Basic Overview & Information on AIDS & HIVAIDS -
acquired immunodeficiency syndrome - was first reported in the
United States in 1981 and has since become a major worldwide
epidemic. AIDS is caused by the human immunodeficiency virus (HIV).
By killing or damaging cells of the body's immune system, HIV
progressively destroys the body's ability to fight infections and
certain cancers. People diagnosed with AIDS may get life-threatening
diseases called opportunistic infections, which are caused by
microbes such as viruses or bacteria that usually do not make
healthy people sick.
More than 790,000 cases of AIDS have
been reported in the United States since 1981, and as many as
900,000 Americans may be infected with HIV. The epidemic is growing
most rapidly among minority populations and is a leading killer of
African-American males ages 25 to 44. According to the U.S. Centers
for Disease Control and Prevention (CDC), AIDS affects nearly seven
times more African Americans and three times more Hispanics than
whites.
How is HIV transmitted?HIV is spread most commonly by
having unprotected sex with an infected partner. The virus can enter
the body through the lining of the vagina, vulva, penis, rectum, or
mouth during sex.
HIV also is spread through contact with
infected blood. Before donated blood was screened for evidence of
HIV infection and before heat-treating techniques to destroy HIV in
blood products were introduced, HIV was transmitted through
transfusions of contaminated blood or blood components. Today,
because of blood screening and heat treatment, the risk of getting
HIV from such transfusions is extremely small.
HIV
frequently is spread among injection drug users by the sharing of
needles or syringes contaminated with very small quantities of blood
from someone infected with the virus. It is rare, however, for a
patient to give HIV to a health care worker or vice-versa by
accidental sticks with contaminated needles or other medical
instruments.
Women can transmit HIV to their babies during
pregnancy or birth. Approximately one-quarter to one-third of all
untreated pregnant women infected with HIV will pass the infection
to their babies. HIV also can be spread to babies through the breast
milk of mothers infected with the virus. If the mother takes the
drug AZT during pregnancy, she can reduce significantly the chances
that her baby will get be infected with HIV. If health care
providers treat mothers with AZT and deliver their babies by
cesarean section, the chances of the baby being infected can be
reduced to a rate of 1 percent.
A study sponsored by the
National Institute of Allergy and Infectious Diseases (NIAID) in
Uganda found a highly effective and safe drug regimen for preventing
transmission of HIV from an infected mother to her newborn that is
more affordable and practical than any other examined to date.
Results from the study show that a single oral dose of the
antiretroviral drug nevirapine (NVP) given to an HIV-infected woman
in labor and another to her baby within three days of birth reduces
the transmission rate by half compared with a similar short course
of AZT.
Although researchers have found HIV in the saliva of
infected people, there is no evidence that the virus is spread by
contact with saliva. Laboratory studies reveal that saliva has
natural properties that limit the power of HIV to infect. Research
studies of people infected with HIV have found no evidence that the
virus is spread to others through saliva by kissing. No one knows,
however, whether so-called "deep" kissing, involving the exchange of
large amounts of saliva, or oral intercourse increase the risk of
infection. Scientists also have found no evidence that HIV is spread
through sweat, tears, urine, or feces.
Studies of families
of HIV-infected people have shown clearly that HIV is not spread
through casual contact such as the sharing of food utensils, towels
and bedding, swimming pools, telephones, or toilet seats. HIV is not
spread by biting insects such as mosquitoes or bedbugs.
HIV
can infect anyone who practices risky behaviors such as
- Sharing drug needles or syringes
- Having sexual contact with an infected person without using a
condom
- Having sexual contact with someone whose HIV status is unknown
Having a sexually transmitted disease such as syphilis,
genital herpes, chlamydial infection, gonorrhea, or bacterial
vaginosis appears to make people more susceptible to getting HIV
infection during sex with infected partners.
What are the early symptoms of HIV infection?Many people do
not have any symptoms when they first become infected with HIV. Some
people, however, have a flu-like illness within a month or two after
exposure to the virus. This illness may include
- Fever
- Headache
- Tiredness
- Enlarged lymph nodes (glands of the immune system easily felt
in the nece and groin
These symptoms usually disappear
within a week to a month and are often mistaken for those of another
viral infection. During this period, people are very infectious, and
HIV is present in large quantities in genital fluids.
More
persistent or severe symptoms may not appear for 10 years or more
after HIV first enters the body in adults, or within two years in
children born with HIV infection. This period of "asymptomatic"
infection is highly individual. Some people may begin to have
symptoms within a few months, while others may be symptom-free for
more than 10 years.
Even during the asymptomatic period, the
virus is actively multiplying, infecting, and killing cells of the
immune system. HIV's effect is seen most obviously in a decline in
the blood levels of CD4 positive T cells (also called T4 cells) --
the immune system's key infection fighters. At the beginning of its
life in the human body, the virus disables or destroys these cells
without causing symptoms.
As the immune system worsens, a
variety of complications start to take over. For many people, their
first sign of infection is large lymph nodes or "swollen glands"
that may be enlarged for more than three months. Other symptoms
often experienced months to years before the onset of AIDS include
- Lack of energy
- Weight loss
- Frequent fevers and sweats
- Persistent or frequent yeast infections (oral or vaginal)
- Persistent skin rashes or flaky skin
- Pelvic inflammatory disease in women that does not respond to
treatment
- Short-term memory loss
Some people develop frequent
and severe herpes infections that cause mouth, genital, or anal
sores, or a painful nerve disease called shingles. Children may grow
slowly or be sick a lot.
AIDS Information & ExplanationThe term AIDS applies to the most advanced
stages of HIV infection. CDC developed official criteria for the
definition of AIDS and is responsible for tracking the spread of
AIDS in the United States.
CDC's definition of AIDS includes
all HIV-infected people who have fewer than 200 CD4 positive T cells
per cubic millimeter of blood. (Healthy adults usually have CD4
positive T-cell counts of 1,000 or more.) In addition, the
definition includes 26 clinical conditions that affect people with
advanced HIV disease. Most of these conditions are opportunistic
infections that generally do not affect healthy people. In people
with AIDS, these infections are often severe and sometimes fatal
because the immune system is so ravaged by HIV that the body cannot
fight off certain bacteria, viruses, fungi, parasites, and other
microbes.
Symptoms of opportunistic infections common in
people with AIDS include
- Coughing and shortness of breath
- Seizures and lack of coordination
- Difficult or painful swallowing
- Mental symptoms such as confusion and forgetfulness
- Severe and persistent diarrhea
- Fever
- Vision loss
- Nausea, abdominal cramps, and vomiting
- Weight loss and extreme fatigue
- Severe headaches
- Coma
Children with AIDS may get the same opportunistic
infections as do adults with the disease. In addition, they also
have severe forms of the bacterial infections all children may get,
such as conjunctivitis (pink eye), ear infections, and tonsillitis.
People with AIDS are particularly prone to developing
various cancers, especially those caused by viruses such as Kaposi's
sarcoma and cervical cancer, or cancers of the immune system known
as lymphomas. These cancers are usually more aggressive and
difficult to treat in people with AIDS. Signs of Kaposi's sarcoma in
light-skinned people are round brown, reddish, or purple spots that
develop in the skin or in the mouth. In dark-skinned people, the
spots are more pigmented.
During the course of HIV
infection, most people experience a gradual decline in the number of
CD4 positive T cells, although some may have abrupt and dramatic
drops in their CD4 positive T-cell counts. A person with CD4
positive T cells above 200 may experience some of the early symptoms
of HIV disease. Others may have no symptoms even though their CD4
positive T-cell count is below 200.
Many people are so
debilitated by the symptoms of AIDS that they cannot hold steady
employment or do household chores. Other people with AIDS may
experience phases of intense life-threatening illness followed by
phases in which they function normally.
A small number of
people first infected with HIV 10 or more years ago have not
developed symptoms of AIDS. Scientists are trying to determine what
factors may account for their lack of progression to AIDS, such as
particular characteristics of their immune systems or whether they
were infected with a less aggressive strain of the virus, or if
their genes may protect them from the effects of HIV. Scientists
hope that understanding the body's natural method of control may
lead to ideas for protective HIV vaccines and use of vaccines to
prevent the disease from progressing.
How is HIV infection diagnosed? Because early HIV infection
often causes no symptoms, a doctor or other health care provider
usually can diagnose it by testing a person's blood for the presence
of antibodies (disease-fighting proteins) to HIV. HIV antibodies
generally do not reach detectable levels in the blood for one to
three months following infection. It may take the antibodies as long
as six months to be produced in quantities large enough to show up
in standard blood tests.
People exposed to the virus should
get an HIV test as soon as they are likely to develop antibodies to
the virus - within 6 weeks to 12 months after possible exposure to
the virus. By getting tested early, people with HIV infection can
discuss with a health care provider when they should start treatment
to help their immune systems combat HIV and help prevent the
emergence of certain opportunistic infections (see section on
treatment below). Early testing also alerts HIV-infected people to
avoid high-risk behaviors that could spread the virus to others.
Most health care providers can do HIV testing and will
usually offer counseling to the patient at the same time. Of course,
individuals can be tested anonymously at many sites if they are
concerned about confidentiality.
Health care providers
diagnose HIV infection by using two different types of antibody
tests, ELISA and Western Blot. If a person is highly likely to be
infected with HIV and yet both tests are negative, the health care
provider may request additional tests. The person also may be told
to repeat antibody testing at a later date, when antibodies to HIV
are more likely to have developed.
Babies born to mothers
infected with HIV may or may not be infected with the virus, but all
carry their mothers' antibodies to HIV for several months. If these
babies lack symptoms, a doctor cannot make a definitive diagnosis of
HIV infection using standard antibody tests until after 15 months of
age. By then, babies are unlikely to still carry their mothers'
antibodies and will have produced their own, if they are infected.
Health care experts are using new technologies to detect HIV itself
to more accurately determine HIV infection in infants between ages 3
months and 15 months. They are evaluating a number of blood tests to
determine if they can diagnose HIV infection in babies younger than
3 months.
How is HIV infection treated?When AIDS first surfaced in
the United States, there were no medicines to combat the underlying
immune deficiency and few treatments existed for the opportunistic
diseases that resulted. During the past 10 years, however,
researchers have developed drugs to fight both HIV infection and its
associated infections and cancers.
The U.S. Food and Drug
Administration (FDA) has approved a number of drugs for treating HIV
infection. The first group of drugs used to treat HIV infection,
called nucleoside reverse transcriptase (RT) inhibitors, interrupts
an early stage of the virus making copies of itself. Included in
this class of drugs (called nucleoside analogs) are AZT, ddC
(zalcitabine), ddI (dideoxyinosine), d4T (stavudine), 3TC
(lamivudine), abacavir (ziagen), and tenofovir (viread). These drugs
may slow the spread of HIV in the body and delay the start of
opportunistic infections.
Health care providers can
prescribe non-nucleoside reverse transcriptase inhibitors (NNRTIs),
such as delvaridine (Rescriptor), nevirapine (Viramune), and
efravirenz (Sustiva), in combination with other antiretroviral
drugs.
More recently, FDA has approved a second class of
drugs for treating HIV infection. These drugs, called protease
inhibitors, interrupt virus replication at a later step in its life
cycle. They include
- Ritonavir (Norvir)
- Saquinivir (Invirase)
- Indinavir (Crixivan)
- Amprenivir (Agenerase)
- Nelfinavir (Viracept)
- Lopinavir (Kaletra)
Because HIV can become resistant
to any of these drugs, health care providers must use a combination
treatment to effectively suppress the virus. When RT inhibitors and
protease inhibitors are used in combination, it is referred to as
highly active antiretroviral therapy, or HAART, and can be used by
people who are newly infected with HIV as well as people with AIDS.
Researchers have credited HAART as being a major factor in
significantly reducing the number of deaths from AIDS in this
country. While HAART is not a cure for AIDS, it has greatly improved
the health of many people with AIDS and it reduces the amount of
virus circulating in the blood to nearly undetectable levels.
Researchers, however, have shown that HIV remains present in hiding
places, such as the lymph nodes, brain, testes, and retina of the
eye, even in patients who have been treated.
Despite the
beneficial effects of HAART, there are side effects associated with
the use of antiviral drugs that can be severe. Some of the
nucleoside RT inhibitors may cause a decrease of red or white blood
cells, especially when taken in the later stages of the disease.
Some may also cause inflammation of the pancreas and painful nerve
damage. There have been reports of complications and other severe
reactions, including death, to some of the antiretroviral nucleoside
analogs when used alone or in combination. Therefore, health care
experts recommend that people on antiretroviral therapy be routinely
seen and followed by their health care providers. The most common
side effects associated with protease inhibitors include nausea,
diarrhea, and other gastrointestinal symptoms. In addition, protease
inhibitors can interact with other drugs resulting in serious side
effects.
A number of drugs are available to help treat
opportunistic infections to which people with HIV are especially
prone. These drugs include
- Foscarnet and ganciclovir to treat cytomegalovirus (CMV)eye
infections
- Fluconazole to treat yeast and other fungal infections
- Trimethoprim/sulfamethoxazole (TMP/SMX) or pentamidine to
treat Pneumocystis carinii pneumonia (PCP)
In
addition to antiretroviral therapy, health care providers treat
adults with HIV, whose CD4+ T-cell counts drop below 200, to prevent
the occurrence of PCP, which is one of the most common and deadly
opportunistic infections associated with HIV. They give children PCP
preventive therapy when their CD4+ T-cell counts drop to levels
considered below normal for their age group. Regardless of their
CD4+ T-cell counts, HIV-infected children and adults who have
survived an episode of PCP take drugs for the rest of their lives to
prevent a recurrence of the pneumonia.
HIV-infected
individuals who develop Kaposi's sarcoma or other cancers are
treated with radiation, chemotherapy, or injections of alpha
interferon, a genetically engineered naturally occurring protein.
How can HIV infection be prevented?Because no vaccine for
HIV is available, the only way to prevent infection by the virus is
to avoid behaviors that put a person at risk of infection, such as
sharing needles and having unprotected sex.
Many people
infected with HIV have no symptoms. Therefore, there is no way of
knowing with certainty whether a sexual partner is infected unless
he or she has repeatedly tested negative for the virus and has not
engaged in any risky behavior.
People should either abstain
from having sex or use male latex condoms or female polyurethane
condoms, which may offer partial protection, during oral, anal, or
vaginal sex. Only water-based lubricants should be used with male
latex condoms.
Although some laboratory evidence shows that
spermicides can kill HIV, researchers have not found that these
products can prevent a person from getting HIV.
The risk of
HIV transmission from a pregnant woman to her baby is significantly
reduced if she takes AZT during pregnancy, labor, and delivery, and
her baby takes it for the first six weeks of life.
What research is going on?NIAID-supported investigators are
conducting an abundance of research on all areas of HIV infection,
including developing and testing preventive HIV vaccines and new
treatments for HIV infection and AIDS- associated opportunisitc
infections. Researchers also are investigating exactly how HIV
damages the immune system. This research is identifying new and more
effective targets for drugs and vaccines. NIAID-supported
investigators also continue to trace how the disease progresses in
different people.
Scientists are investigating and testing
chemical barriers, such as topical microbicides, that people can use
in the vagina or in the rectum during sex to prevent HIV
transmission. They also are looking at other ways to prevent
transmission, such as controlling sexually transmitted diseases and
modifying people's behavior, as well as ways to prevent transmission
from mother to child.
Keeping on Top of Your Condition
Keeping in tune with your disease or condition not only makes treatment less intimidating but also increases its chance of success, and has been shown to lower a patients risk of complications. As well, as an informed patient, you are better able to discuss your condition and treatment options with your physician.
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More Information on AIDS & HIV
To receive materials or to talk with a Health Communication
Specialist, contact the CDC National HIV and STD Hotline. This
service is available 24 hours a day.
1-800-2278922
1-800-342-2437
1-800-243-7889
(TTY/Deaf Access) For information about Food and Drug
Administration-approved HIV-related clinical trials being conducted
throughout the United States, contact the AIDS Clinical Trials
Information Service. This service operates from 12 p.m. to 5 p.m.
Eastern Time, Monday through Friday. Spanish-speaking specialists
are available.
1-800-TRIALS-A (1-800-874-2572)
301-519-0459
(International)
1-888-480-3739 (TTY/Deaf Access)
http://actis.org/ For
federally approved treatment guidelines on HIV/AIDS, contact the
HIV/AIDS Treatment Information Service. This service operates from
12 p.m. to 5 p.m. Eastern Time, Monday through Friday.
Spanish-speaking specialists are available.
1-800-HIV-0440 (1-800-448-0440)
1-888-480-3739
(TTY/Deaf Access)
301-519-0459 (International)
http://hivatis.org/
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