Chlamydia trachomatis, infertility, and population growth in sub-Saharan Africa
Brunham, R.C.; Cheang, M.; McMaster, J.; Garnett, G.; Anderson, R.
Sexually Transmitted Diseases 20(3): 168-173
1993
ISSN/ISBN: 0148-5717 PMID: 8511712 DOI: 10.1097/00007435-199305000-00010Document Number: 328874
Researchers applied estimates of Chlamydia trachomatis transmission and disease parameters to a compartmental mathematical model of heterosexual, sexually transmitted disease (STD) transmission to determine the potential effect of chlamydia infection via its link to tubal infertility on population growth in sub-Saharan Africa. Epidemiologic parameters included transmission efficiency, salpingitis rate per cervical infection, tubal fertility rate per salpingitis episode, and average duration of infectivity. Sexual behavior parameters were sexual partner change and networks of sexual mixing. Demographic parameters consisted of a constant mortality rate (.02/year), a mean life expectancy (50 years), age of menarche (15 years), age of menopause (45 years), and maximum potential fertility rate. The mathematical model estimated that as the probability of infertility due to chlamydia infection increases, population growth falls almost linearly at various values of basic reproductive rates. In fact, 10% decline in population growth accompanies a 10% chlamydia prevalence. When the researchers applied estimates of gonorrhea transmission to the model, they learned that a 10% prevalence of gonorrhea results in a 30% reduction in population growth, indicating that gonorrhea has more of an effect on population growth than does chlamydia infection. Gonorrhea has higher transmissibility and shorter duration of infectivity than chlamydia infection, resulting in a higher incidence rate at any given prevalence of infection. Improved diagnosis and treatment of STDs as a result of AIDS prevention programs should result in considerable changes in the epidemiology of gonorrhea and chlamydia infection. These changes will likely speed up population growth unless STD control programs are integrated with effective family planning programs.