Mycobacteriosis and HIV infection: the new public health challenge.

Human immunodeficiency virus (HIV) infection alters the epidemiology of mycobacterial infections. In the industrialised world, this has led to an increase in severe illness associated with Mycobacterium avium-intracellulare complex (MAC) and, in the developing world, to doubling of tuberculosis cases in some countries in Sub-Saharan Africa. The interaction with Mycobacterium tuberculosis occurs when the CD4 count is relatively high (> 200) and tuberculosis (TB) is now the commonest presenting AIDS defining disease in Africa. In international public health terms the interaction between TB and HIV infection has led to the World Health Organisation declaring TB to be a global emergency. Both TB and HIV are diseases of poverty and the key to the reduction of incidence of both diseases is the improvement of socio-economic conditions. Other control methods are case finding and treatment, chemoprophylaxis and BCG vaccination. Finding active (sputum positive) case of tuberculosis and treating them is the function of TB control programmes in all countries, but poor adherence to medication has lead to low cure rates and increasing development of drug resistance. Resources are needed to improve adherence to medication and for research to improve diagnostic methods and treatment.