With regards to Jammeh, the same website which reported his ill health in the link above ran a story yesterday that he had narrowly escaped death after he was attacked by his pet lion. In 2011 the very same site also reported that he was dying of pancreatic cancer and last month they raised concerns about his sex addiction.
Hehe, yes, African politics is a bit of a bloodsport... There's so little restraint it looks like parody to us. And it reminds me of the time an opponent of then-presidential candidate Muhammadu Buhari of Nigeria said he had prostate cancer, asthma and dementia and "wouldn't last long in office". Only then Buhari won and now the old, corrupt regime is running away from justice, including the oil minister you mentioned, because Buhari means business.
The situation in Gambia becomes even more complicated because just a few days later, Yahya Jammeh banned female genital mutilation. It's apparently a hugely progressive policy stance there, so maybe there was a truthful leak, or some fabrication, from inside his own camp. The régime hadn't exactly been known for it's progressive policies before.