Background: Methods for accessing large sexual networks are essential for investigating the mechanisms for the spread of sexually transmitted infections.
Goal: Four samples of cases were compared with the total population to determine which identified the largest networks.
Study design: Individuals with positive test results for chlamydia during a 6-month period were selected from a laboratory database and linked with sex partner information from a notifiable disease registry. Sexual networks were constructed for a random sample, people with positive results from two or more tests for chlamydia, people with positive tests results for both gonorrhea and chlamydia, and the preceding two groups combined.
Results: The coinfected people combined with the repeaters yielded the highest proportion (47.8%) of large networks (>10 people), followed by the coinfected people, the repeaters, and finally the random sample.
Conclusions: People coinfected with chlamydia and gonorrhea and those with repeated chlamydial infection present ideal opportunities for both research and prevention.