It’s interesting you brought this up because mental health, disabilities, and the like have been a contentious and often rejected topic in many African countries for quite some time. There’s some fascinating research out there speaking to why many African nations reject assertions of such things like autism to indeed be present. To be fair, many African nations aren’t exactly progressive in social issues, much less science. I did some work on that continent in a past life and have seen it on display first hand.
Autism’s causes aren’t always concrete, and in fact, speculative in many regards (though there is some strong evidence for some cases). I’m not saying autism comes from a pregnant woman smoking cannabis. Only wanted to say, just because you haven’t heard of something doesn’t mean it doesn’t exist 