The unexpected impact of a Chlamydia trachomatis infection control program on susceptibility to reinfection.

BACKGROUND After the introduction of a program to control Chlamydia trachomatis infection in British Columbia, Canada, case rates fell from 216 cases/100,000 population in 1991 to 104 cases/100,000 population in 1997. Since 1998, rates have increased, and case counts now exceed those recorded before the intervention. METHODS We used Cox proportional-hazards survival analysis and developed a compartmental mathematical model to investigate the cause of resurgence in chlamydia cases. RESULTS Cox proportional-hazards survival analysis showed that the relative risk of C. trachomatis reinfection has increased 4.6% per year since 1989, with the increased risk greatest among the young and greater among women than men. A compartmental mathematical model of C. trachomatis transmission showed that a control strategy based on shortening the average duration of infection results in an early reduction in prevalence followed by a rebound in prevalence, reproducing the observed trends. CONCLUSIONS We speculate that a C. trachomatis infection control program based on early case identification and treatment interferes with the effects of immunity on population susceptibility to infection and that, in the absence of strategies to alter sexual networks, a vaccine will be needed to halt the spread of infection at the population level.

[1]  R. Kaslow,et al.  Human leukocyte antigen and cytokine gene variants as predictors of recurrent Chlamydia trachomatis infection in high-risk adolescents. , 2005, The Journal of infectious diseases.

[2]  S. Franceschi,et al.  The natural course of Chlamydia trachomatis infection in asymptomatic Colombian women: a 5-year follow-up study. , 2005, The Journal of infectious diseases.

[3]  B. Sibai,et al.  Spontaneous Resolution of Asymptomatic Chlamydia trachomatis in Pregnancy , 2005, Obstetrics and gynecology.

[4]  R. Brunham,et al.  Immunology of Chlamydia infection: implications for a Chlamydia trachomatis vaccine , 2005, Nature Reviews Immunology.

[5]  R. Brunham,et al.  Effect of immune response on transmission dynamics for sexually transmitted infections. , 2005, The Journal of infectious diseases.

[6]  Irene A. Doherty,et al.  Determinants and consequences of sexual networks as they affect the spread of sexually transmitted infections. , 2005, The Journal of infectious diseases.

[7]  P. Bearman,et al.  Chains of Affection: The Structure of Adolescent Romantic and Sexual Networks1 , 2004, American Journal of Sociology.

[8]  G. Burstein,et al.  Sexually transmitted diseases treatment guidelines , 2003, Current opinion in pediatrics.

[9]  R. Brunham,et al.  Impact of Mass Treatment on Syphilis Transmission: A Mathematical Modeling Approach , 2003, Sexually transmitted diseases.

[10]  Mark E. J. Newman,et al.  The Structure and Function of Complex Networks , 2003, SIAM Rev..

[11]  R. Brunham,et al.  Targeted mass treatment for syphilis with oral azithromycin , 2003, The Lancet.

[12]  W. Levine,et al.  SEXUALLY TRANSMITTED DISEASES TREATMENT GUIDELINES 2002 , 2002, MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports.

[13]  J. Lindbäck,et al.  Is the Increase in Notifications of Chlamydia trachomatis Infections in Sweden the Result of Changes in Prevalence, Sampling Frequency or Diagnostic Methods? , 2002, Scandinavian Journal of Infectious Diseases.

[14]  J. Fortenberry,et al.  Determinants of Persistent and Recurrent Chlamydia trachomatis Infection in Young Women: Results of a Multicenter Cohort Study , 2001, Sexually transmitted diseases.

[15]  P. Saikku,et al.  Serotypes of Chlamydia trachomatis and risk for development of cervical squamous cell carcinoma. , 2001, JAMA.

[16]  R. Carpenter,et al.  The duration of human ocular Chlamydia trachomatis infection is age dependent , 1999, Epidemiology and Infection.

[17]  H. Caldwell,et al.  The effect of doxycycline treatment on the development of protective immunity in a murine model of chlamydial genital infection. , 1999, The Journal of infectious diseases.

[18]  P. Ketchum.  Canadian STD guidelines--1998 edition. , 1998, Canadian family physician Medecin de famille canadien.

[19]  W. M. Mac Kenzie,et al.  Recurrent chlamydial infections increase the risks of hospitalization for ectopic pregnancy and pelvic inflammatory disease. , 1997, American journal of obstetrics and gynecology.

[20]  N. Nagelkerke,et al.  The epidemiology of Chlamydia trachomatis within a sexually transmitted diseases core group. , 1996, The Journal of infectious diseases.

[21]  J. P. Davis,et al.  Risk factors for recurrent Chlamydia trachomatis infections in women. , 1994, American journal of obstetrics and gynecology.

[22]  R M May,et al.  Age-dependent choice of sexual partners and the transmission dynamics of HIV in Sub-Saharan Africa. , 1992, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[23]  P. Piot,et al.  Cofactors in male-female sexual transmission of human immunodeficiency virus type 1. , 1991, The Journal of infectious diseases.

[24]  F. Plummer,et al.  A general model of sexually transmitted disease epidemiology and its implications for control. , 1990, The Medical clinics of North America.