Dermacentor tick

The vector matters because it predicts the pathogen. Dermacentor transmits Rocky Mountain spotted fever, whose rash begins on the wrists and ankles and moves centripetally, involving palms and soles, and which is most common in the south-eastern and south-central United States; empirical doxycycline must be started on clinical suspicion in any age group because delay increases mortality. Dermacentor also transmits tularaemia and Colorado tick fever. By contrast Ixodes transmits Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti; Amblyomma americanum, the lone star tick, transmits Ehrlichia chaffeensis, causes southern tick-associated rash illness, and induces alpha-gal allergy to red meat; and Ornithodoros soft ticks transmit endemic relapsing fever. Tick paralysis is a distinct entity: a female tick attached for several days, often on the scalp, secretes a toxin that blocks presynaptic acetylcholine release, producing an ascending flaccid paralysis with areflexia that mimics Guillain-Barre but resolves within hours of removing the tick, and has normal CSF protein.