According to Kenya's Sunday Standard, Obama told the crowd: "If a senator from the United States and his wife can get tested, then everyone in this crowd, and in this town and in this province can get tested."
HIV/AIDS has been one of the senator's key messages during his trip to Kenya, where his father was born. He encouraged people to know their status, as this was the "first step to controlling the spread of the disease".
The senator's visit is especially significant in Kisumu, where the prevalence rate is 15 percent - more than double the national average of about six percent.
Obama, the only black US senator, visited South Africa last week, where he criticised the government for promoting traditional medicines to fight AIDS rather than life-prolonging antiretroviral therapy.
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