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York University
Natural Science
NATS 1670
Motti Anafi

thMay 8Emerging infectious diseasesMicrobes are the leading causes of devastating epidemics in human history Influenza for example was the 1 cause of death during WW1 exceeding bullets and such More examples are small pox HIV and infectionsEpidemic a disease that affects a large group of people at the same timeVirulent microbe a microbe that tends to cause a severe disease very violent and infectiousMicrobeshost equilibrium the relationship between microbes and the hosting bodyAn infection occurs when the balance between virulent microbes and nonvirulent microbes in the body is upsetMicrobial diseases are often very severe Ebola and such There are 2 different groups of these diseasesTuberculosisHIV VS Ebola virusSARS TB and HIV allows those infected to live a normal life without drugs for a longer period of time symptoms often do not arise and are not noticed until the disease is close or in its full development Successful pathogens doesnt kill the host immediately Most of the successful viruses can be in a hosts body for years without the host knowing while successfully infecting many of the people that person came into contact withEbola on the other hand is extremely deadly kills infected rapidly however it has low spreading activity and cant be transmitted as quickly Ebola can be found in animals SARS is just as aggressive Natural evolution of a microbe operates on its spreading capacity not on its ability to cause a disease It operates on its ability to reproduce itself by continually infecting new hosts Death of an infected host compromises the survival of the infecting microbe Hospitals usually become cases of disease origins Natural selection favours less or nonvirulent microbes A welladapted microbe can live in its host without causing significant damage ie TB and HIV cases Many microbial diseases can be viewed as a failure of the microbe to adapt to its hostPeople can survive Tuberculosis and HIV for years and years hence being carriers Where as people with the Ebola virus and SARS that are killing the host person relatively fastThe natural evolution the way the virus naturally evolves of a microbe operates on its spreading capacity not on its ability to cause a disease Death of a host normally and usually compromises the survival of the infecting microbe the virus that killed the person cant transmit when host is dead and the virus is dead as wellBeneficial Roles of MicrobesWe are all infected in viruses such as Herpes and Chicken poxOur entire environment is covered in bacteria what we touch eat drink etc literally in every corner of the earth Microbes are very important to our ecology system The bad disease causing part of microbes is a tiny fraction of all microbes 0001Microbes are important for digestionmake food such as cheese and bread wine and beerhelp absorb vitamins in the human bodyTurn inorganic molecules into organic compounds nitrogen and CO2 into amino acids and nucleic Oxygen is a direct product of microbes without them we wouldnt be able to breatheMicrobes are also used for waste breakdownDrug production is also made with the help of microbes penicillin and insulin for examplesnatural microbrial flora protect against virolent microbes microbes that cause diseaseo Molds are multicellular organisms that grow as long filaments which intertwine to make up the body of the moldo Growths on cheese bread and jams are examples of molds Penicillium chrysogenum is a mold that produces penicillino Yeasts are unicellular typically oval to round and reproduce asexually by buddinga daughter cell grows off the mothercello Some yeasts also produce sexual sporeso Saccharomycescerevisiae which causes bread to rise and produces alcohol from sugarAway From Infectious DiseasesSmall pox can only affect human beings It cannot be carried by anything else It was eradicated by the mid 1970s by vaccinationsUsinginventing antibiotics and vaccinations is the leading cause of growing life expectancy in the western countries Since the 1950s most scientists have shifted their attention away from infectious diseases thinking human kind has beaten bad microbes Assuming we can just treat everything with vaccines and antibiotics was a dire mistake Microbes are always developing and evolving hence becoming antibiotics resistant appearing and reappearing as newold strains In 1969 The US Sargent General said Its time to close the books on infectious diseasesThat was a very bad statement Although infectious diseases appear to be on the way out it is NOT TRUEEmerging infectious diseases divided into 3 groupsInfectious diseases as a group will never disappearDrug resistant strains Tuberculosis has reappeared and is now mostly drug resistant and has an extremely high mortality rateOutbreaks of existing diseases 1West Nile Virus WNV suddenly appearing in North America which was always exclusively contained in the Middle east and Africa Alongside with its classic form 2 Flu is often coming in slightly different forms as well such as the Swine H1N1 strainDrug Resistant Bacteria ARB have several adaptations to prevent efficacy of treatment drugs 1 mutations in a target protein that affect binding of an antibiotic to a protein 2 Some ARB make enzymes that destroy drugs others alter pores in the Cell Membrane so drugs cant enter3 Some ARB develop mechanisms that actively pump drugs out of the cell4 genes for antibiotic resistance are sometimes found on plasmids DNA molecule separate from chromosomes whose transfer among bacteria facilitates the spread of antibiotic resistance within and between bacteria populationsNew Disease Causing Agent unanticipated and comes as a surprise ex1 HIVAIDS made the jump from monkeys to humans in the 1930s without warning 2 Severe Acute Respiratory Syndrome SARS is another example of an unforeseen disease that no one anticipated emerging 3 Ebola virus wasnt even known until the 1970s 4 Monkey Pox is a cousin of small pox its course to north America was from someone importing a giant Gambian rat later being contracted by prairie dogs captured in Texas later to become pets later scratchingbiting their owners humans contracting them with the monkey pox Monkey Pox is potentially a very dangerous disease able to re generate the small pox Since the 1980s no small pox vaccine is offered to humans This makes the monkey pox very dangerous and easily contractible on people that were born in the 1990sHow Mother Nature and Human collaborate in emerging infectionsDiseaseWildlife OriginManmade amplifier
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