Pest Alert: tick-vectored diseases spreading

Doctors are concerned that the spread of tick-vectored diseases, such as babesiosis, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, STARI (southern tick-associated rash illness), etc.

A recent MSNBC story said:

Most Lyme cases occur in the Northeast and upper Midwest; if you don't live there, you might be safe from Lyme but still at risk for other diseases. Cases of a tickborne illness known as ehrlichiosis grew from 200 to 957 nationwide — a 378 percent jump — between 2000 and 2008, according to the Center for Disease Control. The infection anaplasmosis nearly tripled in the same period, and Rocky Mountain spotted fever quintupled. The new disease STARI (southern tick-associated rash illness) has spread across the South, and strains of an infection called rickettsiosis have hit the Gulf and Pacific coasts.

All of these non-Lyme tick diseases attack victims in a similar way, bringing on fever, headache and muscle and joint pain — making it easy to misdiagnose them as anything from flu to meningitis, says Gary P. Wormser, M.D., the chief of infectious diseases at Westchester Medical Center and New York Medical College and head of a team researching tick diseases.

If the patient remembers finding a tick, or develops a rash, that's a big clue. If not, "it is somewhat common for these to be missed. The symptoms resemble so many other common viral infections," says Gregory A. Storch, M.D., a pediatric infectious-disease specialist at Washington University in St. Louis, which created a multidisciplinary tickborne-disease research team because cases have surged there.

This lack of awareness can be deadly. Tickborne infections cause only minor or no symptoms in some people but become dire in others. Rocky Mountain spotted fever, for one, almost always results in hospitalization. And among people who develop symptoms of babesiosis, 5 percent to 10 percent will die. The death rate reaches 20 percent in those whose immune system is compromised.

"Although babesiosis is less common than Lyme, you can argue that it creates as big a health burden, because of its severity and fatality rates," says Peter J. Krause, M.D., senior research scientist at the Yale School of Public Health in New Haven, Conn. "There are more cases than we previously thought, and babesiosis is also the No.1 reported cause of infections through blood transfusions in the United States." But because medical awareness has not kept up, patients have been overlooked, undertreated and taken by surprise when their enjoyment of the outdoors — a hike, a run, a round of golf, their own backyard—turns into a life-altering threat.

Are the outbreaks our fault?

Some of the sharp rises in tick disease cases could be due to better counting and diagnostic tests, McQuiston cautions. "But we also have a suspicion it could be differences at the ground level, a changing ecology." What's especially troubling is that these ecological changes—which wildlife researchers confirm—aren't natural or accidental. "Unfortunately, there is mounting evidence that the increase in risk for exposure to tickborne diseases is a consequence of the ways humans modify the environment we live in," says Brian F. Allan, Ph.D., assistant professor of entomology at the University of Illinois at Urbana-Champaign. For starters, Allan says, we're seeing more contact between ticks and people, possibly because we're moving farther into woody areas. And ticks and the wildlife they feed on are thriving because we've created appealing backyards for them to live in.

To fully understand how we've increased our own risks, you have to know how tickborne diseases spread. Ticks bite and draw blood only three times in their life. For most species, the first and second meal is from something small, a mouse or a chipmunk, and the third is usually from something larger, such as a white-tailed deer, a dog — or a human being. When ticks take blood, they can pick up disease organisms from the animal they bit and then pass them along to whatever they bite next.

Risk spike in spring and summer

The chance you'll be infected spikes in the spring and summer, when you are outside more and wear less clothing and when ticks are also most active — particularly eager, hungry young nymphs. The risk is highest when you are in the kind of landscape ticks and their hosts prefer: shady forests, places with lots of moist leaf litter and areas where woods transition into meadows or lawns. In other words, the suburbs.

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