L16: Disease & Epidemiology Flashcards
Pathology
the study of disease
Etiology
the study of the cause of a disease
Disease
an abnormal state in which the body is not functioning normally (diabetes is a disease, but it is not infectious)
Infection
colonization of the body by pathogens
Pathogenesis
the development of disease
Infectious disease
a disease that can be transmitted between hosts
Transient microbiota
may be present for days, weeks, or months
Normal microbiota
permanently colonize the host OR at least a very long-term association until conditions change
Symbiosis
the relationship between normal microbiota and the host
Microbial antagonism
competition between microbes
Normal microbiota
mutualistic microbes that protect the host via…
- occupying niches that pathogens might occupy
- producing acids and bacteriocins
Symptom
a change in body function that is felt by a patient as a result of disease and is reported by the patient
Sign
a change in a body that can be measured or observed as a result of disease
Syndrome
a specific group of signs and symptoms that accompany a disease
Communicable disease
a disease that is spread from one host to another
Contagious disease
a disease that is easily spread from one host to another
Noncommunicable disease
a disease that is not transmitted from one host to another
Acute disease
symptoms develop rapidly (i.e. Norovirus)
Chronic disease
disease develops slowly (i.e. Brucella abortus)
Subacute disease
symptoms are between acute and chronic level
Latent disease
disease w/ a period of no symptoms when the causative agent is inactive
Sepsis
toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection
Bacteremia
bacteria in the blood
Septicemia
growth of bacteria in the blood
Toxemia
toxins in the blood
Viremia
viruses in the blood
Primary infection
acute infection that causes the initial illness
Secondary infection
opportunistic infection after a primary/predisposing infection (i.e. AIDS patients susceptible)
Subclinical disease
no noticeable signs or symptoms; disease that poses as an inapparent infection
Direct contact
disease transmitted via close association or exchange of mucous membranes (mainly sexual contact)
Indirect contact
disease transmitted via fomites
Droplet transmission
disease transmitted in concentrated sections of air
Mechanical transmission
a type of transmission by arthropod in which the arthropod carries the pathogen on feet
Biological transmission
a type of transmission by arthropod in which the arthropod injects pathogen via bite/saliva; the pathogen reproduces in the vector
Descriptive epidemiology
collection and analysis of data
Analytical epidemiology
comparison between a diseased and healthy group
Experimental epidemiology
controlled experiments
Sporadic disease
disease that occurs occasionally in a population (i.e. Ebola virus)
Endemic disease
disease constantly present in a population; low frequency normally present (i.e. Vibrio cholerae in South Asia)
Epidemic disease
disease acquired by many hosts in an area in a short time (i.e. outbreak of V. cholerae in Haiti after earthquake)
Propagated epidemic
disease is continuously transmitted from the infected (i.e. Influenza A/seasonal flu, may be related to 1918 pandemic)
Pandemic disease
worldwide epidemic (i.e 1918 Spanish flu, COVID-19)
Incidence
refers to the fraction of a population that contracts a disease during a specific time (i.e. influenza each year)
Prevalence
refers to the fraction of a population having a specific disease at a given time (i.e. HIV)
Morbidity
incidence of a specific notifiable disease
Mortality
deaths from notifiable diseases
Morbidity rate
number of people affected in relation to the total population in a given time period
Mortality rate
number of deaths from a disease in relation to the population at a given time
COVID-19: Basic reproduction number R_0
the # of infections produced on average by an infected individual in the early stages of the epidemic when all contacts are susceptible
COVID-19: Incubation period
period of time between exposure resulting in infection and the onset of the first clinical symptoms
COVID-19: Serial interval
the period of time from the onset of symptoms in the primary case to the onset of symptoms in a contact case
COVID-19: Secondary infection rate
measure of the frequency of new infections among contacts of confirmed cases in a defined period of time
COVID-19: Secondary clinical attack rate
measure of frequency of new symptomatic cases of infection among contacts of confirmed cases in a defined period of time
Virology testing
testing for the presence of virus in a patient by detecting viral nucleic acid and antigens
Serological testing
testing for the presence of antibodies against an infectious agent in a patient (i.e. antibody-capture/indirect ELISA)
Stages of Disease: Incubation period
interval between initial infection and first signs and symptoms
Stages of Disease: Prodromal period
short period after incubation characterized by early, mild symptoms
Stages of Disease: Period of illness
disease reaches its peak (most severe)
Stages of Disease: Period of decline
signs and symptoms subside
Stages of Disease: Period of convalescence
body returns to its prediseased state; recovery
