[HIV testing: the medical laboratory role in HIV diagnosis and monitoring].

Diagnosis of HIV infection is performed via enzyme immunoassay (EIA), an assay based on screening for antibodies against HIV. Confirmation of diagnosis is performed by Western-Blot, a more specific assay directed at a number of viral proteins for which antibodies exist. Routine follow-up of HIV-infected individuals includes measurement of CD4 cell count to evaluate the immune status, of viral load to assess virus replication, and of changes in the viral genome to characterize resistance to drugs and tropism. In addition, absence of the HLA B*57:01 allele is verified before prescription of abacavir, and drug levels of protease-inhibitors are determined in treatment-failing individuals after ruling out other causes of failure. Rapid diagnosis and regular follow-up improve the quality of life of patients and extend their life expectancy, also helping to control the spread of the epidemic at the national level.