AIDS primary prevention

Associate Editors-in-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

Overview
Acquired immune deficiency syndrome (AIDS) is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV) in humans, and similar viruses in other species (SIV, FIV, etc). There is currently no vaccine or cure for HIV or AIDS. The only known methods of prevention are based on avoiding exposure to the virus or, failing that, an antiretroviral treatment directly after a highly significant exposure, called post-exposure prophylaxis (PEP).

Prevention
The diverse transmission routes of HIV are well-known and established. Also well-known is how to prevent transmission of HIV. However, recent epidemiological and behavioral studies in Europe and North America have suggested that a substantial minority of young people continue to engage in high-risk practices and that despite HIV/AIDS knowledge, young people underestimate their own risk of becoming infected with HIV (Dias et al., 2005). However, transmission of HIV between intravenous drug users has clearly decreased and HIV transmission by blood transfusion has become almost obsolete in this population.

Underlying science

 * Unprotected receptive sexual acts are at more risk than unprotected insertive sexual acts, with the risk for transmitting HIV from an infected partner to an uninfected partner through unprotected insertive anal intercourse (UIAI) greater than the risk for transmission through receptive anal intercourse or oral sex. According to the French ministry for health, the probability of transmission per act varies from 0.03% to 0.07% for the case of receptive vaginal sex, from 0.02 to 0.05% in the case of insertive vaginal sex, from 0.01% to 0.185% in the case of insertive anal sex, and 0.5% to 3% in the case of receptive anal sex [1].
 * Sexually-transmitted infections (STI) increase the risk of HIV transmission and infection because they cause the disruption of the normal epithelial barrier by genital ulceration and/or microulceration; and by accumulation of pools of HIV-susceptible or HIV-infected cells (lymphocytes and macrophages) in semen and vaginal secretions. Epidemiological studies from sub-Saharan Africa, Europe and North America have suggested that there is approximately, a four times greater risk of becoming HIV-infected in the presence of a genital ulcer such as caused by syphilis and/or chancroid; and a significant though lesser increased risk in the presence of STIs such as gonorrhoea, chlamydial infection and trichomoniasis which cause local accumulations of lymphocytes and macrophages (Laga et al., 1991).
 * Transmission of HIV depends on the infectiousness of the index case and the susceptibility of the uninfected partner. Infectivity seems to vary during the course of illness and is not constant between individuals. An undetectable plasma viral load does not mean that you have a low viral load in the seminal liquid or genital secretions. Each 10 fold increment of seminal HIV RNA is associated with an 81% increased rate of HIV transmission (Tovanabutra et al., 2002).
 * People who are infected with HIV can still be infected by other, more virulent strains.
 * Oral sex is not without its risks as it has been established that HIV can be transmitted through both insertive and receptive oral sex (Rothenberg et al., 1998).
 * Women are more susceptible to HIV-1 due to hormonal changes, vaginal microbial ecology and physiology, and a higher prevalence of sexually transmitted diseases (Sagar et al., 2004; Lavreys et al., 2004).

Prevention strategies
During a sexual act, only condoms, be they male or female, can reduce the chances of infection with HIV and other STIs and the chances of becoming pregnant. They must be used during all penetrative sexual intercourse with a partner who is HIV positive or whose status is unknown (Cayley, 2004). The effective use of condoms and screening of blood transfusion in North America, Western and Central Europe is credited with the low rates of AIDS in these regions. Adopting these effective prevention methods in other regions has proved controversial and difficult. Some claim this is in part because of the strong influence of the Roman Catholic Church, which opposes the use of condoms. With consistent and correct use of condoms, there is a very low risk of HIV infection. Studies on couples where one partner is infected show that with consistent condom use, HIV infection rates for the uninfected partner are below 1% per year
 * The male latex condom is the single most efficient available technology to reduce the sexual transmission of HIV and other sexually transmitted infections. In order to be effective, they must be used correctly during each sexual act. Lubricants containing oil, such as petroleum jelly, or butter, must not be used as they weaken latex condoms and make them porous. If necessary, lubricants made from water are recommended. However, it is not recommended to use a lubricant for fellatio. Also, condoms have standards and expiration dates. It is essential to check the expiration date and if it conforms to European (EC 600) or American (D3492) standards before use.
 * The female condom is an alternative to the male condom and is made from polyurethane, which allows it to be used in the presence of oil-based lubricants. They are larger than male condoms and have a stiffened ring-shaped opening, and are designed to be inserted into the vagina. The female condom also contains an inner ring which keeps the condom in place inside the vagina - inserting the female condom requires squeezing this ring.

Government programs
The U.S. government and U.S. health organizations both endorse the ABC Approach to lower the risk of acquiring AIDS during sex:


 * Abstinence or delay of sexual activity, especially for youth,
 * Being faithful, especially for those in committed relationships,
 * Condom use, for those who engage in risky behavior.

This approach has been very successful in Uganda, where HIV prevalence has decreased from 15% to 5%. However, the ABC approach is far from all that Uganda has done, as "Uganda has pioneered approaches towards reducing stigma, bringing discussion of sexual behavior out into the open, involving HIV-infected people in public education, persuading individuals and couples to be tested and counseled, improving the status of women, involving religious organizations, enlisting traditional healers, and much more." (Edward Green, Harvard medical anthropologist). Also, it must be noted that there is no conclusive proof that abstinence-only programs have been successful in any country in the world in reducing HIV transmission. This is why condom use is heavily co-promoted. There is also considerable overlap with the CNN Approach. This is:


 * Condom use, for those who engage in risky behavior.
 * Needles, use clean ones
 * Negotiating skills; negotiating safer sex with a partner and empowering women to make smart choices

The ABC approach has been criticized, because a faithful partner of an unfaithful partner is at risk of AIDS [3]. Many think that the combination of the CNN approach with the ABC approach will be the optimum prevention platform.

Circumcision
Current research is clarifying the relationship between male circumcision and HIV in differing social and cultural contexts. UNAIDS believes that it is premature to recommend male circumcision services as part of HIV prevention programmes [4].

Moreover, South African medical experts are concerned that the repeated use of unsterilised blades in the ritual circumcision of adolescent boys may be spreading HIV.

WHO states that male circumcision provides only partial protection, and therefore should be only one element of a comprehensive HIV prevention package.

According to WHO the prevention package includes:
 * The provision of HIV testing and counseling services.
 * Treatment for sexually transmitted infections.
 * The promotion of safer sex practices.
 * The provision of male and female condoms and promotion of their correct and consistent use.

Underlying science

 * Sharing and reusing syringes contaminated with HIV-infected blood represents a major risk for infection with not only HIV but also hepatitis B and C. In the United States a third of all new HIV infections can be traced to needle sharing and almost 50% of long-term addicts have hepatitis C.


 * The risk of being infected with HIV from a single prick with a needle that has been used on an HIV infected person though is thought to be about 1 in 150 (see table above). Post-exposure prophylaxis with anti-HIV drugs can further reduce that small risk.
 * Universal precautions are frequently not followed in both sub-Saharan Africa and much of Asia because of both a shortage of supplies and inadequate training. The WHO estimates that approximately 2.5% of all HIV infections in sub-Saharan Africa are transmitted through unsafe healthcare injections.Because of this, the United Nations General Assembly, supported by universal medical opinion on the matter, has urged the nations of the world to implement universal precautions to prevent HIV transmission in health care settings.

Prevention strategies

 * In those countries where improved donor selection and antibody tests have been introduced, the risk of transmitting HIV infection to blood transfusion recipients has been effectively eliminated. According to the WHO, the overwhelming majority of the world's population does not have access to safe blood and "between 5% and 10% of HIV infections worldwide are transmitted through the transfusion of infected blood and blood products."


 * Medical workers who follow universal precautions or body substance isolation such as wearing latex gloves when giving injections and washing the hands frequently can help prevent infection of HIV.


 * All AIDS-prevention organizations advise drug-users not to share needles and other material required to prepare and take drugs (including syringes, cotton balls, the spoons, water for diluting the drug, straws, crack pipes etc). It is important that people use new or properly sterilized needles for each injection. Information on cleaning needles using bleach is available from health care and addiction professionals and from needle exchanges. In the United States and other western countries, clean needles are available free in some cities, at needle exchanges or safe injection sites.

Mother to child transmission
School-age children exposed to HIV before birth are at increased risk for language problems and could benefit from early diagnosis and classroom intervention, according to a new study.

Underlying science

 * There is a 15–30% risk of transmission of HIV from mother to child during pregnancy, labour and delivery (Orendi et al., 1998). In developed countries the risk can of transmission of HIV from mother to child can be as low as 0-5%. A number of factors influence the risk of infection, particularly the viral load of the mother at birth (the higher the load, the higher the risk). Breastfeeding increases the risk of transmission by 10–15%. This risk depends on clinical factors and may vary according to the pattern and duration of breastfeeding.

Prevention strategies

 * Studies have shown that antiretroviral drugs, cesarean delivery and formula feeding reduce the chance of transmission of HIV from mother to child (Sperling et al., 1996).


 * When replacement feeding is acceptable, feasible, affordable, sustainable and safe, HIV-infected mothers are recommended to avoid breast feeding their infant. Otherwise, exclusive breastfeeding is recommended during the first months of life and should be discontinued as soon as possible.

CDC Recommendations for education and prevention counseling of pregnant women regarding HIV
When the pretest process is simplified to providing essential information, the value of prevention counseling should not be lost. For some women, the prenatal care period could be an ideal opportunity for HIV prevention and subsequent behavior change to reduce risk for acquiring HIV infection. Thus, the following steps are recommended:


 * Information regarding HIV and assessment of risks for HIV infection (i.e., risk screening) should be provided to all pregnant women as part of routine health education. Reluctance to provide HIV prevention counseling should never be a barrier to HIV testing. Similarly, a focus on increased HIV testing should not be a barrier to providing effective HIV prevention counseling for persons determined to be at increased risk for acquiring or transmitting HIV.


 * Pregnant women found to have behaviors that place them at high risk for acquiring HIV infection (e.g., multiple sex partners, current diagnosis or history of STDs, exchange of sex for money or drugs, substance abuse) or who want more intensive client-centered HIV prevention counseling should be provided with or referred to HIV risk-reduction services (e.g., drug treatment, STD treatment, HIV centers with personnel trained in HIV counseling).

HIV and prisons
Prisons are key points of contact with millions of individuals living with or at risk of HIV. Globally, an estimated 9 million people are incarcerated per year.

Prisons form high risk settings because:
 * Higher rates of HIV in prisons than in the community (Hepatitis C and TB rates are even higher)
 * High prevalence of risk behaviours such as injecting drug use, sharing of injecting equipment and unprotected sexual activity
 * Documented cases of HIV outbreaks in prisons
 * High turnover of populations.

Prevention strategies

 * The evidence shows that such programmes should include all the measures against HIV transmission which are carried out in the community outside prisons, which are as follows
 * HIV/AIDS education.
 * Testing and counselling performed on a voluntary basis.
 * Distribution of clean needles, syringes and condoms.
 * Drug-dependence treatment, including substitution treatment.


 * All these interventions have proved effective in reducing the risk of HIV transmission in prisons.


 * They have also been shown to have no unintended negative consequences. The available scientiﬁc evidence suggests that such interventions can be reliably expanded from pilot projects to nationwide programmes.

HIV and Injecting drug abusers
Globally, around 16 million people inject drugs and 3 million of them are living with HIV. On average, one out of every ten new HIV infections is caused by injecting drug use and in some countries in Eastern Europe and Central Asia over 80 per cent of all HIV infections is related to drug use.

Prevention strategies
WHO strongly supports harm reduction as an evidence-based approach to HIV prevention, treatment and care for people who inject drug and defined a comprehensive package which includes:
 * Needle and syringe programmes.
 * Drug dependence treatment - in particular opioid substitution therapy.
 * HIV testing and counselling.
 * HIV treatment and care.
 * Information, education and risk reduction counseling.
 * Condom distribution and STI management.
 * Management of TB and viral hepatitis.

CDC Update

 * The specific interventions to reduce risk behaviors varied by city but included one or more of the following:
 * Individual and group counseling,
 * Efforts to build peer support for behavior change, and/or
 * Demonstration and practice of behaviors that reduce risk.
 * All interventions emphasized termination of IV-drug use. IVDUs were urged to start drug treatment as soon as it became available to them.


 * In all cities, the programs strongly encouraged those who did not stop IV-drug use to
 * Stop sharing drug-injection equipment (e.g., needles and syringes, drug-cooking implements, and rinse water);
 * Use only sterile needles and syringes from unopened packages; and/or
 * Disinfect drug-injection equipment with bleach or other appropriate agents.
 * The interventions related to sexual activity advocated celibacy and, for persons who were sexually active, safer sexual practices, including use of condoms and reduction of the number of sex partners.


 * Fourteen percent to 35% of IVDUs participating in the first follow-up interview had entered a drug-treatment program during the approximately 6 months after enrollment. Forty-nine percent to 75% of IVDUs reported stopping or decreasing their frequency of drug injection during the approximately 6 months between the initial intervention and follow-up interview --including 16%-47% who reported stopping all use of IV drugs.

HIV among Sex-workers
Sex workers, their clients and regular partners are key populations at risk for HIV infection. Contextual factors such as stigma and poverty may further exacerbate sex workers' vulnerability to HIV.

Prevention strategies

 * Interventions aimed at empowering sex workers and providing them with:
 * HIV prevention.
 * Treatment, care and support services have proven effective in a wide range of formal and informal sex work settings.
 * Sex workers should be proactively involved in programme design and delivery.
 * The needs and vulnerabilities of sex workers should be considered.
 * Legal and social frameworks, consistent with human rights principles, are also needed.

Approach to the immunocompromised traveler
The pre-travel preparation of travelers with immune suppression due to any medical condition, drug, or treatment must address several categories of concern:
 * Is the traveler’s underlying medical condition stable? The travel health provider may need to contact the traveler’s primary and specialty care providers (with the patient’s permission) to discuss the traveler’s fitness to travel, give specific medical advice for the proposed itinerary, and verify the drugs and doses composing the usual maintenance regimen.
 * Do the conditions, medications, and treatments of the traveler constitute contraindications to or decrease the effectiveness of any of the disease-prevention measures recommended for the proposed trip? Depending on the destination, these measures include but are not limited to immunizations and drugs used for malaria chemoprophylaxis and management of travelers’ diarrhea.
 * Could any of the disease-prevention measures recommended for the proposed trip destabilize the underlying medical condition, directly or through drug interactions?
 * Are there specific health hazards at the destination that would exacerbate the underlying condition or be more severe in an immunocompromised traveler? If so, can specific interventions be recommended to mitigate these risks?

Special consideration

 * The traveler’s immune status is particularly relevant to immunizations. Overall considerations for vaccine recommendations, such as destination and the likely risk of exposure to disease, are the same for immunocompromised travelers as for other travelers, although the consequences of not administering an indicated vaccine may be more severe.


 * In some complex cases when travelers cannot tolerate recommended immunizations or prophylaxis, the traveler should consider changing the itinerary, altering the activities planned during travel, or deferring the trip. For purposes of clinical assessment and approach to immunizations, immunocompromised travelers fall into 1 of 4 groups, based on mechanism and level of immune suppression.

HIV without significant immunologic compromise

 * HIV patients with >500/mm3 CD4 T lymphocytes are not considered significantly immunocompromised and should be prepared as any other traveler, although the nature of the previous or underlying disease needs to be kept in mind.

Asymptomatic HIV Infection
Asymptomatic HIV-infected people with CD4 cell counts of 200–500/mm3 are considered to have limited immune deficits. CD4 counts increased by antiretroviral drugs, rather than nadir counts (referred to white blood cells), should be used to categorize HIV-infected people. The exact time at which reconstituted lymphocytes are fully functional is not well defined. To achieve a maximal vaccine response with minimal risk, many clinicians advise a delay of 3 months after reconstitution, if possible, before immunizations are administered. While seroconversion rates and geometric mean titers of antibody in response to vaccines may be less than those measured in healthy controls, most vaccines can elicit seroprotective levels of antibody in most HIV-infected patients in this category.

Transient increases in HIV viral load, which return quickly to baseline, have been observed after administration of several different vaccines to HIV-infected people. The clinical significance of these increases is not known, but they do not preclude the use of any vaccine.

Symptomatic HIV/AIDS

 * Knowledge of the HIV-infected traveler’s current CD4 T-lymphocyte count is necessary for pre-travel consultation.
 * In following the patient is termed to have sever immunosupression:
 * HIV-infected people with CD4 cell counts <200/mm3.
 * History of an AIDS-defining illness.
 * Clinical manifestations of symptomatic HIV.

Related Chapters

 * HIV vaccine
 * AIDS education and training centers
 * Abstinence, be faithful, use a condom
 * Condoms, needles, and negotiation
 * Criminal transmission of HIV