I was recently bitten by a deer tick during a trip to Minnesota. I never did form the bull’s eye rash, but my glands were swollen. What are the symptoms of Lyme disease?
We are now in the Lyme disease season, and Minnesota is one of the Lyme disease hotspots in the United States, though the disease is not nearly as common there as in the North Atlantic states. The New England Journal of Medicine (NEJM) recently published two important articles on Lyme disease which contained lots of information that is relevant to your question.
First, a brief review of Lyme disease. It is caused by a spirochete, a corkscrew-shaped bacterium named Borrelia burgdorferi. It is now the most common disease caused by an insect bite (deer tick or Ixodes scapularis) found in the United States. In over 80 percent of cases, a typical rash with a bull’s eye appearance will develop at the site of the bite. If not treated, an infected person may develop joint pains, nerve problems or heart beat irregularities weeks to months later.
One study reported in the NEJM was done to determine if prophylactic treatment of people bitten by a deer tick would prevent Lyme disease (Nadelman R.B., Nowakowski J., Fish D., Falco R.C., Freeman K., McKenna D., Welch P., Marcus R., Aguero-Rosenfeld M.E., Dennis D.T., Wormser G.P. Prophylaxis with Single-Dose Doxycycline for the Prevention of Lyme Disease after an Ixodes scapularis Tick Bite. N Engl J Med. 2001; 345:79-84). The study was done in Westchester County in New York, an area of very high Lyme disease prevalence. Because it was a research study, all the ticks were identified by an entomologist. Most doctors, even in areas with lots of Lyme disease, are not able to identify Ixodes ticks, which are very small. The young nymph stage of the tick is only pinhead-sized.
The findings of the study showed that people developed the typical bull’s eye rash only if bitten by nymph ticks, not the adults, and only if the tick remained attached for at least 72 hours. No one bitten by an adult tick or a nymph that was attached for less than 72 hours became ill. A tick that has been attached for 72 hours will be engorged with blood. You didn’t mention blood when your tick was removed, therefore, it may have been attached for much less time.
The overall incidence of a Lyme rash developing after a tick bite was only 3.2 percent, even in this highly infested county. Taking an antibiotic did significantly reduce the number of people developing the rash, to 0.1 percent, but despite that, an accompanying editorial came out against prophylactic treatment because the incidence of disease was so low, and because the antibiotic can cause side effects (Shapiro, E.D. Doxycycline for Tick Bites — Not for Everyone. N Engl J Med. 2001;345: 133-134). No one would argue, though, that it is inappropriate to treat someone who develops the typical rash.
It took from 4 to 17 days for the rash to develop at the site of the tick bite in those subjects who did not receive prophylactic antibiotics. Since all the study subjects were promptly treated if they developed the rash, no long-term complications of Lyme disease like arthritis, neuropathies or heart arrhythmias developed.
The other article examined the effectiveness of prolonged antibiotic treatment for people with persistent long-term symptoms which they attributed to Lyme disease, such as fatigue, joint pains, muscle pains and memory disturbances (Klempner M.S., Hu L.T., Evans J., Schmid C.H., Johnson G.M., Trevino R.P., Norton D., Levy L., Wall D., McCall J., Kosinski M., Weinstein A. Two Controlled Trials of Antibiotic Treatment in Patients with Persistent Symptoms and a History of Lyme Disease. N Engl J Med 2001; 345:85-92). About half the subjects had blood tests positive for Lyme disease, and the others did not. All had previously been treated with standard antibiotics. The study subjects received intravenous antibiotics for 30 days followed by oral antibiotics for 60 days. The control group received intravenous and oral placebos.
There was no significant difference in symptoms after this treatment between the treated subjects and the control subjects. The study authors found that the subjects did not have evidence of persistent Lyme disease infection.
If you were bitten by an infected nymph deer tick you will have developed the rash by now, and hopefully will have gone for treatment. If you did not develop the rash, then the odds are strongly in favor of your not being infected and no treatment would be advised now. Your throat infection and swollen glands would not be a part of Lyme disease infection, and were probably a separate throat infection.
What can someone living in a highly infected Lyme disease area do to prevent catching the disease? There is now a vaccine available, which while not 100 percent effective, does offer some protection. People outdoors in grassy or wooded areas should wear white pants tucked into white socks, so that the ticks cannot climb up a leg. Everyone outdoors should carefully inspect their body for pinhead-sized black ticks every evening, and if any are found they should be removed promptly. This is particularly important for children, who are more likely to be bitten while playing in the woods. In areas of the country where Lyme disease is not common, most tick bites will be from ticks other than Ixodes. These are usually larger, like dog ticks, and cannot transmit Lyme disease, although there are other less common infections transmitted by them.