Dynamics of non-cohabiting sex partnering in sub-Saharan Africa: a modelling study with implications for HIV transmission.
OBJECTIVE
To develop an analytical understanding of non-cohabiting sex partnering in sub-Saharan Africa (SSA) using nationally representative sexual behaviour data.


METHODS
A non-homogenous Poisson stochastic process model was used to describe the dynamics of non-cohabiting sex. The model was applied to 25 countries in SSA and was fitted to Demographic and Health Survey data. The country-specific mean values and variances of the distributions of number of non-cohabiting partners were estimated.


RESULTS
The model yielded overall robust fits to the empirical distributions stratified by marital status and sex. The median across all country-specific mean values was highest for unmarried men at 0.574 non-cohabiting partners over the last 12 months, followed by that of unmarried women at 0.337, married men at 0.192 and married women at 0.038. The median of variances was highest for unmarried men at 0.127, followed by married men at 0.057, unmarried women at 0.003 and married women at 0.000. The largest variability in mean values across countries was for unmarried men (0.103-1.206), and the largest variability in variances was among unmarried women (0.000-1.994).


CONCLUSIONS
Non-cohabiting sex appears to be a random 'opportunistic' phenomenon linked to situations that may facilitate it. The mean values and variances of number of partners in SSA show wide variation by country, marital status and sex. Unmarried individuals have larger mean values than their married counterparts, and men have larger mean values than women. Unmarried individuals appear to play a disproportionate role in driving heterogeneity in sexual networks and possibly epidemiology of sexually transmitted infections.
Division of Bioinformatics, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan Infectious Disease Epidemiology Group, Weill Cornell Medical College-Qatar, Cornell University, Qatar Foundation-Education City, Doha, Qatar Department of Healthcare Policy and Research, Weill Cornell Medical College, Cornell University, New York, New York, USA.
Ryosuke
R
Omori
Infectious Disease Epidemiology Group, Weill Cornell Medical College-Qatar, Cornell University, Qatar Foundation-Education City, Doha, Qatar.
Hiam
H
Chemaitelly
Infectious Disease Epidemiology Group, Weill Cornell Medical College-Qatar, Cornell University, Qatar Foundation-Education City, Doha, Qatar Department of Healthcare Policy and Research, Weill Cornell Medical College, Cornell University, New York, New York, USA Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
Laith J
LJ
Abu-Raddad
D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000704:Analysis of Variance; D017280:Condoms / Q000706:statistics & numerical data*; D005260:Female; D015658:HIV Infections / Q000517:prevention & control / Q000523:psychology / Q000635:transmission*; D006801:Humans; D008297:Male; D017533:Marital Status / Q000706:statistics & numerical data*; D008393:Marriage; D012307:Risk Factors; D012309:Risk-Taking; D012725:Sexual Behavior / Q000523:psychology / Q000706:statistics & numerical data*; D012747:Sexual Partners / Q000523:psychology
AFRICA; MATHEMATICAL MODEL; SEXUAL BEHAVIOUR