CDC Warns of Another Emerging Tick-Borne Threat

THURSDAY July 12, 2012 -- Babesiosis -- a parasitic illness spread by ticks -- is posing a serious threat this summer, especially in certain parts of the country, a U.S. government report warns.

Meanwhile, mosquitoes continue to spread the West Nile virus, according to another report in the July 13 issue of the Morbidity and Mortality Weekly Report.

Babesiosis, the lesser-known disease, is endemic in the Northeast and upper Midwest, where states reported more than 1,100 cases in 2011, according to the U.S. Centers for Disease Control and Prevention. Of those, 847 were confirmed cases and the rest were probable cases.

The bulk of cases came from seven states: Connecticut, Massachusetts, Minnesota, New Jersey, New York [including New York City], Rhode Island and Wisconsin.

"This is the first time we have collected information about babesiosis cases on a national level," said Dr. Dana Woodhall of the CDC.

Babesiosis can be life-threatening, especially for people without a spleen and for the elderly.

"Most healthy people remain asymptomatic; some people develop nonspecific illness: headache, fever, chills," Woodhall said.

Most people get the disease from the same tick as the one that carries Lyme disease. And like Lyme disease, babesiosis is treatable with antibiotics.

"Babesiosis is a disease transmitted mainly by ticks and there are steps people can take to prevent the disease," Woodhall said.

The best way to protect yourself is to use tick spray, stick to paths when in the woods and check yourself for ticks after being in the woods or tall grass, Woodhall said.

In addition, pets can carry these ticks home, so they should have tick collars or anti-tick lotions.

Babesiosis can also be transmitted through blood transfusions or from mother to child during pregnancy, the CDC noted.

"This is the first year we are able to get the big picture, but since it's the first year there is no way of telling how widespread the disease is or estimate how many cases there actually are," Woodhall said.

It will take several years before the CDC knows whether cases of babesiosis are increasing. "We don't know the trend," she added.

The more well-known West Nile virus is an arbovirus, which are viruses carried by mosquitoes and ticks. Of nearly 900 cases of arboviral disease cases reported to the CDC in 2011, more than 700 were West Nile virus.

"West Nile continues to be the leading cause of arboviral disease in the United States, however, other [arboviruses] do continue to cause sporadic outbreaks," said CDC's Dr. Stephanie Yendell. "We see West Nile throughout the United States."

Another such disease, called La Crosse virus, was the most common cause of arboviral disease in children, according to the CDC.

Reported cases are, however, just the tip of the iceberg, experts say. Because many people contract these arboviruses but have no symptoms or only mild symptoms, most cases are never reported, Yendell noted.

"We estimate there could have been as many as 13,000 to 34,000 cases of West Nile," she said. This estimate is pretty constant from 2008 to 2010.

"There are a number of people who never show symptoms and for many who do get sick, many will have mild symptoms like fever, rash and body ache. Fewer of these cases get reported," Yendell said.

Severe symptoms can include high fever, neck stiffness and even coma. "The mortality rate is about 6 percent for West Nile," she said.

Most cases occur in the late spring, summer and early fall, when ticks and mosquitoes are active, she added.

Because there is no treatment for these viruses, the key is prevention. These measures include repellents, protective clothing, repairing or installing screens, eliminating tall grass and standing water near homes, and community insect-control programs, Yendell said.

Commenting on the reports, Dr. Marc Siegel, an associate professor of medicine and infectious disease expert at NYU Langone Medical Center in New York City, said that "babesiosis is something we physicians have to be aware of."

One of the problems is the symptoms are nonspecific, he added.

"This is not something the general public needs to be worried about, but doctors need to follow it," Siegel said. "It's not an epidemic, but it's increasing because ticks are increasing," he explained.

Siegel stressed that both of these diseases are fairly rare, and people should not be overly concerned because their odds of getting either one are very low.

More information

To learn more about insect-borne diseases, visit the U.S. Centers for Disease Control and Prevention.

Posted: July 2012


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