RT2 Flashcards
where are most respiratory infections
in the upper respiratory tract
viral agents commonly involved in RT infections
- Adenoviruses
- Rhinoviruses
- Coronaviruses
- HPIV
- RSV
- Influenzaviruses
- Emerging: non- polio picornaviruses
viruses than enter through the respiratory but do not exert their pathology in the RT
Measles (Both Rubella and Rubeola)
Chickenpox aka Varicella-Zoster aka HSV-3
Smallpox Coxsackievirus Norwalk Virus
upper RT infections
Sinusitis (most common) Rhinitis (runny nose aka common cold) Otolaryngitis (nose clogged and scared to talk) Laryngitis Pharyngitis
lower RT infections
Bronchitis/Bronchiolitis
Pneumonias
types of pneumonias
CAPs (Community- Acquired Pneumonia)(exogenous)
[Acute CAPs Subacute/Chronic]
Nosocomial Usually acute (hospital acquired and deadly)
why is mucus elevator more important in lower RT
in URT gravity pushes the mucus down so not needed
sinusitis and otitis media have mainly what potential etiologic agent
bacterial
microbial causes of rhinitis
viral agents: rhinovirus, adenovirus, coronavirus, non-polio picornavirus
no significant bacterial agents
clinical syndrome of rhinitis
symptoms of common cold which include: •Runny or stuffy nose •Itchy or sore throat •Cough •Congestion •Slight body aches or a mild headache •Sneezing •Watery eyes •Low-grade fever •Mild fatigue
what does a person get in most viral agents that they do not get in rhinitis
high fever (low grade in rhinitis) or high/significant fatigue
many cases of rhinitis are due to what?
allergies rather than infection
what happens to nasal discharge as the common cold runs its course
it becomes thicker and yellow or green in color
rhinovirus is from what viral family
picornavirus
describe physical features of rhinovirus (picornavirus)
small, +ssRNA, icosahedral, non enveloped virus
what are features of rhinovirus that contributes to its pathogenicity
relatively stable in the environment, non enveloped, opt temp of growth at 33-35oC, antigenic drift
how do the features of rhinovirus help with its pathogenicity
stable in environment: enables transmission
non enveloped: less sensitive to surface cleaners like alcohols and disinfectants
opt temp of 33-35: ideal for URT infection
antigenic drift: high number of viral serotype (greater than 153)
sole known reservoir of rhinovirus
humans
who is susceptible to rhinovirus
all ages: more severe in younger children because they haven’t built immunity against it
transmission and survival time of rhinovirus
transmission - breathing on one another, droplets, formites, sneezing
survival time: 2 hours to a week
what happens to most people infected with enterovirus
they do not get sick or they get mild illness
what are symptoms of those who develop mild illness from enterovirus
fever, runny nose, sneezing, cough, skin rash, mouth blisters, body and muscle aches
clinical syndrome of adenovirus
pharyngitis (sore throat), conjunctivitis (inflammation of conjuctiva of eye)
significant about the structure of adenovirus
icosahedral and there are fibers at the end of each penton
how are adenovirus placed into groups and haemagglutination group
group based on their fiber length and DNA homology (A, B, C)
haemagglutination group based on their capability to agglutinate erythrocytes (I, II, III, IV)
how many serotypes do adenovirus have?
a hell of a lot
what do the adenovirus component do once it gets into the cell
it hijacks the cell and interferes with the host immune response then takes over the cell in order for the host to make more adenovirus
adenovirus pathogenicity
fiber protein at the end of the penton enables attachment to host cell receptor which varies with viral serotype
what is the receptor for serotype 2 and 5 for adenovirus
CAR = Coxsackie Adenovirus Receptor
where does the toxic activity of adenovirus come from
penton base
what are the toxic activity of adenovirus provided by the penton base
- Inhibition of cellular mRNA synthesis
- Cell rounding
- Tissue damage
most infections with adenovirus occurs when
before the age of 14
adenovirus can be associated with what other systems
ocular, respiratory, GI systems
outcomes of adenoviral infection
lytic (mucoepithelial cells)
latent (Adenoid cells)
what is significant about adenovirus and swimming pools
adenovirus can survive chlorination of swimming pools
clinical symptom of coronavirus
common cold, SARs
describe physical features of coronavirus
enveloped, helical nucleocapsid, surface/spike proteins, +ssRNA class IVb
what is the 20mm projecting surface proteins on coronavirus called?
peplomers
importance of peplomers
attach to carbs or proteins and is the site of antigenic epitopes
importance of the antigenic epitopes on the coronavirus
antibodies can bind to it and neutralize its effects aka stop it from getting into cells
transmission of coronavirus
droplets and fecal oral route
why are re-infection by the same coronavirus possible
the neutralizing antibody is short lived
total number of serotypes in coronavirus
undetermined because coronavirus is very difficult to isolate
survival time of coronavirus
3 hours
survival time of adenovirus
7days - 3 months
pathogenesis of coronavirus
it’s optimum growth occurs at 33-340C in the ciliated nasal epithelium which there are no good animal models for because it is hard to isolate and grow
hence the specifics of pathogenesis and immune response is not clear
what is the new coronavirus that originated in Guandong province in China
SARS-CoV
clinical syndrome of SARS-CoV
severe acute respiratory syndrome
another new coronavirus other than SARS-CoV and what is it found in
MERS-CoV and it is found in bats
