From a 2014 lecture by Dr William Lockwood (ID):
The most common: RMSF and Lyme disease (most likely to be on the Boards). But there are others!
Rickettsia: RMSF, Ehrlichia, Anaplasma, others.
Borellia: Lyme, relapsing fever, Stari.
Babesia: B. microti
Bacteria: F. tularensis, B. quintana
Viral: tick-borne encephalitis (3 types in Europe), Powassan virus, Colorado tick fever
Chemical: tick paralysis
– Rickettsia rickettsii
– central-south US – OK, MO, NC, SC, AR
– causes a vasculitis
– young males most often
– incubation: 2-14 days
– Early symptoms: fever, HA, myalgias, abd, N/V (latter two esp children)
– Later symptoms: petechial rash around day 3-5, 10% no rash; wrist, ankles, palms, soles
– Late symptoms: coma, seizures, gangrene of extremities
– WBC variable, platelets typically low, LFTs typically elevated, CSF moderate pleocytosis
– Best test: skin biopsy of the rash lesions: DFA, immunoenzyme (biopsy doesn’t have to be a petechial lesion, but extremity best location)
– Serology is often positive too late!
– Doxycycline 100mg PO q 12h
– This is the ONE time to use doxycycline in children!
– In pregnancy, use chloramphenicol (if you can find it).
Other rickettsial diseases:
Rash (plus fever, HA) – Mediterranean spotted fever
Eschar (plus fever, HA) – African tick bite fever
Tx for all: doxycycline as above.
TICK BORNE RELAPSING FEVER:
– Borrelia species
– Biphasic symptoms: fever x 1-3 days, then okay for 4-14 days, then fever.
– occasional neuro sxs
– Dx: thick/thin smears, PCR; antibody testing not helpful.
– Tx: tetracycline/doxycycline, or erythro/PCN
TICK BORNE ENCEPHALITIS
– Europe only
– Incubation 7-14 days
– Biphasic illness
– fever, HA, malaise
– encephalitis, paralysis
– 8-10% mortality, only supportive care available
– NE, N central US, Canada, Russia
– Dx PCR, Ab testing
– no tx, no vaccine
EHRLICHIA AND ANAPLASMA
– infects monocytes (Anaplasma infects granulocytes)
– mid-Atlantic states through OK area
– Sxs: fever, HA, myalgias, rash in only 30% for Ehrlichia, 1% for anaplasma (“Rocky Mountain spotless fever”)
– Dx – PCR, serology
– Tx – amox in children, tetracycline
TICK PARALYSIS (looks a lot like G-B syndrome!)
– reaction to chemical in tick saliva
– weakness, fatigue
– ascending paralysis in 1-2 days, no fever, normal sensorium
– usually normal WBC, normal CSF
– Tx is removal of tick, symptoms self-limited
COLORADO TICK FEVER
– from 4K – 10K feet elevation
– spring to summer
– fever, HA, myalgias, conjunctivitis
– mildly low WBC, platelets
– Dx serology
– Tx none, self-limited up to 6 weeks.