The rise of tick-borne diseases

Researchers from the Centers for Disease Control and Prevention announced the discovery of a new tick-borne virus this week, one of several newly identified pathogens that ticks are passing to humans. Why are so many new tick-borne diseases being reported?

Improvements in medical technology, mostly. The newly discovered tick-borne diseases have probably been infecting humans for years, but they’re not easy to spot. Many victims never realize a tick has bitten them, and the symptoms, such as fevers, aches, and fatigue, are not distinctive and mirror those of common summer viral infections. The patient’s immune system usually fights off the illness unassisted, so doctors don’t bother running the battery of tests required to identify a new pathogen.  

Only in the rare cases when a patient struggles with the infection are physicians likely to make a genuine discovery. (The disease identified this week, a member of the phlebovirus family, hospitalized two men in Missouri.) They order blood smears or antibody tests to identify the presence of a pathogen, and genetic analyses—which were either inefficient or completely unavailable to doctors just a few years ago—alert researchers to the presence of the previously unidentified bug. Researchers have also become more aggressive recently, with some searching within ticks themselves for evidence of new pathogens.

Lyme disease is a classic example of how long a disease can exist in a population without being identified.

Genetic research has suggested that the pathogen responsible for Lyme disease has afflicted humans for more than 5,000 years. Examinations of a mouse specimen collected from Central Park in the late 1800s suggest that the disease has been present in the United States for more than a century, and case reports indicate that Europeans were carrying the disease at about the same time.  

In the early 1970s, fishermen in Long Island complained of a form of arthritis they called “Montauk knee,” but it wasn’t until later in the decade that doctors figured out that it was caused by an infectious agent. In 1982, researchers finally identified the spirochete that carried the illness. And Lyme disease, with its telltale bull’s-eye rash, is usually easier to identify than many other tick-borne illnesses.

Read the full article for more.

Don't let the ticks bite

Ticks are a real problem where I live, which is not all that far from Lyme, Connecticut, which gave Lyme Disease its name. Once farmland, it's now covered with second-growth trees, which attack the deer, which have no predators after them.

We have our property sprayed for ticks. When our kids were little, we'd strip them down and examine every square inch of flesh, looking for a little black dot no larger than a pencil point.

Now, it seems, disease-bearing ticks are spreading. The Wall Street Journal reports:

Reported cases of Lyme, the most prevalent of tick-borne diseases, have risen sharply over the last decade, with 35,198 cases in 2008 compared with 13,000 cases in 2000. The CDC says because of under-reporting, the actual number of cases may be three times as high. Though still largely a problem in the Northeast and upper Midwest, Lyme is turning up all over the U.S. If not correctly diagnosed and treated, Lyme can cause chronic joint inflammation, neurological symptoms such as facial palsy, impaired memory and heart-rhythm irregularities.

Other tick-borne illnesses, though less widespread, are also on the rise. In 2008, there were 2,563 reported cases of Rocky Mountain spotted fever , compared with 579 in 1999. The fever can be quickly fatal unless treated with a powerful antibiotic. Last May, Wisconsin and Minnesota warned about a new species of the tick-borne bacteria ehrlichia, not previously found in North America, which can cause flu-like illness. The disease is transmitted by lone star ticks, which have spread to more states in recent years and are also linked to a new illness, called STARI, for southern tick-associated rash illness. 

There are things you can do outside to lessen the risk, the Centers for Disease Control says.

Studies by Kirby Stafford, chief entomologist at the Connecticut Agricultural Experiment Station, show that 82% of ticks on a property are within three yards of the lawn perimeter, particularly along woodlands, stone walls, and ornamental plantings.Dr. Stafford's recommendations include making a barrier of wood chips made of cedar—a natural tick repellent—between wooded areas or stone walls and lawns heavily used by the family, keeping pets out of woods, and avoiding vegetation that attracts deer. 

More advice on making your home safe here. Oh, if you think we were nutty about checking the kids, here's what the CDC recommends:

Check your children for ticks, especially in the hair, when returning from potentially tick-infested areas. Check these parts of your body and your child's body for ticks:

• Under the arms
• In and around the ears
• Inside belly button
• Back of the knees
• Under the arms
• In and around the hair
• Between the legs
• Around the waist

Well, it's something to do.