The spread of HIV can be prevented if precautions are taken by those already infected and those who are uninfected but at risk for exposure. The advent of HAART represents a major advance in blocking the transmission of HIV from infected people due to its ability to greatly reduce viral titers in body fluids. However, most who are infected with HIV do not have access to HAART, as it is expensive and requires lifelong treatment, and many of those infected are unaware that they carry the virus. Even where HAART is unavailable, access to regular screening for those at risk is critical to inform those infected so they can take measures to avoid passing the virus to others. This, in turn, requires strict confidentiality and mutual trust. A barrier to the control of HIV is reluctance of individuals to find out whether they are infected, especially as one of the consequences of a positive HIV test is stigmatization by society. Here, education becomes an important component of the prevention strategy, both to remove the stigma and to provide guidance on how transmission of the virus can be prevented.
Precautions that can be taken by uninfected individuals are relatively inexpensive and involve measures to protect against contact with body fluids, such as semen, blood, blood products, or milk, from people who are infected. It has been repeatedly demonstrated that this is sufficient to prevent infection, as exemplified by healthcare workers who care for AIDS patients for long periods without seroconversion or signs of infection. The routine use of condoms greatly reduces the risk of HIV transmission, as does restraint from breastfeeding by infected mothers of newborns. Male circumcision also reduces transmission rates, as the foreskin is a major site of viral entry in uncircumcised males. Additional measures that have been considered include the use of microbicidal gels or suppositories, improvements in which have led to products that show promise in recent trials. Some of these agents can also reduce the transmission of other sexually transmitted diseases (for example, genital herpes) that increase the risk of HIV transmission. Finally, there is increasing interest in the prophylactic use of antiretroviral drugs (referred to as preexposure prophylaxis, or PrEP), which are administered either topically or orally to individuals at high risk for contracting HIV. To date, two reverse transcriptase inhibitors have shown efficacy in trials, and combined daily use of both drugs taken orally has demonstrated over 90% reduction in the risk of HIV infection. Moreover, use of antiretroviral therapy immediately postexposure—for example, in hospital workers exposed to contaminated blood by accidental needlestick—substantially reduces the risk of acquiring HIV. One concern with this approach is the risk of developing drug resistance in those who do contract HIV while on PrEP, particularly in individuals with poor adherence to the dosing regimen. Although the significance of this risk has yet to be established, it remains an issue. Nevertheless, testing of new PrEP strategies based on additional antiretrovirals or of longacting formulations that reduce the risk of poor compliance represents areas of considerable promise.
Summary.