Two confirmed human cases of West Nile Virus (WNV), as well as 90 confirmed mosquito pools that have tested positive have been announced by the Massachusetts Department of Public Health (DPH). An elderly lady from Worcester Country developed symptoms on August 19th and was admitted to hospital – she has since been released. A woman in Middlesex County is still in hospital, but is improving, health authorities report.
Although we have reached the end of the summer – Labor Day marks its unofficial end – residents are urged to remember that until the first hard frost of autumn, mosquitoes can continue to become infected with West Nile Virus and Eastern Equine Encephalitis.
Aerial spraying for mosquitoes was carried out in Southeastern Massachusetts last month.
The recent rains, which result in more quantities of standing water, have created favorable conditions for mosquitoes that are capable of carrying both WNV and the Eastern Equine Encephalitis virus.
DPH State Epidemiologist Dr. Al DeMaria, said:
Efforts to reduce the risk of mosquito-borne illness continue across the state. Even so, we all need to continue to take simple, common-sense steps to protect ourselves and our families from mosquito bites.
Residents are reminded that peak biting times are usually from the hours from dusk to dawn. If you can rearrange your outdoor activities that occur in the evening or early morning you may significantly reduce your risk of being bitten, say health authorities.
Wear long-sleeves, long pants and socks when outside.
Use insect repellent that contains N, N-diethyl-m-toluamide (DEET), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus p-methane 3, 8-diol (PMD) or IR3535 – read the instructions for use carefully.
Do not use DEET-containing products on babies less than two months of age, and only in concentrations of up to 30% maximum on older children. Oil of lemon eucalyptus should not be used on toddlers and babies aged less than three years.
Standing/stagnant water – mosquitoes lay their eggs in stagnant/standing (non-flowing) water. Make sure any stagnant water is drained, check your gutters, flowerpots, wading pools, birdbaths, etc.
Screens – make sure the screens on your windows and doors are tightly-fitting.
West Nile Virus, also known as WNV, is a virus that belongs to the Flaviviridae family – it is spread by the bite of an infected mosquito. Viruses that cause dengue fever, Japanese encephalitis, and yellow fever also belong to the Flaviviridae family.
WNV infects birds mainly, but squirrels, skunks, horses, pets (dogs and cats), bats, chipmunks and domestic rabbits may also become infected. Humans may become infected too.
Most infected humans either have just a skin rash, headache or no symptoms at all. A small percentage of infected individuals develop complications such as encephalitis (inflammation of the brain), myelitis (inflammation of the spinal cord), or meningitis (inflammation of tissues surrounding the brain and spinal cord), which are potentially fatal.
Individuals with weakened immune systems, chronic diseases, as well as very elderly people have a higher risk of complications.
At least 15,000 people in the United States have tested positive for WNV since 1999 – over 500 of them have died, occording to the CDC (Centers for Disease Control and Prevention), USA. Authorities say the real number of human infections is much higher, because those with either no symptoms or very mild ones would not have sought medical help.
A bird-mosquito life cycle maintains West Nile virus in the environment. According to the U.S. Geological Survey’s National Wildlife Health Center, American crows (Corvus brachyrhynchos) and other corvids (e.g., blue jays) seem more susceptible to fatal infection – nobody knows why. The death of these birds has allowed many local health departments to utilize dead birds as an indicator of the virus emergence or re-emergence in their areas.
Click here to read more about West Nile Virus.
Source: Massachusetts Department of Public Health, Medical News Today archives.
Written by Christian Nordqvist