A double-blind study of the value of treatment with a single dose tinidazole of partners to females with trichomoniasis.

Tinidazole 2 g single oral dose was given to 137 females with positive trichomonal cultures. On a random basis the same dose of tinidazole was given to half the sexual partners, and matching placebo to the other half. One to two weeks after treatment 5 females had positive cultures, indicating a primary cure rate of 96.4%. At an average of 2 months after treatment and 6 weeks after resuming sexual activity, 118 females were reexamined; 17 had a positive culture, giving an overall relapse rate of 14.4%. The relapse rate with tinidazole-treated partner was 5.1%, and with placebo-treated partner 23.7% (p equals 0.01). The definitive cure rate after a single dose of tinidazole 2 g was in females with treated partner 91.8% and with untreated partner 72.6%. It is concluded that a single dose of tinidazole is an effective treatment for females with trichomoniasis but to avoid relapse it is necessary to treat the sexual partner too.