Sexual networks of U.S. military service members with chlamydia at Joint Base San Antonio, June-December 2023.

Limited data on sexual networks in the U.S. military makes designing strategies to combat sexually transmitted infections (STIs) challenging. This retrospective evaluation assessed reported sexual networks of military service members with chlamydia, to inform future interventions for decreasing transmission of the infection. Thirty-two active duty service members at Joint Base San Antonio-Fort Sam Houston tested positive for chlamydia infection during the evaluation period, June through December 2023. Service members who tested positive for chlamydia were interviewed by Army Public Health Nursing staff and were asked to identify their sexual partners from the preceding 60 days, for routine contact tracing. Patient responses were then anonymized for comparisons of sexual networks of military service members-by sex, branch of service, and whether they were participating in military training or had completed training ("permanent party"). Service members with chlamydia were predominantly female (n=19, 59.4%), in the Army (n=18, 56.3%), and in military training (n=20, 62.5%). Of the 45 sexual contacts of the 32 service members identified through contact tracing, the majority (n=30, 66.7%) of those sexual contacts were civilians. Those still in military training were more likely to report sexual contacts who were also military service members, compared to permanent party service members (n=12, 50% vs. n=3, 14.3%, p=0.014). This evaluation determined that most service members who developed chlamydia were in sexual networks with only a single partner (n=22, 68.8%). These data should form an initial assessment of a military sexual network that needs to be confirmed in larger settings. This analysis of sexual networks at Joint Base San Antonio-Fort Sam Houston involving 32 military service members with chlamydia found that sexual networks for service members who were in training had a greater proportion of sexual partners who were also in the military compared to service members who were not in training (50% vs. 14.3%, p=0.014).