Slide 2
The objectives of this presentation are: to explain why prevention of
HIV is important; demonstrate the progress made in HIV prevention; discuss
the modes of HIV transmission; and to describe the most effective
interventions for reducing HIV transmission.
Slide 3
HIV/AIDS is a worldwide pandemic of unprecedented proportions.
Low-resource settings, primarily in the developing world, bear the
greatest burden of disease in terms of absolute numbers, proportions of
adults and children infected, and disease and death secondary to HIV.
However, many sexually active young women living in the developing world
do not believe they are at risk of getting AIDS.
Slide 4
When we examine the actual HIV prevalence rate in pregnant women in
major cities in these countries, there is a significant difference between
perception and reality. For example, although half of young sexually
active women in Zimbabwe feel they are at no risk for contracting AIDS,
one third of pregnant women in major urban areas in Zimbabwe are already
HIV-infected and will develop AIDS, given our current understanding of the
natural history of HIV and the lack of antiretroviral treatment in these
areas. Even in countries where the HIV prevalence is much lower, because
many young women do not think they are at risk of getting AIDS, they will
be less likely to protect themselves with safer sexual practices.
The reasons people may think they are not at risk for HIV/AIDS include
lack of knowledge about HIV infection, how it is transmitted and the level
of risk in their area. However, it may also be because they do not know or
believe that their behavior or their partner’s behavior places them at
personal risk for becoming infected with HIV.
This underscores the importance of wide-reaching education to convey
accurate information about HIV, to counter or dispel misperceptions and
myths and, most important, to promote prevention.
Slide 5
Prevention can work! This graph demonstrates the progress that has been
made in three different countries to reduce HIV infection or to keep
infection rates low in certain populations.
Slide 6
In Uganda, the HIV epidemic was recognized relatively early and
prevention efforts were started on a national level, including commitment
and involvement of political, community and religious leaders; radio
messages on HIV/AIDS; social marketing of condoms; and extensive
availability of HIV voluntary counseling and testing. As shown in this
figure, since 1989 these efforts have resulted in a delay in the age of
first sexual experience of both young men and women.
Slide 7
Few countries have shown the link between behavior and HIV infection as
clearly as Thailand. Overall, behavioral changes have reduced the number
of new HIV infections each year from almost 143,000 in 1991 to 29,000 in
the year 2000. With support from the Thai government and leaders from all
levels of society, emphasis was placed on reducing the risky sexual
practices and the vulnerability of young people as well as on more
specific risky behaviors of particular groups. Efforts were made to
increase knowledge and awareness of HIV, as well as to improve life
skills, such as decision-making and negotiation. Condoms were promoted and
educational opportunities for young girls were increased so that they were
less likely to become sex workers. Also, national policy guidelines to
protect the human rights of people living with HIV/AIDS were issued. As
shown in the graph, one of the most striking effects of the national
program was a reduction in visits to sex workers, the behavior most
closely linked with HIV infection in Thai studies.
Slide 8
Globally, sexual transmission, primarily heterosexual, is the most
common mode of HIV transmission. The magnitude of risk varies with
different types of sexual activity. The greatest risk per episode is with
receptive vaginal or anal intercourse, which means that women are at
greater risk for sexual transmission of HIV. Anal sex is somewhat riskier
than vaginal sex. Although the risk with oral sex is low, there are now
data to suggest that it may account for a significant minority of
transmissions, particularly in sex between men.
Slide 9
There are several factors that increase or decrease the risk of sexual
transmission of HIV. For example, individuals who are newly infected with
HIV or who have AIDS are more infectious because they have higher levels
of virus in their blood and genital secretions. Antiretroviral therapy
lowers the amount of virus in an infected individual and therefore reduces
the risk of transmission. Sexually transmitted infections, both ulcerative
and nonulcerative, increase both infectiousness and susceptibility to HIV
approximately 2–5 times. Uncircumcised men appear to be at increased
risk of transmitting and acquiring HIV. When a woman is menstruating,
pregnant or has cervical ectopy, she may have an increased risk of HIV
transmission.
Barrier contraceptive methods, including the male and female condom,
provide the greatest protection against both transmission and acquisition
of HIV. The role of hormonal contraceptive methods in HIV transmission is
inconclusive, although some data suggest that they may increase genital
tract HIV shedding. Although spermicides (most of which use nonoxynol-9 as
the spermicidal agent) have activity against HIV in the laboratory, a
recent clinical trial conducted by the Joint United Nations Programme on
HIV/AIDS in Africa and Thailand in sex workers who averaged over 3
partners daily found significantly increased rates of HIV seroconversion
in nonoxynol-9 users as compared to placebo. Finally, the intrauterine
device or IUD was associated with increased susceptibility to HIV
transmission in an Italian cross-sectional study, but not in prospective
studies.
Slide 10
The second major way HIV is transmitted is through parenteral exposure,
where there is a break in skin integrity and direct exposure to infected
blood or blood products. HIV is very efficiently transmitted with
transfusion of infected blood; there is a 95% chance of infection when a
single unit of whole blood that is HIV-positive is transfused.
Contaminated transfusions remain a significant problem in areas where the
blood supply is not routinely screened for HIV. Injection drug use carries
a risk of 0.67% per exposure and is responsible for the recent dramatic
increases in HIV infections in Eastern Europe. Healthcare workers have an
approximately 0.4% risk of contracting HIV per needlestick exposure from
an infected patient.
The third major mode of HIV transmission is mother-to-child
transmission during pregnancy, labor and childbirth, or with
breastfeeding. Without access to therapies known to decrease risk,
perinatal transmission occurs in 25–45% of pregnancies where the mother
is HIV-infected. The risk of HIV transmission from traditional practices,
such as female circumcision, ear piercing, tattooing or ritual
scarification with shared and non-sterile or non-disinfected instruments,
is unknown.
Slide 11
There is no evidence that HIV is transmitted by insect bites, kissing
or hugging an infected person, touching toilet seats or by sharing eating
utensils.
Slide 12
Several interventions can reduce HIV infection rates or reduce the
incidence of behaviors known to increase risk of HIV transmission. These
include: voluntary counseling and testing, or VCT, which includes risk
assessment, development of a risk reduction plan and voluntary HIV
testing; behavioral interventions to reduce risk behavior; use of male or
female condoms, either alone to provide protection against both HIV and
pregnancy or with another method of contraception; prevention and
treatment of sexually transmitted infections; the use of antiretroviral
drugs and alternatives to or modifications of breastfeeding practices to
reduce mother-to-child-transmission; and safe transfusion practices.
Slide 13
A number of studies in limited-resource settings have now demonstrated
that HIV counseling and testing are effective in reducing HIV risk
behaviors and also can reduce actual rates of HIV or other STIs. A recent
comprehensive meta-analysis of VCT concluded that HIV testing resulted in
risk reduction in persons who were HIV-seropositive and in serodiscordant
couples. Most recently, a randomized clinical trial of voluntary HIV
counseling and testing versus basic health information was conducted in
Kenya, Tanzania, and Trinidad involving over 3100 individuals and 586
couples. In both couples and individuals, VCT was associated with a
greater reduction in unprotected sex than basic health information alone.
In a separate analysis of this study, VCT was found to be cost effective
in terms of cost per HIV infection prevented.
Slide 14
Several well-designed randomized and controlled trials have been
conducted to assess the effectiveness of different behavioral intervention
strategies and most conclude that such interventions result in decreased
sexual risk taking and, in some studies, STI and HIV incidence. Behavioral
interventions to prevent HIV infection include basic information about HIV
— what is HIV and AIDS; the natural history of HIV infection, including
a prolonged asymptomatic phase; how HIV is transmitted; and how
transmission can be prevented. However, knowledge is not enough to
motivate change. Individuals must also be helped to recognize their
personal risks and motivated to change. Barriers to risk reduction should
be identified and strategies developed to overcome them. With these
variables in mind, an individualized risk reduction plan is formulated by
the individual and the healthcare provider. Behavioral interventions do
not necessarily include HIV testing.
Slide 15
Risk assessment is important in the setting of both VCT and behavioral
interventions for two reasons. In countries where there is a low HIV
prevalence, risk assessment helps determine who is most appropriate to
target for counseling and testing. It is also important on an individual
basis to identify specific risky behaviors in order to provide effective
risk reduction counseling. The factors listed here help identify
individuals who may be at increased risk for HIV infection.
For example, young single men and women and mobile populations often
have less stable sexual relationships that put them at greater risk
because of unsafe sexual behaviors. Women who have conditions such as
sexually transmitted infections, which increase risk for transmission and
acquisition of HIV, or tuberculosis, which often coexists with HIV, have
an increased likelihood of having HIV. In populations with high HIV
prevalence, these characteristics will be less useful and all sexually
active individuals should be considered at risk. Young women may also be
more vulnerable to HIV for physiologic reasons, such as increased rates of
cervical ectopy.
Pregnant women are a priority for counseling and voluntary testing
because of greater availability of effective short-term antiretroviral
therapies to reduce the risk of mother-to-child transmission. Finally, any
individual who has symptoms such as unexplained weight loss, chronic
diarrhea , fevers of unclear cause, or oral thrush should be offered HIV
testing since these symptoms may indicate the presence of underlying HIV
disease.
Slide 16
There are a number of ways to reduce the risk of sexual transmission of
HIV. Delaying the start of sexual activity, lowering the number of
lifetime sexual partners, practicing monogamy and abstaining from sexual
activity all will help reduce the risk of both HIV infection and other
sexually transmitted infections. Non-penetrative sex or mutual
masturbation can be safer and satisfying alternatives to intercourse.
Certain practices, such as anal sex; dry sex in which herbs or other
substances are used to dry the vaginal mucosa; and douching may increase
trauma and irritation to mucosal surfaces, possibly increasing
infectiousness and susceptibility. Sex should be avoided during menses
because it has been found to increase both infectiousness and
susceptibility; Furthermore, use of alcohol or drugs increases the
prevalence of unsafe sexual practices. Perhaps the best way to reduce the
risk of sexual transmission is by using a condom with every act of sex.
Slide 17
Promoting the use of condoms is the most basic and the most important
HIV prevention activity. In Uganda the national HIV program resulted in
significant increases in the percentage of sexually active men and women
of all ages who had ever used a condom.
Slide 18
When they are used consistently and correctly, male and female condoms
are the most effective methods in preventing HIV transmission and
transmission of most STIs, as well as acquisition of these infections.
Clients should be instructed in proper use. Only water-based lubricants
or appropriate spermicide should be used with latex male condoms.
Oil-based lubricants, such as petroleum jelly, cooking oils, shortening,
or lotions, result in a 90% reduction in latex strength in just 60 seconds
and promote breakage. For latex condoms to be effective they should be
stored in a cool, dry area, out of direct sunlight to prevent
deterioration. Common errors in use of male condoms include delaying
condom application until just prior to full penetration, failure to extend
the male condom all the way to the base of the penis, insufficient
application of a water-based lubricant, and failure to hold the base of
the condom during withdrawal. Finally, it is essential to emphasize
consistent condom use with every sexual act. This means that for condoms
to be effective for prevention of HIV and STI transmission, they must be
used even when prevention of pregnancy is not needed; in postmenopausal
women, during pregnancy, when the woman or her partner is infertile, or
when other more effective contraceptive methods are used.
Slide 19
Even though the female condom is more expensive than the male condom,
there is evidence that it may be cost-effective and even cost-saving in
reproductive health programs, particularly in target groups that practice
high-risk behaviors. Furthermore, the female condom has some benefits over
the male condom. First, it is made of polyurethane, while most male
condoms are made of latex. Polyurethane is stronger than latex and causes
no allergic reactions. Unlike latex, polyurethane may be used with both
oil-based and water-based lubricants and is not susceptible to
deterioration from temperature or humidity. It is not tight or
constricting. It can be inserted prior to intercourse and does not require
immediate withdrawal after ejaculation, so it will not interrupt sexual
spontaneity. The female condom offers more extensive barrier protection,
covering both the woman’s internal and external genitalia and the base
of the penis. Furthermore, unlike the male condom, female condoms can be
reused if washed, rinsed and air dried after use. The female condom has no
serious side effects, with less than 10% of users reporting mild temporary
irritation.
Slide 20
Dual protection is defined as protection against pregnancy as well as
HIV and other sexually transmitted infections. Dual protection can be
achieved in the following ways: - By avoiding penetrative sex - By
practicing mutual monogamy between noninfected partners using an effective
method of contraception - By using condoms alone - Or by using condoms and
another method of contraception
If condoms are used correctly and consistently with every act of sex,
they are very effective, providing 98% protection against HIV and STIs and
95–97% protection against pregnancy.
Slide 21
Although other methods of contraception may provide the same level or
better protection against pregnancy, they provide little, if any
protection against HIV and STIs. Although spermicides may have activity
against gonorrhea and chlamydia and have demonstrated activity against HIV
in the laboratory, their use, particularly if frequent, has been
associated with an increase in mucosal irritation and even genital ulcers.
The clinical trial conducted by UNAIDS in Africa and Thailand, as already
noted, found that HIV seroconversion rates in nonoxynol-9 users were
actually increased as compared to placebo.
The diaphragm has limited STI protection and no significant protection
against HIV transmission. The fact that sexual transmission of HIV can
occur in women who have had a hysterectomy shows that covering the cervix
does not provide sufficient protection.
Slide 22
Whether women who use the IUD are at increased risk for HIV remains
controversial. An Italian cross-sectional study reported an increased risk
of HIV acquisition in IUD users. Also, the increased menstrual flow and
duration seen in nonprogesterone-containing IUDs may increase transmission
risk. The new levonorgestrel-containing intrauterine device or Mirena,
however, decreases menstrual flow and duration. There has been no increase
in cervical HIV shedding in HIV-infected IUD users measured 4 months after
IUD insertion. On the other hand, the IUD does not offer protection
against either HIV or sexually transmitted infections.
Slide 23
Hormonal contraceptive methods offer no significant STI protection.
There are some data, although inconclusive, that they may increase genital
tract HIV shedding, as well as increase HIV susceptibility for women not
infected with HIV. Voluntary sterilization, although it may reduce the
risk of acquiring tubal infection or salpingitis, does not offer other STI
or HIV protection.
Slide 24
Because sexually transmitted infections and HIV are so closely related,
preventing STIs is an important intervention to prevent HIV infection.
There are a number of ways that STIs and HIV are closely linked.
First, both ulcerative and nonulcerative STIs increase the risk of HIV
transmission 2-5 times and genital ulcers disrupt the epithelial barrier.
STIs also increase the number of cells vulnerable to HIV in the genital
tract, increasing susceptibility in uninfected individuals. On the other
hand, HIV-infected persons with STIs have increased genital tract HIV
viral load, which increases infectiousness. Therefore, prevention and
treatment of STIs is another important component of HIV prevention.
Indeed, in one clinical trial in Tanzania, syndromic treatment of STIs
decreased HIV seroconversion by 38% over 2 years.
The best way to prevent STIs is to reduce sexual risk behaviors and to
use condoms consistently and correctly. Both men and women should be
educated about personal risk factors and early symptoms of STIs. They
should be encouraged to seek care and treatment as early as possible, if
symptoms occur. In areas where laboratory facilities are not available,
treatment of STIs is based on groups of symptoms and signs that may be
explained by more than one condition. Treatment is given for all of the
most likely STIs causing the syndrome, based on local epidemiologic data.
The syndromic approach is quite effective for management of genital ulcers
and urethral discharge, but is less useful in managing women with abnormal
vaginal discharge because of decreased accuracy in the diagnosis and
treatment of cervicitis.
Slide 25
Antenatal screening for syphilis with appropriate treatment of
asymptomatic women and presumptive treatment of their partners has been
shown to decrease the incidence of complications in pregnancy, such as
stillbirth, low birth weight, and premature rupture of membranes. It may
also decrease both sexual and perinatal transmission of HIV. Reproductive
health programs for women should have linkages with STI programs treating
symptomatic men, so that asymptomatic infections, which are more common in
women, may be identified or presumptively treated and further transmission
of STIs and HIV interrupted. Although all sexually active individuals are
at risk for STIs and need education and risk reduction counseling, studies
have confirmed the impact that individuals with high rates of partner
change and high rates of STIs have on maintaining both STI and HIV
epidemics. Targeting for interventions these “core transmitters,”
including sex workers and their clients, drug users, military personnel
and long-distance truck drivers, for interventions is believed to be most
cost-effective in reducing the burden of STIs and the transmission of HIV
related to STIs.
Slide 26
Senegal has maintained one of the lowest rates of HIV infection in
sub-Saharan Africa and has long emphasized prevention and primary
healthcare. As in Uganda and Thailand, there was a unified response to HIV
from the government and religious leaders. HIV prevention was included
when sex education was introduced in schools, HIV voluntary and
confidential counseling and testing were made available, condoms were
promoted to sex workers and their clients, and STI care was integrated
into regular primary healthcare services. As these interventions were
introduced, rates of all STIs measured among pregnant women in Dakar
dropped dramatically, and HIV rates have remained low.
Slide 27
In Thailand, rates of STIs in males decreased by over 90% at the same
time that condom “non-use” declined by similar proportions. These
changes parallel the dramatic decreases in HIV prevalence also seen in
Thailand.
Slide 28
For injection drug users, drug treatment should be offered, if
available, to help individuals stop using drugs altogether. If they cannot
or will not stop using drugs, it is important to avoid sharing or reusing
needles or other injection equipment or supplies. Needle exchange programs
have reduced HIV risk behavior and resulted in prevention of new HIV
infections, as well as prevention of hepatitis B and C infection. If
needles or other drug supplies are going to be shared or reused, injection
drug users should be taught how to clean and disinfect these instruments
correctly, to use boiled water to prepare drugs, and to clean the
injection site. Finally, drug users should be taught how to safely dispose
of syringes and needles after use to reduce the possibility of
transmission to others from needlestick injuries.
Slide 29
Although the degree of risk in transmitting HIV with traditional
practices is unknown, female circumcision should be avoided, because it
may increase the risk of sexual transmission or acquisition of HIV due to
increased trauma and bleeding with sexual intercourse. Sharp instruments
used in ritual cutting or tattooing should not be shared or should be
correctly disinfected after each use.
Slide 30
Another way to prevent transmission of HIV is by providing
antiretroviral treatment to pregnant women to decrease mother-to-child
transmission. This method of transmission has dramatically declined in
developed countries. In early 1994, the results of the Pediatric AIDS
Clinical Trials Group (PACTG) 076 showed a 66% reduction in
mother-to-child transmission with use of zidovudine or AZT given at 14
weeks gestation and continuing through the remainder of pregnancy, during
labor by intravenous infusion, and to the newborn for the first 6 weeks of
life. Perinatal transmission rates have subsequently decreased by
approximately 80% in the United States. This regimen, however, is both too
costly and too complex for limited-resource settings.
Since the PACTG 076 study, there have been several clinical trials of
more abbreviated oral regimens in both breastfeeding and nonbreastfeeding
populations in limited-resource countries. These show efficacy ranging
from 37% to 52% in reduction of mother-to-child transmission. The most
exciting of these and the most cost-effective is the use of a single dose
of nevirapine to the mother at the onset of labor and a single dose to the
newborn within the first 48-72 hours of life; this was conducted in a
breastfeeding population in Uganda and resulted in a 47% reduction in
mother-to-child transmission at 4 months followup, as compared to oral
zidovudine given to the mother in labor and for one week to the newborn.
Slide 31
Breastfeeding carries significant risks of mother-to-child
transmission, especially in mothers newly infected during pregnancy or
postpartum. In fact, breastfeeding may account for over 50% of new
pediatric HIV cases globally each year. Women who are HIV-uninfected or
whose HIV status is unknown should exclusively breastfeed their newborns
for 6 months to reduce the morbidity and mortality from diarrheal,
respiratory and other infections associated with not breastfeeding. At the
same time, the use of safer sexual practices, including consistent condom
use, should be reinforced during lactation to prevent maternal primary HIV
infection.
In women with acute HIV infection who breastfeed, there is
approximately a 29% risk of transmission to the newborn. In women who are
HIV-infected, breastfeeding should be avoided if acceptable, affordable,
sustainable and safe alternatives are available. However, in many areas
with limited-resources, there are no good alternatives to breastfeeding
and avoiding breastfeeding altogether will be associated with increased
rates of non-HIV-related newborn illness and death and increased stigma
for the mother.
There has been increased attention to specific risk factors for HIV
transmission associated with breastfeeding and incorporation of this
information to help reduce risk when breastfeeding is desired. All new
mothers should be taught how to breastfeed properly and to seek prompt
treatment if they think they may have a breast infection, if they develop
breast sores or cracked nipples, or if their newborn develops oral
lesions, such as thrush. Because of recent studies showing an increased
risk of transmission associated with breastfeeding combined with other
liquids or solids, and because risk of transmission increases with
duration of breastfeeding, current recommendations call for exclusive
breastfeeding for up to 6 months with rapid weaning and transition to
replacement feeds.
Slide 32
Transfusion of infected blood carries a 95% risk of infecting the
patient when a single unit of blood is transfused. Prevention of HIV
transmission through this route should first involve preventing or
treating causes of anemia and blood loss in order to reduce the need for
transfusion. Reducing this need can be done by providing nutritional
interventions to prevent or treat nutritional deficiencies; giving
medication to prevent or treat malaria and parasitic infestations;
performing routine active management of the third stage of labor to
minimize the likelihood or severity of postpartum hemorrhage; and
encouraging use of effective contraceptive methods to better space
pregnancies and allow better recovery from anemia related to pregnancy and
birth.
In many cases, volume replacement with crystalloid or colloid can
reduce the need for transfusion. When transfusion is required, the use of
paid or professional donors without screening for HIV is very risky; the
use of family members as blood donors is safe only if those family members
do not have HIV or other blood-borne infections. Screening the blood
supply is ultimately the most important step to eliminating HIV infection,
as well as other infections, such as hepatitis C, through transfusion.
Slide 33
The information we have reviewed so far shows that prevention of HIV is
possible and prevention efforts have been successful in several areas with
limited-resources. There are a number of barriers to prevention, however,
several of which affect women disproportionately. There is still an
enormous stigma associated with HIV infection because of ignorance and
fear. In many areas, women may be blamed for transmitting infection to
their newborns or to men through sex work. Women are often unaware of
their partner’s infection status or risky behaviors and, therefore, may
not realize they need to use protection during sex. Furthermore, women may
be unable to negotiate safer sex practices because of sexual coercion,
physical or emotional violence, or fear of abandonment because they are
economically depending on their partners.
Slide 34
Studies of HIV prevention interventions have resulted in several
important lessons. Although high-risk groups may be targeted for certain
interventions, it is not enough to focus only on these individuals. The
general population must also be involved if prevention is to succeed. In
working with individuals and communities, it is important to emphasize
specific risk behaviors and vulnerability, rather than specific groups,
such as sex workers or men having sex with men. The behaviors place the
individual at risk, and labeling can be stigmatizing. Knowledge and
awareness of HIV/AIDS and the scope of the problem are important, but not
enough to prevent infection. Individuals need to recognize their own level
of risk and learn skills associated with sexual negotiation. Condom
promotion is an essential part of any prevention program, but long-term
changes in social norms will be necessary to make condom use and other
behavioral changes more acceptable. Ultimately, socioeconomic
interventions are needed to reduce the vulnerability of women and girls
and to protect individuals with or at risk for HIV.
Slide 35
Antiretroviral therapy not only reduces the risk of mother-to-child
transmission, but also reduces the risk of sexual transmission because it
decreases viral load. It also reduces incidence of tuberculosis by
strengthening the immune system, and promotes HIV testing by giving hope
that something can be done if HIV is diagnosed. More persons with HIV may
be diagnosed at earlier stages of infection and receive not only effective
treatment for themselves but also counseling about prevention of
transmission to others. The use of antiretroviral drugs, however, is
complicated by the need for long-term, even life-long treatment, the need
for strict adherence to avoid development of resistance, the complexity of
current regimens, high cost, and the possibility of side effects and
toxicity from these agents. These side effects may potentially be worsened
in individuals with underlying malnutrition and anemia.
Slide 36
Research is now underway to try to develop more effective prevention
methods for the future. These methods include topical microbicides that
are effective against HIV and other sexually transmitted organisms and
that can be used by women without the need for sexual negotiation and in
secrecy, if necessary; effective methods of prophylaxis after high-risk
sexual or nonsexual exposures; and, most important, an effective vaccine.
