How HIV infection and associated HBV and HCV co-infections impact "fragile" populations, evolve and spread in Italy
Continuous surveillance of HIV infection and HBV and HCV co-infections, in "fragile" populations and in the general population, is a key tool to implement timely public health interventions in order to limit spread of these infections and, at the same time, optimize and customize effective preventive and therapeutic strategies. CNAIDS is committed to establishing a surveillance system for HIV variants.
The HIV virus is characterized by an extensive genetic variability, responsible for the extreme diversification of circulating viruses in clades, which vary according to geographical areas. Subtype B is predominant in the USA, Europe, and Australia. Subtype C is widespread in the Indian Peninsula, Southern Africa, and the Horn of Africa and, alone, is responsible for about 50% of infections, worldwide. Subtype A is predominant in Eastern Europe and Central Asia. Finally, subtype D is present in Eastern Africa, south of the Sahara. The remaining clades have a local spread in different geographical regions, especially in Western Sub-Saharan Africa and Asia, where several clades are present. The infection with various subtypes also generates recombinant forms (CRF) whose number is constantly increasing, adding further complexity to the heterogeneity of HIV that appears significantly higher than initially thought.
The global distribution of HIV strains is constantly evolving, fueled by trade, travel, military missions and migration. In Western countries, including Italy, infections supported by non-B subtypes are constantly increasing. As HIV continues to circulate globally, the current geographical distribution is likely to change in the short to medium term. The presence of numerous subtypes and CRFs can have an important impact on the public health. In fact, variants of the various viral subtypes and CRFs may show different capacities of transmission, avoidance of host immune response, resistance to antiretroviral therapy and disease progression. In addition, the genetic variability of the virus can have an impact on the sensitivity of the tests used for laboratory diagnosis and viral load measurement in the blood.
“Fragile" populations are more exposed to HIV infection and co-infections by HBV and HCV (hepatitis viruses), which are also genetically variable and present, like HIV, with numerous genetic forms and different prevalence in the different geographic areas of the world.
In this context, CNAIDS promoted a national programme for monitoring the HIV, HBV and HCV genotype variability of viruses circulating in the general Italian population and in “fragile” populations, such as immigrants and prisoners, as suggested by the European Union and the WHO.