The acquired immunodeficiency syndrome (AIDS) was initially recognized in the first half of the twentieth century and has since become a major worldwide epidemic (Discovery Health). Debate about the origin of AIDS has enticed considerable concern and controversy since the advent of the epidemic. It is has been proven that AIDS is caused by the human immunodeficiency virus (HIV) by stimulating the destruction and functional impairment of cells in the immune system, potentially destroying the human bodys ability to fight infection (CDC).
While there is no cure for the AIDS epidemic, a combination of historical studies and expanding medical technology enable it to be controlled in the course of the future. Knowing where the disease came from and the development of HIV is essential in creating a vaccine and more efficient treatment against the virus. Evidence that the AIDS disease is caused by the HIV virus include numerous international studies indicating that virtually all patients diagnosed with AIDS are HIV seropositive; they carry antibodies that depict HIV – infection.
Also, modern techniques have allowed the isolation of HIV in all AIDS patients, as well as in nearly all HIV seropositive individuals with both early and late stage disease. Furthermore, a 1999 case reported to the Center of Disease Control and Prevention (CDC) accounted three laboratory employees as infected with AIDS after accidental exposure of concentrated replicas of HIV in the laboratory; in all three instances, HIV was insulated and attest to be the infecting cause of disease (CDC).
Such examples, demonstrating HIV as the cause of AIDS, satisfy nineteenth century physicians, Robert Kochs, accredited postulates of disease stating that: one, the suspected cause [HIV] must be strongly associated with the disease [AIDS]; two, the suspected agent can be isolated and propagated outside the host, and three, the transfer of the agent to an uninfected host, man, or animal, produces the disease in that host (Kochs Postulate).
Thus, to find the genesis of AIDS, scientists must find the source of the HIV virus. HIV is subdivision of a group of viruses classified as lentiviruses. Lentiviruses excluding HIV have been discovered in a broad range of nonhuman primates, scientifically referred to as simian immunodeficiency viruses (SIV); it has been universally accepted that HIV is a descendant of SIV since certain simian immunodeficiency viruses share a mutual resemblance to HIV – 1 and HIV – 2, the two types of HIV. * (Avert).
For example, in February 1999, it was declared that a group of researchers from the University of Alabama had studied frozen tissue from a chimpanzee and found that the simian virus it carried (SIVcpz)* was almost identical to HIV – 1. The researchers contended that such evidence indicates that chimpanzees were the source of HIV – 1, and that the virus, at some point, intersected between human and simian species (Edell). However, it is not necessarily certain that chimpanzees are specifically the original cause for HIV – 1 because chimpanzees are seldom infected with the SIV virus.
It has been ascertained that viruses can pass from animals to humans by the process of zoonosis (CDC). It has been suggested that HIV could have extended from chimpanzees as a result of human consumption. During recent years it has become possible to determine the particular subtype of the virus. Analyzing the subtype of virus of some of the earliest known cases of HIV infection can provide indication about the time of origin and succeeding development of HIV in humans.
Three of the earliest instances of HIV infection include a plasma sample taken in 1959 from an adult male subsiding in what is now Democratic Republic of Congo, tissue specimens from an African – American teenager who died in St. Louis in 1969 and a Norwegian sailor who died in 1976 (Avert). Studies of the plasma sample from 1959 indicate that HIV – 1 was introduced into the human race around the late 1940’s. On the contrary, other scientists have interpreted that the epidemic could have begun over one hundred years ago.
Furthermore, in January 2000, the results of a recent study presented at the Seventh Conference on Retro Viruses and Opportunistic Infections, suggested that the first case of HIV infection occurred around 1930 in the West African region. The study, led by Dr. Bette Korber of the Los Alamos National Laboratory, is dependent upon a complex computer simulation of HIV evolution (Avert). Based on such incompatible scientific findings, it is highly likely that the HIV virus crossed over to humans on more than occasion; HIV presumably emerged simultaneously in different regions of the world.
More radical theories put forth about the origin of HIV include a number of conspiracies suggesting that HIV may have been fabricated by the CIA, while others believe that it could have been genetically engineered (Avert). It is rather improbable that humanity will recognize exactly when and where the first HIV virus emerged, but it apparent that sometime in the middle of the twentieth century, HIV infection in humans evolved into the global epidemic now referred to as AIDS. Despite its origin, there are a number of factors that have contributed to the accelerated spread of AIDS.
The main transmission routes are through shared use of needles, direct sexual contact, especially among homosexuals, blood transfusions, blood transplants, penetration of infectious fluids in open wounds, and breast feeding (CDC). As blood transfusions became a routine medical procedure in the 1960’s, the growth of an industry made consistent requests for blood. In countries, such as the United States, paid donors were used for blood transplants, including intravenous drug abusers.
The 1970’s also experienced an increase in intravenous drug use due to the availability of heroin following the Vietnam War and conflicts in the Middle East (Avert). The creation of plastic syringes and the establishment of shooting galleries, areas where people could buy, sell, and rent drugs and distribute equipment, initiated another route through which the HIV virus could easily be spread. Moreover, the role of intercourse in the spread of HIV was emphasized by the case of Gaeton Dugas, a Canadian flight attendant, dubbed Patient Zero, who traveled internationally on a regular basis.
Observations of the earliest indications of AIDS depicted that the infected persons experienced direct sexual contact with Patient Zero; these cases could be traced to several different American cities during the early 1980’s, demonstrating the dangerous implications of unprotected sexual relations (Avert) . An understanding of how the AIDS epidemic emerged is crucial in both mapping the future course of the epidemic and establishing effective education and prevention programs to control the spread of disease.
Also, knowledge of the origin and development of HIV is essential in creating a vaccine and more efficient treatment against the virus. In the long term, a safe preventive vaccine is the most effective manner of bringing the global epidemic under control. The HIV virus was discovered by three sets of researchers: Luc Montagnier in 1983, Robert Gallo and Jay Levy in 1984. They discovered that people infected with the HIV virus had weak immune systems, which left them vulnerable to infections and diseases. When a person is infected with the HIV virus, the CD4 T-cell count in their body goes down.
CD4 T-cells are a major type of white blood cells that tell the status of the immune system. A normal persons CD4 count is about 500 cells per milliliter while an infected person is around 200 cells per milliliter. Anyone with fewer than 200 cells per milliliter is considered to be at risk of serious illnesses and diseases. When a persons CD4 count becomes low, their immune system does not function properly; they are referred to as immunosuppressed. (Encarta 97, www. medicinenet. com) There are ways in which doctors can predict whether a patients CD4 cells will decrease.
The viral load can predict whether or not a person will lose these cells. A person with a high viral load will tend to have decreasing number of CD4 cells. Observing the viral load helps monitor the effectiveness of therapy and drugs which are given to patients. (medicinenet. com) When a persons CD4 cells decreases below 350 cells per milliliters, many illnesses and symptoms will occur. With fewer than 350 cells per ml, illnesses such as herpes and tuberculosis are likely to develop. A person having less than 200 cells per ml could have a yeast infection of the esophagus called Candida Esophagitis.
If a person has less than 100 cells per ml, it could result in Aids Dementia. This is the slowing down of mental functions caused by the HIV virus. Even further more, if a person was to have less than 50 cells per ml, they could suffer from a cytomegalovirus infection. This is an infection that can affect almost any organs in the body, but is mainly targeted at the eyes. (www. merksource. com) A sure way of stopping the spread of aids is by coming up with a vaccine that would target the HIV virus. The sole purpose of vaccines is to protect the immune system from viruses.
When a vaccine is used, B and T cells are released. The immune system is then able to use those two cells to destroy a certain virus. B cells are antibodies. They prevent a certain virus from infecting other cells in the immune system. The T cells are called helper or killer cells. They organize the immune systems response to the virus. They also attack cells, which are infected by the virus. When a new virus is introduced to a body, it contains molecules which are foreign to the body. These molecules are called antigens.
The B and T cells are able to recognize and activate in accordance with the antigens. The B and T cells are able to clone themselves, with some attacking the virus and some serving as memory cells. When the same virus is once again introduced to the immune system, the memory cells kick in and the B and T cells once again generate to fight off the virus. If a vaccine could be found, it would be able to fight off the HIV virus. (www. niaids. nih. gov) Although vaccines cannot yet cure the spread of aids, there are ways in which the spread of the virus can be slowed down.
There are five nucleosides that have been approved by the Food and Drug Administration currently being used. Those five are D4T (stavudine), AZT (zidovudine), DDC (zalcitabine), DDI (didanosine), and 3TC (lamivudine). These five nucleosides are called DNA chain terminators. When they are inserted into a persons body, the drugs appear to be a normal nucleotide base. It is seen as the building blocks of DNA. The Rt enzyme then mistakenly inserts the drug into the growing DNA chain. Once the drug is inserted into the DNA chain, no other bases can be added.
This causes the DNA synthesis to be terminated. (www. medicinenet. com, Encarta 97) Researchers from the University of Alabama did studies between the different types of nucleosides available and came to believe that certain nucleosides were more effective in slowing down the spread of aids. It was found that the nucleosides D4T and AZT when inserted attacked the immune systems active cells, the other three (DDC, DDI, and 3TC) only attacked the resting cells. D4T and AZT were able to fight off the spread of aids longer than the other three.
When D4T was compared to AZT, it resulted in a greater viral load drop and there was a greater increase in the number of CD4 cells. The AZT however had somewhat of lesser side effects. (Encarta 97) Another way to slow down the process of aids is by using ritonavir and indinavir. They are two protease inhibitors which when inserted in the body cripples the enzyme protease. Enzyme protease is important to the reproduction of HIV. When the protease inhibitors are inserted into the body, the HIV virus is no longer able to infect other cells.
They however are able to reproduce themselves. With the use of these inhibitors, the number of CD4 cells increase therefore enables the immune system to resist illnesses and diseases for a longer amount of time. On the negative side however, the HIV virus can develop resistance to these inhibitors rather quickly when used alone. Resistance is delayed for a short amount of time when it is given along with nucleosides. (www. aidsmed. com, www. mercksoure. com) With so many different kinds of treatment for AIDS, which one is the best medicine for the patient?
There isnt a real answer to the question because the HIV virus either mutants or creates its own immunity to the antibiotics. The best treatment for AIDS is hospital treatment because doctors can measure the amount of CD4 the patient have and then can give certain medicine depending on where the CD4 reads (Majure, 1998). AIDS epidemic can be control thanks to already known knowledge about how the virus works, successful medicines that only help in the short-run, and Dr. David Hos theory and experiment.
