ABSTRACT
From the early years of the HIV/AIDS epidemic, it was apparent that international travel-for business and for pleasure-played a necessary though not sufficient role in the geographic and social diffusion of HIV infection (Conway et al., 1990; Gould, 1993; Hawkes, 1992; Hawkes and Hart, 1993). HIV is transmitted from person to person primarily by unprotected penetrative sex or through sharing of injecting equipment. Consequently, its initial emergence within the resident populations of regions, countries and districts previously unaffected, must have been due to contact with individuals from ‘elsewhere’; either by uninfected individuals travelling away from home to areas where HIV infection was present, or through contact with HIV-infected persons visiting an area initially free from infection. As Conway, Gillies and Slack (1990) note, the majority of the early cases of AIDS reported in Denmark, Italy, Germany and the United Kingdom, were among ‘men who had had sexual contacts with men who lived in the United States’. Equally, the crucial significance of travel in the early stages of the development of the epidemic in the USA, is graphically illustrated by Gould’s (1993) account of the epidemiological work that led to the identification of the so-called ‘Patient Zero’:
The sexual contacts of 40 men who had converted to AIDS were carefully traced (…), and led to the probable identification of Patient Zero, later identified as an airline steward with international connections. Even within the United States the trail of structuring connections led from Los Angeles, to New York, to San Francisco, and five other states, and most of the men reported large numbers of sexual partners. (…) Whether Patient Zero was the initiator of the pandemic in the United States will never be known with certainty, and in any event it is of little importance since at a global scale airline travel virtually guarantees rapid transmission (…) It is reasonable to assume that he was infected in the early seventies (…) and then spread the virus to perhaps scores or even hundreds of partners.
