Biology of AIDS and STDs - Essay Example

BIOLOGY OF AIDS AND STDs Answer a) The Sexually Transmitted Infections (STIs) which are currently reportable in the United s are: the viral diseases such as: Human Immunodeficiency Virus (HIV) which causes Acquired Immunodeficiency Syndrome (AIDS), Hepatitis B, Herpes, Human Papillomavirus (HPV) which causes genital infection, and bacterial infections such as Chancroid, Chlamydia, Gonorrhea, and Syphilis. The most commonly reported sexually transmitted disease is: genital infection caused by HPV. The group of people most affected by this particular sexually transmitted infection is the age group of Americans 15 to 49 years of age ( which is about 15% of the population) and includes one-third of a random group of college students (McGraw-Hill’s Access Medicine 2006: pp.1-2). b) The second and third most commonly reported sexually transmitted diseases (STIs) in the United States are: Hepatitis B Virus (HBV) and Human immunodeficiency virus (HIV). An estimated 1.25 million people in the United States have chronic HBV, and an estimated 1 – 1.2 million U.S. individuals are living with HIV. The rate of infection for HBV has increased from 60,000 in 2004 to 1.25 million; and the number of HIV infections increase by roughly 40,000 each year, presently at 1.2 million (Guttmacher Research in Sexual and Reproductive Health, 2006: pp.1-2) The groups most affected by these STIs in this country are: for HBV, men who have sex with men, and injection drug users, and for HIV: “core populations” having high rates of partner change, concurrent partners e.g. prostitutes and their clients, homosexual men and persons involved in the use of illicit drugs (McGraw-Hill’s Access Medicine 2006: p.1). c) The most commonly reported STI globally is the Trichomoniasis (Aral, et al, p.315). WHO estimated the global prevalence of Trichomonas vaginalis at 174 million in 1999. The region of the globe with highest burden of this most common STI is South Africa (WHO 2001: p.27) Answer 2. The two different viruses that cause herpes are: Herpes simplex virus type 1; and Herpes simplex virus type 2. Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus and is usually acquired in childhood. HSV-1 often causes lesions inside the mouth such as cold sores (fever blisters) and is transmitted by contact with infected saliva. Herpes simplex virus 2 (HSV-2) is sexually transmitted. Symptoms include genital ulcers or sores. In addition to oral and genital lesions, the virus can also lead to complications such as meningoencephalitis (infection of the lining of the brain and the brain itself) or cause infection of the eye -- in particular the conjunctiva, and cornea. However, some people have HSV-2 but do not display symptoms. Infection with HSV-2 is now one of the most common STIs worldwide. Up to 30% of U.S. adults have antibodies against HSV-2 (Aral et al, p.315). The major feature of the herpes viral life cycle are: HSV undergoes the lytic cycle: entry, uncoating, viral transcription and DNA replication in the nucleus, particle assembly, and exit from the cell: in epithelial cells of the skin to cause of primary infection (Expert Reviews 2003, p.1). Some virus enters the sensory neuron terminals and travels to the neucleus where it establishes latency. Periodic reactivation results in recurrent lesions. Answer 3. Hepatitis A virus (HAV) is one of several viruses that specifically target the liver. Infection with HAV generally leads to a self-limited illness that causes temporary liver inflammation (damage to cells) but does not require specific treatment. However, in rare cases, the infection may result in a more serious illness, leading to liver failure (loss of liver functions) or death. The virus is found in the feces of infected persons and is most commonly transmitted through person-to-person contact and through the ingestion of water or food that has been contaminated with feces from infected individuals. The disease is preventable, by the observation of cleanliness and sanitation. Also routine vaccination against HAV is recommended (Ringold, 2005: p.270). Answer 4. Hepatitis B is one of the major diseases of mankind and is a serious global public health problem. It is preventable with safe and effective vaccines that have been available since 1982. Hepatitis B virus is transmitted by contact with blood or body fluids of an infected person in the same way as human immunodeficiency virus (HIV), the virus that causes AIDS. However, HBV is 50 to 100 times more infectious than HIV. Worldwide, most infections occur from sexual contact, infected mother to child, from child to child contact in household settings, and from reuse of unsterilized needles and syringes. Of the 2 billion people who have been infected with the hepatitis B virus (HBV), more than 350 million have chronic infections. These chronically infected persons are at high risk of death from cirrhosis of the liver and liver cancer, diseases that kill about one million persons each year (World Health Organization)1. Answer 5. Hepatitis C Virus (HCV) is a major cause of acute hepatitis and chronic liver disease, including cirrhosis2 and liver cancer. Globally, an estimated 170 million persons are chronically infected with HCV and 3 to 4 million persons are newly infected each year. HCV is spread primarily by direct contact with human blood. The major causes of HCV infection worldwide are use of unscreened blood transfusions, and re-use of needles and syringes that have not been adequately sterilized. No vaccine is currently available to prevent Hepatitis C and treatment for chronic hepatitis C is too costly. The greatest impact on hepatitis C disease burden will likely be achieved by focusing efforts on reducing the risk of HCV transmission from blood transfusions, unsafe injection practices and high-risk behaviours (e.g. injection drug use). Answer 6. Human papillomavirus (HPV) found in association with invasive cancers of the cervix, vulva, penis or anus are considered as high-risk. The low-risk, non-oncogenic HPV can cause benign or low-grade cervical cell changes and anogenital warts, but are rarely if ever found in association with invasive cancers. Approximately 20 million Americans (15 to 49 years of age) are currently infected with HPV. Genital infection with HPV is the most common sexually transmitted infection (STI) in the United States today. Most HPV infections are asymptomatic, transient, and resolve without treatment. HPV commonly causes epithelial proliferations at cutaneous and mucosal surfaces. However, in some individuals, HPV infections result in genital warts, Pap test abnormalities, or rarely: cervical cancer. Early detection and treatment of pre-cancerous lesions can prevent development of cervical cancer (Aral et al, p.315). Question 7. B.V. is Bacterial Vaginosis. The agent that causes it is Gardnerella vaginalis, also various anaerobic bacteria and mycoplasmas. This syndrome is characterized by symptoms of vaginal malodor, moderately increased white discharge, which appears homogenous, is low in viscosity and smoothly coats the vaginal mucosa. It affects young women, individuals with multiple sexual partners, and after recent intercourse with a new partner. The vaginal fluid of women with bacterial vaginosis is characterized by markedly increased prevalence and concentrations of G.vaginalis, Mycoplasma hominis, and several anaerobic bacteria. The vaginal fluid usually lacks hydrogen-peroxide producing lactobacillus: which constitute most of the normal vaginal flora and perhaps help protect against certain cervical and vaginal infections. The risk factors are: vaginal douching, use of intravaginal nonoxynol-9 spermicide, feminine hygiene products and new sexual partners. All these can result in loss of vaginal colonization by hydrogen peroxide-producing lactobacilli. Diagnosis of bacterial vaginosis clinically with the Amsel criteria, which include any three of the following four clinical abnormalities. 1) signs of increased vaginal white discharge 2) a vaginal discharge pH of >4.5 3) liberation of a fishy odor (attributable to volatile amines trimethylamine) immediately after vaginal secretions are mixed with a 10% solution of KOH; and (4) microscopic demonstration of "clue cells" (vaginal epithelial cells coated with coccobacillary organisms giving them a granular appearance and indistinct borders). A diagnostic card test facilitates screening of vaginal fluid for pH > 4.5 and amines, and a dipstick test detects proline aminopeptidase, an enzyme associated with this syndrome (McGraw-Hill’s Access Medicine 2006: p.1). The main complications of infection are: risk of pelvic inflammatory disease, with either chlamydia or gonorrhia, the risk of surgery following vaginal surgery or abortion. Answer 8. Chancroid is a genital ulcer disease caused by Haemophilus ducreyi. The causative organism is difficult to culture, and as a result, the condition may be substantially underdiagnosed. The infection is spread through direct contact, mostly through unprotected sex. Its incidence has declined in both developing and in developed countries. In 2005, 17 cases of chancroid were reported in the United States, the lowest number of cases ever reported. This decline is associated with the provision of STI diagnostic and therapeutic services to sex workers, and with improved syndromic management of genital ulcers. Like other genital ulcer diseases, chancroid is related to increased acquisition and transmission of HIV. The condition is easily treatable by antibiotics. If left untreated, abscesses can form in the groin area and leave deep scars. Answer 9. Donovanosis is also known as Granuloma inguinale. Among the numerous nomenclature suggested for this disease, Donovanosis was proposed by Marmell et al in 1950 to honour Donovan who first demonstrated the causative microbe in 1905. This condition and Lymphogranuloma venereum continue to cause genital ulceration in developing countries but rarely occur today in North America or Europe. Other causes of genital ulcer include (1) candidiasis and traumatized genital warts—both readily recognized; (2) lesions due to genital involvement of more widespread dermatoses; and (3) cutaneous manifestations of systemic diseases with genital mucosal ulceration (Rashid, et al 2006: p.14) Answer 10. Syphilis is the “great imitator”. The disease is known by this term because the symptoms are often very similar to the disease caused by the Herpes simplex virus type 1. Syphilis is caused by Treponema pallidum. Herpes simplex virus type 1 causes infection through the saliva. Men usually do not have symptoms of Syphilis, but may experience irritation while urinating or a slight or mild discharge. Women may have irritation and itching of the vaginal area, and a yellow-green vaginal discharge with a strong odor. In 1999, the WHO estimated the global prevalence of syphilis at 12 million, with high prevalence rates in South and Southeast Asia and Sub-Saharan Africa. Those most likely to be affected are populations in developing countries and disadvantaged sub-populations in developed countries. Since 1999, syphilis outbreaks have re-emerged in developed countries among men who have sex with men (Centers for Disease Control and Prevention 2004). Among heterosexuals, sexual contact with sex-workers is an important risk factor. If untreated, syphilis during pregnancy may lead to stillbirth and congenital syphilis (Genc and Ledger 2000, quoted in CDC 2004). The 3 main stages of the “great imitator” disease are: primary, secondary and tertiary. 2 The primary stage generally constitutes a single sore, however there could be multiple sores, appearing between 10 and 90 days following infection. The sores generally appear where infection entered the body and last 3-6 weeks, healing with treatment. The secondary stage is characterized by skin rash and mucous membrane lesions. The rash may appear as rough, red, or reddish brown spots both on the palms of the hands and the bottoms of the feet. Rashes may occur on other parts of the body and remain unnoticed or resemble rashes caused by another illness. Moreover, other symptoms of fever, sore throat, swollen glands, patchy hair loss, headaches, weight loss, muscle aches, and fatigue may occur. Symptoms resolve with or without treatment, but without treatment the infection progresses into the latent stage. The tertiary stage of syphilis begins when the symptoms of the secondary stage disappear. Without treatment, the infection remains in the body, causing damage to the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints. Damage of internal organs may appear later. Answer 11. According to the World Health Organization Report 1996, There were at least 333 million new cases of sexually transmitted diseases worldwide in 1995, excluding HIV infections. Roughly 40,000 new HIV infections occur each year, as stated by Guttmacher Institute. The WHO estimated that 340 million new cases of STDs have occurred throughout the world in 1999, in men and women aged 15 to 49 years. These estimates may be considered as accurate since they are given by reputed organizations like the WHO and the Guttmacher Institute, at New York and Washington DC. The latter focuses on advancing sexual and reproductive health worldwide through research, policy analysis and public education. Answer 12. The major risk factors and risk markers for acquiring an STI are: close sexual activity with an infected individual or the use of infected needles, etc. Sexual activity with a member from the “core population” who have high rates of partner change, concurrent partners, or “dense” sexual networks : e.g. prostitutes and their clients, some homosexual men, and persons involved in the use of illicit drugs are also high risk behaviours. Rate of exposure of susceptible to infectious people, efficiency of transmission per exposure, and duration of infectivity of those infected. These are significant criteria, and counteractive measures can be undertaken in a timely manner, to neutralize risks. Efforts to prevent and control the efficiency of transmission are crucial. These can be done through counseling, promoting condom use, and safer sexual practices.The major risks and consequences of having had an STI are that: the infected individual’s health deteriorates, and he becomes a social outcaste. When an STI is acquired, the person becomes susceptible to HIV entering his body through the skin sores, and will be lilely to suffer from AIDs also. Answer 13. The bacteria Neisseria gonorrhoeae infects through sexual activity, in most cases. The characteristic symptoms in women are vaginal discharge and painful and frequent urination. These are common symptoms for women, and they tend to ignore them. The bacteria may involve the urethra, the vagina and the cervix. A profuse gonorrheal discharge may be produced. Gonococcal proctitis develops because of the bacteria travelling to the anus from the infectious vagina. In about 50% of untreated women, the bacteria spread to the upper genital tract and cause major complications. The inflammation of the fallopian tubes: salpingitis can be acute with pain, high temperature, nausea and vomiting. When the peritoneum and the ovaries are involved, the condition is: acute gonorrheal salpingo oophoritis, less accurately called as “pelvic inflammatory disease”. May further lead to tubal and/or ovarian abscess. The scarring of the fallopian tubes that results, is a major reason for infertility and ectopic pregnancy. Occassionally the gonorrhea bacteria can enter other vital organs also. As protection against neonatal eye infections during the process of delivery, pregnant women should be screened for possible gonorrhea early in pregnancy and also several times during the last months. Also, the pregnant woman should take care to maintain scrupulous personal hygiene, and should refrain from sexual activity with a possibly infected individual. Several kinds of gonorrhea vaccines are being tested in the laboratory and clinically ( Sloane, 2002: p.271-272). REFERENCES Aral, Sevgi O; Over, Mead; Manhart, Lisa; Holmes, King K. Disease Control Priorities in Developing Countries. Chapter 17: Sexually Transmitted Infections. Centers for Disease Control and Prevention. Sexually Transmitted Disease Surveillance, 2005. Atlanta, GA: U.S. Department of Health and Human Services, November 2006. Web site: http://www.cdc.gov/std/stats/05pdf/2005-exordium.pdf Expert Reviews in Molecular Medicine. The Herpes simplex virus life cycle. December 2003, Vol.5, No.5. Guttmacher Institute: Advancing Sexual and Reproductive Health Worldwide Through Research, Policy Analysis, and Public Education, 2006. Web site: policyinfo@guttmacher.org McGraw-Hill’s Access Medicine, Chapter 115. Sexually Transmitted Diseases: Overview and Clinical Approach. 2006. Rashid, Rashid M; Janjua, Shahbaz A; Khachemoune, Amor. “Granuloma inguinale: A Case Report”. Journal: Dermatology Online Journal, Vol.12, No.7 (2006). Ringold, Sarah. “Hepatitis A Virus”. Journal: The Journal of the American Medical Association, Vol.294, No.2, July13, 2005. Sloane, Ethel. Biology of Women, 4th Edition. U.S: Thomson Delmar Learning, 2002. World Health Organization (WHO). Global Prevalence and Incidence of Selected Curable Sexually Transmitted Infections: Overview and Estimates. Geneva 2001. Web site: http://www.who.int/hiv/pub/sti/en/who_hiv_aids_2001.02.pdf Read More