SPHU 1020: Cell, Individual, and Community, 2. 29. 16 HIV/AIDS and Tuberculosis
SPHU 1020: Cell, Individual, and Community, 2. 29. 16 HIV/AIDS and Tuberculosis SPHU 1020
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This 6 page Class Notes was uploaded by Claire Jacob on Saturday March 5, 2016. The Class Notes belongs to SPHU 1020 at Tulane University taught by Dickey-Cropley, Lorelei in Summer 2015. Since its upload, it has received 21 views. For similar materials see Cell, Individual & The Community in Public Health at Tulane University.
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Date Created: 03/05/16
HIV/AIDS 2. 29.16 AIDS acquired immunodeficiency syndrome ● caused by the human immunodeficiency virus (HIV) ● is pandemic, has spread throughout the world, particularly in Africa ● this syndrome diagnosed by certain signs and symptoms ○ HIV positive ○ low CD4+ (helper T cell) cell count ○ one or more opportunistics infections (bacterial, viral, protozoal, and fungal) ○ swollen lymph nodes, sudden weight loss, and a rare vascular cancer called Kaposi’s sarcoma Where did HIV come from? ● found in monkeys… it’s a zoonotic disease AIDS considered an “emerging disease” ● HIV mutated in 1930s from a form exclusive to apes to one that could live in humans ○ genetic studies link HIV to the chimpanzee Pan troglodytes ● such diseases that move from one species to another are known as zoonoses ○ ebola and TB both examples of other zoonoses ● 1st welldocumented case of AIDS occurred in an African man in 1959; he was diagnosed decades after his death ● 2 researchers claimed discovery of HIV ○ Luc Montagnier of the Pasteur Institute in Paris ■ created the patent for HIV determination ○ Robert Gallo of the National Institutes of Health ■ found the link between AIDS and HIV Biology of HIV ● HIV is a retrovirus ○ as an obligate parasite, targets a host cell ○ once inside the host cytoplasm, uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backwards) virus ○ new DNA is then incorporated into host cell genome by an enzyme ○ host cell then treats viral DNA as part of its own genome, translating and transcribing viral genes along with cell’s own genes, producing proteins required to assemble new copies of the virus ○ it is difficult to detect until it has infected the host ● new virus particles released from the cell by budding ● there are at least 2 types of HIV Transmission of AIDS ● HIV can be transmitted in 4 ways 1. sexual contact with an infected partner 2. contact with contaminated blood or blood products 3. sharing bloodcontaminated needles and syringes, as with IV drug use (high frequency of transmission) or by accidental needle stick in health provider (0.5% risk of transmission) 4. transmitted from mother to child ○ through passage of HIV across the placenta ○ transmission during birth due to contaminated blood and secretions ○ transmission via breast milk 5. Premastication, prechewing food for infants HIV/AIDS Risk Groups in US ● paid/commercial sex workers ● men who have sex with men ● injecting drug users ● any sexually active person who does not assume he/she is at risk and take preventive measures ● HCW ● Women ○ HIV/AIDS mother to child transmission ○ risk ■ acquiring HIV during delivery without intervention: 15% to 30% ■ HIV transmission during delivery if mother is taking ARVs: <2% ■ acquiring HIV from breastfeeding without intervention: 25 to 45% ■ HIV transmission during breastfeeding if the mother is taking ARVs: much lower HIV/AIDS epidemiology ● 2.3 million adults and children newly infected with HIV in 2012 ○ represents 33% reduction in annual new cases compared to 2001 ○ new HIV infection among children fell 52% to 260,000 in 2012 ○ greater access to antiretroviral TX led to a 30 percent drop in AIDSrelated deaths from the peak in 2005 ● in the U.S., deaths typically through Pneumocystis carinii ● in other parts of the world, it is TB ● >90% of new HIV infections are in developing countries ○ in Africa (mostly subsaharan), >24 million people with HIV infection and about 1 million new cases of AIDS per year ● of adult infections, 40% are in women and 15% are in individuals of 1525 years of age AIDS in US ● US has one of the largest populations of HIVinfected in the world ● annual number of new infections remains relatively stable ○ ~50,000 newly infected people every year ● 1.7 million people in U.S. infected with HIV since start of epidemic in 1981 ● 619,000 people have died AIDS: the disease ● HIV depletes number of Thelper cells, resulting in individual’s becoming immunocompromised and vulnerable to opportunistic diseases caused by an array of microbes ● HIV positive individuals without tx progress to clinical AIDS over an incubation period that can vary from a few years to 15 years or longer The course of the disease from HIV Infection to AIDS Acute infection (acute retroviral syndrome) ● initially, HIV infection produces a mild disease ○ not seen in all patients ● IN period immediately after infection, virus titer rises (about 4 to 11 days after infection) and continues at a high level over a period of a few weeks ● mononucleosislike symptoms (fever, rash, swollen lymph glands) but none of these are lifethreatening ○ may mimic the flu ● result is an initial fall in the number of CD4+ cells but the numbers quickly return to near normal Treatment Interventions for HIV/AIDS ● antiretroviral drugs ○ highly active antiretroviral therapy: combination of antiretroviral drugs that are used as medications to control retroviruses ○ extend years between infection and onset of clinical AIDS ○ extend years between onset of AIDS and death ■ works against HIV by using drugs in combo to suppress HIV replication as many times as possible ● problems for HIV replication, keeps HIV offspring low, and reduces the possibility of HIV mutating ■ must be used in combo to suppress HIV symptoms Testing for HIV ● antibody tests: once infected, takes 36 months for enough antibodies to be formed for screening tests to be positive ● PCR tests ● once positive additional tests may be done for: ○ CD4 count to show how the disease is progressing ○ viral load ○ drug resistance need to know strain so they know what kind of antiviral medication they should be taking HIV/AIDS key driver of change in public health ● enormous impact because ○ no biological control mechanism ○ enormous cost ○ many are vulnerable ● effect on other infectious disease programs ○ TB surveillance and control programs were successful public health interventions ● effect on maternal child health programs and reproductive health programs ○ changes to program planning and infrastructure due to: ■ use of antiretroviral drugs for treatment ■ prophylactic treatment for exposed babies ■ breast feeding Role of Advocacy and Activism ● International response to epidemic ○ U.S. PEPFAR program ○ Global fund to treat AIDS, TB, and Malaria ○ Bill and Melinda Gates Foundation ○ World Bank HIV/AIDS critical challenges ● developing vaccine ● costeffective approaches to prevention in different settings ● universal treatment for all those who are eligible ● management of TB and HIV coinfection AIDS treatment and prevention: vaccines ● difficult to develop a safe and effective vaccine for AIDS because viruses mutate ● several AIDS vaccine “breakthroughs” have been failures ● ideal vaccine would be a one dose, safe, effective, oral vaccines that would establish lifelong protection against all subtypes of HIV ● AIDS “should be” easy to control, if not eradicate, because there are no vectors or animal reservoirs; the reality is very different ● modifying sexual behavior currently is best protection against contracting AIDS Tuberculosis ● Mycobacterium tuberculosis is the cause of tuberculosis (TB) ● TB is a leading cause of death worldwide ● in the US and other developed countries, it is an emerging disease ● become resistant to medications A brief History ● TB originally spread from animals to humans, probably from cows, about 80,000 to 100,000 YA ● TB afflicted Ancient Egyptian Civilization ● “Sanatorium cure” provided the first public health step against TB ● early 1880s Koch visualizes TB under a microscope Tuberculosis ● agent: Mycobacterium tuberculosis ○ 2 categories: ■ pulmonary TB ● only kind which is contagious ■ extrapulmonary TB ● ex. skin, cervical, lymph nodes ● 2 manifestations ○ TB infection (latent TB): more than ⅓ of the world’s population worldwide have TB infection in their body ■ do not present symptoms, aren’t sick, not contagious ○ TB disease (active TB): about 1/10 of infected people will, at some point during their lives develop, contagious form of the disease and have symptoms of TB (cough, weight loss, etc) ● 89 million new cases worldwide ○ are sick, frequently symptomatic, and very often contagious ■ considered a global emergency Current Status ● in 1993, WHO declared TB a global emergency ● 510% of infected people will develop active TB during lifetime ● the number of TB cases has been falling since 2006 ● as of 2010, an estimated 8.8 million incidents of TB globally ○ 59% in Asia ○ 26% in Africa Tuberculosis epidemiology ● new infection every second ● 2 million deaths annually ○ HIV causes death due to TB because it suppresses the immune system ● TB occurs in every part of the world ○ 10 million new cases every year ○ 12 million people living with TB disease ○ 1 million deaths… Factors contributing to Reemergence ● a 20% increases in TB occurred from 1985 to 1992 in the United States due to: ○ TB and HIV Coinfection (each accelerates the other’s progress) ■ those infected by HIV are 800 times more likely to develop active TB ■ TB is the leading cause of death in HIVinfected populations Multiple drug resistant (MDR) and extremely drugresistant (XDR) TB ● MDR resistant to at least 2 first line drugs, isoniazid and rifampin ● XDR rare; resistant to isoniazid, rifampin and at least 3 secondline drugs Factors contributing to reemergence ● complacency factor in 1980s, when more developed countries of the world relaxed their TB control programs ● Travel and immigration recommended that immigrants from countries with high TB rates be tested for latent t and active TB ○ concern exists about risk of transmission of TB during long airplane flights Transmission ● TB is an airborne disease ● it can be spread when a patient with pulmonary TB talks, spits, coughs, or sneezes ● estimated that each person with active TB who is not put on appropriate TB treatment will infect an average of 1015 other people annually ● special immune cells form a barrier shell to keep the tubercle bacilli latent/contained The course of TB infection
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