Chapter 9: Principles of Infectious Disease and Epidemiology Flashcards
Sporadic Cases
isloated infections in a particular population
Endemic Infections
rountinely detected in a population or region (cold virus)
Epidemic
widespread diasese outbreak in a particular region during a specific time frame
Pandemic
occurs if an epidemic spreads to numerous countries
Emerging Pathogen
include newly identified agents as well as pathogens that previously caused only sporadic cases (SARS-CoV-2) or exhibit an expanded geograhical districubtion (ziki virus)
Reemerging Pathogen
an infectious agent that was undercontrol but is now resurfacing
Noncommunicable diseases
do not spread from person to person
Communicable Diseases
transmits from human to human
Contagious Diseases
easily transmitted from one host to the next
Symptomatic
during an active infection the patient exhibits signs and symptoms
Signs
objective indicators of disease that can be measured or verified; fever, rash, etc
Symptoms
sensed by the patient and are subjective rather than precisely mesaurable; pain fatigue and nausa etc
Acute Diseases
have a rapid onset and progression
Chronic Diseases
have a slower onset and progression
Kochs Postulates
same organism must be present in ever case of the disease; the organism must be isolated from the diseased host and grown as a pure culture; isolated organism should cause disease in question when inoculated in a susceptible host; organism must then be reisolated from the inoculated diseased animal
Limitations of Kochs Postulates
do not apply to noninfectious disease; certain infectious disease cannot be isolated; some microbes become attenuated in pure cultures; some microbes do nt infect nonhuman hosts; not easily applied to infectious agents that primarily cause latent disease
Reservoirs
are an animate or inanimate habitat where the pathogen is naturally found
Sources
disseminate infectious agent from the reservoir to new hosts
Endogenous Source
means the pathogen came from the hosts own body; like bacteria on skin entering a surgical incision or yeast in vagina proliferting when antibiotics kill off normal bacteria
Exogenous Source
means the pathogen is external to the host; contaminated food, zoonotic disease, transmitting between humans
Mode of Transmission
how the pathogen spreads to a host; generally classed as direct contact and indirect contact
Direct Contact
host comes into physical contact with the source of the pathogen; such as a bite, touching, kissing, going in a pond
Vertical Transmission
specialized form of diret contact; occurs when pathogen passes from mother to offspring during pregnancy (in utero), delivery (transcervical) or breatfeeding (post partum)
Indirect Contact
pathogen spreads without direct physical contact with the source; three main categories- airborne transmission, vehicle transmission, and vector transmission
Airborne Transmission
pathogen enters through respiratory route; usually occurs by inhaling pathogen-laden respiratory droplets
Vehicle Transmission
pathogen is found on contaminted fomite (doorknowbs, needles, sheets, food)
Vector Transmission
transmission by vectors (arthropods)
Biological Vector
vector organism has a role in the pathogens life cycle; ticks mosquitoes
Mechanical Vector
vector spreads disease without being integral to a pathogens life cycle; flies, rodents and cockroaches
Infectivity
describes how good an infectious agent is at establising an infection
Pathogenicity
is the general ability of an infectious agent to cause disease
Virulence
describes severity of disease following infection