High chlamydia and gonorrhoea repeat positivity in remote Aboriginal communities 2009-2011: Longitudinal analysis of testing for re-infection at 3 months suggests the need for more frequent screening

Background Extremely high rates of diagnosis of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) have been recorded in remote communities across northern and central Australia. Re-testing at 3 months, after treatment administered, of CT or NG is recommended to detect repeat infections and prevent morbidity and ongoing transmission. Methods: Baseline CT and NG laboratory data (2009-2010) from 65 remote health services participating in a cluster randomised trial was used to calculate the proportion of individuals re-tested after an initial CT or NG diagnosis at <2 months (not recommended), 2-4 months (recommended) and 5-12 months and the proportion with repeat positivity on re-test. To assess if there were difference in re-testing and repeat positivity by age group and sex, t-tests were used. Results: There was a total of 2054 people diagnosed with CT and/or NG in the study period; 14.9% were re-tested at 2-4 months, 26.9% at 5-12 months, a total of 41.8% overall. Re-testing was higher in females than in males in both the 2-4-month (16.9% v. 11.5%, P<0.01) and 5-12-month (28.9% v. 23.5%, P≤0.01) periods. Women aged 25-29 years had a significantly higher level of re-testing 5-12 months post-diagnosis than females aged 16-19 years (39.8% v. 25.4%, P<0.01). There was a total of 858 people re-tested at 2-12 months and repeat positivity was 26.7%. There was higher repeat NG positivity than repeat CT positivity (28.8% v. 18.1%, P