Press Release

August 17, 2007


State health department working to confirm source of strange bug bite rash

 Bites not a major health threat but cause intense itching

SPRINGFIELD – Dr. Eric E. Whitaker, state public health director, announced today the Illinois Department of Public Health (IDPH) continues to diligently work to positively identify the cause of numerous bug bite rashes reported in northeastern Illinois during the past couple weeks. Based on its distinctive characteristics and activities of person who have developed this rash, the oak leaf gall itch mite is the likely cause.

“After receiving hundreds of phone calls, we understand many people are worried about these bites and we want to eliminate fears and inform people about what is happening. The bites we are seeing do not pose a major health threat – they mostly cause an annoying, intense itch,” said Dr. Whitaker. “Do not scratch the bites, however, or you could cause an infection which would create other health problems. I suggest using an anti-itch cream for the bites or taking an oral antihistamine.”

In efforts to identify the source of the bites, IDPH has set sticky traps or glue boards in an attempt to trap mites under oak trees in effected areas. At this time the specific type of mite has not been identified from collected traps. IDPH has sent samples of oak leaf galls and glue boards to an entomologist at the University of Nebraska Extension, who worked on a 2004 Nebraska outbreak, to help identify the species of mite. IDPH continues to collect glue boards and samples of oak leaf galls for identification. There are more than 45,000 different species of mites and definitive identification must be performed by expert entomologists who specialize in this group of arthropods.

IDPH has responded to numerous reports of bites and sent information to local health departments, hospitals, emergency departments and physicians concerning these rashes. IDPH has also sent word to local health department environmental health divisions in northeastern Illinois to set glue traps and some departments have already done so.

The itch mite cannot be identified without a microscope. The oak leaf gall mite caused similar outbreak in 2004 in Kansas, Missouri, Nebraska and Texas and is believed to be a likely cause of this outbreak in northeastern Illinois.

The itch mite feeds on the larvae of a small fly. The larvae are found in brown, crusty shells on the edge of oak leaves and are known as galls. However, the mites may drop from the trees and bite people when looking for food. Oak leaf gall mites are so small they can float on the wind and pass through window or door screens as well as loosely-woven clothing.

The mites usually are on a person’s body about four hours before they bite. The bite site will develop red welts that look like chigger bites – but on the neck, face, arms and upper body. Unlike the bites of chiggers, itch mites are not typically found on the legs and do not hurt when they occur. The bites form into pimple-like lesions after 10-16 hours. The bites cause intense itching and last for up to two weeks.

Do not scratch the bite as this could lead to an infection. Use over-the-counter anti-itch creams and oral antihistamines to control the itching. If the itching is intense or you develop a skin infection, contact your doctor or health care provider. While severe bite victims (up to 100 or more bites) and a few very sensitive individuals have been hospitalized in the past, there is no known instance of a human death due to itch mites.

To help prevent being bitten, wear tightly-woven clothing and take a warm, soapy shower after coming inside from areas where itch mite associated rashes have been reported. Also wash clothes after wearing outdoors. The effectiveness of DEET insect repellents against mites is not conclusive, but you should wear insect repellent to protect yourself from being bitten by mosquitoes, which can carry West Nile virus.

Mites will not survive in your home because they need to feed on insect larvae. Spraying oak trees is not effective against mites and tree removal is not necessary because these mites are not likely to be a problem every year.

idph online home
idph online home

Illinois Department of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
Phone 217-782-4977
Fax 217-782-3987
TTY 800-547-0466
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