1 intro Flashcards
white spots in back of throat
group A strep throat
measles
koplik’s spots
measles
- highly contagious
- child should be quarantined
varicella zoster virus (shingles)
- 1/2 of body has sores
- should not contact pregnant women
caries pathogen
strep mutans
pathogenic diseases found in oral cavity
caries, gingivitis, TB, pneumonia, whooping cough, gonorrhea, syphilis, clhlamydia
viruses found in oral cavity
influenza, measles, herpes simplex, epstein barr, hep B and C, HIV
how to think about infections
encounter entry spread multiplication damage outcome
virulence
ability to cause disease
susceptibility of host
predisposition for infection
incubation period
time between exposure and onset of symptoms
reservoir
host species in which a pathogen can be maintained indefinitely with no or few ill effects
encounter: where pathogens come from?
environment, infected person, infected insect or animal, normal flora
types of transmission
vertical, horizontal, iatrogenic, nosocomial
vertical transmission
transplacental, birth, neonatal
horizontal
all other types
iatrogenic
by healthcare workers (nonsterile)
nosocomial
hospital setting
entry: how pathogens get insde
mucosa of respiratory, gastrointestinal, urogenital
cornea
skin
entry of pathogens that don’t cross epithelial borders
inhalation
ingestion
sexual contact
entry or pathogens crossing epithelial barriers
insect bites
wounds
medical or dental procedures (organ transplants, blood transfusions)
spread
from original site or distant
rotavirus infects elsewhere after spread
entry in intestinal epithelium, local disease (diarrhea)
poliovirus infects elsewhere after spread
entry in the intestinal epithelium, then spread to blood, then to CNS (paralysis)
pathogen damages host directly
- cell death bc of toxin or multiplication
- altered cellular metabolism due to effects of toxin or multiplication
3 mechanical obstruction
pathogen damages host indirectly (host response)
1 damage due to inflammation
2 damage due to the immune response
possible outcomes of pathogen
host wins
organism wins
they coexist
microbiota (normal flora)
10x microbial than human cells
normally colonized areas
skin nose and oropharynx mouth large intestine genital system urinary tract eyes lungs
low amounts of microbes in which areas
urinary tract, eyes, and lungs
normally sterile (no microbes)
blood
deep tissues and organs
microbiota may be good
keeps out invaders, stimulates the immune system
microbiota may be bad
colonization with a pathogenic microbe may increase the chances of developing disease
microbiota may be harmless
if microbes stay where they belong but may cause disease if they go elsewhere or if the host state changes (antibiotics, weakened immunity)
physical barriers for host defense
skin
mucous membranes
fluid flow like saliva + urine
chemical barriers for host defense
saliva + mucus
constitutive host defenses
inflammatory response
complement
phagocytoses
induced defenses
antibodies + T-cells
how do microbes avoid host defenses?
avoid being washed away by fluids like adhering to host cells with pili
- avoid complement (block complement activation)
- avoid phagocytosed by having a capsule
- avoid immune response by varying surface antigens
pili
- threadlike structures found on the bacterial surface
- contain adhesins that bind host cell receptors
how are infections treated
antibiotics
problem with antibiotics
- resistance
- do not work against viruses, fungi, and parasites
- diseases may be caused by bacterial toxins (botulism) instead of live bacteria
measles virus is also called
rubeola
symptoms of measles
fever
COUGH
CORYZA (runny nose)
CONJUNCTIVITIS ( red, watery eyes)
2-3 days after measles
koplik’s spots (white spots in mouth)
3-5 days after measles
rash (head, then body)
encounter of measles
direct contact with airborne droplets
how long can measles survive for in the air
2 hours
entry of measles
respiratory tract
spread of measles
respiratory tract->blood (viremia)-> other organs like skin (rash)
damage from measles
virus (cytotoxicity) and host (imune response)
viremia
presence of viruses in blood
measles epidemiology
EXTREMELY INFECTIOUS- 4 days before the rash to 4 days after
live attenuated vaccine for Measles
MMR (measles, mumps, rubella . 1963) 2 doses: 1yr and 4-6 yr lifelong immunity >95% -has reduced measles in US from 4,000,000 to 50 cases/yr -but epidemic since 2000
what causes measles cases and outbreaks
unvaccinated travellers to philippines where there was a huge outbreak
- travelers may bring it back from other countries
- measles are not common in US but still common in other parts of the world
- people who visit you from other countries can bring it with them
most people who got measles were
unvaccinated
mild measles complications
bacterial: otitis media, pneumonia
viral: pneumonia
severe measles complications
.1-.3% mortality among small children
- measles encephalitis (1 in 1000, week 2); 10-20% mortality
- subacute sclerosing pan encephalitis (SSPE) (1 in 1,000,000 cases, years later, usually fatal
important points about measles
highly contagious and NOT benign
-preventable by vaccination (safe, effective, no link to autism)
is there a link between autism and measles?
NO link between autism and measles
