"...why is HIV in Africa about as common among women and among men?"
if the anal sex bunch is bisexual, they practice it with the women as well.
Also, no-one will EVER convince me that you can get aids from a needle but not biting insects.
I too worry about those big giant mosquitoes we have down here. A couple of generations back most of my forbearers were killed by yellow fever spread by mosquitoes. My Dad got malaria down here. I am suspicious of them and wish DDT would come back. That ban has been a disgrace.
Or the Nile virus, or malaria, or ... ;)
A needle, yes, but there are no documented cases of AIDS transmission from insect bites. I believe the experts say AIDS is highly unlikely to be transferred from insects bites, but to say it's impossible to transfer AIDS via insects would seem wrong.
This article makes a case against HIV transmission via mosquitos: Why Mosquitos Cannot Transmit AIDS. Here's another helpful article: Can I get AIDS from a mosquito bite?
Well, one thing is quantity of sample, and another is time spent out of the body.
Insects which draw blood tend not to go and bite another person for a while. HIV is quite fragile. The amount of blood that a biting insect carries with it is generally well below the amount which would allow HIV to survive a significant length of time.
Needles tend to both hold more blood than most of the insects (aside from ticks...which don't bite multiple people within a short period of time); don't digest the contents; and have a region protected from light that can form a region protected from things that would deactivate the virus; and unfortunately tend to be reused for injections pretty soon after contamination.
I suspect that it IS possible to convey via insect bite, but it clearly isn't very likely.