It is an incalculable loss in every way to lose so many so heavily engaged in efforts to fight AIDS, or any disease...but the drug regimens and vaccine trials for the prevention of mother-to-child transmission underway will no doubt go on.
The mothers who contract aids, and subsequently transfer it to their offspring, get infected in one of two ways:
#1 Anal sex
#2 A dirty needle
Not necessarily in that order...
Anything else is a 1 in a million chance. AIDs is NOT transmitted through normal sex.