HIV AND AIDS (part II)

Stages of AIDS

Most of the HIV infections in the United States and throughout most of the world are due to a strain of the virus known as HIV-I which, it is believed, initially originated on the African continent. Having the HIV infection does not mean necessarily that the patient is sick with AIDS because the infection may stay dormant for many years and in a small number of people it may never progress to AIDS.

There are several sequential stages of the infection:

1. There is a symptom-free incubation period which lasts anywhere between two and twelve weeks which follows the initial infection.
   During the incubation period the virus gradually proliferates by attacking certain types of cells, particularly the so-called CD4+ T cells which are part of the body’s defense system, but also other related cells and tissues. As a result of this, the number of CD4+ T cells decreases and the number of infective viral particles (the so-called "virus load") in the blood increases.
2. Primary HIV stage. When the number of viral particles (copies) in the blood reaches a certain level, and the decrease in CD+4 is pronounced enough, the patient develops symptoms of weakness, fever, sore-throat, a rash, swollen glands, and, occasionally, diarrhea. Some of the symptoms resemble those present in Infectious Mononucleosis.
   This period lasts three to four weeks, and during this period antibodies (immune bodies against the virus) can be detected.
3. Silent (quiescent) period. Following the manifestations of the primary HIV infections, the virus may stay dormant for months and even for as long as nine to ten years while it is hidden inside some of the body tissues, and particularly inside lymph nodes (glands). However, there are a number of factors which can re-activate infection, some unknown and some known such as STD (sexual transmitted diseases), other viral infections, or physical or mental stress.
4. Re-activation of the HIV infection and AIDS. Once the virus is reactivated the patient starts to develop symptoms of AIDS. The 1993 Center for Disease Control’s (CDC) diagnosis of AIDS requires two conditions for diagnosing AIDS:

• The presence of a low CD4+ T cell count (less than 200 cells/mm3)
• The presence of one or more of infectious diseases, known as opportunistic infections. Opportunistic infections are caused by different bacteria, molds and viruses which rarely affect healthy individuals. The diseases are called opportunistic because they take advantage of the opportunity to infect an individual with decreased immune resistance, as present in AIDS.

The most common of such opportunistic infections include:

a) PCP pneumonia (a pneumonia due to a microscopic organism close to fungi, called Pneumocystis Carinii).

b.) Tuberculosis.

c.) An infection (Mycobacterium Avium Complex or MAC) due to an organism similar to that causing tuberculosis.

d.) A host of generalized mold infections that can affect the brain, the liver or intestines (e.g. Cryptococcus meningitis, Toxoplasmosis brain abscesses, gastroenteritis etc.).

e.) A number of cancers usually caused by viruses, such as Kaposi Sarcoma or KS (a cancer caused by a strain of Herpes virus) and Malignant Lymphoma (a cancer of lymphatic tissue).

Who should be tested for the HIV virus?

People who should be tested for the HIV virus include individuals belonging to the groups which are at high risk (see previously E-mailed part I) and individuals who are engaged in unprotected sex. Such individuals should be tested periodically at least.

Also, testing for the HIV virus is required for individuals, such as police officers and health care providers, who are significantly exposed to blood or other body fluids of individuals infected with AIDS. A significant exposure would include for example splashing of infected blood over the face, particularly eyes and mouth, or over areas of skin with open injuries or rashes. Such individuals must also be treated within twenty-four hours, preferably within two hours of exposure, with HIV antiviral therapy, tested for HIV and re-tested at three and six months after exposure. If still negative, the anti-HIV treatment may be discontinued.

What tests are available for HIV detection?

The most common tests for HIV require blood samples, although more recently a saliva test has been developed.

The most common screening blood test is a test called ELISA followed by a confirmatory test called the WESTERN BLOT.

Both tests check for the presence of antibodies (immune substances) against AIDS produced by the body. However, in the early stages of HIV infection antibodies are not yet present in the blood and therefore the tests may be falsely negative. This is the reason why such tests, if negative, must be repeated after three and six months.

In recent years, very sensitive tests have been developed that detect the virus itself, in concentrations as low as 50 copies of virus/ml cube (a cubic ml is about the volume of twenty drops of blood).

Treatment and prognosis of AIDS

The treatment of HIV infections and AIDS consists of anti-viral therapy, prevention and control of opportunistic infections, control of the adverse reactions and side effects of the antiviral drugs and a general good nutrition and moderate exercise program.

For the first two years of the HIV epidemic, there were no effective antiviral medications available. The first anti-HIV virus drug, although hailed initially as a panacea, proved to be quite toxic and only temporarily helpful because of the great ability of the virus to mutate and develop resistance. This was AZT, and for some time it was the only drug available. Even though the armamentarium has grown significantly since then, AZT still forms a part of some drug cocktails.

In recent years a combination of drugs has proven to be very effective in reducing the amount of circulating virus, increasing the levels of CD4+ T cells and improving immunity and reducing both the AIDS illness and mortality.

The current combination treatment includes one or two of the following types of medications:

1. Medications known as NRTI (Nucleosides Reverse Transcriptase Inhibitors) - those are medications that stop the manufacturing of genetic HIV infecting material (HIV DNA) from being produced from a template of the infecting HIV virus (RNA viral copies). As a result, although the virus can infect the cell, it cannot reproduce.
2. Medications known as NNRTI (Non-nucleoside Reverse Transcriptase Inhibitors) - those are medications interfering with enzymes that are involved in the manufacturing of genetic HIV infecting material (HIV DNA) from being produced from template of the infecting HIV virus (RNA viral copies). As a result, although the virus can infect the cell, it cannot reproduce.
3. Medications known as PI (Protease inhibitors) that are involved in the maturation of the infective virus and its release from the infected cells. As a result the virus is inert and cannot be released from the infected cells.

Numerous studies are conducted all over the world in an attempt to find new medications that attack different stages of development of the HIV virus and/or make the current medications more effective.

Two pilot projects, one in Pittsburgh, PA, and the other in Asia, are about to start this fall and will test a vaccine against the virus. The Pittsburgh project will involve more than 5,000 volunteers.

At this time an HIV infection may be prevented only if therapy is started early enough following a known exposure (twenty-four hours or less). However, an established HIV infection cannot be totally cured or eradicated because, even when the concentration of virus is reduced to less than 50 copies/ml cube, the virus it is still hiding in some tissues (usually the lymph nodes) where it is protected from therapy and may re-emerge.

Nevertheless, one should emphasize that medicine has succeeded in the less than twenty years since the start of the epidemic to improve both the quality of life and the survival of people with HIV and AIDS.

Finally, one cannot emphasize enough that people who acquired HIV and are under treatment must consistently follow their medical regimen because failure to do so results in the emergence of a drug-resistant HIV virus which may result in a much more serious and less treatable AIDS condition.