A STUDY in Kenya has been seized upon by critics who claim that the scale of the HIV epidemic is being exaggerated by what some call 鈥渁n AIDS establishment pursuing money and power鈥�. The government survey of 3000 households suggests only 1 million people in Kenya have HIV 鈥� nearly 1 million fewer than the latest UNAIDS estimate.
鈥淭here is no one measurement that tells us everything we need to know about HIV/AIDS,鈥� says Kevin DeCock, director of the Kenyan branch of the US Centers for Disease Control, who was involved in the study. While household surveys of the kind done in Kenya reach a broader cross section of the population than other methods, they can underestimate the number of cases. For instance, people who travel a lot 鈥� a high-risk group 鈥� are less likely to be sampled, while those who suspect they are infected may refuse to provide a saliva sample.
The UNAIDS estimates of the size of the African epidemic are based largely on surveys of women in antenatal clinics, where every patient can be tested. However, pregnant women are a high-risk group, as they have had unprotected sex, so this method might overestimate numbers. On the other hand, HIV and other sexually transmitted infections reduce fertility, which means this method might underestimate levels of infection.
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There simply is no gold standard for working out how many people in a country have HIV, says Catherine Hankins, chief scientific adviser at UNAIDS. It will incorporate the latest Kenyan data into its own estimates, she says. 鈥淎nything we can get, we will use.鈥�