EPI 390 Lecture 20Outline of Last Lecture I. The State of Disease in the 20th CenturyII. Introduction to Typhoid FeverIII. The Oyster Bay OutbreakIV. Soper on the CaseV. Introduction to “Typhoid” Mary MallonVI. Mallon’s Disbelief and her DangerVII. North Brother IslandVIII. The Threat ReturnsIX. Latter Years of Mallon’s LifeOutline of Current Lecture I. Zoonotic DiseasesII. Modes of TransmissionIII. Comparing Epidemic, Endemic, and PandemicIV. Looking at Spongioform encephalitisV. BSE VideoVI. Key Years and Policy Responses to EpidemicsVII. Risk, Casualties, and Cases of Creutzfeldt-Jakob DiseaseVIII. Difficulties of vCJDIX. Implications and the Future of vCJDCurrent LectureI. Zoonotic Diseasesa. To understand a disease and how to treat/cure it, it’s crucial to understand the lifestyle of the organism, including transmission b. Definition – diseases that pass from animals to humans (strictly human to humandiseases are not zoonotic; zoonotic diseases do have some instances in the infection cycle in which they transmit human to human but the key point is that there is the possibility for animals to be a vector)c. Examplesi. Lyme disease (spirochete/tick)ii. Viruses: Swine flu/influenza, Rabies, West Nile, MERS/Middle Eastern Respiratory Syndrome (from camels), ebola (from primates)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. Bacteria: E. coli (beef); salmonella (eggs), Bruculosis, tuberculosis, listeria,anthrax, plague/yuseniaiv. Metazoes: hook worms, round worms, tapewormsv. Parasites: toxoplasmosis (protozoan), trichnosis (parasite transmitted through raw pork/pig feces, metazoese/worms)vi. Protozoa: Giardia (through water)vii. Fungi/Mycoses: Cryptococcus (from pigeons); viii. Mad cow?II. Modes of Transmissiona. Modes of transmission: i. Direct contact (bite, tumoremia – in rabbit, cut yourself when skinning a rabbit)ii. Aerosol/respiratoryiii. Ingestion/food (food contaminated with fecal matter, cross contaminationfrom soil or you cut raw meat with a knife and use that knife to cut something that isn’t cooked and therefor sterilized, etc., milk and meat, iv. Vectors (i.e. mosquitos, tick, flea; an intermediary that spreads infected blood/fluids)v. Fomites (i.e. brush or blankets; the spores of anthrax transmit via blanket)vi. Contaminated environment (spores or organisms in the soil/water/etc.)b. When a disease is in humans only, we have a much better chance of containing and treating it (with vaccination, quarantine, etc.). Animal vectors and reservoirs make treatment/quarantine more complicated.i. Reservoir – a sink that holds the disease. This becomes a problem when we come in contact with the reservoir. Animal reservoirs make it almost impossible to eradicate a disease so you must find other means of managing infection.c. Transmission cyclesi. Dead-end host (human can’t spread it to human) Reservoir -> intermediate -> human –X-> can’t pass to human (i.e. toxoplasmosis from felines feces to human. The only exception of human-to-human transmission of toxoplasmosis is mother to fetus. Also transferred through raw meat.)ii. Not dead-end host (i.e. plague) Reservoir-> intermediate ->human and either back to reservoir or to another human. This gives you two areas in the cycle where you have to control transmission.III. Comparing Epidemic, Endemic, and Pandemica. Epidemic – Sharp increase of the incidence of disease in a defined location/place over a specified/short period of time. An increase in the people affected and an increase over time. Among the people in a defined time and place, there are more cases than you expect to occur.b. Endemic – a disease that is continuously present; finding one or two cases is not going to help you decide if there’s an epidemic (if there’s always a background of infection, it will take many cases to show there’s an epidemic. If it’s an uncommon disease, it only requires a couple of cases to show there’s a disease epidemic)c. Pandemic – a disease that has spread to multiple regions.IV. Looking at Spongioform encephalitisa. This is a brain pathology; the disease gives the brain a spongy/hole-y appearance. b. It passes from person to person, animal to animal.c. Animali. Bovine spongiform encephalopathy (BSE, Mad cow); Scrapie (sheep); Mink encephalopathy; wasting Disease (Elk/deer)d. Humani. Creutzfeldt-Jakob disease (CJD, humans); Kuru; fatal familial insomniae. There are 4 human ‘subtypes’i. Sporadic (it comes and goes; no explanation for why the infection occurs)ii. Familial/genetic – it tends to appear in families, may be a genetic predisposition towards getting infectediii. Iatrogenic (acquired) – human behaviour promoted the infection; often comes from medical care (i.e. transplants, growth hormones from cadavers that were harbouring CJD and introduced to the recipients).iv. New Variant (indicated by a lowercase v; vCJD; a strain that has been unfolding since the 1980s)V. BSE Videoa. BSE/Mad Cow started in England. Caused aggression, lack of coordination, etc. No cure, always fatal. England tried to destroy the cattle to prevent spread but had already transmitted to humans (Steven Churchill was first human case – caused hallucinations, lack of coordination; CJD – a human disease in the same family as mad cow. Could CJD have transmitted from infected meat?)b. Kuru outbreak in the place – means to tremble with fear. Known nowhere else in the world. Effected children of both genders and young women. Started with lackof coordination/slight stumbling. Then over the months they needed assistance to walk. After a while they wouldn’t be able to stand at all. Most died within 9 months. i. Spread via cannibalism – they would eat dead relatives to honour them. Men got the choice parts, the muscle. Women and children were left withintestines and other organs so the disease was spread when the women and children ate infected brains. Then those that died of Kuru would get eaten, thus spreading the infection and causing an epidemicc. BSE/mad cow also likely from cannibalism – Sheep had Scrapies (named as such because the infected sheep scraped their skin raw). Cattle feed included protein from animals so sheep infected with scrapies or cows with BSE would be shopped up and included in the feed given to cattle. Those cattle that then died were included in the feed for other cattle,