chpt 18 definitions Flashcards
disease
disturbance in the normal functioning of an organism
infectious diseases
disease caused by a microbe that can be transmitted from host to host
zoonotic diseases
infectious disease of animals that can cause disease when transmitted to humans
symptoms
subjective disease state such as muscle aches
pathogens
a microbe that routinely causes disease
pathogenesis
process by which a pathogen causes disease
infection
successful colonization and invasion by a pathogen of a host
primary pathogens
microbe that causes disease in otherwise healthy hosts
opportunistic pathogens
microbe that causes disease only when a host has been compromised
virulence
degree of severity of disease a pathogen is capable of causing
case-to-case infection ratio (CI ratio)
proportion of infected individuals who develop disease
attenuation
regulatory mechanism that occurs after the initiation of transcription but before transcription of the operon is complete; decrease in virulence
vaccines
preparation containing antigens used to immunize against disease
carriers
asymptomatic host that can transmit an infectious agent to others
host range
the diversity of cells that can be infected by a pathogen or support the replication of a virus or plasmid
antigenic variation
change in molecules on the surface of a pathogen to which the immune system responds; can allow pathogen to avoid immune detection
latency
infection characterized by a delay or cessation of disease; in viral disease, characterized by limited transcription of the viral genome; results in reduced immune response
Reactivation
resumption of disease after a latent period; can occur due to cellular stress i the hose; in viruses, resumption of transcription of a previously latent viral genome
toxins
substance of biological origin that damages a host
apoptosis
cell death accomplished through a highly ordered and tightly controlled cascade of chemical signaling events within the cell that results in its destruction without the release of damaging cell constituents or triggering of inflammation
transmission
spread of an infectious agent from one host to another or from its source
reservoir
source of an infectious agent
direct contact transmission
spread of an infectious agent that occurs via physical contact between an infected person and a susceptible person
indirect contact transmission
spread of an infectious agent that occurs from one person to another via an inanimate object or a vector
fomite
inanimate object via which pathogens may be transferred to a susceptible host
fecal-oral transmittion
spread of an infectious agent that is eliminated in the feces of one individual and then ingested by another individual
respiratory transmittion
spread of an infectious agent that replicates in the respiratory tract and leaves the infected host as an aerosol during coughing, sneezing, laughing, or similar activities
vector-borne transmittion
spread of an infectious agent from an infected individual to another organism such as an insect that then transmits the infectious agent to a different susceptible host
sexual transmittion
spread of an infectious agent that occurs during vaginal, anal, or oral sex
sexually transmitted infections (STIs)
infectious disease that is spread sexually through vaginal, anal, or oral sex
vertical transmission
spread of an infectious agent from part to child
horizontal transmittion
spread of an infectious agent between members of a species that are not parent and offspring
zoonotic transfer
spread of pathogen from its natural animal host to a human
reservoir host
natural host that supports replication of a pathogen
dead-end host
individual in which a pathogen may replicate and cause disease but int transferred efficiently to another individual; also called incidental host
epidemiology
study of patterns of disease within populations
morbidity rate
rate of disease
mortality rate
rate of death associated with disease
incidence
number of new cases of a disease appearing in a population during a specific time period
prevalence
total number of cases of a disease in a population at a particular time or during a particular time period
emerging diseases
disease that was previously unknown or that shows a significant increase in incidence
endemic diseases
disease that is normally present in a population
epidemic
significant rise in incidence of a disease above that normally expected in a population
pandemic
global epidemic, usually on ore than one continent
outbreak
cluster of cases appearing within a short period of time in a localized population
common-source epidemic
an outbreak that results from exposure to a single source of infection
incubation period
time between entry of a pathogen into a host and appearance of illness
propagated epiemics
pattern of disease characterized by infection passing from one host to another, either directly or indirectly
koch’s postulates
guidelines for demonstrating that a specific microbe causes a specific disease
molecular kock’s postulates
guidelines for using molecular tools to demonstrate that a specific microbial product is a virulence factor
pathogenicity islands (PAIs)
region of a chromosome containing multiple virulence factor genes
signs
objective disease state that can be readily observed or measured, such as a rash or a fever
