Since 1997 Vancouver (British Columbia, Canada) has experienced an outbreak of heterosexually transmitted infectious syphilis, which prompted a mass treatment campaign in early 2000 in an attempt to control the disease. By 1 year postintervention, syphilis cases had rebounded significantly. We investigate the cause of this postintervention rebound.
We argue that the observed rebound postintervention may have been the result of the natural dynamics of disease transmission in an open population, in response to the partial application of mass treatment in the sexually active subgroup.
We used a mathematical model that describes the transmission dynamics of syphilis in a population.
The observed postintervention rebound is related to the mass treatment intervention.
Our results suggest that mass treatment may not be an optimal strategy to control the transmission of syphilis if complete coverage of high-frequency transmitters cannot be achieved and if population mobility is relatively high.
Mass treatment may not be an optimal strategy to control the transmission of syphilis if complete coverage cannot be achieved and if population mobility is relatively high.
From the University of British Columbia Centre for Disease Control and British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada
Reprint requests: Babak Pourbohloul, PhD, UBC Centre for Disease Control, 655 West 12th Avenue, Vancouver, BC, Canada, V5Z 4R4. E-mail: email@example.com
Received June 14, 2002,
revised September 20, 2002, and accepted September 23, 2002.