Syphilis is a chronic systemic infection caused by the spirochete Treponema pallidum, which can be transmitted sexually and during a blood transfusion (acquired syphilis), and vertically (congenital syphilis) through the mother’s placenta to the foetus. Pregnant women who are infected with syphilis can transmit the infection to their foetus, causing congenital syphilis. Several studies in different parts of the world have shown that syphilis in pregnancy continuing as a public health concern, leading to perinatal morbidity and mortality in most of the developing countries including Tanzania and is one of the most important public health problems. However; the availability of the study on syphilis and its associated factors is limited in Tanzania and especially among pregnant women population living with HIV/AIDS (PWLHIV) and on antiretroviral therapy (ART). Objectives: To determine the seroprevalence and factors associated with Syphilis infection among pregnant women living with HIV/AIDS attending Prevention of mother to child transmission (PMTCT) in selected health facilities in Mtwara region.

Keywords : Influenza, Seroprevalence, Syphilis infection, Hepatitis B infection, Human immunodeficiency virus.