News Flash

Mosquitoes can spread diseases that make you sick. In Massachusetts, mosquitoes can give you eastern equine encephalitis (EEE) virus and West Nile virus (WNV).

Eastern equine encephalitis (EEE) is a rare but serious disease. Symptoms include high fever, stiff neck, headache, and lack of energy. Swelling of the brain, called encephalitis, is the most dangerous complication, and can cause coma and death. Most cases in Massachusetts occur in the southeastern part of the state.

West Nile virus infections are more common than EEE, but most do not cause any symptoms. Mild WNV infections can cause fever, headache and body aches, often with a skin rash and swollen lymph glands. A small number of people (less than 1 out of 100) who get infected with West Nile virus develop more serious illness; this is more common in people over the age of 50. Symptoms of serious illness include headache, high fever, stiff neck, confusion, muscle weakness, tremors (shaking), convulsions, coma, paralysis swelling of the brain, and sometimes death.

Only a small number of mosquitoes are infected at any given time, so being bitten by a mosquito does not mean you will get sick. However, the best way to avoid both of these illnesses is to prevent mosquito bites.

Different repellents work against different bugs. It is important to look at the active ingredient on the product label. Repellents that contain DEET, permethrin, picaridin or IR3535 provide protection against mosquitoes. In addition, oil of lemon eucalyptus has been found to provide as much protection as low concentrations of DEET.

DEET products should not be used on infants under 2 months of age. Children older than two months should use products with DEET concentrations of 30% or less. In general, the higher the percentage of DEET, the longer it lasts. Products with DEET concentrations higher than 30% do not provide better protection, but they do last longer. Be sure to read the label to see what the concentration of DEET is, and how often it should be reapplied.

Permethrin products are intended to be used on items such as clothing, shoes, bed nets and camping gear and should not be applied to skin. Apply the permethrin to your clothes before you put them on and follow the instructions on the label.

Oil of lemon eucalyptus products should not be used on children under the age of three.

A number of "natural" products are available for use as mosquito repellents. Tests show that most of these products do not provide the same level of protection, or work as long as products like DEET or permethrin. The exception is oil of lemon eucalyptus, which provides as much protection as low concentrations of DEET.

If you suspect that you or your child is having an adverse reaction to a repellent (for example, if you develop a rash or other symptoms you think were caused by using a repellent), remove any treated clothing, wash the affected area with soap and water, and contact your doctor or local poison control center. If you go to the doctor, take the

repellent with you; the label information may be useful. The toll-free telephone number for the Regional Center for Poison Control is (800) 222-1222.

Mosquitos can infect horses and other animals. Horses are susceptible to WNV; and horses, llamas, alpacas, emus, ostriches and certain exotic game birds can get EEE. WNV and EEE viruses are not spread from horses or other mammals to humans in any way.

1. Vaccines licensed for horses are considered highly protective and can even be used in some other species. Talk to your veterinarian about vaccinating your animals.
2. Eliminate standing water by avoiding water overflow from troughs, reducing run-off and pooling of irrigation water, eliminating accumulated water in flower pots, and removing old tires and other containers in which water can collect.
3. Eliminate piles of leaves, lawn clippings, and manure.
4. Keep animals indoors during peak periods of mosquito activity (dusk and dawn).
5. Avoid turning on lights inside barns during the evening and overnight. Mosquitoes are attracted to light.
6. Apply mosquito repellants approved for use in animals. Read the product label before using, and follow all instructions carefully.

For additional information on EEE and WNV:

Massachusetts Department of Public Health (MDPH)

(617) 983-6800 or toll-free at (888) 658-2850

For information on mosquito control in your city or town:

Massachusetts Department of Agricultural Resources

(617) 626-1777

Or call your local Board of Health.

Massachusetts Department of Public Health

Bureau of Infectious Disease

Division of Epidemiology and Immunization

305 South Street

Jamaica Plain, MA 02130

Phone: 617-983-6800

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