Human Immunodeficiency Virus (HIV, AIDS) (cont.)
What happens after an exposure to the blood or genital secretions of an HIV-infected person? What are symptoms of primary HIV infection?
The risk of HIV transmission occurring after any
potential exposure to bodily fluids is poorly defined. The highest risk sexual
activity, however, is thought to be anal intercourse without a condom. In this
case, the risk of infection may be as high as 3%-5% for each exposure. The
risk is probably less for vaginal intercourse without a condom and even less for
oral sex without a latex barrier. Despite the fact that no single sexual
exposure carries a high risk of contagion, HIV infection can occur after even
one sexual event. Thus, people
must always be diligent in protecting themselves from potential infection.
Within two to six weeks of an exposure, the majority of infected people will
have a positive HIV antibody test, with virtually all being positive by six
months. The test used most commonly for diagnosing infection with HIV is
referred to as an ELISA. If the ELISA finds the HIV antibody, the presence of
the antibody is confirmed by a test called a Western blot. There are now several rapid antibody tests that can be performed on blood or saliva and provide preliminary results within 20 minutes. These tests are fairly accurate but also need be confirmed with a Western blot. It is currently recognized that approximately 20% of HIV-infected individuals in the United States are not aware that they are infected, largely as a result of not having been tested. In September 2007, the Centers for Disease Control and Prevention recommended that HIV antibody testing be performed as part of routine care for individuals presenting to medical attention for any reason. The hope is that this strategy will reduce the number of infected individuals
who are not aware of their status in order to both get them into medical care earlier and to counsel them as to how they can prevent spread to others. This strategy can be markedly enhanced with the rapid testing which can provide preliminary results before the patient leaves the medical facility.
During
this period of time shortly after infection, more than 50% of those infected
will experience a "flu-like" or "infectious mono-like"
illness for up to several weeks. This illness is considered the stage of primary
HIV infection. The most common symptoms of primary HIV infection are
It is not known, however, why only some HIV-infected people develop these
symptoms. It also is unknown whether or not having the symptoms is related in
any way to the future course of HIV disease. Regardless, infected people will
become symptom-free (asymptomatic) after this phase of primary infection. During the first weeks of infection when a patient may have symptoms of primary HIV infection, antibody testing, if performed, may still be negative. If there is suspicion of early infection based upon the types of symptoms present and a potential recent exposure, consideration should be given to having a test performed that specifically looks for the virus circulating in the blood, such as a viral load test. Once the patient enters the asymptomatic phase, infected individuals will know whether or not they are infected if a test for HIV antibodies is done. Therefore, anyone who might possibly have been exposed to HIV should seek testing even if they are not experiencing symptoms.
During all stages of infection, literally billions of HIV particles (copies) are produced every day and circulate in the blood. This production of virus is associated with a decline (at an inconsistent rate) in the number of CD4 cells in the blood over the ensuing years. Although the precise mechanism by which HIV infection results in CD4 cell decline is not known; it probably results from a direct effect of the virus on the cell as well as the body's attempt to clear these infected cells from the system. In addition to virus in the blood, there is also virus throughout the body, especially in the lymph nodes, brain, and genital secretions. The time from HIV infection to the development of AIDS varies. Rarely, some individuals develop complications of HIV that define AIDS within
one year, while others remain completely asymptomatic after as many as 20 years from the time of infection. However, the time for progression from initial infection to AIDS is usually approximately
eight to10 years. The reason why people experience clinical progression of HIV at different rates remains an area of active research.
Next: What laboratory tests are used to monitor HIV-infected people? »
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