International collaborative efforts through histocompatibility workshops have helped greatly in collating useful data on interpopulation differences in genetic susceptibility to mycobacterial and viral infections. These are imperative in exploring the genetic basis of disease pathogenesis and host resistance. Because infectious diseases involve multigenic complex traits, several genetic variants contribute modifying effects on the disease but disease outcome depends on the net relative hazards of individual genetic loci taken together. Further because occurrence of genetic variants varies in a population-specific manner, it becomes even more complicated to show genetic influences across populations. For this, large study cohorts representing different ethnicities are needed. Information thus gained could lead to the development of more effective vaccine design to combat or diminish the emergence of pathogenic multidrug resistant forms.