Doxycycline for the prevention of tick-borne relapsing fever.

is safe and efficacious for the prevention of tickborne relapsing fever (TBRF) in a person who has been bitten by an infected tick. We dispute both points. Healthy male soldiers, who were the subjects in the study, are not an appropriate population for determining drug safety. General travelers are a more suitable study group for this purpose. A survey of 383 Australian tourists taking doxycycline (100 mg daily) as chemoprophylaxis against malaria found that 15% reported nausea and vomiting, 12% reported diarrhea, and 9% of women reported vaginal itch. 2 Other studies have linked doxycycline taken prophylactically with photoallergic rash and with photoonycholysis. 3 Adverse drug effects affect compliance and, hence, drug efficacy. 4 The safe and effective way to prevent TBRF is to pretreat clothing, including military uniforms, with a synthetic pyrethroid insecticide such as permethrin. Both hard ticks (Ixodidae) and soft ticks (Argasidae) are acutely sensitive to pyrethroids, and all stages of tick in these families will avoid attachment to humans who have sprayed or impregnated their clothing with permethrin. 5