Most people
infected with HIV carry the virus for years before manifesting AIDS.
During that period, infected people will have few, if any, symptoms yet
they can transmit the virus.
The
percentage of women with AIDS has increased steadily, and the percentage
of people infected heterosexually has also increased, surpassing the percentage
infected through injecting drug use.
During 2001, there were 35575 newly diagnosed cases of HIV infection.
The Centers of Disease Control and Prevention (CDC) estimates
now
that 40,000 new cases of HIV transmission occur every year.
Of
the people infected with the virus of AIDS in the USA in the year 2001, 42%
were whites, 37% blacks, 20% Hispanics and <1% Asians and Pacific
Islanders and <1% American Indians and Alaska Natives.
During the 1990s, the HIV epidemic shifted steadily toward a growing
proportion of AIDS cases in blacks and Hispanics and in women.
Human Immunodeficiency Virus
(HIV) is the cause of AIDS (Acquired
ImmunoDeficiency Syndrome).
The presence of HIV in the body can be detected in several ways. The
most common is the HIV-ELISA Antibodies test.
The
HIV-ELISA
looks for the body
response to thevirus
manifested by the
presence in your blood of
Antibodies
to HIV proteins. Antibodies are special proteins that our Immune System
produce in response to the presence of HIV.
The test performed on your
sample actually consists
of two tests: a Screening test and a Confirmatory test. The
screening test procedure is called an
ELISA—Enzyme Linked Immuno-Sorbent Assay
or an EIA (Enzyme Immunosorbent Assay). The
confirmatory test is used in the event your HIV-ELISA is positive and/or
equivocal and is the procedure used is the Western
Blot Assay (WB)
The screening and
confirmatory tests are usually done using small samples of blood. If a
sample of blood tests positive repeatedly in the screening test, it will be
confirmed through the Western Blot test. People will be informed that they are infected
with HIV only after both the screening and confirmatory tests
have shown a positive (reactive) result.
Positive HIV antibody tests results
are over 99% accurate when confirmed. Negative HIV antibody tests are over
99% accurate if it has been at least six months after a contact with a
potentially HIV-infected partner. False negatives or false positives occur
rarely.
Antibodies to HIV can be
detected in the blood, in the urine or in the saliva. People produce
antibodies with different speeds and therefore the time interval between
infection and the development of antibodies to HIV can go from four weeks
to six months from the exposure date or SDC (
Suspected
Date
of
Contact).
The appearance of antibodies in a blood or urine sample of a person which
was known to be negative to HIV is called
Seroconversion.
The HIV Elisa results are usually available in one or two business days.
THE WINDOW PERIOD
The time period between a person’s
contact with the virus (infection) and when HIV antibodies become
detectable in blood or other fluids is called the "window period".
Most people will develop antibodies detectable within 4-6 weeks after infection with HIV. Some people may take
longer; but nearly all (99%) will have antibodies by 6 months following
infection. Therefore, the test may not be accurate if a person gets tested too soon after a potential exposure.
People waiting six months from the time of the exposure before testing
will have a 99% accurate test result. Until now there have been no
studies showing antibodies present in people with longer than six
months exposure to HIV.
