If you've spent any time outdoors the past few days, you've probably noticed the growing, itchy nuisance caused by mosquitoes. Preventing bites is the best way to decrease the likelihood of getting mosquito-borne illnesses.
Laying their eggs
"All of the rain that has pooled in birdbaths and toy buckets during the past week is about to yield a bumper crop of mosquitoes," said Dr. Richard Gerstein, Chair of Emergency Medicine at Baystate Mary Lane Hospital.
"The main rule when it comes to breeding grounds for mosquitoes is that they need stagnant water in order to lay their eggs," said Dr. Gerstein. "What most people don't realize is the surprising number of areas around their own house where mosquitoes can find the stagnant water they need. Any temporary body of water that is present for more than a week can be a mosquito breeding habitat. Ever flooded tire tracks and footprints in a muddy field have been known to produce dozens of mosquitoes each."
According to the Massachusetts Department of Public Health, there are more than 3,000 different kinds, also called “species” of mosquitoes have been identified worldwide, with more than 150 different kinds of mosquitoes found in North America. Fifty-one different kinds of mosquitoes have been found in Massachusetts.
Only female mosquitoes bite to suck blood and use the blood to make eggs. Mosquitoes are attracted to carbon dioxide, a gas that humans and other animals breathe out and can follow a stream of carbon dioxide from as far as 50 feet away.
Making people sick
"Some mosquitoes carry germs that can make people and some animals sick,” said Dr. Gerstein. “In Massachusetts, the diseases linked to mosquitoes are West Nile virus (WNV) and eastern equine encephalitis (EEE) virus."
EEE is relatively rare in humans, although there are occasional outbreaks in certain regions of the country. Fewer than 100 people have died from EEE in Massachusetts in the past 75 years, according to the Department of Public Health. In the United States, approximately five to ten EEE cases are reported annually. The risk of getting EEE is highest from late July through September when more mosquitoes are present and active.
"It is possible that some people who become infected with mosquito borne viruses may not develop any symptoms or in some cases only flu-like symptoms," said Dr. Gerstein. "The incubation period for the virus from the time of an infected mosquito bite to onset of illness ranges from four to 10 days and the illness can last one to two weeks. Those infected usually develop lifelong immunity."
No treatment for mosquito-borne viruses
Antibiotics are not effective against viruses, and no effective anti-viral drugs have been discovered for the treatment of EEE. Severe illnesses are treated by supportive therapy, which may include hospitalization, respiratory support, IV fluids and prevention of other infections.
West Nile virus (WNV) is a mosquito-carried virus most commonly spread to people through the bite of an infected mosquito.
“The majority of people who are infected with WNV (approximately 80%) will have no symptoms,” said Dr. Gerstein. “A smaller number of people who become infected, less than 20% will have symptoms such as fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands. Less than 1% of people infected with WNV will develop severe illness, including encephalitis or meningitis. There is no specific treatment for WNV infections,” said. Dr. Gerstein. “People with mild WNV infections usually recover on their own. People with severe WNV infections almost always require hospitalization.”
Dr. Gerstein encourages community members to follow The Department of Public Health tips that will help people protect themselves and their loved ones from illnesses caused by mosquitoes:
- 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.
- 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.
- 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. Mosquitoes can begin to multiply in any puddle or standing water that lasts for more than four days, and Mosquito breeding sites can be anywhere. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Remove containers that may hold water in places that are hard to see such as under bushes, porches, decks, or stairs.
- Install or Repair Screens. Keep mosquitoes outside by having tightly-fitting screens on all of your windows and doors.
Learn more about different types of mosquitoes that can spread the virus.
The mission of the Baystate Mary Lane Hospital Emergency Department is to provide timely and exceptional care. With our 30-minute pledge, our goal is for a provider to see every patient within 30 minutes of their arrival at our facility. Check out iTriage, a smartphone-based application for Android and iPhone to see our actual ER wait times.