A sex-structured model for the transmission of trichomoniasis with possible reinfection

ABSTRACT Trichomoniasis is a sexually transmitted disease caused by an infection from the parasite Trichomonas vaginalis. A model of its transmission shows a backward bifurcation when the basic reproduction number is less than one. A stable disease-free equilibrium co-exists with a stable endemic equilibrium with the consequence that the disease may invade the population even when . The backward bifurcation is due to reinfection among the people who have recovered. In the absence of a backward bifurcation and when , the disease-free equilibrium has global asymptotic stability. In the absence of reinfection, the model has a unique global asymptotically stable endemic equilibrium when . Contact rates are the major parameters in the persistence of the disease, compared to rates of recovery after treatment, infectiousness of asymptomatic individuals, and rates of reinfection.