Estimated burden of Chlamydia trachomatis female genital infection, Italy, 2009-2016

Abstract

Purpose: In Italy, the nationwide burden of genital Chlamydia trachomatis (Ct) is absent because of passive voluntary reporting, its frequent asymptomaticity and consequent undiagnosed cases. Therefore, no specific health intervention has been taken so far. We aimed to estimate incidence rate (IR) and prevalence of Ct female genital infection and its nationwide burden in terms of disability-adjusted life years (DALY). Methods & Materials: We performed an ecological study on women aged 15-70 years affected by Ct genital infection registered from 2009 through 2016 in the two Italian sentinel surveillance systems (SSS) for sexually transmitted infections (STI): SSS-STIClin (composed by 12 public STI clinics, only symptomatic cases reported) and SSS-STILab (composed by 13 public microbiology laboratories, symptomatic and asymptomatic cases reported). Endo-cervical swab and/or first void urine were tested by nucleic acid amplification test (NAAT). We calculated IR by dividing the number of Ct-positive women reported in SSS-STIClin with the number of women resident in the cities where clinics are located. We calculated prevalence by dividing the number of Ct-positive women reported in SSS-STILab by the number of those tested. To estimate DALY (95% uncertainty intervals), we used data on symptomatic cases from both SSS by the Burden of Communicable Diseases in Europe (BCoDE) toolkit. Results: In the 8-year period considered, we found 981 Ct-positive women reported in SSS-STIClin (median age 25 years, interquartile range (IQR) 22-30). Mostly (70.1%), they had Italian nationality. Their number has almost tripled from 71 in 2009 to 188 in 2016. IR increased from 2.7 in 2009 to 7.1 in 2016 per 100,000 (p < 0.0001). In SSS-STILab, 2,275 Ct-positive women were reported (median age 27 years, IQR 22-34). Mostly (81.3%), they had Italian nationality. Prevalence increased from 2009 (2.4%) to 2014 (3.2%) (p < 0.05), then decreased to 2.6% in 2016. Overall, among Ct-positive women, those aged 20-24 years had the highest DALY estimation equal to 105 DALY per 100,000 stratum-specific population. Conclusion: Ct female genital infection has increased in Italy, mostly among the youngest sexually active women. Non-Italian women amounted for over one-third of cases. We recommend starting nationwide active surveillance and targeted screening programmes among women aged 20-24 years.