BooknotesPerlinCohen - CHAPTER ONE CATCHING ON TO...

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CHAPTER ONE – CATCHING ON TO INFECTIOUS DISEASES Infectious diseases cause 1/3 of all deaths worldwide each year What is an Infectious Disease? Illness caused by microorganisms, viruses, or other tiny biological agents Can be spread in a variety of ways Very diverse Some already live inside us; some live in the environment Some can survive a long time without a host Those that pass the disease along are called vectors Those that are infected but don’t show signs are called carriers e.g. Typhoid Mary The Ongoing Battle Against Disease Some diseases have been eradicated, whether totally or in the US Hospital patients in recent years: acute diseases to chronic diseases Major Outbreaks Outbreak – localized occurrence of a specific infectious disease Epidemic – spreads beyond local population, lasting longer, reaching more people Pandemic – worldwide epidemic Epidemiologists Epidemiology – the study of epidemics Incidence – number of new cases within a given time period – how quickly it’s spreading Prevalence – absolute number of cases – old and new – impact of disease on population Threat of new diseases e.g. Lyme disease, toxic shock syndrome, West Nile, AIDS, etc. May rise by several mechanisms, due to a number of factors Environmental changes and disturbances to the balance of natural habitats e.g. global warming, more dams Human demographics and behavior e.g. poverty, urbanization, poor sanitation, refugee camps International travel and commerce esp. air travel Immune suppression due to acute and chronic illness e.g. chemo infections (temporary), AIDS (permanent) Microbial adaptation and change Genetic mutations, resistance, etc. Breakdown of public health measures Good vaccination programs in US, but not the rest of the world Cycles Epidemics tend to go in cycles, with or without drugs/other health measures
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CHAPTER TWO – A HISTORY OF INFECTIOUS DISEASES Disease and development go hand in hand Long ago – when people traveled in small groups, diseases didn’t spread easily As people settled down, it was easier for disease to spread Immunity occurs after a person has already been exposed to a disease Fighting Infection Quarantine and enforced isolation Primitive treatments e.g. Peruvians used Cinchona tree bark to treat malaria – has quinine Early vaccination methods Cleaning up the water Improve sanitation, reduce water-borne diseases such as cholera Early theories on causes of infection Henle said disease was caused by living particles that acted as parasites in people Present when someone was sick, could be isolated, and could make healthy person sick Parasites are organisms that feed off a host, but contribute nothing back Germ theory Pasteur developed pasteurization – heat treatment that killed microbes in milk No more salmonella from milk The organism must be present in every case of the disease The organism must not be presenting any other disease
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BooknotesPerlinCohen - CHAPTER ONE CATCHING ON TO...

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