Zimbabwe (2005-2006) (Lesotho Government and ORC Macro, 2005; Swaziland Government and ORC Macro 2008; Zimbabwe Government and ORC Macro, 2007).

In each country, the DHS uses a two-stage sampling design. In the first stage, the clusters are selected from a list of enumeration areas from the latest national census (e.g. the 1996 Lesotho Population Census). In the second stage, a complete listing of households is created in each selected cluster. In each household, randomly selected from the complete listing, all women aged 15-49 who were either usual residents or visitors present in the household on the night before the survey were eligible to be interviewed. For the male survey, only a fraction of the sampled households were selected. In this subsample, all men aged 15-59 years were eligible to be interviewed if they were either permanent residents or visitors present in the household on the night before the survey. Our final sample includes 9,892 individuals in Lesotho, 9,143 in Swaziland and 16,082 in Zimbabwe.

One of the great advantages of the DHS is that it includes HIV test results. All women and men eligible to be interviewed were asked to voluntarily provide a blood sample for HIV testing. The 2006-2007 Swaziland DHS estimated that 31.3 percent of women between 15-49 years and 19.5 percent of men between 15-59 years are HIV positive. These figures are slightly lower in Lesotho, with an HIV prevalence of 26 percent among women and 18.5 percent among men in the same age group. In Zimbabwe, DHS data report that 20.7 percent of women are HIV positive compared to 14 percent of men. The difference in HIV prevalence between genders is common to many other subSaharan African countries,<sup>7</sup> reflecting, on the one hand, a higher biological probability of transmission from men to women than from women to men and, on the other, a disparity due to sociological factors including economic resources and power differentials in sexual relationships.

HIV test results are missing for some individuals who were randomly selected to be tested in the survey because they refused to be tested, were absent or because of a technical problem. The proportion of people being tested is equal to 83 percent in Swaziland, 74.3 in Lesotho and 70 percent in Zimbabwe. Refusal to be tested is the main reason for the absence of a test.<sup>8</sup>

# [Figures 3 and 4]

Figures 3 and 4 report the age profile for HIV prevalence for males and females in the sample. For both genders and in all countries, the age profile for HIV prevalence is hump shaped, first increasing and then decreasing with age. For women, the highest HIV prevalence is for individuals between 25 to 39 years old, while for men it is more tilted toward older ages (to the right) and is highest for men approximately between 30 to 44 years old. Interestingly, the graph also shows that HIV prevalence is considerably higher among young women than among young men. Multiple studies have suggested that this discrepancy might be explained by adult men’s unprotected sexual relationships with younger girls (Laga et al., 2001; Luke and Kurz, 2002; Kelly et al. 2003; Dupas 2011). Indeed, older men may be more likely to be HIV infected compared to younger men, because they have been sexually active for longer and they generally have a higher income to

> 7For example, HIV prevalence in Ghana is 2.7% for women and 1.5% for men (Ghana and ORC Macro 2004). The corresponding figures for Kenya are 8% and 4.5% (Kenya and ORC Macro 2009) and for Malawi are 13% and 10% (Malawi and ORC Macro 2005).

> 8 See Corno and de Walque (2007) for additional details related to the HIV testing sample selection in the Lesotho DHS.

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