Acquired Immunodeficiency Syndrome
Acquired Immune Deficiency Syndrome – AIDS – has stimulated more interest in history than any other disease of modern times. Since the epidemic was first identified in 1981, scientists, physicians, public officials, and journalists have frequently raised historical questions. Most often these questions have been about contemporary social and epidemiological history: Why did the disease emerge when and where it did? How has it spread among members of particular groups?
What does the history of medical science and public health in this century suggest about our ability to control the epidemic and eventually to cure the disease?
Current discussions concerning the AIDS epidemic reference about its possible African origin and hypotheses regarding the introduction and spread of the disease in the United States. It seems plausible to postulate that a set of biological factors, perhaps a viral mutation, had to find a favorable ecological niche – made possible by new attitude toward homosexuality and widespread drug – to trigger the appearance of AIDS. At the same time, our social reaction to the epidemic, presently undergoing painful reexamination, needs to be considered carefully. Why do sufferers of disease have to be stigmatized? What is all that
moral judging for? Voices urge that AIDS cease to be a civil rights problem and become instead a public health issue. The implicit message to the authorities is quite simple: cease quibbling about civil liberties and start protecting public health even if it means returning to previous measures of screening, reporting, and isolation deemed successful in control other diseases.
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How Can History Help Us Understand AIDS?
To study past and present disease patter, including AIDS, we need to employ an ecological model that allows us to discover and integrate the multiple factors involved in the arrival of epidemic diseases. The dynamic relationship between the biosocial environment and human – an “ecology” of disease – helps explain the appearance, spread, and departure of specific health problems.
The first’s case study is the final outbreak of bubonic plague among the inhabitants of Rome, which occurred in 1656. For a variety of political reasons – not least the vanity of the reigning pope – this episode was well-documented. The epidemic was fought with measures developed during the Renaissance, refined over nearly two centuries of organized responses to plague in the cities of northern Italy. These measures were widely adopted elsewhere in Europe and in the
ensuing centuries became the prototype for public health regulations regarding other disease, notable yellow fever and cholera.
Although contemporary observers had detected a gradual decrease in the frequency and intensity of plague epidemics in Eastern Europe, authorities of the Papal States, which included Rome, were nevertheless carefully monitoring the health situation in the Mediterranean. This watch focused especially on the movement of potentially infected ships and their supposed lethal cargoes. One may ask why the plague was retreating in the face of growing urbanization and increases commercial contacts among nations. Was public health policy on epidemics gradually bearing fruit? Probably not. The quarantine system simple stemmed the flow of goods, humans, and ships, only indirectly hampering the movement of the real culprits, namely, infected rodents and the fleas. In fact, the regular recurrence of plague epidemics after 1349 owed more to contacts between urban rodents and their increasingly plague ridden cousins in the countryside than to the movement of ships with human victims, plague remained foremost a disease of rodents.
Stalking the Virus
From the very beginning, suspicion fell on cytomegalovirus (CMV).
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Early in the AIDS epidemic, some sing s of a possible relationship between this pathogen and Kaposi’s sarcoma had been identified. Almost all the original
patients had elevated titers of antibodies against this virus, and CMV itself had been found in their urine, blood, and even pulmonary tissue. Yet CMV infection had been recognized for years prior to the new epidemic and had been found in many individuals with none of the manifestation of the immune deficiency syndromes.
What is a Virus
The term “virus” in Latin means “juice,” “humor,” or more commonly “poison,” was used in the nineteenth century to described any substance capable of multiplying within an organism and making it stick. It was applied indiscriminately to all pathogens.
In 1891 Dmitri I. Ivanoski, a Russian botanist, was able to demonstrate that a pathogen could indeed be “inframicroscopic.” He passed liquid, containing infected material derived from a plant disease with tobacco mosaic, through a porcelain filter and demonstrated that it did not lose its virulence. Before the term “virus” was applied exclusively to this category if living beings, they were give other names, such as “filterable virus” and “ultravirus.” Viruses may have no autonomous life, but they are nonetheless “alive” because they can control and accomplish their own reproduction through the use of a foreign cellular apparatus. Viruses are absolute parasites, fundamentally different from bacteria. Pathogenic
bacteria are only relative parasites. They live off their host, but they use their own metabolic and reproductive machinery.
Discovery of the AIDS Virus
In the United States, where private enterprises flourishes, basic research on AIDS is done by two government institutions: the Centers for Disease Control (CDC) and the National Institution of Health (NIH).
Yet, paradoxically, in Western Europe, where state control over centers of higher learning and scientific research is the rule, the study of AIDS is the uncontested domain of a private foundation: the Pasteur Institute.
Many theoretical and practical questions were resolved with cloning and sequencing of the AIDS virus. Its structural organization is decidedly different from that of the HTLV family. It is indeed a lentirvirus, related to the visna virus of sheep. These features were demonstrated by comparative morphology and by caparison of sequencing of the visna virus done in 1985. The structure of HIV and its mechanism of action came to be understood between 1984 and 1986. It is a RNA virus, typical retrovirus, with a roughly globular shape and fairly high molecular weight. Its string of genetic information, its payload, is encased in a protein capsule, called the “core” or “nucleoid,” which in turn is packed in an
envelope made up of lipid and two glycoppritiens. Each viron contains two copies of RNA, reminiscent of chromosome pairs
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The Structure of HIV
The genome of HIV is more complicated than that of most other known retroviruses. As in other retroviruses, the genes code for the structure (gag forinternal proteins, pol for transcripts, and env for the envelope), but HIV has a particular genomic organization with several other genes that code for regulation of the viral processes. HIV has a particular affinity for T-4 lymphocytes. The glycoprotein, gp120, of the external envelope recognizes and reacts with a molecule, know as CD4, on the surface of the lymphocyte and certain other cells, thereby fixing the virus to the cell. The receptor role of the CD4 molecule was also demonstrated by two independent groups. The virus is attracted to this molecule, and its binding with it results in cellular damage. After lymphocytes have been incubated with antibodies directed to the CD4 molecule, they can not be affected by the AIDS virus.
Haunts of HIV
Contrary to early medical ideas, HIV does not attack lymphocytes only; it infects all cells having the CD4 molecule on their membranes. Targets include cretins white cells called monocytes, especially the macrophage, which is derived from monocytes. They probably constitutes the most important reservoir of the virus. Macrophages can provide virus to sustains the infection of lymphocytes for a long time after the virus enters the organism. Actual numbers of infected lymphocytes circulating in an HIV positive individual, or even in a person with full blow AIDS, are relatively small. The virus can be found in monocytes of the lung and brain; its actions in these organs is not due solely to immunodepression.
The virus may come to the body surface, but it cannot be transmitted by touch. It is highly susceptible to heat and disinfectants. Virologists confirmed the conclusions of epidemiologists: The principle vehicle of spread are semen and blood. The virus is found in the vagina, but only in relatively small numbers. This explains the possibility of infection from female to male through vaginal intercourse, and the even greater ease which this can occur in the opposite direction.
DNA sequences identical to those of HIV were found in the genomes of African insects by Jean-Claude Chermann and his team in 1986. This, however, is insufficient to implicate insects as vectors of the human disease, especially since, at the time of writing, epidemiological evidence argues strongly against this
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hypothesis. Nevertheless, it is not impossible that insects could play some role in the natural history of the retrovirus.
The AIDS Virus
AIDS is a deadly syndrome, or collection of clinical features, that is known to be caused by the human immunodeficency virus (HIV, previously called
HTLV-III or LAV).
HIV damages the immune system – the system that ordinarily protects the body against infection – leaving a person especially susceptible to other infections and to variety of malignancies. AIDS itself is actually the end of infection, many people have no visible symptoms, whereas others experience various types of mild illness or more serious health problems that can be debilitating but do not fit the diagnostic criteria for full-blown case of AIDS. While there is some uncertainty about how many of those infected with HIV will ultimately develop AIDS, it is increasingly apparent that the majority will eventually all die of this disorder.
How the AIDS Virus Works
The clinical manifestations or first symptoms and signs of AIDS seem to have five aspects, some of which are completely independent of the others.
1. Serious abnormalities of the immune system with the inevitable consequences of opportunistic infections.
2. Reaction of functional components of the immune system to the virus.
3. Infection of the brain and resultant thinking disorders.
4. Induction of certain kinds of abnormal cell growth, such as B-cell lymphoma and Kaposi’s sarcoma.
5. Miscellaneous disease due to an increased incidence of infection with disease-causing microbes (pathogens).
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Since cancer usually occur within one or more of one’s internal organs, they spread invisibly, sparing the patient and others the additional psychological horror of having to watch them grow. Kaposi’s sarcoma, however, often occurs on the skin surface or in the mouth or other visible body openings. First described in 1872 by the Austrian dermatologist Moricz Kaposi, Kaposi’s sarcoma remained a rare tumor, unknown even to some physicians, until the recent full force impact of AIDS. Kaposi’s sarcoma was first se in older men of Jewish and Italian ancestry, and later in others of Mediterranean ancestry, especially Greeks. It was much later found in Central Africa, but this time in the young and old men.
The cause of these tumors has been ascribed to genetic mechanisms, and some results support the possibility of inheriting susceptibility to the classic form.
Cancer, as we have seen, is clonal – the tumor cells are derived from one original transformed cell, and spreading occurs because some cells acquire the capacity to move to another site and grow there (metastasis).
But Kaposi’s sarcoma seems to begin in many places at the same time. In the case of AIDS-associated Kaposi’s sarcoma, the lesions that may be found in the internal organs, mucosal surfaces of the gastrointestinal system, and skin, all appear to develop de novo rather than by metastasis from an original tumor site.
Paths of Transmission
In the last five years, clinical observations, epidemiological statistics, and laboratory experiments have all confirmed that HIV is not very contagious and that its routes of transmission are quite limited. It is transmitted only by three routes: sexual contact, direct inoculation or injection of blood in tissues or blood vessels, or mother-child transmission through the placenta or breast milk.
Sexual transmission is without doubt the most common means of infection.
In semen and in vaginal secretions of infected persons, the virus is present in small quantities in a free state and in a much greater quantity in close association with the infected cells. Historically, transmission between homosexual partners was the first recognized path of infection. Since the epidemic began, with an outbreak in the American homosexual community, there was a fairly long delay before doctors recognized the possibility of spread by heterosexual relations. For several years, female to male transmission was considered to be an unlikely event, but epidemiological surveys in Africa have dispelled all doubt that this does occur.
Potentially everyone is at risk of coming into contact with an infected person, or body fluids (e.g., blood, saliva, tears, etc.) that contain the virus HTLV-III/LAV.
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The following persons and types of occupations are categorized within various risks groups. Although persons in Risk Group I are reported to have the highest risk of contracting AIDS, many of those listed in the other groups are likewise at risk due to their potential contact with infected persons and contaminated body fluids.
RISK GROUP I: High Risk Persons
* Sexually active homosexual and bisexual men
* Present or past abusers or intravenous drug
* Persons with hemophilia or other coagulable disorders
* Persons who have heterosexual contact with persons who have AIDS
* Persons who have had transfusions with contaminated blood or blood products
* Infants born to infected mothers
RISK GROUP II: Health-Care Workers
RISK GROUP III: Personal-Service Workers
RISK GROUP IV: Food-Service Workers
RISK GROUP V: Child-Care Workers
RISK GROUP VI: Other Workers
Symptoms of AIDS
Most persons infected with the AIDS virus HTLV-III/LAV have no symptoms and feel well. Some develop symptoms which may include: constant fatigue, recurrent fever including “night sweats”, rapid weight loss for no apparent reason; diarrhea and diminished weight loss, white spots or unusual blemishes in the mouth, and swollen glands usually in the neck, armpits or groin.
How is AIDS Diagnosed
The diagnosis of AIDS depends on the presence of certain “opportunistic” diseases (e.g., Kaposi’s sarcoma, pneumocystits carinii pneumonia) that often indicates the loss of immunity. Certain test, which involve the detection of specific types of white cells, are used to assess the damage to various parts of the immune system. New evidence shown that HTLV-III/LAV may attack the nervous system, causing damage to the brain and spinal cord.
The presence of an “opportunistic” disease plus positive test for antibodies to HTLV-III/LAV may help to establish a diagnosis of AIDS. The antibody test for HTLV-III/LAV is used to screen donated blood and plasma and assist in preventing cases of AIDS resulting from blood transfusion or used of blood products. However, persons infected with the virus HTLV-III/LAV may not always show a positive test for the antibody and could unknowingly transmit the virus to other persons.
How can AIDS be Prevented
Case of AIDS that are related to the medical use of blood or blood products can be greatly reduced by the use of HTLV-III/LAV antibody screening tests at blood donor sites, and by members of high risk groups not volunteering to donate blood. Heat treatment of various blood products helps prevent AIDS in patients with hemophilia and other clotting disorders. Since there is no know vaccine for AIDS, community and private organizations along with places of employment can help minimize the risk of transmitting and contracting this disease by educating and informing their members and workers, about the illness and preventive measures to control it.
* Request that your Health-Care professional wear disposable gloves when examining mucous membranes, wounds, abrasions or other parts of the body where there may be a portal of entry for the virus.
* Request that your dentist wear disposable gloves when examining your teeth or doing any dental work. Ask if all dental instruments are sterilized or properly disinfected.
* Request that your Health-Care professional who performs eye exams wear disposable gloves. Make sure that all contact lenses are disinfected with a hydrogen peroxide contact lenses disinfecting system.
* If receiving transfused blood, plasma, or other blood products, make sure that appropriate tests have been performed to screen for HTLV-III/LAV.
* Request that your barber and hairdresser use disposable instruments when possible, or have them appropriately disinfected.
* In any situation or work environment where contaminated body fluids (e.g., blood, saliva, tissue) may come into contact with surfaces, the use of household bleach is an effective germicide.
* Sexual contact should be avoided with persons known or suspected to have AIDS. Menders of high risk groups should be aware that multiple sexual partners increase the probability of developing AIDS.
As long as the cause remains unknown, the ability to understand the natural history of AIDS and to undertake preventive measures is somewhat compromised. However, the above recommendations are prudent measures that should reduce the risk of acquiring and transmitting AIDS.
How Does the Future Look?
More and more cases have been recognized since AIDS was first seen in 1979-1980. At first, most of the victims were homosexual men in New York and California, but soon heterosexual Haitians and drug addicts were diagnosed. Then blood recipients, particularly hemophiliacs, fell before this new, puzzling, and deadly epidemic. There were many questions and few answers. There were demands for drastic actions, but no one was quite certain what to do. Although medical advances are being made in the treatment of AIDS related disease, there is no known cure for AIDS.