Lyme Disease Cases Up in Vermont

Lyme disease cases up in state
June 19, 2008
By Mel Huff Times Argus Staff


Cases of Lyme disease have been confirmed in every county in Vermont and has increased sharply in recent years, although the disease is not as prevalent here as in other parts of New England.

Since 2001, the number of Vermont-acquired cases has grown from three to 83, according to the Vermont Department of Health. When cases where a person was exposed outside Vermont and cases where the person could have been exposed both in Vermont and elsewhere are added, the total number of cases last year reached 138.

The causes are complex, but health officials say the bottom line is that it's a good idea to protect yourself against tick bites, since deer ticks transmit Lyme disease. In the process, you'll be protecting yourself against another insect-borne disease that the Health Department is keeping an eye on – West Nile virus.

Patsy Tassler Kelso, an epidemiologist for the Health Department, attributes the increase in Lyme disease cases both to better surveillance and to the fact that there is, indeed, more Lyme disease in Vermont.

"We know that there are ticks all over Vermont that are infected with Borellia" – the bacterium that causes Lyme disease – "and so it's possible to get Lyme every place in Vermont, not just the southern part," she said. "I just don't think that increased awareness can account for this much of an increase in the number of cases."

Until this year, the national Centers for Disease Control and Prevention's criteria for confirming Lyme disease required that patients have a certain combination of lab results and clinical symptoms, regardless of whether their doctor had diagnosed and treated them for the disease. But since January, new definitions with graded levels of proof have come into use. In addition to confirmed cases, the CDC now reports "probable" and "suspect" cases. As a result of the new definitions, it's expected that many more cases will be recognized.

Lyme disease is primarily spread by ticks that feed and travel on migrating birds, Kelso said. It's also spread by infected mammals. She explained the interrelationship of species that produces the spread of the disease.

"White footed mice are the natural host for the Lyme disease bacteria. They don't get sick, but they're infected with it," she said. Ticks in the larval and nymph stages feed on white footed mice.

"White-tailed deer play a role, too, because they're the main blood meal host for the (adult female) ticks. The deer aren't so important for the Lyme bacteria itself. The deer keep the tick populations going, and the mice keep the Lyme bacteria going," she explained. "You need the small mammals; the large mammals, the Lyme bacteria and ticks. Once you've got all those pieces, you can build up an enzootic cycle that supports Lyme disease infecting more and more mammals and more and more ticks."

Research shows that a density of about 30 deer per square mile is needed to sustain tick populations, "so the spreading of Lyme disease probably also has something to do with deer spreading out and increasing their habitat and living in close proximity to people," Kelso said.

She noted that Lyme disease is considered curable if it's diagnosed and treated early, but the longer it goes untreated, the more difficult it is to cure. Untreated, the disease can cause devastating damage to the heart and nervous system.

The symptoms of Lyme disease can vary widely but usually include a rash, fever and muscle aches. The trademark bulls-eye rash is not always present. Because ticks in the nymph stage are tiny, the size of a poppy seed or speck of dirt, you may not know that you've been bitten. Nymph ticks are most active in spring and early summer.

The best defense against Lyme disease is to take precautions against tick bites and if you get an unexplained rash, fever and muscle aches, see a doctor – even if you don't remember being bitten by a tick.

"We really stress prevention, both avoiding ticks altogether and daily tick checks to remove ticks promptly," Kelso said.

She added that a tick has to be attached for about 24 hours to transmit Lyme disease. Becoming infected with Lyme disease, being treated with antibiotics, getting rid of the bacteria and recovering does not produce immunity to Lyme disease.
"It's possible to be reinfected by another tick," she noted

Remember to visit the Lyme Awareness Art Project Website (LAAP) at: http://lymeawarenessartproject.com