Introduction:
Infections such as viral hepatitis and syphilis that share similar transmission routes with human immunodeficiency virus (HIV) may adversely affect the course of the disease. We aimed to determine the seroprevalence of viral hepatitis and syphilis among HIV-infected people at the initial stage of diagnosis.

Material and methods:
The medical records of 336 HIV-infected people aged 18 years and older, who were followed up between 2005 and 2018 at a university hospital in Samsun, Turkey, were evaluated retrospectively in terms of initial serological markers for viral hepatitis and syphilis.

Results:
Hepatitis B surface antigen (HBsAg) was positive in 13 (4.2%) of 303 patients, antibody to HBs antigen (anti-HBs) in 117 (39.2%) of 298 patients, antibody to hepatitis C virus (anti-HCV) in 3 (0.9%) of 301 patients, total antibody to hepatitis B core antigen (anti-HBc total) in 70 (29.2%) of 239 patients and total antibody to hepatitis A virus (anti-HAV total) in 224 (84.5%) of 265 patients. Hepatitis B virus (HBV) deoxyribonucleic acid (DNA) was detected in one (12.5%) of eight patients with isolated anti-HBc. Of 224 patients who were examined for syphilis, 34 (15.1%) were positive for Treponema pallidum hemagglutination (TPHA).

Conclusions:
In our study, high seroprevalence of syphilis and low immunity to HBV were detected. Health care facilities that follow up HIV-infected people should determine the serological profiles initially once the patients are diagnosed. It should be kept in mind that due to behavioral risk factors among HIV-infected people prevalence of coinfections may be higher than the rate in the community.