Eastern tick-borne rickettsioses (ETBR) are caused by various rickettsiae transmitted by ixodid ticks. Symptoms are an initial skin lesion, satellite adenopathy, and an erythematous maculopapular rash.

ETBR include North Asian tick-borne rickettsiosis, Queensland tick typhus, African tick typhus, and Mediterranean spotted fever (boutonneuse fever). The causative agents belong to the spotted fever group of rickettsiae.

The epidemiology of these tick-borne rickettsioses resembles that of spotted fever in the Western Hemisphere. Ixodid ticks and wild animals maintain the rickettsiae in nature. If humans intrude accidentally into the cycle, they become infected. In certain areas, the cycle of boutonneuse fever involves domiciliary environments, with the brown dog tick, Rhipicephalus sanguineus, as the dominant vector.

Symptoms and Signs

The symptoms and signs are similar for all ETBR and generally milder than with spotted fever. After an incubation period of 5 to 7 days, fever, malaise, headache, and conjunctival injection develop. With the onset of fever, a small buttonlike ulcer 2 to 5 mm in diameter with a black center appears (an eschar or, in boutonneuse fever, tache noire). Usually, the regional or satellite lymph nodes are enlarged. On about the 4th day of fever, a red maculopapular rash appears on the forearms and extends to most of the body, including the palms and soles. Fever lasts into the 2nd wk.

Complications and death are rare except among elderly or debilitated patients. However, the disease should not be ignored; a fulminant form of vasculitis can occur.

Diagnosis

For diagnosis, see Rickettsiae and Related Organisms: Diagnosis.

Treatment

• Doxycycline or ciprofloxacin

Treatment is doxycycline 100 mg po bid for 5 days or ciprofloxacin 500 to 750 mg po bid for 5 days. Measures can be taken to prevent tick bites (see Sidebar 1: Rickettsiae and Related Organisms: Tick Bite Prevention).

Sidebar 1
Tick Bite Prevention
Preventing tick access to skin includes Staying on paths and trails Tucking trousers into boots or socks Wearing long-sleeved shirts Applying repellents with diethyltoluamide (DEET) to skin surfaces DEET should be used cautiously in very young children because toxic reactions have been reported. Permethrin on clothing effectively kills ticks. Frequent searches for ticks, particularly in hairy areas and on children, are essential in endemic areas. Engorged ticks should be removed with care and not crushed between the fingers because crushing the tick may result in disease transmission. The tick's body should not be grasped or squeezed. Gradual traction on the head with a small forceps dislodges the tick. The point of attachment should be swabbed with alcohol. Petroleum jelly, alcohol, lit matches, and other irritants are not effective and should not be used. No practical means are available to rid entire areas of ticks, but tick populations may be reduced in endemic areas by controlling small-animal populations.

Last full review/revision November 2007 by William A. Petri, Jr., MD, PhD