Should I get prophylactic antibiotic treatment for a tick bite with no symptoms or signs of Lyme disease?
Some physicians offer treatment for tick bites to prevent Lyme disease, because the blood test for Lyme disease is not 100% reliable (sometimes gives a negative result, when it should be positive), and you can not rely on the Lyme disease skin rash (20% of Lyme infected patients do not develop a rash). For prevention of Lyme disease after a recognized tick bite, a single dose of doxycycline may be offered to adult patients (200 mg dose) and to children older than 8 years (4 mg/kg, up to a maximum dose of 200 mg) if all of the following are present:
· The attached tick can be reliably identified as an adult or nymphal I scapularis (deer) tick (see image below) that is estimated to have been attached for longer than 36 hours on the basis of the degree of engorgement of the tick with blood or of certainty about the time of exposure to the tick
· Prophylaxis can be started within 72 hours of the time that the tick was removed
· Doxycycline treatment is not contraindicated
· At least 20% of the local tick population is infected with the Lyme disease organism (B burgdorferi). Lyme disease is endemic in most of Vermont, including Rutland and Bennington counties, and healthcare providers could assume that at least 20% of deer ticks are infected.)
Some argue not to treat for tick bites without more evidence that infection has occurred as in one study the rate of infection was only in 2% of tick bites in areas in which about 15-30% of ticks were infected This finding indicates that many bites from infected ticks do not result in transmission of the infection. These studies form the basis of the often-cited recommendation to withhold tick bite prophylaxis. However, due to the fact that the blood test can be negative, the characteristic skin rash may never develop, and the fact that untreated Lyme disease can later lead to debilitating chronic Lyme disease, some health care providers offer prophylactic antibiotic treatment.
For patients who did not receive antibiotic treatment within the 72 hour recommended time period, a two to three week treatment course can be offered. Amoxicillin should not be substituted for the single dose of doxycycline in persons for whom doxycycline prophylaxis is contraindicated because of the absence of data on an effective short-course regimen for prophylaxis, the likely need for a multiday regimen (and its associated adverse effects), the excellent efficacy of antibiotic treatment of Lyme disease if infection were to develop, and the extremely low risk that a person with a recognized bite will develop a serious complication of Lyme disease.
Symptoms
The symptoms of Lyme disease are quite variable and depend on the body system affected. The skin, joints, nervous system or cardiovascular system may be involved. Early symptoms are not always recognized, and many people will first present to a healthcare provider with disseminated or late disease.
Early symptoms (onset: 3 to 30 days, usually 7 to 10 days):
• Non-specific flu-like symptoms, such as fever, chills, muscle and joint aches, headache and fatigue are common. Swollen glands may also occur.
• An expanding red rash that grows outward, although not always present.
• occurs in up to 80% of people.
• usually appears as an expanding red rash at or near the site of the tick bite; it is at least 5 cm in diameter; the classic “bulls-eye” appearance is less commonly present.
• It may be warm, but it is usually not painful or itchy. Vesicles or pustules may be present.
• For pictures of EM rashes go to http://www.aldf.com/EMPoster.shtml Note: The EM rash should be distinguished from a rash caused by an allergic reaction to a tick or insect bite. A rash due to an allergic reaction usually appears within a day or two after the bite, does not grow, and disappears within a couple of days.
Disseminated disease (onset: days to months):
• Joint pains, muscle aches, headache, and fatigue - common
• Multiple red round to oval rashes
• numbness and pain in the arms or legs
• Bell’s palsy
• meningitis
• heart block and inflammation in and around the heart (myopericarditis)
• arthritis
• Up to 60% of people, who do not receive treatment, develop intermittent bouts of arthritis several months after infection. The arthritis is characterized by severe joint pain and swelling, usually of large joints, most commonly the knee.
Late disease (onset: months to years):
• Chronic nervous system manifestations occur in approximately 5% of untreated patients. Symptoms include shooting pains, numbness
From: INFECTIOUS DISEASE BULLETIN- SPRING SUPPLEMENT ON LYME DISEASE
108 Cherry Street • PO Box 70 • Burlington, VT 05402 • healthvermont.gov • 800-640-4374