# **1. Introduction**

The HIV/AIDS pandemic is one of the greatest challenges facing Africa. According to UNAIDS (2009a), in 2008, 22.4 million people were infected with HIV/AIDS in Sub–Saharan Africa (about 67 percent of the world total), 1.4 million died from the virus, and approximately 1.9 million became newly infected. Swaziland and Lesotho are the countries with the highest HIV prevalence rate in the world. Recent nationally representative estimates reveal an adult HIV prevalence equal to 26% in Swaziland (Swaziland Government and ORC Macro, 2008) and to 23.2% in Lesotho (Lesotho Government and ORC Macro, 2005).<sup>3</sup> These countries have two main features in common: they are small countries bordering South Africa (see figure 1) and, during the past decades, they were exposed to massive recruitment to work in South African mines. For more than a century, 90 percent of those employed in the mining sector in the Republic of South Africa were black and about 60 percent were migrant workers from Lesotho and Swaziland (Lucas, 1985; Harington, McGlashan and Chelkowska, 2004). This evidence poses a crucial and still unanswered question in the economic literature: is there a relationship between the proportion of migrant miners in a country and HIV infections?

This paper investigates whether the massive percentage of migrant workers employed in South Africa’s mining industry for a long period in the past might be one of the main explanations for the high HIV prevalence observed in Swaziland and Lesotho. We hypothesize that mining activities might influence the risk of HIV infection through three main channels. First, working in South African mines implies temporary long-term migration from the household of origin and this increases the probability of engaging in multiple concurrent sexual partners. Second, miners have traditionally been accommodated in single-sex hostels and this has boosted an active sex industry in the area surrounding the mining sites where miners have disposable income to engage in sexual relationships with commercial sex workers. Finally, women, who wait for their husbands to come back from the mines, might be more likely to engage in sexual relationships with other partners as well.

The data used in the paper come from the Demographic and Health Survey (DHS) conducted in Swaziland (2006-2007) and Lesotho (2004). In this set of African countries, the DHS provides the information required for our empirical analysis: a complete standardized questionnaire on sociodemographic characteristics and HIV test results for a nationally representative sample of the adult population. The latter represents a great advantage compared to previous surveys that collected information on HIV/AIDS based exclusively on self-reported behaviors.

To analyze the relationship between migrant miners and HIV status, we estimate a _probit_ model for the probability of being HIV positive and adopting the safer sexual behaviors promoted

> 3 Botswana is also considered one of the countries with the highest HIV prevalence in the world. The available and most recent data on HIV prevalence in Botswana reveal an HIV prevalence equal to 24.8% (UNAIDS, 2009b). This data comes from Sentinel Surveillance Surveys among pregnant women attending antenatal clinics but are not nationally representative. Because there is no recent DHS survey with HIV testing for Botswana, we cannot include it in the analysis.

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