symbiosis
A close relationship between two species
mutualism
A relationship between two species in which both species benefit
parasitism
A relationship between two organisms of different species where one benefits and the other is harmed
commensalism
A relationship between two organisms where one benefits and the other is neither harmed nor benefited
normal (resident) flora (microbiota)
Microbes that live and grow in a certain area of the body; know where and where not
pathogen
A disease causing agent
infection
invasion of the body by pathogenic organisms and their multiplication
probiotic
Live microbes applied to or ingested into the body, intended to exert a beneficial effect
opportunistic pathogen
Doesn't cause disease in healthy individuals, but under certain conditions (e.g. change of environment, immunity) can cause disease.
reservoir of infection
Living or nonliving continuous source of infectious disease
fomite
inanimate object to which infectious material adheres and can be transmitted.
tetanus
bacterial; R: soil, dust, animal feces; Tr: broken skin
zoonoses
Diseases naturally spread from non-human animal to human
biological vector
Organism that transmits a pathogen and within which the pathogen can multiply significantly
mechanical vector
A vector that simply conveys pathogens to a susceptible individual and is not essential to the development of the pathogen
influenza
viral; r: pigs, birds; Tr: direct contact
rabies
viral; r: certain mammals; Tr: bite
anthrax
bacterial; R: livestock; Tr: air, food, direct contact
plague
bacterial; R: rodents; Tr: fleas
human carrier
do not exhibit signs/symptoms but carry the pathogen and able to give it to others
typically development of infection
colonization, spreading and multiplication, disease
pathogenicity
Ability to cause disease
virulence
degree of pathogenicity
virulence factor
characteristic or structure of microbe that contributes to its virulence
infectious dose (ID)
The number of microbes necessary to establish an infection; ID and virulence are inverse correlated - high ID = low virulence and vice versa
sign of disease
measurable/observable (objective) indications, e.g. fever, rash, swelling
symptom of disease
subjective changes sensed by patient, cannot be observed/ measured by others; e.g. pain, dizziness
incubation period
The time between contracting the pathogen and the appearance of the first signs/symptoms
prodromal period
short period of mild, usually vague signs and symptoms occurring at the end of the period of incubation
illness period
specific signs and symptoms of disease; pathogens multiply well at optimal rate
convalescence
gradual recovery after illness
local infection
An infection that is limited to the specific part of the body
systemic infection
An infection throughout the body
focal infection
local infection spread to other parts of the body
sepsis
sometimes called blood poisoning; reaction to the pathogens or toxins; high mortality rate
mixed infection
Infection caused by two or more organisms.
primary infection
Initial infection
secondary infection
another infection followed a primary infection or cause that weakened the body's defenses
acute infection
An infection characterized by symptoms that develop fairly quickly and last a relatively short time
chronic infection
an infection that progresses and persists over a long period of time
epidemiology
study of the distributions, causes, and transmission of disease conditions in defined areas and populations
endemic
disease that occurs in a relatively stable frequency within a given area or population
epidemic
If an infection occurs more frequently than normal within a population.
pandemic
A worldwide epidemic
morbidity rate
number of people afflicted of a disease in relation to the total population
mortality rate
number of people who have died from a disease
prevalence
number or proportion of cases of a particular disease or condition present in a population at a given time
incidence
number of new cases occurring in a specific period
nosocomial
An infection that is acquired in a hospital (health care) setting
salmonellosis
bacterial; R: poultry, reptiles; Tr: contaminated food and water
ringworm
fungal; R: certain mammals; Tr: direct contact, fomites
sporotrichosis
fungal; R: (plants), cats; Tr: direct contact
Cysticercosis
parasitic; R: pigs; Tr: food
Chagas disease
parasitic; R: wild animals; Tr: Triatomine bugs = reduviid bugs = "kissing" bugs
BSE
mad cow disease; prion; R: cows; Tr: direct contact, food