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Introduction
Human Immunodeficiency Virus (HIV) has become a worldwide epidemic since it emerged in the early 1980s. HIV is an example of lentivirus that attacks the immune system of human beings and the causative agent of Acquired Immune Deficiency Syndrome (AIDS) in the infected individuals. People infected with this deadly virus remain infected for life and if not on retroviral therapy these individuals can develop full blown AIDS which is accompanied by fatal opportunistic infections. Ever since HIV and AIDS came into existence, many studies have been going on to determine what this virus is and how it leads to the etiology of AIDS. This paper therefore discusses HIV, its transmission, prevention, how it may have come into existence and how it results into AIDS.
Historical Relevance
HIV is believed to have been in existence since the 1950s or maybe as earlier as the 1940s. Earlier on it was thought that HIV came into existence in the 1980s. For instance, plasma samples that were taken from a man in Democratic Republic of Congo in 1959 were found to be containing HIV. Other tissue samples from an American teenager who died in 1969 were found to be having HIV. HIV is believed to have also been found in tissue samples of a soldier in Norway that died in 1976 (Weeks et al., 2013).
However, 1981 was the year HIV was recognized as a pandemic for the first time in the United States (Merson et al., 2008). The disease was associated with cases of pneumonia caused by Pnuemocytis carinii in Los Angeles among gay men and it made them believe that it was only for homosexual men. At the end of that year, however, other cases of the same had emerged among non-homosexual drug addicts who shared needles to inject themselves. The association drawn from homosexual men and this disease was further disapproved when similar cases were reported from many other countries. These cases were mainly from drug addicts, heterosexual and homosexuals who had multiple partners. In the late 1985, chemical tests were conducted to test and about 17 thousand cases were reported over 71 countries (Merson et al., 2008).
Epidemiology
It is believed that HIV prevalence is on the rise currently due to the fact that HIV patients on retroviral therapy live longer. Cases of new infections have been seen to decline from 3.3 to 2.3 million in 2002 and 2012 respectively. By 2012, approximately 9.7% people were infected with HIV in developing countries, according to the statistics of those who were put on retroviral therapy (Maartems et al., 2014). New HIV infection cases have, however, been on the rise in the Middle East and North Africa. The same trend has also been observed in Eastern Europe and Central Asia despite there being a decline in Ukraine over the recent years (UNAIDS, 2013).
Countries like India, Nigeria and Tanzania were leading by an estimated 100,000 number of new cases experienced per year by the year 2005 (Merson et al., 2008). The United States, Zimbabwe, Brazil and Chad among others had new cases of between 10,000<50,000 per year while Middle East countries like Afghanistan and other countries like Egypt and Poland had the lowest number of new cases per year. These countries experienced less than 1,000 new cases per year (Merson et al., 2008). [Need an essay writing service? Find help here.]
Etiology of HIV
Many theories have been put forth to try and explain the origin of HIV virus. Most of these theories are based on the fact that HIV is a lentivirus and shares a lot of similarities with some strains of Simian Immunodeficiency Virus (SIV). It is therefore thought both strains of HIV (HIV-1 and HIV-2) are descendants of Simian Immunodeficiency Virus (SIV). HIV-2 was the first strain to be linked to Simian Immunodeficiency Virus when it was found to be corresponding to a Simian Immunodeficiency Virus, (SIVsm) found in a monkey. HIV-1 on the other hand took quite some time before a clear match of SIV could be found. However, in the year 1999 SIVcpz was found to be a closer match for this strain. SIVcpz was found in chimpanzees though there still existed some significant differences between the two viruses.
Viruses are known to be very specific for the species and cells they attack. However, HIV virus has been found to be zoonotic based on the theories and studies done so far. One of these theories is the Hunter Theory which is among the most commonly accepted theories about the origin of HIV. In this theory, SIVcpz, a strain in chimpanzees, was transmitted to humans when hunters killed and ate the infected animal and even blood entering their wounds and cuts. The result was SIVcpz adapting and altering its genome which resulted into a new strain. It is also thought that other viruses like Simian Foamy Virus also got their way into human beings through the same way. This is evidenced by a study done in Cameroon in which it was found that 1% of the individuals that participated were infected with Simian Foamy Virus, a virus that was thought to infect only chimpanzees (Calattini et al., 2011).[“Write my essay for me?” Get help here.]
The Heart of Darkness Theory just like the hunter theory claims that HIV originated from primates. This theory claims that during the late 19th and early 20th century, most Africans were under colonial rule. It is during this particular time that Africans were subjected to forced labor in labor camps that had very poor sanitation. In this camps, they could have resorted to wild meat especially chimpanzee as the source of food. These camps were also associated with poor sanitation and health conditions. Poor health conditions of these laborers could have paved way for the SIV virus that had already infiltrated into their bodies to mutate into the deadly HIV virus. Use of unsterile needles among these laborers played a key role in onward transmission and cross-transmission.
Although theories connecting HIV to primates have been accepted by a number of people, conspiracy theories have also had their part in explaining origin of this virus. Some people believe that HIV was created by man with intentions or reasons yet to be understood. Africa is thought to have been the target for HIV, given the fact that monkeys and chimpanzees from South America and Asia have never been found to be infected with SIVs which are thought to have mutated to HIV in humans. This has resulted into many people, especially African Americans, to believe that HIV invention was part of a biological warfare program that targeted Africans, something that has been disapproved several times.
Host and Transmission HIV
HIV just like the other viruses is specific to its host, the human being. No current studies have found documented existence and successive cause of infections by HIV in other organisms. Closer counterparts, the Simian Immunodeficiency Virus, have been found to have very many differences with HIV and are thought not to be infectious in humans.
The main portal of entry for HIV is through body fluids for instance blood. HIV does not require a vector for it to gain entry into the host. All it requires is just the contact between body fluids from the infected person and those from the other uninfected individuals. HIV is an acquired infection that occurs after fluid exchange among individuals.
There are several means by which HIV is transmitted from infected individuals to those not infected. One of these modes is through having unprotected vaginal or anal sex with infected person. During sexual intercourse, sexual fluids are produced by both partners to aid in lubrication including semen containing sperms are produced by the male partner. These fluids from an infected person contain HIV virus, and once the other partner comes into conduct with them, he or she could get infected. Also, during sexual intercourse friction could result into minor tears in the mucosa of the anal or vaginal tract and the skin of the penis of the male. It is through these cuts that this virus gains entry into the tissues then into blood where it attacks cells of the immune system.
Sharing sharp objects such as needles and razor blades with infected individuals can result into one contracting the infection. Once on the used needle, HIV can stay alive for some time, even up to 42 days, depending on the environmental conditions like moderate temperatures. Sharing syringes, cannulas and other equipment used in drug preparation with infected helps in HIV transmission.
Infected mothers who do not deliver under the care of health workers may also transmit HIV to their newborns. Mothers not taking medication pose a higher risk than those under retroviral therapy. Other uncommon means of HIV transmission include oral-sex, receiving blood infected with HIV virus during transfusions, deep-kissing with infected individuals with mouth ulcers and contact between broken skin. They are referred to as uncommon since they occur in extremely rare circumstances. For instance, before blood is transfused, it is checked to ensure there are no pathogens in it making it impossible to transfuse infected blood to an individual.
A study conducted in Bulgaria to characterize HIV-1 infections revealed that majority (69.3 %) of HIV infections were as a result of unprotected heterosexual behaviors, 16.8 % from homosexual behavior among men, 9.4 % through intradermal drug injection, 2.5% through blood transfusion and 2.0 % being mother to child in newborns (Ivanov et al., 2013). The study was a replica of other epidemiological data present during the study. Epidemiological data showed that 67.9 % of transmissions were from heterosexual behaviors, 20.4 % for injections by drug users, 9.5 % from homosexual males, 1.6 % for blood transfusion and 0.7% for mother to child (Ivanov et al., 2013).
HIV Pathogenesis and Pathology
Target cell for HIV infection are the CD4 T lymphocytes, which are crucial cells of the immune system. HIV gains entry into CD4 cells via interactions with CD4 receptors and chemokine receptors CCR5 and CXCR4 receptors. Other cells like monocytes, macrophages and dendritic cells have these chemokine receptors but lack CD4 receptors and thus they are also infected by the virus. HIV infection involves the following 8 stages; primary infection, dissemination of viral particles into lymphoid tissues, latency stage, elevated HIV levels, opportunistic infections and eventually death of the individual. The cause of HIV infection is averagely 10-15 years for those individuals not receiving retroviral therapy but longer for those on retroviral therapy.
Primary infection involves HIV entry into one’s system through either of the means mentioned above. In primary infection, the virus infects mucous membranes for about 4-11 days. Immediately, mucosal is followed by initial viremia which can be detected for about 8-12 weeks. During this period, the virus is transported throughout the body through blood. It is during this time that lymphoid organs are seeded with HIV viral particles. This viremia is accompanied by an acute mononucleosis-like syndrome in some patients. This occurs at about 3-6weeks after one acquires the infection. Circulating CD4 cells also reduce during this time.
Body immune system has the mandate of guarding us against infections. The immune system responds to HIV infection 1 week to 3 months after primary infection. This response is attributed to the production of neutralizing antibodies (Maartems et al., 2014) which results into a drop in viremia and returning CD4 cells back to their levels. However, the body immune system does not eliminate the virus completely and HIV-infected cells persist in lymphoid organs sending the infection into a latency stage.
Latency period of HIV lasts for several years with the individual being asymptomatic. During this period, there is increased viral replication while at the same time there is viral destruction by the immunes system. This is attributed to work performed by CD8 cells in killing the infected CD4 cells and adaptive immune responses during this period (Maartems et al., 2014). However, due to inherent errors during HIV genome replication, HIV genome is known to mutate very rapidly something that is impossible for the immune system to cope up with, and so with time the virus levels in the individual’s system are elevated.
With elevated viral loads, the patient eventually develops symptoms and opportunistic infections. This is a result of a compromised immune system of the individual that is brought about by the many CD4 cells infected and their eventual killing by CD8 cells. HIV virus levels during this time are very high and very virulent. HIV viruses in late stage of HIV infection are believed to have shifted from macrophage-tropic (M-tropic) to lymphocyte-tropic (T-tropic) strains which have high virulence.
Elevated virus levels in the body are characterized with gross destruction of cells of the immune system. Monocytes, macrophages, dendritic cells and the CD4 lymphocytes are cells that fall victims. Destruction of CD4 and other cells of the immune system results into immune suppression. This therefore means that this individual can be infected by other diseases that would have not infected him/her with their non-compromised immunity. It is this state of immunity that results into Acquired Immunodeficiency Syndrome (AIDS). Diseases such as tuberculosis, pneumonia and some other fungal infections can now attack this patient. Opportunistic infections are the predominant causes of death in HIV/AIDS patients. [Click Essay Writer to order your essay]
Signs and Symptoms for HIV
HIV infection is characterized by several signs and symptoms associated with its stages of infection. HIV patients are known to experience varying signs and symptoms during the different stages but there are some that are typical in most of the patients. The following is an outline of the stages of HIV and its signs and symptoms.
Primary infection is the stage in which one acquires the virus. The duration of this period varies among different individuals but it is known to be up to 3 months. Majority of infected individuals present with signs and symptoms during this period. Some of these symptoms would include fever for about 14 days, sore throat, severe headaches and mouth ulcers. Other HIV patients will only report cases of mild flu that which they report in less than 7 weeks after the day they believe to have contracted the disease. All these symptoms are brought about by the body producing antibodies against the virus. During this period most individuals would test negative when tested.
Asymptomatic stage is the stage when individuals that have already tested positive continue to stay healthy with no symptoms. However, this period varies greatly among different individuals but it takes several years. It is during this period that the HIV virus infection is at its latency stage. These differences are attributed to genetic differences among individuals and differences in immunity.
Symptomatic infection is the period during which symptoms occur. These symptoms include experiencing diarrhea or watery stool, sweating during the night, one feeling fatigued and cases of weight loss among others. These symptoms are attributed to the fact that viral loads are high, the body immune system has been overwhelmed and at the same time is undergoing destruction by the virus.[Click Essay Writer to order your essay]
The last stage is advanced HIV infection also known as AIDS. People said to have reached this stage have low CD4 counts. These individuals also have opportunistic infections such as tuberculosis, pneumonia and mycoses. These opportunistic diseases are the causers of the life-threatening symptoms such as rapid wasting, severe diarrhea and uncontrolled coughing. Finally, when the individuals are overwhelmed they die, not from AIDS but from this opportunistic infections. It should be understood that AIDS is not a disease but rather a condition.
HIV Treatment
There is no cure for HIV infection at the moment. However, there are many studies going on with the aim of finding a cure or vaccine. The ever mutating HIV virus poses a big problem towards the development of a definite cure. Retroviral therapy is what is currently used by HIV patients to prolong their lives. HIV virus is a retrovirus and so is susceptible to retroviral agents. However, diseases progression of HIV-2 is slow as compared to HIV-1. HIV-2 is also less susceptible to most of the retroviral agents.
Retroviral agents work on the basis that they block processes of the virus necessary for replication. Retroviral drugs include nucleoside and nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors, fusion inhibitors, intergrase inhibitors and CCR5 antagonists.
Nucleoside/nucleotide reverse transcriptase inhibitors block replication of viral genomes by inhibiting incorporation nucleotides and terminating elongation of pro-viral DNA. These drugs inhibit both strains of HIV. Examples of these drugs include lamivudine and tenofovir. Non-nucleoside inhibitors on the other hand bind to the hydrophobic pocket on the reverse transcriptase and reduce the conformational change of this enzyme hence reducing its activity. Examples include nevirapine and entravine.[Need an essay writing service? Find help here.]
Protease inhibitors (prevent cleavage of produced proteins to finalize viral assembly), fusion inhibitor (prevents fusion of the virus with the host cell), intergrase inhibitors (prevents integration of viral genome into the host genome example is raltegravir) and CCR5 inhibitors (inhibits viral entry an example being maraviroc) also help in the control of HIV virus replication. However this drugs need to be used in combination for them to be effective. They are classified into regimens and are alternated in case the patient becomes unresponsive to one.
Relevance to the Society
HIV has impacted more negatively to the society with no known positive impacts. HIV has resulted into many deaths in the world since it was declared a pandemic in 1981. Many families have also been left poor due to financial resources pumped into combating this infection.
Stigmatization is also a problem among those infected with this deadly disease. Marriages have been reported to have been broken once one partner is found to be positive. During early days, some cases of people getting killed or committing suicide once tested positive have also been reported.
References
Calattini, S., Betsem, E., Bassot, S., Chevalier, S. A., Tortevoye, P., Njouom, R., … & Gessain,
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Ivanov, I. A., Beshkov, D., Shankar, A., Hanson, D. L., Paraskevis, D., Georgieva, V., …
Switzer, W. M. (2013). Detailed Molecular Epidemiologic Characterization of HIV-1 Infection in Bulgaria Reveals Broad Diversity and Evolving Phylodynamics. PLoS ONE, 8(3), e59666.
Merson, M. H., O’malley, J., Serwadda, D., & Apisuk, C. (2008). The history and challenge of
HIV prevention. The Lancet, 372(9637),
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UNAIDS. Report on the global AIDS epidemic 2013.
Weeks, B. S., & Shors, T. (2013). AIDS: The biological basis. Jones & Bartlett Publishers.
