Men having concurrent long-term (over one year) relationships is not the only thing that differentiates African countries from other places, but that a significant number of African women also have multiple long-term partners.
To amplify HIV transmission through unprotected heterosexual sexual encounters, women also have to have concurrent partners too, after all â€œbeing faithfulâ€ takes two.
Fewer African women compared to men have concurrent relationships, but their numbers are higher compared to other countries-in Lusaka, Zambia (11 percent), Tanzania (9 percent), Lesotho (39 percent) compared to Brazil and Asia where it is less than 3 percent.Â Â
Studies have shown that oddly enough, women are good at gauging if their men are seeing someone else, but men greatly underestimate if women are involved in other relationships.
Serial monogamy (staying faithful to one partner) traps the virus within a single relationship for months or years but in situations where both men and women are having concurrent relationships, it takes one person in the network to pass it on to a number of people.
The risk is also greater because recently infected individuals are more likely to pass on the virus. In monogamous relationships that last for a while, by the time the relationship has ended, the newly infected partner may have a lower viral load and be less infectious.
Mathematical models have demonstrated this interlinked web that only requires a few people to have concurrent partners to create islands of infections that spread rapidly in a community. A network with an average of two concurrent partners for both men and women is enough to link a large number of sexually active people.
This has been shown among the population of people at Likoma Island. A study found that because of concurrent relationships in the seven villages on the island, two thirds of the 1 070 people were all connected to each other through a sexual network.
West African countries, where HIV prevalence is lower than southern African countries, have extramarital sexual patterns similar to Asian countries i.e. one-off sexual encounters and fewer reports of concurrent relationships. Condom use is also factor as people in long-term concurrent relationships are less likely to use condoms.