The methodology for the 2003 Kenya survey is discussed
here. I don't know if there was a more recent survey. The 2003 survey was a voluntary household survey of a large sample of the Kenyan population.
According to the Washington Post story I linked in my prior response, these new national surveys (most done by ORC Macro of Maryland) have shown that AIDS rates in most African countries were much lower than the UN has historically been reporting based on so-called sentinel surveys of preganant women.
"The methodology for the 2003 Kenya survey is discussed here."
Thanks for the link. I think the discussion there shows that there are indeed problems with the sampling.
"these new national surveys (most done by ORC Macro of Maryland) have shown that AIDS rates in most African countries were much lower than the UN has historically been reporting based on so-called sentinel surveys of preganant women."
Which reflects favorbly on the methodology, but I don't think it's reliable yet.