Many species of mammals are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period.
Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses.
The risk of acquiring HIV from a needle stick from an HIV-infected person is estimated as 0.3% (about 1 in 333) per act and the risk following mucous membrane exposure to infected blood as 0.09% (about 1 in 1000) per act.
Preventive treatment involves the mother taking antiretrovirals during pregnancy and delivery, an elective caesarean section, avoiding breastfeeding, and administering antiretroviral drugs to the newborn.
The World Health Organization recommends treating all children less than 5 years of age; children above 5 are treated like adults.
Measures to prevent opportunistic infections are effective in many people with HIV/AIDS.
HIV is transmitted by three main routes: sexual contact, significant exposure to infected body fluids or tissues, and from mother to child during pregnancy, delivery, or breastfeeding (known as vertical transmission).and is frequently associated with adverse effects—where zidovudine is used, about 70% of cases result in adverse effects such as nausea (24%), fatigue (22%), emotional distress (13%) and headaches (9%).If replacement feeding is acceptable, feasible, affordable, sustainable, and safe, mothers should avoid breastfeeding their infants; however exclusive breastfeeding is recommended during the first months of life if this is not the case.Blood-borne transmission can be through needle-sharing during intravenous drug use, needle stick injury, transfusion of contaminated blood or blood product, or medical injections with unsterilized equipment.The risk from sharing a needle during drug injection is between 0.63 and 2.4% per act, with an average of 0.8%.