Another La Nina Winter Means More Lyme Disease Cases

From the WebMD Archives

Nov. 28, 1999 (Atlanta) -- Another warm, wet La Niña winter is forecast for a wedge of the northern U.S., and that could mean a big leap in Lyme and other tick-borne diseases, says one public health official.

In the northeastern U.S. and the upper Midwest, tick-borne diseases in general have become an increasing public health threat, Thomas Mather, PhD, director of Rhode Island's Center for Vector-Borne Diseases, tells WebMD. "In a year that's more moist [such as 1998], we see the number of ticks going way up as well as the number of sites in which they're found," says Mather.

"Most Lyme disease cases are contracted between the spring and fall. In fact, ticks are most active during mid to late fall," Kristine A. Smith, a spokesperson for the New York State Department of Health, tells WebMD. "Although cases may be diagnosed during the winter, exposure likely occurred earlier in the year. Early symptoms appear from a week to a few months after exposure."

Lyme disease is a bacterial infection that is especially prevalent in the northeastern and north-central U.S., and is transmitted primarily by infected deer ticks found in moist, shaded environments, especially where there is leaf litter and low-lying vegetation in wooded, brushy, or overgrown grassy areas.

About 70% of those bitten by infected ticks will develop a red, ringlike rash and flu-like symptoms that last between five and seven days -- fatigue, fever, stiff neck, headache, and joint pain. Removing ticks within 24-36 hours may prevent the infection. Adult ticks of fall and winter are easier to see than the tiny baby ticks of spring and summer.

Since 1993, Rhode Island has participated in the CDC's surveillance of ticks and Lyme disease. The patterns he's seen mirror what's happening across the U.S., says Mather. "The large increase in ticks is a significant public health problem."

"For the vast majority of people who contract Lyme disease, it becomes a chronic disease that can be quite debilitating," Sam T. Donta, MD, a Lyme disease expert with the Division of Infectious Diseases at Boston University School of Medicine, tells WebMD

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"Lyme disease has befuddled everyone dealing with it," says Donta. "The disease has not been taken very seriously by a number of experts. They see a swelling of the knee that goes away by itself, and they don't see it as a very serious disease. The disabling aspect is the chronic fatigue, the chronic aches and pains, the concentration problems. It's a completely disabling disease for those who get it, but it's not a killing disease."

Blood tests used to confirm the condition -- even when performed at 'Lyme disease specialty labs' -- are of variable quality, says Steven E. Schutzer, MD, lead author of a study appearing in the Nov. 24 issue of the Journal of the American Medical Association. Even so-called 'Lyme disease specialty labs' can produce results that are "no better, no worse, than the others [labs]," he says.

One problem is that tests thus far have picked up both 'free' antibodies from old Lyme disease infections (even a year earlier) as well as antibodies from current infections, Schutzer says. The new Lyme disease lab procedure his group has devised is capable of detecting antibodies from only the active, newly acquired infection. In a test involving 168 patients with obvious Lyme disease and 147 without the disease, 96% of those with Lyme disease tested positive, and only two of those without tested positive. "It means that the group that didn't have the classical rash ... the group that needed it most, was found to be positive," says Schutzer.

False-negative tests, when people test negative but really have the condition, are the most critical because Lyme disease treatment is most successful when initiated in the first six months, says Donta. If Lyme disease is caught within the first half-year to year, the results will be much better than if the person has had it for more than three or four years. "Unfortunately, there are a lot of symptoms people just accept because they're not overwhelming. They're almost embarrassed to go to their doctors. They feel like they should be able to put up with it. It's an insidious disease."

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Many rheumatologists diagnose the disease as fibromyalgia or chronic fatigue, but that's not correct, says Donta. "It is amenable to [antibiotic] treatment. But the longer you wait before getting treatment, the harder it is to treat."

Nancy Shadick, MD, MPH, director of the Lyme Disease Center at Boston's Brigham and Women's Hospital, tells WebMD, "The great majority of [Lyme disease] cases can be treated effectively with antibiotics. In rare cases, or cases where people don't have treatment promptly, it can be somewhat difficult to treat, requiring another course of antibiotics or perhaps ... antibiotics [given in the vein]."

A very small number of patients -- despite treatment -- may develop 'post-Lyme disease syndrome,' which resembles fibromyalgia (with fatigue, joint aches, and difficulty concentrating), Shadick says. "It's very important to see a doctor and make sure there is not residual arthritis or joint swelling, residual signs of meningitis (infection of the fluid surrounding the spinal cord) or nerve damage, or even to make sure that you didn't contract a different illness [such as hypothyroidism] that could be mistaken as post-Lyme disease syndrome," she tells WebMD.

As far as prevention, the CDC recommends Lyme disease vaccinations for anyone between ages 15 and 70 who are considered at high risk and whose exposure to tick-infested areas is frequent or prolonged. However, Mather adds a caveat, "The Lyme vaccine doesn't protect against similar-appearing [though rarer] infections like ehrlichiosis or borrelia, which are transmitted by ticks also. From a public health standpoint, the vaccine gives people a false sense of security. They think they don't have to worry, but they do have to worry about these other types of infections."

Wearing long-sleeved shirts, with long pants tucked into shoes; spraying DEET repellants on clothing; and performing daily 'tick checks' -- of humans and pets -- are most effective preventive measures, the CDC advises. If you find a tick, remove it with tweezers and take it to your doctor for analysis.

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