New Tick Threat For Humans

Researchers have for the first time detected in humans a potentially fatal tick-borne bacterial infection that was thought to occur only in dogs, cattle, and other animals, reports CBS News Health Correspondent Dr. Emily Senay.

In a study published in Thursday's New England Journal of Medicine, researchers found the disease, called ehrlichiosis, is similar to Lyme disease. Their findings show the disease is usually associated with deer ticks.

The doctors found four human cases of the infection, all in Missouri, between 1996 and 1998, and four more cases during this tick season in Missouri, Tennessee and Oklahoma.

Two forms of ehrlichiosis have previously been documented in people since 1986, when the disease was first found in the United States. Since then, approximately 1,200 cases have been reported, according to the Centers for Disease Control and Prevention.

But this was the first time researchers found cases of the type of ehrlichiosis thought to only be carried in dogs and other animals.

While Lyme disease is transmitted by ticks primarily in New England and the upper Midwest, ehrlichiosis is though to be carried by ticks from the southeastern U.S. to the upper midwestern states.

No matter which form of bacteria causes the infection, an antibiotic can essentially cure it. In the study, all four patients from 1996-98 were treated successfully.

But, the new vaccine to protect against Lyme disease will not work in preventing ehrlichiosis.

Ehrlichiosis and Lyme disease have some symptoms in common, including headache, nausea, chills, fever, malaise, fatigue and muscle pain. But typically, ehrlichiosis doesn't usually come with a rash and can be fatal if left untreated. Up to 5 percent of cases result in death.

"This is a much more acute and rapidly progressing disease that can be much more serious because it can be fatal in the most severe cases," said study co-author Dr. Gregory A. Storch of the St. Louis Children's Hospital. "Lyme disease is not fatal. It can become chronic and can produce some significant and annoying manifestations."

Staying out of tick-infested areas, wearing protective clothing like long sleeved shirts and pants, and using anti-tick insect repellant are preventative measures that can be taken.

"Be aware that if you're out in areas where there are ticks, and this can be hunting, hiking, fishing, camping, you should always check yourself and remove any crawling or attached ticks as quickly as possible," said Christopher Paddock of the CDC.