to have been the first EEE death reported this year was likely exposed in the town of Westborough. As a result, the EEE threat level has been raised to “Critical” in Westborough and to “High” in Grafton, Hopkinton, Northborough, Shrewsbury, Southborough, and Upton. Communities that have been designated at either “Critical” or “High” risk for EEE are urged to cancel any planned evening outdoor events for the remainder of the season until the first hard frost.
DPH has also detected multiple EEE-positive mosquito pools in Mattapoisett. Based on these findings, the EEE threat level has been raised to “High” in Mattapoisett. Communities designated at “High” risk for EEE are urged to cancel any planned evening outdoor events for the remainder of the season until the first hard frost.
Finally, health officials have confirmed that a EEE-infected horse stabled in New York state was likely exposed to the virus while in the town of Halifax in southeastern Massachusetts. This finding does not affect the current EEE threat level in Halifax or the surrounding communities.
WNV infected mosquitoes have been found in 106 communities from nine counties so far during 2012, and health officials predict that the state is on track to have the greatest number of WNV-positive mosquito pools since WNV was first seen in Massachusetts in 2000. There have been nine human cases of WNV in Massachusetts prior to today’s announcement – six in Middlesex County, one in Hampden County and one in Berkshire County. There were six cases of WNV in Massachusetts residents and one in a horse last year. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. WNV is usually transmitted to humans through the bite of an infected mosquito. 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.
There have now been two confirmed human cases of EEE in a Massachusetts resident this year.There were two cases of EEE in August of last year acquired in Massachusetts; a fatal case in a Bristol County man and an infection in a tourist from out of state. EEE activity in both 2010 and 2011 raised public concern and prompted DPH to work with a panel of experts to evaluate and enhance the state’s surveillance and response program. EEE is spread to humans through the bite of an infected mosquito. EEE is a serious disease in all ages and can even cause death.
People have an important role to play in protecting 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. Wearing long-sleeves, long pants and socks when outdoors will 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 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 from 2012, can be found on the Arbovirus Surveillance Information web page at www.mass.gov/dph/wnv or by calling the DPH Epidemiology Program at 617-983-6800.