Tickborne Disease

Lyme Disease General Overview

Seasonal Pattern of Lyme Disease Cases

General Overview

Got a summer-time flu?

Fever and chills, muscle and joint aches, headaches, exhaustion! If that is how you feel, and you live or play in rural, suburban and even peri-urban parts of the northeastern United States, then one or more tick-transmitted infections should, at least, be considered as a possible cause. Tick bites can result in transmission of bacteria, protozoans, rickettsias and even viruses. In the northeastern United States, tick-transmitted pathogens can cause:

Common to Rarel
  • Lyme disease
  • Babesiosis
  • Anaplasmosis (formely granulocytic ehrlichiosis
  • Rocky Mountain Spotted Fever
  • Tularemia

Although each of these diseases also have their own unique diagnostic symptoms, and can be detected using appropriate blood tests, acute disease often is described as a summer-time flu.

Lyme Disease

Tick Check and Tick Removal

Lyme disease was first identified in 1975, and since then the disease has continued to increase, both in the number of people afflicted and in the geographic distribution. National surveillance for Lyme disease began in 1982, when 491 cases were reported. In 2004, the latest year for which statistics are available, there were 19,804 human cases verified by the Centers for Disease Control and Prevention. More than 60,000 cases are reported each year in Europe.

  • Lyme disease is caused by infection with a spirochete (a type of bacteria) which can be transmitted to people by bites from nymphal and adult Blacklegged ticks.

  • American dog ticks are NOT able to transmit Lyme disease spirochetes.

  • Larval and nymphal Blacklegged ticks can become infected when they take a blood meal from infected rodents and birds. Deer do NOT pass the infection to ticks.

Symptoms and signs of Lyme disease

Early Lyme Disease

The early stages of Lyme disease is usually marked by one or more of the following symptoms:

  • fatigue
  • chills and fever
  • headache
  • muscane and joint pain
  • swollen lymph nodes
  • a characteristic skin rash, called erythema migrans (EM)

Erythema Migrans (EM)

Erythema migrans

Erythema migrans (EM) is a red circular patch that appears usually at the site of the tick 5 days to 1 month after the bite of an infected tick. The patch then expands, often to a large size. Sometimes many patches appear, varying in shape, depending on their location. Common sites are the knee, thigh, groin, trunk, and the armpits. The center of the rash may clear as it enlarges, resulting in a bulls-eye appearance. The rash may be warm, but it usually is not painful. Not all rashes that occur at the site of a tick bite are due to Lyme disease (i.e. an allergic reaction to tick saliva at the site of the bite which can be confused with the rash of Lyme disease). Allergic reactions to tick saliva usually occur within a few hours to a few days following the tick bite, but usually do not expand and normally disappear within a few days.

Late Lyme Disease

Some symptoms and signs of Lyme disease may not appear until weeks, months, or years after a tick bite:

  • Arthritis is most likely to appear as brief bouts of pain and swelling, usually in one or more large joints, especially the knees.
  • Nervous system abnormalities can include numbness, pain, Bell's palsy (facial paralysis which usually occurs on one side), and meningitis (fever, stiff neck, and severe headache).
  • Less frequently, irregularities of the heart rhythm occur.
  • In some persons the rash never forms; in some, the first and only sign of Lyme disease is arthritis, and in others, nervous system problems are the only evidence of the disease.

Lyme Disease and Pregnancy

In rare cases, Lyme disease acquired during pregnancy may have possibly lead to infection of the fetus and to stillbirth, but adverse effects to the fetus have not been conclusively documented.


Lyme disease is often difficult to diagnose because its symptoms and signs mimic those of many other diseases. The fever, muscle aches, and fatigue of Lyme disease can easily be mistaken for viral infections, such as influenza, infectious mononucleosis or chronic fatigue syndrome. Joint pain can be mistaken for other types of arthritis, such as rheumatoid arthritis, and neurologic signs can mimic those caused by other conditions, such as multiple sclerosis. At the same time, other types of arthritis or neurologic diseases can be misdiagnosed as Lyme disease.

Diagnosis of Lyme disease depends upon:

  • Exposure to ticks, especially in areas where Lyme disease is known to occur. If you are bitten by a tick, always save it - correct indentification and testing can confirm the presence or absence of the Lyme disease spirochete within the tick.
  • Symptoms and signs as described above.
  • The results of blood tests used to determine whether the patient has antibodies to Lyme disease bacteria. These tests are most useful in later stages of illness.
  • Consultation with a health care provider.

Treatment and prognosis

Lyme disease is treated with antibiotics under the supervision of a physician. Several antibiotics are effective. Usually they are given by mouth but may be given intravenously in more severe cases. Patients treated in the early stages with antibiotics usually recover rapidly and completely. Most patients who are treated in later stages of the disease also respond well to antibiotics. In a few patients who are treated for Lyme disease, symptoms of persisting infection may continue, making additional antibiotic treatment necessary. Varying degrees of permanent damage to joints or the nervous system can develop in patients with late chronic Lyme disease. Typically these are patients in whom Lyme disease was unrecognized in the early stages or for whom the initial treatment was unsuccessful. Rare, indirect deaths from Lyme disease have been reported.

Preventive Antibiotic Treatment of Tick-bites

Deer tick hypostome

Currently, the Infectious Disease Society of America does not recommend antibiotic therapy for patients bitten by Ixodes scapularis ticks estimated to have been attached for more than 48 hours.

New guidelines for physicians are being developed for release later in 2006. These may include findings from a newer study suggesting that a single 200-mg dose of doxycycline administered within 72 hours after a recognized Blacklegged tick bite was 87% effective in preventing Lyme disease transmission.

(Ref. Nadelman RB, Nowakowski J, Fish D, et al. 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).