infectious disease Flashcards
adhesions
help pathogens stick and colonize tissues, both normal and pathogenic microbes have them
what do pathogens have to allow them to cause disease and remain unrecognizable in the host?
virulence factors
parasite
microbes that colonize the surface and infect the host
endoparasite vs ectoparasite
endoparasite, colonize within the host
ectoparasite, colonize on the host surface
why are not all infections considered a disease
the host needs to present symptoms based on disruption to the host structure or function to be considered a disease
acute infection
symptoms present and decline quickly
chronic infection
symptoms present quickly and are slow to decline
latent infection
infection goes into a state of dormancy
opportunistic infection
strikes only when the host is compromised
what are the two main factors of pathogenicity?
1) virulence- how severely it infects
2) infectivity- how well it infects
ID50 vs LD50
ID- how much it takes to infect 50%
LD-how much it takes to kill 50%
the higher the LD the lower the virulence, the lower the LD the higher the virulence
invasion vs invasiveness
what always does invasion?
invasion is getting into a living cell and all intracellular pathogens do invasion
invasiveness is how well it can spread in the tissues
what 3 things must happen to establish a successful infection?
1- attachment (adhesions)
2- immune avoidance (don’t get caught)
3- steal nutrients from the host (selective competition).
infectious disease
disease that spreads from person to person
signs
objective and measurable
symptoms
subjective and felt by the patient
sequelae
long term symptoms after the pathogen has exited
five general stages of infection?
1- incubation
2- prodromal
3-illness
4-decline
5-convalescence
bacteremia
bacteria in blood
septicemia
bacteria in blood, replicating
viremia
virus in blood
toxemia
toxins in blood
primary infection
infections in a previously healthy individual
secondary infection
infection caused by a new organism when the body is weak, follows a primary infection
latrogenic infection
healthcare worker to a patient
nosocomial infection
hospital-acquired infection
community-acquired infection
acquired within community (not the hospital)
morbidity
rate of illness in a population due to a disease
mortality
rate of death in a population due to disease
what do epidemiologists uncover?
etiologic agents of disease, portal of pathogen entry, transmission modes, and rates, biosafety considerations, populations most vulnerable to disease
horizontal transmission
most common form, spread from one person to another, either directly or indirectly (airborne, fomites, or vectors)
compare direct and indirect horizontal transmission
direct: kiss hug
indirect: fomites, food, water, airborne droplets or aerosols
vertical transmission
from parent to offspring (placental or breastfeeding)
airborne vs fomite vs vector
airborne- respiratory droplets/aerosols
fomite- inanimate object
vector- arthropods or mechanical (needles)
arthropod vectors
indirectly transmit pathogens through blood feedings they feed on the blood of an animal reservoir, become infected, and then maintain productive replication of the pathogen (ticks, flies, mosquitos)
how does an arthropod spread disease
it needs to be actively replicating a pathogen
what are the portals of entry?
1- fecal-oral
2- skin
3- respiratory
4- urogenital
5- parenteral (by injection)
6- eye
what are the 8 standard precautions?
1 proper hand hygiene
2 ppe
3 respiratory/coughing hygiene
4 safe injection practices
5 handle sharps safely
6 patient isolation precautions
7 sterile instruments/devices
8 clean/disinfect environmental surfaces
what is the purpose of biosafety levels and what are they from lowest to highest
for each infectious agent level determined by the CDC to contain/prevent lab personnel infection
BSL1-> BSL 2 -> BSL 3 -> BSL 4
BSL 1
lowest level, little to no risk of disease (basic precautions)
BSL 2
human pathogens causing mild disease (barrier precautions)
BSL 3
human pathogens causing serious illness (separate rooms, ventilation, work done in biosafety cabinet)
BSL 4
high virulence pathogens, pathogens where exposure can be lethal (separate facilities)
host factors that affect vulnerability to infectious disease
age, host genetic makeup, pre-existing conditions, immune status/immunopathogenesis, host hygiene/behavior, nutrition/exercise, occupation
endemic
regularly-occurring disease
emerging pathogen
one that leads to rapid incidence of a disease in a population
zoonotic
cross-species animals to humans
epidemic
a pattern of disease characterized by both rapid incidence and widespread geographical distribution
pandemic
worldwide epidemic
