|
World AIDS Day, observed each December 1, is designed
to encourage public support for programs to prevent the spread of
HIV and provide education and awareness of issues surrounding
HIV/AIDS.
|
The cause of AIDS is a virus known as the human
immunodeficiency virus or HIV. The evidence that HIV
causes AIDS is overwhelming. First, evidence of HIV
infection is easily found in patients with AIDS when
such evidence is sought. Second, the virus has been
isolated and grown in pure culture from persons with the
disease. Finally, studies of AIDS cases resulting from
blood transfusions have documented the transmission of
HIV to previously uninfected persons who have
subsequently developed the disease.
If you have questions about HIV infection and AIDS,
please call the CDC National AIDS Hotline at our toll
free number, 1-800-342-2437. If you wish to write to us
regarding this subject, please write to the CDC National
Prevention Information Network , Post Office Box 6003,
Rockville, Maryland, 20849-6003.
|
|
Three important facts about HIV transmission
are:
- The virus is mainly spread by unprotected sex and
sharing needles with an HIV-infected person.
- Babies born to HIV-infected women may become
infected.
- You do not become infected by casual contact or
through insect bites or stings.
AIDS is caused by a virus called human
immunodeficiency virus or HIV. HIV is found in the
blood, semen, and vaginal secretions of an infected
person. The virus is spread by unprotected sexual
intercourse with an infected person, by needle-sharing
among injecting drug users, or, less commonly and now
very rarely, through transfusions of infected blood or
blood clotting factor. Babies born to HIV-infected women
may become infected before or during birth, or shortly
after birth through breast-feeding.
HIV has been transmitted in very few cases in the
household setting. These transmissions are believed to
have resulted when infected blood or other body fluids
came in contact with skin or mucous membranes. Common
sense precautions should be taken in all settings --
including the home -- to prevent contact with the blood
and other body fluids of persons who are HIV infected,
at risk for HIV infection, or whose infection and risk
status are unknown. For example, hands and other parts
of the body should be washed whenever contact with blood
and other body fluids occurs, and surfaces soiled with
blood should be cleaned and disinfected appropriately.
People should avoid sharing razors and toothbrushes,
which are practices that increase the likelihood of
blood contact. Needles and other sharp instruments
should be used only when necessary for medical
procedures and disposed of according to recommendations
for health care settings. You can call the CDC National
Prevention Information Network at 1-800-458-5231 to
request copies of health care recommendations for
preventing transmission of bloodborne diseases, such as
HIV.
There is no known risk of HIV transmission to
coworkers, clients, or consumers from contact in
industries such as food service establishments. Food
service workers known to be infected with HIV need not
be restricted from work unless they have other
infections or illnesses (such as diarrhea or hepatitis
A). The Public Health Service recommends that all food
service workers follow recommended standards and
practices of good personal hygiene and food sanitation,
which should be available from your local or state
health department.
In 1985, CDC issued routine precautions that all
personal service workers, such as hairdressers, barbers,
cosmetologists, and massage therapists should follow,
even though there is no evidence of HIV transmission
from a personal service worker to a client or vice
versa. Instruments that are intended to go through or
penetrate the skin, such as tattooing and acupuncture
needles or ear piercing devices, should be used once and
thrown away or thoroughly cleaned and then sterilized.
Instruments such as razors, which are not intended to
penetrate the skin but which may become contaminated
with blood should be used for only one client and thrown
away or thoroughly cleaned and disinfected after each
use.
Casual contact through closed-mouth or
"social" kissing is not a risk for
transmission of HIV. However, CDC recommends against
"French" or open-mouthed kissing with an
infected person because of the possibility of contact
with blood.
An investigation by a state health department found a
possible case of blood-to-blood transmission of HIV by a
human bite. There have been other reports in the medical
literature in which HIV appeared to have been
transmitted by a bite. Severe trauma with extensive
tissue tearing and damage and presence of blood were
reported in each of these instances. Biting is not a
common way of transmitting HIV. In fact, there are many
reports of bites that did NOT result in HIV infection.
The possibilities of transmission of bloodborne
diseases, such as HIV, through vaccines and various
blood products is a concern for some persons. Vaccines
such as the hepatitis B vaccine and various immune
globulins approved for use in the United States have not
been implicated in the transmission of HIV. Hepatitis B
vaccine is now genetically engineered and contains no
human tissue, blood, or blood product. Other products
that are made from screened plasma and blood donations
undergo purification processes which destroy any viruses
or bacteria.
Some people have asked why HIV is not transmitted by
insects. Studies about the potential for insect
transmission of HIV have been carried out by CDC and
other scientists the world over. These studies have
shown no evidence of HIV transmission--even in areas
where there are many cases of AIDS. These studies have
also shown no biological evidence to indicate that HIV
is able to infect insect cells or to reproduce in
insects. Even if the virus enters the insect via blood
it ingests, the insect does not become infected and its
saliva does not contain the virus. In contrast, other
mosquito-borne viruses, such as dengue or yellow fever,
do multiply in the mosquito.
Since the virus cannot reproduce in the insect,
theoretical transmission of HIV via mosquitoes would
require the ingestion of a large quantity of blood with
large amounts of the virus, and the transfer of this
blood to the next person it bites. This has not been
observed to occur because: (1) The amount of virus in
the circulating blood of HIV-infected persons is very
low compared with the levels observed with other viruses
known to be transmitted by insects. (2) Mosquitoes do
not regurgitate blood into the next person they bite.
The blood someone sees when they slap a mosquito on
their skin is usually their own. (3) The saliva of
mosquitoes does not contain the virus.
It should also be reassuring to know that insect
transmission of hepatitis B virus or HBV, another
bloodborne virus, has never been reported. This lack of
insect transmission is evident even though the amounts
of HBV in blood are many times greater than the amounts
of HIV in blood.
In addition, community or village-wide studies were
conducted in Africa and Florida and included people who
often worked and lived together in unsanitary and
crowded conditions. In these studies, no secondary or
household transmission was observed despite countless
opportunities for shared mosquito and bed bug bites.
|
|
CYTOMEGALOVIRUS (CMV) INFECTION
AND HIGH RISK GROUPS PREGNANCY |
The incidence of primary (or first) CMV infection in
pregnant women in the United States varies from 1% to
3%. Healthy pregnant women are not at special risk for
disease from CMV infection. When infected with CMV, most
women are without symptoms and only a few have a disease
resembling mononucleosis. It is their developing unborn
babies that may be at risk of developing congenital CMV
disease. CMV remains the most important cause of
congenital (meaning "from birth") viral
infection in the United States. For infants who are
infected by their mothers before birth, two potential
problems exist.
- Generalized infection may occur in the infant and
symptoms may range from moderate enlargement of the
liver and spleen (with jaundice) to fatal illness.
With supportive treatment, most infants with CMV
disease usually survive. However, from 80% to 90%
will have complications within the first few years
of life that include hearing loss, vision
impairment, and varying degrees of mental
retardation.
- Another 5% to 10% of infants who are infected but
without symptoms at birth will subsequently have
varying degrees of hearing, visual, and mental or
coordination problems.
However, these risks appear to be almost exclusively
associated with women who have never been infected with
CMV and who are having their first infection with the
virus. Even in this case, two-thirds of the babies will
escape infection, and only 10% to 15% of the remaining
third will have symptoms at the time of birth.
There appears to be little risk of CMV-related
complications for women who have been infected at least
six months prior to conception. For this group, which
makes up 50% to 80% of the women of child-bearing age,
the rate of newborn CMV infection is 1%, and these
infants appear to have no significant illness or
abnormalities.
The virus can also be transmitted to the infant at
delivery from contact with genital secretions or later
in infancy through breast milk. However, these
infections usually result in little or no clinical
illness in the infant.
To summarize, during a pregnancy when a woman who has
never had CMV becomes infected with CMV, there is a
potential risk that, after birth, the infant may have
complications, the most common of which are associated
with hearing loss, visual impairment, or diminished
mental capabilities. On the other hand, infants and
children who acquire CMV after birth have few, if any,
symptoms or complications.
Recommendations for pregnant women with regard to CMV
infection are as follows:
- Throughout the pregnancy, practice good personal
hygiene, especially hand washing, after contact with
diapers or oral secretions.
- Women who develop a mononucleosis-like illness
during pregnancy should be evaluated for CMV
infection and counseled about the possible risks to
the unborn child.
- Recovery of CMV from the cervix or urine of women
at or before the time of delivery does not warrant a
cesarean section.
- Laboratory testing for antibody to CMV can be
performed to determine if a woman has already had
CMV infection.
- The demonstrated benefits of breast-feeding
outweigh the risk of the child acquiring CMV from
the breast-feeding mother.
- There is no need to either screen for CMV or
exclude children excreting CMV from schools or
institutions, because the virus is frequently found
in many healthy children and adults.
|
PEOPLE WHO WORK WITH INFANTS AND CHILDREN |
For most healthy people working with infants and
children there is no special risk from cytomegalovirus
infection. However, for women of childbearing age who
previously have not been infected with CMV, there is a
potential risk to the developing unborn child. (A
thorough explanation of this risk is provided under the
topic entitled "pregnancy" in this service.)
Since CMV is transmitted through contact with infected
body fluids, including urine and saliva, child care
providers (meaning day care workers, special education
teachers, therapists, as well as mothers) should be
educated about the risks of CMV and the precautions they
can take. Day care workers appear to be at a greater
risk than hospital and other health-care providers, and
this may be due in part to the increased emphasis on
personal hygiene in the health-care setting.
Recommendations for individuals providing care for
infants and children are as follows:
- Female employees should be educated concerning CMV,
its transmission, and hygienic practices, such as
hand washing, which minimize the risk of infection.
- Routine laboratory testing for CMV antibody in
female workers is not recommended but can be
performed to determine her immune status.
- Susceptible nonpregnant women working with infants
and children should not routinely be transferred to
other work situations.
- Pregnant women working with infants and children
should be informed of the risk of acquiring CMV
infection and the possible effects on the unborn
child.
|
IMMUNOCOMPROMISED PATIENTS |
While the initial cytomegalovirus infection can cause
serious disease in the immunocompromised patient, the
more common problem is the reactivation of the dormant
virus. Infections by CMV are a major cause of disease
and death in immunocompromised patients, including organ
transplant recipients, patients undergoing hemodialysis,
patients with cancer, patients receiving
immunosuppressive drugs, and HIV-infected patients.
Pneumonia and an infection of the eyes called retinitis
appear to be the common manifestation of the disease.
Due to the significant risk, the exposure of
immunosuppressed patients to outside sources of CMV
should be minimized. Whenever possible, patients who
have never had CMV should be given organs and/or blood
products that are free of the virus.
At the time of initial infection, the person may be
asymptomatic or may develop an acute syndrome similar to
mononucleosis with accompanying aseptic
meningitis. Antibodies may be developed in most
adults 6-12 weeks after exposure, but rarely, the latent
period before antibodies are detectable is longer.
After seroconversion, an asymptomatic period of variable
length usually follows. Evidence of immune
dysfuction may be followed by a wide range of clinical
conditions that include:
- Fever
- Weight loss
- Malaise
- Lymphadenopathy
- Central nervous system dysfunction
- Abnormal PAP tests
- Recurrent cervical intraepithelial neoplasia
- Oral and vaginal candidiasis
These nonspecific conditions are usually progressive
and are a prelude to opportunistic infections diagnostic
of AIDS. |
To prevent HIV infection:
- Do not have sex with an infected person.
- Do not share needles with an infected person.
To prevent the spread of HIV infection,
avoid behavior that might result in contact with blood, semen,
vaginal secretions, or body fluids with visible blood.
Specifically, avoid sex with anyone who might be infected with
HIV, and do not share "injecting drug works." The following
prevention measures apply to personal sex practices and
injecting drug use:
To prevent sexual transmission of HIV, abstain from sex
with an infected person.
Ask about the sexual history of current and future sex
partners.
Reduce the number of sex partners to minimize the risk
of HIV infection.
Always use a condom from start to finish during any type
of sex (vaginal, anal, and oral). Use latex condoms rather
than natural membrane condoms. If used properly, latex
condoms offer greater protection against sexually
transmitted disease agents, including HIV.
Use only water-based lubricants. Do not use saliva or
oil-based lubricants such as petroleum jelly or vegetable
shortening. If you decide to use a spermicide along with a
condom, it is preferable to use spermicide in the vagina
according to manufacturer's instructions.
Avoid anal or rough vaginal intercourse. Do not do
anything that could tear the skin or moist lining of the
genitals, anus, or mouth and cause bleeding.
Condoms should be used even for oral sex.
Avoid deep, wet, or "French" kissing with an infected
person. Possible trauma to the mouth may occur, which could
result in the exchange of blood. It is safe, however, to
hug, cuddle, rub, or dry kiss your partner.
Avoid alcohol and illicit drugs. Alcohol and drugs can
impair your immune system and your judgment. If you use
drugs, do not share "injecting drug works." Do not share
needles, syringes, or cookers.
Do not share personal items such as toothbrushes,
razors, and devices used during sex which may be
contaminated with blood, semen, or vaginal fluids.
If you are infected with HIV or have engaged in sex or
needle-sharing behaviors that lead to infection with HIV, do
not donate blood, plasma, sperm, body organs, or
tissues.
Back to Home
|