Micro 19

• A hungarian who traveled to Vienna to study medicine
• Made the connection between transferring "poison" between cadavers and women in childbirth
• Was before Pasteur and Koch, was rudely discarded and forced to go back to Hungry

• study of disease patterns in populations
• epidemiologists are "disease detectives"

describes percent of people who become ill in population after exposure to infectious agent

the number of new cases in a specific time period in a given population

the total number of cases at any time or for a specific period in a given population

morbidity refers to the incidence of disease in a population at risk

Mortality refers to the overall death rate in population

percentage of population that dies from a specific disease

• diseases that are constantly present in a given population
• Ex: common cold is endemic in US

when cases occur only from time to time

• when there is an unusually large number of cases in population 
• May be causes by diseases not normally present in population

• describes a cluster of cases occurring during a brief time interval and affecting a specific population
• may herald the onset of an epidemic

• when an epidemic spreads worldwide
• Ex: AIDS

• the natural habitat of a pathogen
• sum of the potential sources of an infectious agent

the body orifice or surface from with a microbe is shed

the means of which the microbe enters through a body surface or orfice

transmission of a pathogen from one person to another through the air, by physical contact, by ingestion of food or water, or via a living agent such as an insect

the transfer of a pathogen from a prego woman to fetus, or from mother to her infant during childbirth or breast feeding

• inanimate objects such as clothing, table-tops, drinking glasses
• can transfer pathogens via indirect contact

• way people can spread respiratory disease
• People in close proximity can inhale droplets

results when pathogens from one food are transferred to another

• composed of microbes attached to a thin coat of dried material
• can remain suspended in air indefinitely in presence of even slight air currents

• moves microbes from one place to another
• Ex: if the fly lands on poo and picks up intestinal pathogens on it's legs, and then lands on your food
• E. coli spread this way

• Participates in the life cycle of pathogen and provides place for it to multiply
• Malaria is spread this way. Mosquitos transmits but also provides place for it to multiply

• british physician who illustrated power of epidemiology 150 yrs ago
• documented that cholera epidemics plaguing england were due to contaminated water

• study done when a disease outbreak occurs
• collect data that characterize the occurrence, from the time and place of the outbreak to the individuals affected
• Info is used to compile list of possible risk factors involved in spreading disease
• Involves: the person(s), place, and time

• refers to the timing of an outbreak
• when a rapid rise in the numbers who become ill suggests they were all exposed to a single, common source
• Ex: contaminated chicken at picnic

• refers to the timing of an outbreak
• numbers of ill people rise gradually
• disease is likely contagious, with one person transmitting it to several others, with then transmit it to several more

• the first case in an outbreak (propagated epidemic)
• time btwn onset of sx and next cases reflects incubation period

designed to determine which of the potential risk factors identified by the descriptive studies are actually relevant in the spread of disease

• surveys a range of people to determine the prevalence of such characteristics as infection, presence of risk factors associated with disease, or previous exposure to a disease-causing agent
• May suggest associations btwn risk factors and disease
• does NOT attempt to establish cause of disease

• done following a disease outbreak
• actions and events surrounding clinical cases (those who developed disease) are compared to those surrounding appropriate controls (who remained healthy)

starts with disease and attempts to id causative chain of events leading to it

looks ahead to see if the risk factors identified by retrospective study predict a tendency to develop the disease

• study groups that have a known exposure to the risk factor
• selected and followed over time

used to judge the cause-and-effect relationship of the risk factors, or more commonly, the preventive factors, and the development of disease

neither researchers nor pt's know who is receiving experimental tx

• Centers for Disease Control and Prevention
• provides support for infectious disease lab in US and abroad and collects data on diseases that impact public health
• puts out weekly Morbidity and mortality weekly report (MMWR) which summarizes the status of many diseases

Chlamydia

• also conducts research relating to infectious diseases
• can dispatch teams worldwide to assist with identifying and controlling epidemic
• Provides refresher coures for lab and infection control personnel

• Common healthcare-associated infection
• Environmental bacterium found on skin of healthy people
• resistant to many antimicrobial meds
• Causes variety of HAI including bloodstream and surgical site infections and pneumonia

• Yeasts, part of normal microbiota, common cause of healthcare-associated bloodstream infections
• Some are resistant to number of antifungal meds

• Toxin-producing strans of bacterium can cause diarrhea and colitis in people taking antibiotics
• Because bacterium produces endospores, which can't be killed by disinfectants, thorough handwashing is important means of preventing transmission

These bacteria, part of normal intestinal microbiota, are common cause of nosocomial UTI as well as wound and bloodstream infections