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tick

Lyme's Disease
Ticks harbor many infectious diseases. Ticks typically lie on shrubbery and will crawl onto people. People infected are usually bitten by the nymph stage, which can be small.

Rarely an adult tick will cause problem. Lyme disease incidence peaks in June and July, which corresponds to when the nymph tick is most active in May, and June.

Lyme Disease Stage

1: Fever, muscle aches, flu-like symptoms, enlarged lymph nodes.
Erythema Migrams
- as symptomatic 5-20cm round or oral rash with central clearing occurs <50% of the time
- occurs 7-10 days after bite at bite site (usually the margins of underwear will stop the ticks ascend up a leg.
- 90% of Lyme patients have erythema migrams, less than are recognized
- diagnosis is clinical. Serology is often negative. This is the best opportunity for diagnosis and treatment. (Do not miss this window of opportunity)
- organisms can be cultured from the leading edge of rash, but this requires special media that is not readily available.

Stage 2: Acute Disseminated Phase

1-secondary skin lesions
2-cardiac disorders
3-CNS disorders
4-neurological diseases

Skin Lesions

- look like red spots
-10-20% of time in untreated people
-usually smaller and less migrations may occur anywhere in the body

Neurologic Lesions

- 15-20% of untreated
-Facial nerve palsy not common
-"Aseptic" meningitis
- headache
-photophobia, neck, stiffness
-CSF fluid (pleocytosis - 10-100) and elevated protein
-chronic confusional state
-leukoencephalitis very rare, similar to multiple sclerosis
-some reversible CT scan abnormalities

Cardiac Lesions
- 8-10% of untreated
-1st-3rd degree heart block
-myocarditis or pericarditis by EKG (60%)
-mild left ventricular dysfunction (50%)
-may require hospitalization for cardiac pacing or observation
-most common cause of death in Lyme Disease

Stage 3: Chronic Widespread Arthritis (60%)

-recruitment a symptomatic pain
-usually 1 joint, lasting about 8 days
-predispostion forknee>shoulder>elbow>TMJ
-Inflammatory synorial fluid, organisms may be detected
-becomes chronic and destructive in 10%
-people with haplotype DRA may be predisposed to developing arthritis

Diagnosis

- Erythema Migrans rash
- pathognomatic for Lyme disease
If no skin lesions:
-thorough examination
-check if history consistent with tick bite and get lab confirmation

Lab Studies
- lgM presents 2 wks, peaks 3-4 wks then declines
- lgg presents 4-6 wks, peaks 8 wks, then may be elevated for years

Early Removal of Tick (is best)

-clean wound
-meticulous search for other ticks which may be very small
-follow-up for fever, headache and rash

Arthropod Avoidance

DEET - effective against mosquitoes, not as good against ticks
Permethrin - very effective -spray lasts 1 or 2 washings
-soaking clothing in solution 1.5cc of 13% solution/L lasts 50 washings
-strong smell but disappears when dried

Vaccine (no longer available)
- from protein (recombinent vaccines)
- effectiveness 49% after 2 injections, 76% after 3 injections
- duration of protection unknown
- vaccinations in outer membrane in Europe, so European Lyme Disease is not prevented
- vaccinees will not develop erythema migrans rash if infected

Babesiosis

- concurrent parasite = with Lyme Disease
-same distribution
-co-infected patients have headache, fever, chills, anorexia, and conjunctivitis symptoms for 3 months or longer
- also Ehrlichosis also has similar distribution as Lyme Disease

Treatment of Lyme Disease

Primary (Stage 1)
Infections where erythema chronicum migrans is seen, can be treated with one of the following:
- Doxycycline 100mg po BID x 10-21days
- Amoxil 500mg po BID x 10-21 days
- Cefuroxime 50mg po BID x 10-21 days
- Zithromax 500mg po BID then 250mg po od x 4 (12 pack)

Arthritis - treat with one of the following:

- Doxycycline 100mg po BID x 30 days
- Amoxil 500mg TID x 30 days
- Ceftriaxone 2g IV q4h x 14-21 days
- Pan G 4million units IV q4h x 14-21 days

Isolate facial palsy (where Lyme disease suspected)

- Doxycycline 100mg po BID x 30 days
- Amoxil 500mg TID x 30 days

Other neurologic SX:
- Ceftriaxone 2g IV od x 14-21 days
- Pan G 4million units q4h x 14-21 days

References:


New Front Against Lyme Disease
www.gene.com/ae/WN/SU/front_against_lyme_disease.html

Centre for Disease Control http://www.cdc.gov/ncidod/diseases/submenus/sub_lyme.htm

European Union Concerned in Action on Lyme Borreliosis (EUCACB)
www.dis.strath.ac.uk/vie/lymeEU/