Introduction Homelessness is a societal problem with public health implications. The U.S rate of homelessness is 17.7/10,000. Nightly, 5 50 000 persons experience homelessness, 6.5% under the age of 18 years. Homelessness is associated with greater engagement in high-risk sexual behaviour. Less is known about sexually transmitted infections (STI) among the homeless.

Methods We systematically identified peer-reviewed articles, published 2000–2016, which reported STI bio-specimen testing and rates among homeless persons in the US. Articles (n=9) were grouped by age (e.g. youth=5; adults=4); STI rates and correlate factors were described by gender.

Results Across STIs, rates varied from 0.4%–17% among homeless youth (n=5), and 0.9%–52.5% among homeless adults (n=4). Rates for chlamydia (CT) were similar for youth (4.2%–11.6%)%) and adults (4.6%–10.8). For gonorrhoea, the highest rates for youth (0.4%–9.9%) were double those for adults (0.9%–4.1%)%). STI rates also varied by age and gender. CT was highest among young females (6.45%–11.0%%); followed by adult females (6.7%); then young males (4.73%–4.8%). Rates of HSV-2 (5.52%–11.85%%), HBV (1.42%–17%) and trichomoniasis (2.3%) were reported only in studies on youth. HCV varied among youth (3.77%–12%)%) and adults (9.8%–52.5%%), with rates highest among homeless adult men. Composite STI rates were most often reported for adults (16.4%–40.7%%), with highest rates among adult women who experienced intimate partner violence (IPV) (25.9%–40.7%)%).For youth, longer periods of homelessness were associated with high-risk sexual behaviours. Peer social networks had protective and risk effects on sexual behaviour. For adults, frequency and length of homelessness, incarceration history, substance use, injection drug use (IDU), and IPV were associated with having an STI.

Conclusion STI rates among homeless persons varied by age and gender. There is a need for more complete STI data on homeless youth and adults. Such data can aid in understanding STI risk while homeless and how best to develop tailored prevention strategies.