AIDS and HIV

o disease is so widely misunderstood or so controversial as Acquired Immuno-deficiency Syndrome, better known as AIDS. Myth and controversy swirl around AIDS because it is primarily a sexually transmitted disease, has only recently been identified, and has caused a seemingly sudden surge of fatalities among certain high-risk groups in this country. While it affects far fewer people than high blood pressure, cancer, or heart disease, it has captured our attention because of its abrupt apocalyptic appearance and its almost certain fatal outcome.

AIDS is simple in neither cause nor effect. Basically, it is a life-threatening disruption of the immune system by the Human Immunodeficiency Virus (HIV). This virus progressively weakens the body's ability to fight off disease, opening it to severe infections with both common and exotic organisms, as well as various forms of cancer. In the United States, most cases of AIDS have been traced to the virus called HIV-1.

HIV is particularly dangerous because it can lie hidden for years. Someone infected by HIV may not yet have AIDS, and, in fact, may have no symptoms at all. As symptoms related to the viral infection do begin to appear, the term AIDS-Related Complex (ARC) is often used to describe the situation. Only when the immune system nears total collapse, or specific infections or cancers develop, is a patient said to have AIDS.

HIV has sparked tremendous fear and controversy, not only because of whom it attacks and the way it is transmitted, but because of its hidden nature and lethal results. No virus since polio has garnered so much scientific attention. Researchers have yet to find a cure; but their efforts have paid off with a growing number of medicines that can slow the progress of the infection and prolong the patient's life.

Our Status Today

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AIDS was not recognized until the early 1980s, when frequent reports of unusual lung infections with Pneumocystis carinii and a rapidly spreading form of cancer called Kaposi's sarcoma, found primarily in homosexual men, reached the Centers for Disease Control and Prevention in Atlanta, Georgia. The fact that these previously rare diseases were clustered in a single group of people led scientists to suspect that some sort of underlying infection was involved. As more and more people developed the exotic diseases now known to be symptoms of AIDS, it became clear that a "new" illness had surfaced in the U.S. HIV, the virus responsible for AIDS, was first identified by French and American research groups in 1984, and since that time, both public and private organizations have committed considerable resources to combat this disease.

By the end of 1989, there were 115,000 reported cases of AIDS in the United States. Before the end of 1993, the number had surpassed 340,000, and over 200,000 had died from the disease.

All told, there are an estimated million to a million and a half people infected with HIV in the United States. While only 10 to 20 percent per year will develop the AIDS group of symptoms, all are believed to be capable of transmitting and spreading the virus.

When the AIDS epidemic struck, it first spread within the homosexual community, whose sexual practices put them at especially high risk. Today, AIDS among heterosexuals is also on the rise, accounting for about a third of all cases.

We now know that women who have had sexual relations with bisexuals, as well as injection drug users and certain other populations, are also at high risk for infection. In 1985, only seven percent of AIDS cases were women; now the proportion is over 12 percent. AIDS is the leading cause of death in women between ages 25 and 44 in New York City. Urban teenagers, according to the American Foundation for AIDS Research, are the next group that will develop widespread HIV infection. HIV infections among urban teens admitted to hospitals rose by 250 percent from 1987 to 1991. Between 1991 and 1993 the number of reported cases among teenagers doubled again.

Total annual costs of AIDS were projected at between $5 and $13 billion by the end of 1992. AIDS is now the seventh leading cause of death in the U.S. and is the leading cause of death among injection drug users and hemophiliacs.

According to the Department of Health and Human Services, "Despite the uncertainty about the incidence of HIV infection and the ultimate magnitude of the problem, HIV and AIDS are a growing threat to the health of the nation and will continue to make major demands on health and social systems for many decades."

The Virus and What It Does

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In order to understand AIDS, it's important to know a few basic facts about the "germs" we call viruses. These tiny invaders are especially difficult to repel. While infections by bacteria can be treated with common antibiotics, a viral infection cannot.

Viruses are minute microorganisms that commandeer the machinery of the body's own cells to survive and reproduce. They can take hold in many parts of the body, but under ordinary circumstances are eventually eradicated--or at least held in check--by the immune system. HIV is scientifically termed a retrovirus. What makes it so deadly is the fact that it attacks certain key cells of the immune system itself.

These cells, known as "helper" or CD4 lymphocytes, play a central role in the body's defense against infections. But as they are themselves infected and destroyed by HIV, their number declines, and the chance of successful attack by other germs steadily rises. Treatment with an anti-retroviral drug such as zidovudine (AZT, Retrovir) can, at least temporarily, halt this decline. In fact, physicians often monitor a patient's helper lymphocyte count to gauge the success of therapy.

Other cells of the immune system are also liable to HIV attack. Called monocytes and macrophages, these cells may serve to transport the virus to the brain. They may also act as a long-term reservoir of infection.

How Do You Get AIDS?

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Most researchers now agree that HIV is the main cause of AIDS. They also agree that, unlike airborne or animal-transmitted viruses, HIV's primary method of transmission is via a substance that contains the virus or infected cells. In most cases, the vehicle seems to have been male seminal fluid, which enters the body through mucous membranes that become torn during anal or vaginal intercourse. AIDS may also be transmitted in infected transfused blood or menstrual blood, on used needles shared among drug users, through deep puncture wounds in healthcare workers, from mother to baby, and possibly by some other unknown routes.

Fortunately, HIV is not spread through routine social interaction. AIDS is not passed on through casual non-sexual contact--shaking hands, attending school with an HIV-positive person, hugging, or even sharing the same plates and utensils. In general, HIV is passed from men to men or men to women during intercourse, but less readily from women to men.

It is this fact that has misled many people to believe that AIDS is simply a "gay" or "drug addict's" disease. But as we have seen, this is increasingly untrue. And because the infection can go undetected for years, an unsuspecting carrier can pass on the virus to sexual partners unknowingly, until symptoms finally appear.

What Are the Symptoms of AIDS?

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HIV infection poses a difficult diagnostic problem because the blood tests most commonly used don't identify the virus itself, but rather, the presence of antibodies that the body gradually develops to fight the infection. The first test, often referred to as an ELISA (enzyme-linked immunosorbent assay), will, when positive, usually lead to a second test called the Western blot. However, if conducted too soon after exposure, both tests may fail to detect any antibodies--even though the person is already infected and capable of transmitting the virus. For this reason, experts recommend repeat testing for six months (or up to one year) after known or suspected exposure.

When first infected with HIV, a person may experience the same symptoms seen in many other viral infections--fever, sore throat, headache, rash, or a mononucleosis-type illness. For the majority of those infected, however, there may be no symptoms at all.

After this first flare-up, if it occurs, there are usually no symptoms for an extended period--typically five to six years. There is some evidence, however, that for those infected through blood transfusions, the time is much shorter.

While this period wears on, some patients develop shingles, itchy skin lesions, tuberculosis, fungal infections of the mouth (thrush), night sweats, fatigue, or swollen lymph nodes. Then, as damage to the immune system increases, additional problems may appear, including bacterial infections of the blood and lungs, a severe form of pneumonia caused by Pneumocystis carinii, various cancers such as lymphoma, severe herpes infections of the genitals or mouth, a fungal form of meningitis, toxoplasmosis involving the brain, and severe diarrhea. Also possible in the more advanced stages of the disease are sight-threatening cytomegalovirus infections of the eyes; generalized infection with Mycobacterium avium- intracellulare, or "MAI" (an organism resembling the cause of tuberculosis); and numerous neurological disorders, including progressive dementia.

Finally, in addition to the many bizarre infections that strike only those with failing immune systems, HIV patients are subject to all the more common infections as well, often in their severest forms.

How Is HIV Infection Treated?

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There is still no cure for HIV; but we do have ways of delaying its progress and fighting the "opportunistic" infections that can seize hold in its wake. To control the virus itself, we now have several anti-retroviral drugs. To fend off opportunistic infections, there are potent antibiotics. And, for the future, work continues on a vaccine to fight the virus in those already infected.

Treatment with anti-retroviral drugs is difficult for several reasons. First, the virus usually has time to become well established before any symptoms appear. Second, a drug must be able to attack the virus within infected cells, while preventing infection of additional cells. Third, many of the drugs currently in use tend to produce significant side effects. These unwanted side effects impose unavoidable limits on the way the drugs can be used.

In developing anti-retroviral drugs, scientists have taken advantage of critical steps in HIV's life cycle. For example, the first four drugs approved for treating HIV infection--zidovudine (AZT, Retrovir), didanosine (ddI, Videx), zalcitabine (ddC, Hivid) and stavudine (d4t, Zerit)--all act by inhibiting an enzyme (reverse transcriptase) that the virus uses to reproduce. Newer drugs--including indinavir (Crixivan), ritonavir (Norvir), and saquinavir (Invirase)--interfere at a different point in the reproductive cycle, inhibiting the action of an enzyme called HIV protease.

Both types of drug increase the body's supply of vital CD4 white blood cells while reducing the amount of viral RNA circulating in the blood- stream. Because the two types attack the virus in different ways, they are more effective when taken together than when taken individually. In addition, if the virus develops resistance to one type of drug, drugs in the other category will continue to work.

Older drugs such as Retrovir have a proven ability to inhibit the development of dangerous infections and thereby prolong patients' lives. The latest protease inhibitors are too new to have a similar track record; but their effect on CD4 counts and circulating viral RNA is even more encouraging than the older drugs'. Still, the effectiveness of all these drugs is likely to decrease with prolonged use; and although they can hold the virus at bay, none of them is a cure.

To prevent the life-threatening infections that can break through the HIV-weakened immune system, doctors use a variety of antibiotics. For example, the development of the serious pneumonia caused by Pneumocystis carinii can be prevented or delayed by medications such as trimethoprim/sulfamethoxazole (Bactrim, Septra), atovaquone (Mepron), or pentamidine (Pentam, NebuPent). Many of the same drugs, usually administered intravenously, are used to treat the infections once they take hold. For some infections, medication may be continued for life because of the high risk of recurrence. Unfortunately, the use of these drugs too may be limited by significant side effects.

Because all of these drugs can, in fact, improve the lives of those with HIV infections, anyone at risk of AIDS owes it to him-or herself to get an HIV test.

 

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