Human Biology Sylvia S. Mader Michael Windelspecht Infectious Diseases Supplement Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

Infectious Diseases Epidemiology: the study of diseases in populations S.1 AIDS and Other Pandemics Infectious Diseases Epidemiology: the study of diseases in populations Infectious Diseases: diseases caused by pathogens Bacteria Viruses Fungi Parasites Protozoans Prions

S.1 AIDS and Other Pandemics Infectious Diseases Epidemic: more cases of the disease than expected in a certain area for a certain period Outbreak: if the epidemic is confined to a local area Pandemic: a global epidemic

History of HIV Originated in Africa in the late 1950’s S.1 AIDS and Other Pandemics History of HIV Originated in Africa in the late 1950’s Originally found in nonhuman primates and may have mutated First documented in the US in 1969 HIV was found to be the cause of AIDS in 1983-1984

Prevalence of HIV ~ 33.2 million people are living with HIV S.1 AIDS and Other Pandemics Prevalence of HIV ~ 33.2 million people are living with HIV At least 0.8% of adults have HIV 2.1 million people died during 2007 Over 25 million people have died since the beginning of the epidemic Most people living with HIV live in developing countries

Prevalence of HIV S.1 AIDS and Other Pandemics Eastern Europe Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Eastern Europe and Central Asia 1.6million (1.2-–2.1million Eastern Europe and Central Asia 1.6million (1.2-–2.1million Western and Central Europe 760,000 (600,000-–1.1million Western and Central Europe 760,000 (600,000-–1.1million North America 1.3million (480,000-–1.9million North America 1.3million (480,000-–1.9million East Asia 800,000 (620,000-–960,000 East Asia 800,000 (620,000-–960,000 Caribbean 230,000 (210,000-–270,000 Caribbean 230,000 (210,000-–270,000 Middle East and North Africa 380,000 (270,000-–500,000 Middle East and North Africa 380,000 (270,000-–500,000 South and Southeast Asia 4.0 million (3.3-5.1 million) South and Southeast Asia 4.0 million (3.3-5.1 million) Latin America 1.6million (1.4–1.9million) Latin America 1.6million (1.4–1.9million) Sub-Saharan Africa 22.5million (20.9–24.3million) Sub-Saharan Africa 22.5million (20.9–24.3million) Oceania 75,000 (53,000-–120,000) Oceania 75,000 (53,000-–120,000)

S.1 AIDS and Other Pandemics Prevalence of HIV

Phases of HIV infection S.1 AIDS and Other Pandemics Phases of HIV infection Category A: Asymptomatic but highly infectious CD4 count above 500 cells/mm3 Category B: Has one or more of a variety of symptoms related to an impaired immune system CD4 count between 200-499 cells/mm3 Category C: At this point the person has AIDS in which they have one or more of the AIDS opportunistic infections that eventually is the cause of death CD4 count has fallen below 200 cells/mm3

Phases of HIV infection S.1 AIDS and Other Pandemics Phases of HIV infection Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 107 Category A: Acute Phase Category B: Chronic Phase Category C: A IDS 1,100 1,000 106 900 800 105 700 CD4 T lymphocytes CD 4T Lymphocyte in Blood (permm3) 600 HIV in Plasma (per mL) 500 104 400 300 103 200 HIV 100 102 1 2 3 4 5 6 7 8 9 10 Years Since Infection

Structure of HIV Two single strands of RNA S.1 AIDS and Other Pandemics Structure of HIV Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. RNA envelope Two single strands of RNA Enveloped with spikes (Gp120) Carries 3 enzymes Reverse transcriptase Integrase Protease protease gp120 (spike) integrase capsid matrix reverse transcriptase

HIV life cycle/replication S.1 AIDS and Other Pandemics HIV life cycle/replication Attachment: Gp120 binds to CD4 receptors Fusion: HIV fuses with the cell membrane Entry: uncoating occurs to release the RNA Reverse transcriptase: RNA is transcribed into double-stranded DNA Integration: new DNA becomes part of the host cell’s DNA in the nucleus (provirus) Biosynthesis: produces more viral RNA and proteins Assembly: assemble new parts into viral particles Budding: viral particles bud from the cell membrane taking a piece with it that becomes the envelope Transmission to a new host: passed to a new host

HIV life cycle S.1 AIDS and Other Pandemics plasma membrane 2. Fusion Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. plasma membrane 2. Fusion envelope spike capsid 8. Budding 1. Attachment protease capsid 3. Entry viral RNA ribosome reverse transcriptase viral RNA c DNA 6. Biosynthesis and cleavage 7. Assembly 4. Reverse transcription receptor viral RNA host DNA double-stranded DNA HIV provirus integrase 5. Integration nuclear pore Nucleus Cytoplasm

Transmission and prevention of HIV S.1 AIDS and Other Pandemics Transmission and prevention of HIV Transmission is through sexual contact, dirty needles, a blood transfusion, or to a baby from their mother Globally, heterosexual sex is the most common mode of transmission HIV is not passed through casual contact Prevention is through abstinence, sex with only one uninfected partner, and proper, consistent use of condoms

HIV testing and treatment S.1 AIDS and Other Pandemics HIV testing and treatment HIV tests test for the presence of antibodies not the virus itself Most people develop antibodies within 2-8 weeks of infection but it can take 3-6 months (consider this when being tested!) Treatments: Drug therapy: highly active antiretroviral therapy (HAART) uses a combination of drugs to inhibit HIV replication Vaccines: scientists have studied 50 different preventive vaccines and 30 therapeutic vaccines

Science Focus: HIV vaccines S.1 AIDS and Other Pandemics Science Focus: HIV vaccines Difficulties in producing a vaccine development: HIV viruses locally and globally are genetically different No vaccine so far is 100% effective and may only provide short-term protection Concerns that the vaccine may increase the chances of getting the disease or even cause the disease There is no ideal animal model for testing besides humans themselves

Tuberculosis 1/3 of the world’s population has been exposed to TB S.1 AIDS and Other Pandemics Tuberculosis 1/3 of the world’s population has been exposed to TB ~ 9 million people are infected and 2 million die each year Cause and Transmission: Mycobacterium tuberculosis Spread when an infected person coughs, sings, or sneezes Likelihood of infection increase with length and frequency of exposure Disease: Incubation period is from 4 to 12 weeks Latent TB Active TB Treatment and Prevention: Multiple anti-TB drugs are given simultaneously for 12 to 24 months Common drugs: INH, RIF, ethambutol, and pyrazinamide It takes at least 6 months to kill all of the TB in the body Active TB patients are isolated and anyone exposed is treated

Malaria ~ 350-500 million cases and over 1 million deaths each year S.1 AIDS and Other Pandemics Malaria ~ 350-500 million cases and over 1 million deaths each year Cause and Transmission: Four species of Plasmodium infect humans Spread by the female Anopheles gambiae mosquito Disease: Incubation period is from 7 to 30 days Symptoms range from very mild to fatal People develop a flulike illness with chills and fever Treatment and Prevention: Antimalarial drugs include quinine and artesunate Prevention includes eliminating the mosquito by removing its breeding sites

S.2 Emerging Diseases Emerging Diseases National Institute of Allergy and Infectious Diseases (NIAID) lists 18 pathogens that are newly recognized in the last two decades. avian influenza (H5N1) swine flu (H1N1) severe acute respiratory syndrome (SARS) Reemerging Diseases: diseases that have reappeared after a significant decline in incidence Streptococcus: bacteria that causes strep throat and other infections

How does antibiotic resistance develop? Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. not drug resistant drug-resistant mutant exposure to drug Remaining population grows overtime. early late a. Initial population of microbes b. Weaker (non resistant) cells killed by antibiotic; resistant cells survive. c. Most cells are now resistant.