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by: Aniyah Koch


Aniyah Koch
GPA 3.95

David Timberlake

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David Timberlake
Study Guide
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This 10 page Study Guide was uploaded by Aniyah Koch on Saturday September 12, 2015. The Study Guide belongs to PubHlth 80 at University of California - Irvine taught by David Timberlake in Fall. Since its upload, it has received 24 views. For similar materials see /class/201913/pubhlth-80-university-of-california-irvine in Public Health at University of California - Irvine.




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Date Created: 09/12/15
Modes of HIV Transmission amp Prevention of HIVAIDS How have the trends in misconception about HIVAIDS changed over time 0 People used to thinks AIDS could be transmitted by kissing sharing a drinking glass or touching a toilet seat and the amount of people who believe that has gone down significantly due to research proving that AIDS is not transmitted through saliva or skin contact Three reasons why HAART is not the ultimate panacea cureall for HIVAIDS 0 There is potential for the virus to acquire multidrug resistance 0 The drugs make the quality of life difficult to deal with 0 It s unaffordable for many people and it s hard to get Three examples of how antiretroviral therapy benefits prevention not sure 0 Therapy reduces mothertochild transmission MTCT o Postexposure prophylaxis PEP reduces HIV infection from needle stick injuries eg in a hospital 0 Therapy reduces viral load lowering risk of sexual transmission Have HIV infection rates increased decreased or remained the same over the past 15 years in the US 0 Refer to slide Current Challenge in the US know three potential reasons for the recent increase in infection rates among MSM HIV Infection rates increased Trend attributed to increase in risky sexual behavior I Reduced concern with the advent of HAART 1996 I Generational forgetting of AIDS deaths in the 1980s I Popularity of club drugs in the late 1990s From the 1980s tol990s what group was targeted for prevention efforts Why 0 general population groups at higher risk but did not intentionally target HIV persons 0 Approach was appropriate due to Stigma associated with HIV status amp Limited HIV testing Positive prevention is endorsed by whom It is consistent with 0 Positive prevention focuses interventions on persons who are HIV CDC officially endorsed positive prevention in 2003 Consistent with principles of infectious disease epidemiology Aim is to reduce their risk of transmission Know the recommendations for Africa outlined in both the required reading and slides I Most HIV persons in Africa don t know HIV status I Knowledge of HIV status I preventive behavior I Make HIV testing a routine part of medical care I Encourage testing in nontraditional settings eg mobile doortodoor testing programs Know the sources of infectious HIV 0 HIV is present in which cells I Macrophages Bloodstream amp mucosal linings internal surface of vagina and penis lining of lungs anus throat I Theper Lymphocytes I Langerhans cells Also found on mucosal linings 0 Why can HIV be readily transmitted via some bodily fluids eg blood but not others eg perspiration 00 0000 I these cells are present in some bodily fluids and secretions but not others 0 High concentrations of HIV are found in which four bodily fluids I Blood I Semen I Vaginalcervical secretions including menstrual fluid I Breast milk o Is HIV fragile outside of its host I Yes lnactivated by Exposure to air or light Contact with soap and water From an epidemiologic perspective why do family members of HIV hemophiliacs offer a unique opportunity to study casual transmission of HIV 0 family members of AIDS patients do not contract the virus through household contact Three modes of HIV transmission 1 Identify the three forms of BIoodtoblood transmission a Birth during pregnancy labor and delivery during breastfeeding b Blood TransfusionNeedlesharing c Sex 0 What can be done to prevent these routes of transmission I Blood transfusions Screening the blood supply I Injection drug use Needle exchange program harm reduction I Needlesticks healthcare exposures Use protective barriers eg wear gloves Prophylactic admin of ART within 36 hrs up to 4 weeks I Mothertochild transmission Administer nevirapine during pregnancy amp labor Csections reduce risk of transmission from birthing but the procedure carries its own risk and is only recommended if mother has high viral load Transmission through breastfeeding Use replacements formula whenever feasible affordable sustainable and safe I Sex Use condoms 2 Sexual transmission 0 Why is intercourse vaginalanal a good mode of transmission I Requires direct contact between HIVinfected body fluid blood semen or vaginalcervical secretions amp target site during Vaginal intercourse between man amp woman or Anal intercourse I Vagina and rectum are 0 sites of macrophages and Langerhans cells 0 Small tears occur during intercourse 9 Susceptible to infection Reasons why one gender is more susceptible to HIV than the other 0 I Male to female transmission is 210x more efficient than female to male I More virus is found in semen than in vaginal fluids I Vaginal surface area is a LOT greater than male urethra and foreskin area 0 What partner engaging in anal sex is more susceptible to infection insertive or receptive I Receptive 0 Review slide on oralgenital transmission of HIV I Risk of HIV infection via oral sex is much lower than anal or vaginal sex I Very difficult to estimate the precise risk due to other sexual behaviors I Risk of HIV infection from oral sex is increased by potential cofactors o Traumas o Ulcerserosions of oral or genital mucosa o Gingival inflammation 0 Sexually Transmitted Infections STls in genitaloral cavity 0 Receiver of ejaculation in mouth 0 Viral RNA in genital anal or salivary secretions Oral infections like Herpes etc 0 0 Be familiar with the ABC campaign What do the three letters represent 0 Abstain from sex or delay first sex 0 Be faithful to 1 partner or have fewer partners 0 Qondoms use male or female versions consistently and correctly 0 Male circumcision lower risks of infection for men amp possibly their female partner Understand the debate over Uganda39s success which groups claim success is due to A B C 0 Proportion of adults living with HIV went from 15 in the early 1990s to about 5 in 2001 0 Many believe this can be attributed to concerted efforts to encourage safer sexual behavior Expanded condom distribution HIV testing Treatment of sexually transmitted infections 0 A Some groups eg religiousbased attribute success to abstinence programs 0 B Others suggest that success is due to partner reduction 0 Helen Epstein Uganda s success was due to partner reduction encouraged by the concept of llcollective efficacy 0 Small intimate discussions led by llgovernment workers home based volunteers churchgoers women srights activists 0 Ability of people to join together and rely on one another 0 C Most donors WHO USAID and donor nations attribute success to condom distribution Why can the concept of quotcollective efficacy not be readily promoted in a publichealth campaign 0 Many societies find it difficult to discuss sex openly o Premarital sex condom use and homosexuality are taboo and even illegal in much of the world 0 Marginalization of sex workers and MSM can make it difficult to target highrisk groups 0 Even with the knowledge 0 Many people young people in particular may have difficulty remaining abstinent 0 Women in maledominated societies are frequently unable to negotiate condom use 0 Couples may feel compelled to have unprotected sex in order to have children 0 Others associate condoms with lack of trust 3 Mothertochild transmission MTCT Know the three routes of MTCT IntrauterineAntenatal during pregnancy I Peripartum during birthdelivery I Postpartum Breastfeeding 0 Without treatment approximately what of babies born to HIV women will become infected I Without antiretroviral treatment 1530 of babies born to HIV positive women will become infected via perinatal transmission 0 Are the preventive measures effective for any of the 3 routes of MTCT I Hint refer to limitations of Csections and formula replacements I Csections reduce risk of transmission from birthing but the procedure carries its own risk and is only recommended if mother has high viral load I Formula replacement for breastmilk challenges longstanding public health support for breastfeeding in developing countries I Also must have clean water for formula I Antiretroviral drugs are not widely available in many resourcepoor countries I Caesarean section is often impractical amp risky I Many women lack the resources needed to avoid breastfeeding their babies I HIVrelated stigma may cause women to be reluctant to visit health Clinics 0 What did the US do in curbing rates of MTCT I Increase in routine screening I Use of antiretroviral drugs I Avoidance of breastfeeding Incidence versus Prevalence 0 Does an increase in prevalence of AIDS reflect an increase in the rate of HIV infection ie incident cases of HIV Individual Assessment of HIV Risk Know characteristics ofthe normative model of risk assessment 0 Do we typically make decisions on the basis of normative models ie by applying laws of logic and statistics 0 Temporal Model of Decision Making I Knowledge collect info I Attitude synthesize draw conclusions I Intention readiness to take action I Behavior the action taken 0 Normative model of risk assessment I Based on laws of logic and statistics I Requires accurately defining risks amp identifying relevant alternatives calculating and choosing the alternative with the highest expected value I Normative model tells us how engineers might make decisions in a laboratory 0 Human brain does not seem to solve probabilistic problems by applying laws of logic or statistics 0 If not how do we assess risk from various probabilities I Difficult to utilize vast amounts of information so brain uses heuristicsI I Heuristics Simple rules of thumb Heuristics are useful in making what kinds ofdecisions o Heuristics help with quick decisionmaking 0 Can the use of heuristics lead to significant biases in decisionmaking I Yes but there are consistent patterns to some of these biases which can be helpful in designing interventions 39 of the 39 heuristic I The more object X is similar to class Y the more likely we think X belongs to Y I Identify and understand the two representative biases 1 lnsensitivity to Base Rates a The base rate of outcomes should be a major factor in estimating frequency b People often ignore it When physicians make diagnoses prior probabilities of diseases are often ignored if a patient seems to fit a raredisease description 2 Misconceptions of Chance a People expect random sequences to be quotrepresentativer random even localy Eg they consider a cointoss run of HTHTTH to be more likely than HHHTTT or HHHHTH The Gambler s Fallacy After a run of reds in roulette black will make the overall run more representative c Views chance as a selfcorrecting process What are the two main contributors to the availability heuristic I The easier it is to considerremember instances of class Y the more frequent we think it is I The frequency of a class or event is often assessed by the ease with which instances of it can be brought to mind I Main contributors to Availability Familiarity Salience I Familiarity frequency of an item or event in our memory 0 Example Paul lives in LA vs Tom lives in NYC are asked to estimate share of pop with cars Paul is likely to overstate share and Tom understate it I Salience vividness of item or event 0 Example Paul who has never been in a major car accident and Tom who has been in a major car accident and are asked to assess the risk of an accident Paul is likely to understate it and Tom overstate it Using the anchoring heuristic adjustments are typically biased towards which values I lnitial estimated values affect the final estimates even after considerable adjustments I People often estimate by adjusting an initial value until a final value is reached I lnitial values might be biased by framing or partial computations I Adjustments are typically insufficient and are biased towards initial values the anchor I Anchoring occurs even when initial estimates were made at random and even with outrageously extreme anchors Do we tend to 39 or 39 39 39 39 events What about disjunctive events I People tend to overestimate the probability of conjunctive events I A conjunctive event Event that involves multiple steps This AND That I People underestimate the probability of disjunctive events I A disjunctive event Event that involves multiple possibilities This OR That I In both cases insufficient adjustment from probability of individual event Know 52 How do we calculate the two events Conjunctive Probability of A and B independent events cooccurring is less than either one PA and B PA PB Disjunctive The probability of A or B must be greater than the probability of any one of those events PA or B PA PB independent events Examples of the two events Conjunctive risk People overestimate risk from needle sticks 2 needle sticks are with HIVcontaminated needles 05 risk of contracting HIV from contaminated needle PHIVcontaminated needle AND Infected 9 risk of 5 2 1 out of 10000 Disjunctive risk The birthday paradox states that given a group of 23 or more randomly chosen people the probability is more than 50 that at least two of them will have the same birthday Described as a paradox bc it belies common intuition o What is the connection between optimistic bias and HIV testing Optimistic bias occurs when people tend to believe they are less likely than others to experience harm HIV Testing Personal invulnerability May be a deeply ingrained survival mechanism Many people underestimate their risk for HIV HIVAIDS happens to other people Cannot happen from sexual contact with good people Characteristics ofthe late testers Persons tested late compared with those tested early gt5 years before developing AIDS were more likely to be young optimistic bias heterosexual representativeness heuristic less educated knowledge and African American or Hispanic representativeness heuristic People who were less likely to think they were at risk and less likely to be identified through targeted testing 0 Why can HIV prevention heuristics be misleading Individuals can gather HIV risk information about a partner by examining certain characteristics of that partner known partners are safe partners heuristic monogamous relationships are safe relationships heuristic trusted partners are safe partners heuristic What are the relationships between the HIV test and antibodies viral levels and the window period o Antibody test 0 Does not directly measure the virus 0 Measures whether the body has produced antibodies to the virus Approximately what of the US population has not been tested for HIV Does this vary by ethnicity 0 Approximately 42 in US Yes varies by ethnicity 45 white 41 Latino 24 African American How does the gold standard pertain to the validity of HIV tests In order to evaluate the validity of a clinical test a goldstandard for diagnosis is required 0 Goldstandards are definitive and often highly invasive Understand the 2x2 table for screening test outcomes Know formulas for sensitivity specificity PPV and NPV 0 Sensitivity aac or TPTPFN Specificity ddb or TNTNFP PPV TP TP FP NPV TN TN FN What is the tradeoff between sensitivity and specificity I High sensitivity may come at the expense of many false positives I Similarly high specificity may come at the expense of many false negatives What are the two stages in HIV sequential testing 0 Step 1 Conduct a less expensive or less invasive test I Start with a highly sensitive test ELISA 0 Step 2 Conduct a 2quotd test among those who tested positive I Rescreen positives with a more specific test Western blot I Effect of rescreening those who initially tested positive I Net Specificity 1 Net Sensitivity l 0 Know characteristics of the tests used in both stages I Elisa amp Western Blot o Sequential testing yields a higher net sensitivity or higher net specificity I Effect of rescreening those who initially tested positive I Net Specificity 1 Net Sensitivity 1 In what setting are we more interested in predictive values PPVNPV o In a clinical setting Unlike sensitivity and specificity predictive values are a function of the characteristics of the population 0 How does this concept relate to efficiency in screening programs I The Positive Predictive Value PPV I Increases with greater disease prevalence up to a certain point I Increases with greater specificity of a test in cases when the disease prevalence is low Rapidhome HIV testing 0 Identify three benefits of rapid HIV testing I Increase receipt of test results I High do not return to receive results from clinics I Increase identification of HIV pregnant women I Increase feasibility of testing in acutecare settings eg emergency rooms 0 Approximately how many US citizens are unaware of their HIV infection quot300000 US citizens who are unaware oftheir HIV infection 0 Who are the typical consumers of home HIV tests I The lworried well those who are primarily seronegative I New couples interested in confirming each other s status I Those with recent highrisk exposures eg college binge drinkers O O O O I Those wanting to confirm their known HIV status 0 What are the problems with home HIV testing I A counselor is not present Applicable to those who test either positive g negative I Lower positive predictive value PPV as a result of a lower HIV prevalence among home testers I Refer to next slide for illustration Like all HIV antibody tests the home test will not detect infection in the lwindow period In 2006 the CDC recommended a switch to the optin or optout testing of individuals in a clinical setting 0 Why was one chosen over the other I Enable HIV people to I Take advantage of HAART extend life I Protect sexual partners I Early treatment more beneficial I Test is reliable and cost is reasonable relative to benefits Global Aspects of HIVZAIDS What region of the world has the highest concentration of HIV approximate of worldwide cases SubSaharan Africa 63 Know the global transmission of HIV as described in slide 5 o Developed countries eg United States I Started primarily among MSM I Moved into drugusing populations I eventually leading to transmission via heterosexual sex 0 SubSaharan Africa and Latin America I Transmission attributed to heterosexual sex 0 Southeast Asia India China amp former Soviet Union I started primarily among intravenous drug users I Male drug users subsequently infected female sex workers I Prostitution contributed to ongoing heterosexual transmission 0 eg military recruits in ThailandCambodia Know potential explanations for variation of HIV prevalence throughout Africa 0 Understand concept of concurrent transactlonal relationships I Large no of sexual partners 0 This theory has been debunked studies demonstrate equal no of partners in Africa and other continents I Highrisk Lowrisk Mixing Theory 0 Prostitutes migrant workerstruckersitinerant workers general population I Longterm concurrent sexual relations 0 Polygamy o 39Transactional sexual relations 0 Not considered a form of prostitution rather women expect gifts of cash or consumer goods from boyfriends 0 Could actually be riskier than prostitution compare to brothels in Asia 0 Why is HIV less prevalent in West and North Africa I Polygamy therefore concurrency is common in the predominantly Muslim countries 2 possible explanations 0 Most men in Muslim societies are circumcised which limits heterosexual transmission 0 Largescale transmission via heterosexual networks requires males amp females who engage in concurrent longterm relationships 0 In many Muslim societies a woman s sexual behavior is monitored by male relatives eg honor killing What is the distribution of HIVAIDS by gender stratified by region 0 Worldwide Women 45 Men 49 Children 6 0 Worldwide prevalence prevalence in subSaharan Africa prevalence outside of sub Saharan Africa Ch ildren 2 Chlldren aw anen 29 Men 33 Men 69 anen 5w Explanations for why women have a higher prevalence of HIV than men 0 Nature ofthe transactional polygamous relationship I Fewer men in sexual network I Older men have more economic resources I Women have limited say amp social power 0 eg cannot insist on partner using a condom o Prostitutes Migrant workers Spouses I Highrisk Lowrisk Mixing Theory 0 Biological factors I Women are more vulnerable to heterosexual transmission 0 Virgin myth What is HAART 0 Highly Active Antiretroviral Therapy HAART combination of several antiretroviral medications that limit the functioning of HIV and slow the rate at which virus multiplies Typically includes 3 drugs from at least 2 different classes I Protease inhibitor I Reverse transcriptase inhibitors nucleoside andor nonnucleoside Why do we consider Brazil39s response to HIVAIDS a success story 0 In 1996 the Brazilian legislature granted free universal access to ART enabling all citizens to access medication and care regardless of socio economic standing 0 With limited resources how did their government obtain expensive HIV drugs I The government also manufactured generic antiretroviral drugs to reduce costs a decision that holds significant lessons for developing countries 0 o Is treatment costeffective in the longterm I Yes 0 How does Brazil39s response contrast with how the South African government dealt with HIV I As a consequence of their policies what has happened to South Africa39s life expectancy o It is now at 51 years improved I What age group in South Africa has been disproportionately affected by HIVAIDS 0 Women aged 2244 What did Thailand do in the early 1990s to control the spread of HIV 0 Enormous prevention efforts including widespread condom use particularly among the most affected groups and consistent clear government messaging Review importance of healthcare infrastructure for treating HIV patients 0 Distribution of HIV drugs without proper careinstructions can lead to I Failure to adhere to regimen 1 chance for multidrug resist Living with AIDS Individual and Societal Issues Review debate of individual rights vs public health in the decision to close bathhouses in San Francisco 0 In San Francisco many gay men believed the calls to cut back on risky behavior stemmed from public condemnation of lifestyle amp rights 0 Opposition to informational brochures in the bathhouses o Delayed closing of public baths 0 Delayed full articulation of transmission modes What governments have been slow in accepting the reality of HIVAIDS 0 South Africa 54 million infected with HIV but in 2000 President claimed that HIV does not cause AIDS 0 US in the 1980 s Ronald Reagan39s inaction What is the pertinence of the Americans with Disabilities Act 1990 o No individual quotshall be discriminated against on the basis of disability in receipt of goods services privileges in any place of public accommodationquot Disability is defined as a physical or mental impairment Courts have historically viewed HIV infection as a disability I What about those with asymptomatic HIV infection How has the perception of HIVAIDS as an urgent health problem in the US changed over time o Decline from 44 to 17 from 1995 to 2006 percent naming HIVAIDS as the most urgent health problem facing the nation Do most people today feel that the US government spends too little or too much on HIVAIDS 0 Too little 0 What is the perception in relation to other diseases Too low 0 Using a crude measure such as expendituresdeath how does HIVAIDS compare to other diseases I More money is spent than on cancer and heart disease but less people die More is spent on stroke but more people die from stroke Contrast the public39s view on US foreign spending in general versus US foreign spending on HIVAIDS 0 Has our view on foreign spending on HIVAIDS changed over time 00


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