Background: It is estimated that over ten percent of the 36.7 million people living with HIV (PLWHIV) globally, are those aged ≥50 years. The objective of this study was to determine the prevalence and risk factors for HIV among adult aged 50 years and above in Rombo district, northern Tanzania.

Methods: This cross sectional study was conducted from April to June 2015 among older adults aged ≥50 year in Rombo district. Interviews were conducted to collect information on socio-demographic characteristics, reproductive and sexual health characteristics of the participants, knowledge on HIV transmission, prevention and risk perception and on awareness and knowledge on voluntary and counselling testing services. In addition, a blood sample was taken for HIV diagnosis.

Results: A total of 600 people were enrolled. Their age ranged from 50 to 90 years with mean of 64.9 (±SD 10.3) years. The HIV prevalence was 1.7% (n=10) and it was higher among women (2.1%) than men (1.3%). Sixty-percent (n=350) were knowledgeable on HIV transmission and only 40% (n=216) on HIV prevention. In bivariate analysis, age of partner <50 years, ever use of condoms, poor knowledge on HIV prevention and perception of risk on HIV were significantly associated with HIV. However, only partner’s age of <50 years remained significant after controlling for confounders.

Conclusion: HIV prevalence and overall knowledge on its transmission among older adults in this rural population were low. There is a need for strategies to improve HIV preventive knowledge and testing in this group in order to continue keeping the transmission at low levels.