The actress, who stars in long-running U.K. serial drama Coronation Street, was rushed to hospital after her trip, and spent nearly two days being treated before doctors ruled out the potentially fatal disease.
It's not yet known when she will return to filming on the series.
A show source tells the Sunday Mirror, "No one really knows what's wrong with Sue, but she's been feeling very ill. It started pretty much as soon as she got back from Kenya. Obviously serious alarm bells start ringing when you come back from Africa feeling unwell because you hear so many horror stories about people contracting diseases out there."
Cleaver visited the country with fellow cast members last month (Jun12) to raise awareness of HIV and AIDS for an upcoming documentary.