Infectious Disease Public Health Lecture 1 PDF

Public Health and Infectious Disease Shannon Layton DMSc, PA-C South College Where Dreams Find Direction  Assessment Type Number of Percentage of Total Evaluations Overall Grade...

Public Health and Infectious Disease Shannon Layton DMSc, PA-C South College Where Dreams Find Direction  Assessment Type Number of Percentage of Total Evaluations Overall Grade Weight for each Assessment Presentation 1 10% 10% Infectious Disease 1 15% 15% Exam Meeting attendance 1 10% 10% and reflection paper Quiz 6 7.5% 45% Final Examination 1 20% 20% TOTAL 6 100% 100%  ARC-PA Accreditation Review Council on Education in the Physician Assistant (Associate) Program B2.15 The curriculum must include instruction in concepts of public health as they relate to the role of the practicing PA and: a) disease prevention, surveillance, reporting and intervention, b) the public health system, c) patient advocacy, and d) maintenance of population health  PANCE BLUEPRINT Medical Content Categories Percent Allocation* Task Categories Percent Allocation* Cardiovascular System 13% History Taking and Performing 17% Dermatologic System 5% Physical Examination Endocrine System 7% Using Diagnostic and Laboratory 12% Studies Eyes, Ears, Nose, and Throat 7% Gastrointestinal System/Nutrition 9% Formulating Most Likely Diagnosis 18% Genitourinary System (Male and Managing Patients 5% Female) Hematologic System 5% Health Maintenance, Patient Education, 10% Infectious Diseases 7% and Preventive Measures Musculoskeletal System 8% Clinical Intervention 14% Neurologic System 7% Pharmaceutical Therapeutics 14% Psychiatry/Behavioral Science 6% Pulmonary System 10% Applying Basic Scientific Concepts 10% Renal System 5% Professional Practice 5% Reproductive System (Male and  Objectives Illustrate the burden of disease caused by communicable diseases (LO 2, 5) Interpret factors that affect the transmissibility of a disease and the meaning of R naught (LO 3,4) Differentiate the conditions that make eradication of a disease feasible (LO 2,3,4) Describe the presentation, signs, symptoms, work- up, and treatment of select infectious diseases (LO 8).  Pollev PollEV.com/shannonlayton503 or Text Shannonlayton503 to 37607  Terminology Basic Reproduction Number Morbidity R0 : Mortality Immunity Vector Incubation Period Zoonoses Latent Period Arboviral Endemic Nosocomial Epidemic Communicable Pandemic Noncommunicable  Communicable Diseases Caused from bacteria, viruses, parasites. Leading cause of death and disability until antibiotics and vaccines World Health Organization (WHO) Malaria Tuberculosis  R0 for Communicable Diseases Disease Estimated R0 Measles 18 Mumps 10 HIV 4 Severe acute respiratory syndrome (SARS) 4 Ebola 2 Hepatitis C 2  Potential Impact R naught (R0) Average number of infections produced by an infected individual  Impact on R0 Route of transmission Period of communicability  Robert Hermann Koch Designed criteria to establish a relationship between a microbe and a disease Studied Cholera and Tuberculosis  Koch’s Postulates Criteria 1. The organism must be present in every case of the disease 2. The organism must be isolated and grown in the laboratory 3. When injected with the laboratory- grown culture, susceptible test animals must develop the disease 4. The organism must be isolated from the newly infected animals and the process repeated  Koch’s Postulates Modified Criteria Association Isolation Transmission Disease Spread  Case Finding Confidential interviewing Challenging due to social stigmas Epidemiological Treatment Treatment of contacts  Public Health Report certain positive cases to your health department Provider responsibility to report. Not the patient CDC has list of reportable diseases  Reportable Diseases Anthrax Gonorrhea West Nile virus Haemophilus influenza, invasive disease Eastern and Western Equine Encephalitis Hantavirus pulmonary syndrome Babesiosis Hemolytic uremic syndrome, post-diarrheal Botulism Hepatitis A, B, C Brucellosis HIV Campylobacteriosis Influenza-related infant deaths Chancroid Invasive pneumococcal disease Chickenpox Lead, elevated blood level Chlamydia Legionnaire disease (legionellosis) Cholera Leprosy Coccidioidomycosis Leptospirosis Cryptosporidiosis Listeriosis Cyclosporiasis Lyme disease Dengue virus infections Malaria Diphtheria Measles Ehrlichiosis Meningitis (meningococcal disease) Foodborne disease outbreak Mumps Giardiasis  Reportable Diseases Novel influenza A virus infections Severe acute respiratory syndrome- Typhoid fever associated coronavirus disease Pertussis Vancomycin intermediate (SARS CoV-2) Staphylococcus aureus (VISA) Pesticide-related illnesses and Shiga toxin-producing Escherichia injuries Vancomycin resistant Staphylococcus coli (STEC) aureus (VRSA) Plague Shigellosis Vibriosis Poliomyelitis Smallpox Viral hemorrhagic fever (including Poliovirus infection, nonparalytic Syphilis, including congenital Ebola virus, Lassa virus, among Psittacosis syphilis others) Q-fever Tetanus Waterborne disease outbreak Rabies (human and animal cases) Toxic shock syndrome (other than Yellow fever streptococcal) Rubella (including congenital Zika virus disease and infection syndrome) Trichinellosis (including congenital) Salmonella paratyphi and typhi Tuberculosis Salmonellosis Tularemia  The Burden of Tuberculosis If the importance of a disease for mankind is measured by the number of fatalities it causes, then tuberculosis must be considered much more important than those most feared infectious diseases, plague, cholera and the like. One in seven of all human beings die from tuberculosis. If one only considers the productive middle-age groups, tuberculosis carries away one-third, and often more. —Robert Koch, March 24, 1882 Mycobacterium tuberculosis  History of Tuberculosis 1700s-1900s: 1 billion deaths Koch demonstrated bacilli are a contributory cause of disease but other factors are needed Reduced immunity Poor nutrition Genetic factors  Victories in Public Health Isolation in sanitariums Vaccine development Screening with PPD skin tests and chest xrays  Timeline 1940s Discovery of streptomycin 1950s Isoniazid (INH) Para-aminosalicyclic acid 1960s Success prompted closures of sanitoriums Cut backs on screening “Eradication”  Timeline 1980s AIDS epidemic Active TB resurfaced Drug resistance increased 1990s DOT (directly observed therapy) Adherence to effective treatment Tuberculosis is: The number one cause of death The number from infectious one killer of disease in the people with HIV world TB is spread through aerosolized droplets This means someone with active, pulmonary TB needs to 1) cough on you. You must then 2) breath droplets containing mycobacterium tuberculosis into your lungs. 3) The TB bacilli then travel to alveoli and proliferate. TB is spread through aerosolized droplets For infection to occur, only about 10 TB bacilli need to reach the lungs Once in the lungs, the bacilli are phagocytosed by macrophages in the lung Instead of being killed, the TB bacilli proliferate in the macrophages for 2-12 weeks until there are thousands of them This is very low! Infectious dose of other pathogens: E. coli: 106 – 108 Vibrio cholera: 104 – 106 Macrophage Campylobacter: 500 Francisella tularensis: 10-50 Tuberculosis: 10 TB is spread through aerosolized droplets At this point, enough antigen has been produced to stimulate a cellular immune response Cellular immune response = CD4 and CD8 T cells attempt to contain the infection and/or kill infected cells (REMINDER: this is in contrast to a humoral immune response in which B cells produce antibodies as a means of neutralizing invaders or indirectly stimulating their death) Macrophage T cell  At this point, one of two things can happen. Do you know what they are? #1: Latent TB: Infection is contained in Granulomas OR #2: Active TB: Spreads  Mycobacterium tuberculosis Primary: asymptomatic or symptomatic Latent: inactive, non-communicable Reactivation: prior containment 90% of the time, primary infection results in latent infection  Latent tuberculosis infection (LTBI)  The primary mechanism the immune system has for controlling TB is walling it off in granulomas, primarily because of a healthy CD4 and CD8 T- cell response. As long the immune system keeps the TB inside granulomas, the infected person is, for all intents and purposes, healthy.  Granulomas This is a caseating granuloma! These areas of caseation are areas of necrosis with complete loss of tissue architecture Caseum = soft, dead cell mush The graunuloma: a rim of healthy macrophages and T cells that are walling off: - infected macrophages - dead and dying infected cells - free bacteria - matrix Lung tissues  Latent infection Question: Why do we care about latent infection? Answer: Latent TB can progress to Active TB. This is called reactivation. The lifetime risk of progression to active disease is approximately 10%. 5% in the first 1.5 years after infection 5% over the remaining lifetime Mycobacterium tuberculosis Diagnosis of Tuberculosis Diagnosis Whom would you test? Has Feels just fine hemoptysis, night sweats, and weight loss Test? Test? Diagnosis: whom to test Feels just fine  Is he from somewhere where TB is endemic?  Is risk of reactivation high? - Does he have HIV? - Otherwise (or about to be) If yes: TEST immunosuppressed? (e.g. on chemotherapy, on TNF inhibitors, getting HD) Diagnosis What are you looking for? Feels just fine  Tuberculin skin test (TST)  TST is performed by injecting 0.1 ml of tuberculin purified protein derivative (PPD) intradermally into the inner surface of the forearm.  48-72 hours later, the diameter of induration (NOT erythema) is measured: - 5 mm is positive for: HIV+, organ transplant, other immunosuppressed people - 10 mm is positive for: recent immigrants from areas with high TB incidence, health care workers, the homeless, and people with hematologic or head/neck malignancies, renal failure, or diabetes - 15 mm is positive for: people with no known risk factors  Interferon gamma release assay (IGRA) Two types: Quantiferon and T spot. In both tests, T cells in a patient’s blood sample are stimulated with tuberculosis-specific peptides and the activity of the T cells is approximated by measuring interferon gamma. IGRA: inside the test tube of someone without latent TB + + T cell TB antigens Antigen presenting cells REMEMBER: T cells only bind to antigens presented by antigen presenting cells IGRA: inside the test tube of someone without latent TB + NOTHING happens. There won’t be any effector T cells in the blood specific for TB T cell Antigen presenting cells in this person who hasn’t been exposed to it before.  IGRA: inside the test tube of someone with latent TB + + Effector T cell TB antigens Antigen presenting cells (these T cells have seen TB REMEMBER: T cells before) only bind to antigens presented by antigen presenting cells  IGRA: inside the test tube of someone with latent TB Interferon gamma production! Effector T cell re-encountering TB antigen  Difference between TST and IGRA? TST IGRA Tuberculin is injected under the skin and produces a delayed- Blood is drawn for testing; test measures the immune type hypersensitivity reaction if the person has been infected response to the TB bacteria in whole blood with M. tuberculosis Requires two or more patient visits to conduct the test Requires one patient visit to conduct the test Results can be available in 24 hours (depending on the Results are available 48 to 72 hours later batching of specimens by the laboratory and transport) Can cause boosted reaction Does not cause boosted reaction Reading by HCW may be subjective Laboratory test not affected by HCW perception or bias BCG vaccination does not cause BCG vaccination can cause false-positive result false-positive result and infection with most nontuberculous mycobacteria does not cause false-positive result A negative reaction to the test does not exclude the diagnosis A negative reaction to the test does not exclude the of LTBI or TB disease diagnosis of LTBI or TB disease  Diagnosis for active TB How to test? Sputum: AFB stain Culture for M. Tb Nucleic acid amplication (PCR) for M. Tb Has hemoptysis, night sweats, Imaging: and weight Chest X ray or CT loss Acid fast bacilli stain  Typically collect 3 smears, 8 hours apart. Ideally one smear is first thing in the morning. Imaging Xray Findings May Include: Parenchymal infiltrates Hilar Adenopathy Cavitation Pleural effusion May progress to Miliary TB Imaging Cavitary tuberculosis Cell necrosis leads to destruction of lung tissue and cavitations This lung destruction is what leads to hemoptysis  Extrapulmonary TB The principles of diagnosis are the same: get tissue – biopsy, get CSF, tissue, fluid, etc and send AFB smear(s), culture, and PCR on the sample Effect of Pott’s disease on the TB in the ileum Miliary TB in the spleen spine of a child Treatment  Patient # 1 42 year old man, recently emigrated from Vietnam and found to have a positive screening TST. He denies weight loss, night sweats, cough/hemoptysis, or any other symptoms of illness. Your exam and a chest X ray are normal. He does mention that prior to moving to the US, he was living with his grandfather who had active, pulmonary TB. He is otherwise healthy. Latent TB treatment REMEMBER: always rule out active OPTIONS: TB before starting treatment for latent 1. Isoniazid (INH) x 9 months TB. If you give a latent TB regimen (monotherapy) to someone with active 2. Rifampin x 4 months TB, you risk development of drug 3. Isoniazid and rifapentin x 3 months resistant TB Get a CXR before starting  Monitoring on LTBI Therapy Monthly follow up suggested Ask: nausea, anorexia, icterus, rash, parasthesias Monitor ALT, AST, Total Bilirubin (INH and rifampin can cause hepatitis) Stop if Asymptomatic >5 fold increase above upper-limit of normal (ULN) AST Symptomatic >3 fold increase above ULN AST Baseline abnormal >3 fold increase above ULN AST Saukkonen AJRCCM 2006  Patient # 2 64 year old woman, recently emigrated from Bolivia, presents with 2 months of night sweats and weight loss. In the last month she has developed hemoptysis. Her sputum is positive for M. Tb.  How would you treat patient #2? What other questions do we want to ask?  Active TB treatment R - Rifampin 2 months = intensive phase I - Isoniazid (if drug susceptibilites return before 2 6! months B P - Pyrazinamide confirming pan-sensitivity, can stop or get f ’t E - Ethambutol ethambutol early) on D Exceptions: - extend continuation phase (7 months) in patients with cavitary pulmonary TB and ongoing M. Tb in sputum samples at Continuation phase 2 months 4 months of isoniazide and rifampin alone - in extrapulmonary TB, continuation phase is 9-12 months  TB Drug Action Early Bactericidal Activity – INH > EMB > RIF > PZA Long-term Sterilizing – RIF > PZA > INH > EMB Resistance prevention – INH > RIF > EMB > PZA Guzman 2013, Chapter in Tuberculosis- Current Issues in Diagnosis and Management Mitchison Tubercle 1985 Patient # 3 64 year old woman, recently emigrated from Bolivia, presents with 2 months of night sweats and weight loss. In the last month she has developed hemoptysis. Her sputum is positive for M. Tb. She is also HIV positive, non-adherent to her HIV medication.  How would you treat patient #3? How does HIV now change this patient TB treatment in patients with HIV Treatment regimen is the same but a few important things to consider: 1. There are often drug-drug interactions between TB medications and antiretrovirals – check before prescribing 2. Duration of treatment is longer for patients with HIV not on HAART(Highly Active Retroviral Treatment) (the continuation phase is extended to 7 months) 3. Remember that TB can look different in HIV: extrapulmonary and CNS TB are much more common and symptoms can progress more quickly Current TB cases  Eradication of Small Pox Small pox 1796: Edward Jenner Characteristics No animal reservoir Short Persistence in Environment Absence of a long-term carrier state Long-term immunity Vaccination also establishes long-term immunity Herd Immunity Easily identified Post exposure vaccination  Can HIV be Eradicated? Disease limited to Humans? Limited persistence in the environment? Absence of long-term carrier state? Long immunity results from infection? Vaccination confers long-term immunity? Herd immunity? Easily diagnosed Disease? Vaccination effective postexposure?  Human Immunodeficiency Virus HIV infection in humans came from a type of chimpanzee in Central Africa. Studies show that HIV may have jumped from chimpanzees to humans as far back as the late 1800s. HIV  HIV in 1981 June 5: First official reporting of what will be known as AIDS. A report described Pneumocystis pneumonia in previously healthy, gay men in LA. Link to the first official report of what will be known as the AI DS epidemic June: CDC forms Task Force on Kaposi's Sarcoma and Opportunistic Infections. About 30 Epidemic Intelligence Service officers and staff participated. July 3: Report of Kaposi's Sarcoma and Pneumocystis pneumonia in 26 homosexual men in New York and California. Link to the report of Kaposi's Sarcoma and Pneumocystis pne umonia in 26 homosexual men in New York and California  HIV in 1982 September 24: CDC uses the term "AIDS" for the first time and releases the first case definition for AIDS. Link to first case definition for AIDS and CDC uses the term AI DS for the first time December 10: Report of AIDS likely from blood transfusion. CDC reports a case of AIDS in an infant who received a blood transfusion. Link to CDC reports a case of AIDS in an infant who received a blood transfusion December 17: Reports of AIDS hinting of perinatal transmission. MMWR reports 22 cases of unexplained immunodeficiency and opportunistic infections in infants. Link to Reports of AIDS hinting of perinatal transmission  HIV in 1984 July 13: Needle-sharing identified as transmission method. CDC states that avoiding injection drug use and reducing needle-sharing "should also be effective in preventing transmissions of the virus." Link to report from CDC to avoid injection drug use an d reduce needle sharing should also be effective in pre venting transmission of the virus Project SIDA begins in Africa. CDC, along with colleagues from Zaire and Belgium, establishes Project SIDA, which would become the largest HIV/AIDS research project in Africa in the 1980s.  HIV in 1986 October 22: Surgeon General, C. Everett Koop, issues the Surgeon General's Report on AIDS. The report makes it clear that HIV cannot be spread casually and calls for a nationwide education campaign (including early sex education in schools), increased use of condoms, and voluntary HIV testing. Link to report of Surgeon General, C. Everett Koop o n AIDS/  HIV in 1987 August 14: CDC issues Perspectives in Disease Prevention and Health Promotion: Public Health Service Guidelines for Counseling and Antibody Testing to Prevent HIV Infections and AIDS. Link to report from CDC perspectives in diseases prevention an d health promotion: Public health service guidelines for counseli ng and antibody testing to prevent HIV infections and AIDS CDC launches first AIDS-related public service announcement, "America Responds to AIDS." Link to CDC's first public announcement on America Responds t o AIDS- Surviving and Thriving: AIDS, Politics, and Culture CDC expands work in Africa. CDC begins working in Côte d'Ivoire, establishing a field station in Abidjan and launching the Retrovirus Côte d'Ivoire (CDC Retro-CI).  HIV in 1988 The brochure "Understanding AIDS" is sent to every household in the US—107 million copies in all. News article: Link to the news article of mailing to every househ old in US about Understa nding AIDS Brochure: Link to brochure called U nderstanding AIDS  HIV in 1990-1994 HIV transmission from healthcare worker reported. CDC issues recommendations for healthcare workers with HIV and for organ transplantation. AIDS deaths increase. CDC expands prevention efforts into businesses, labor, and community organizations.  HIV in 1995-1999 Guidelines issued to prevent opportunistic infections (OIs) and for the use of antiretroviral therapy. Highly active antiretroviral therapy (HAART) introduced; AIDS deaths decline. US racial/ethnic disparities are notable. Africa efforts expand.  HIV in 2000-2004 Global AIDS programs and funding increase as economic concerns over pandemic increase; US emphasizes HIV prevention with people living with HIV.  HIV in 2005-2009 CDC issues recommendations on HIV prevention and testing, releases new incidence estimates, launches new HIV prevention campaigns for general public and healthcare providers. Global programs grow. Link to CDC report on recom mendation to prevent HIV aft er non-occupational exposur e to the virus  HIV in 2010-2014 Non-US citizens living with HIV can enter US, CDC announced High Impact Prevention and focuses funding where the US HIV burden is greatest. Preexposure prophylaxis (PrEP) shown to prevent HIV transmission, as does reducing viral load through treatment. Racial/ethnic disparities persist.  HIV in 2015-present Co-infections addressed, more data about transmission, HIV diagnoses data show progress and challenges, PrEP holds promise  HIV Transmission Blood transfusions/contaminated needles Intercourse Unprotected anal intercourse most common Public Health Interventions Proper use of latex condoms Abstinence programs Aggressive treatment at early stages Safe practices for pregnancy and breast-feeding Safe needle practices Symptoms of HIV Most are  Stages of HIV Stage 1: Acute HIV Infection Very contagious Flu-like symptoms Stage 2: Chronic HIV Infection Asymptomatic HIV still replicates **If treatment is started, they may stay in this stage and viral load is reduced Stage 3: Acquired Immunodeficiency Syndrome (AIDS) Severe stage High viral load possible Opportunistic infections  HIV Infects Helper T cells, macrophages and dendritic cells CD4+ T cells Cell-mediated immunity is lost Can remain dormant for 10 years from primary infection Replication Diagnosis  Diagnosis Step 1: HIV Antibody test If negative, retest in 2-4 weeks If Positive: Go to Step 2 Step 2: HIV Discriminatory Assay (Multispot) If Negative, go to Step 3 If positive: Start Combination Antiretroviral Therapy Step 3: NRNA Nucleic Acid Amplification Test If Negative, Retest in 2-4 weeks If positive, Start Combination Antiretroviral Therapy. Test Sensitivity: 100% Sensitive Test Specificity: 97.4% Specific  Labs and Other Testing CD4 Cell Count Viral Load Tuberculin Skin Test Toxoplasmosis Titer Cytomegalovirus Serology Pap Smears High rates of cervical cancer Syphilis Hepatitis Chlamydia/Gonorrhea  HIV Treatment Obtain a Genotypic Antiretroviral Resistance Testing (GART) before starting therapy Compliance is critical to suppress viral load Adherence of 95% to drug regimen: 81% success rate Adherence of 90-95% to drug regimen: 64% success rate Adherence of 80-90% to drug regimen: 50% success rate Adherence of 70-80% to drug regimen: 24% success rate Adherence of