Migrants have an influence on the health of populations in both places of origin and places of destination because their health tends to differ from those of the non-migrant population at both locations. However, the relationship is more complex than this because migrants can be more vulnerable to health problems than non-migrants and they also can introduce new diseases into populations. It is this latter aspect that has disproportionately engaged the interest of researchers, especially in recent years in relation to the spread of HIV and AIDS (Herdt 1997, Haour-Knipe and Rector 1996).

Health factors alone can be the motivation for migration. In addition, migration can have significant implications for health services in destination contexts. Are migrants at greater risk of ill health because of their lack of immunity to local disease? Is their migrant status a barrier to accessing health services? In this context, the migration of health workers can also be of significance in shaping the availability of health services in places of destination as well as places of origin. These dimensions of the health-migration inter-relationship will be addressed here in the context of the South and South-West Asia subregion.

There has been a significant shift in thinking about the migration and health relationship in recent years as pointed out in the report from the Global Consultation on Migrant Health (Fortier 2010):

In the past there has been a dominance of the healthy migrant approach which recognizes that there is strong selectivity in the migration process, which often is exacerbated by countries of destination imposing health testing as one of the barriers to entry. However, this detracts attention away from the fact that migrant health is often compromised during the migration process and, especially, with time at the destination. Moreover, an overwhelming focus on migrants as ‘spreaders of disease’ has directed attention away from other, often more significant, health-migration relationships.