4- Viral Respiratory Infections Flashcards
how damage predisposes pt’s to super infections (baterial)
interrupt mucocilliary escalator (can’t expel bacteria or pollutants) + weaken immune system (fighting viruses instead of bacteria)
common cold symptoms
- rhinitis (inflamm of nasal mucosa)
- pharyngitis (sore throat)
- NO high fever, lower respir involvement, or respir distress
allergies can mimic symptoms
complications of common cold
- otitis media
- sinus infections
- exacerbation of asthma (rhinovirus C)
common cold treatments
- antihistamines
- decongestants
- NOT antibiotics
- no vaccines bc high variation of viruses
prevention by washing hands and covering coughs
common cold pathology
viruses
- attach in nasal epi
- replication in epi cells
- cell damage
- host defense activated to clear cell debris
- nasal epi regenerate
etiology of colds
viruses causing colds
- rhinovirus
- coronavirus
- other known (adenovirus, coxsackie)
- unidentified
all transmission thru contact/droplet except coxsackie fecal-oral
rhinoviruses
most common cause
-from picorna (small RNA) family non enveloped, +ssRNA
-species A, B,C but tons of diversity
shed in respir secretions so transmit contact or large droplets
coronavirus
coronaviridae family enveloped +ssRNA
-spike proteins to attach
-non SARS that causes common cold
aleviate symptoms to treat, no vaccine
non SARS coronavirus mechanisms
rep in epi cells of respir tract
-transmit thru large droplets
-usually infants and children
adenoviruses features
non enveloped dsDNA adrenovirus family
-fiber proteins protrude from vertices of capsid for attachment and toxic
adenovirus
serotypes 1,2,5 cause colds
-prevalent in children under 5
-can enter lymphoid tissue and stay for 18 mo
-no seasonal pattern
transmit via oral, droplet inhalation, conjuctiva
other illnesses of adenovirus
- pharyngoconjuctival fever
- severe respir infection (croup, pneumonia, bronchiolitis)
- GI disease (serotypes 40 and 41)
treatment adenovirus
-reduce symptoms
-immunity long lived but serotype specific
-military recruits get live oral vaccine for 4 and 7
coxsackieviruses
enterovirus family of picornaviruses
-non enveloped + ssRNA
-replicate in cytoplasm
fecal-oral transmission, no vaccine or treatment needed to recover
-lower sanitation places, children in daycare
herpangina
from coxsackie
-abrupt onset of fever + small vesicles/blisters on soft palate that can rupture
high in children 1-7
can lead to meningitis or encephalitis
hand-foot and mouth disease
fever + vesicular lesions on palms of hand and soles of feet
common in children, goes away on own
influenza viruses
B and C can cause cold symptoms instead of flu symptoms
croup symptoms
swelling in subglottic region of larynx ‘laryngotracheobronchitis’
nasal discharge + mild cough+ pharyngitis > fever + brassy cough (like seal bark) + inspiratory stridor rattling
-chest x ray shows narrowing of air shadow ‘steeple sign’
-worried about hypoxia
highest in kids under 6
croup treatment
alleviate symptoms
-if no stridor at rest then humidify air and hydrate
-if yes stridor at rest then oxygen, epinephrine, glucocorticoids
croup etiology
- parainfluenza virus
parainfluenza viruses
-paramyxovirus family
parainfluenza mechanisms
large droplet and direct contact transmission
-infect/repl in ciliated epithelium of respir tract
can be reinfected more mildly, short lived immunity
acute bronchitis
cough without pneumonia/alternative medical disorder/history of chronic lung
-from influenza A and B
cough lasting more than 5 days (median 18 days)
antibiotics (limited effective) or bronchodilators (if wheezing)
bronchiolitis
expiratory wheezing + nasal flaring + air trapping + subcostal/intercostal retractions + fever
infants prevelent bc airways so small
RSV
causes bronchiolitis and pneumonia
transmission thu inhale large droplets and direct contact
-nearly all children infected by 4, reinfection more mild like colds
RSV season
october-may but varies by part of country
-since covid shifted more towards august
RSV treatment
aerosolized ribavirin
-guanosine analgoue so inhibits nucleotide syn
consider if severe lower tract RSV in premature infants, chronic lung diease, congenital heart disease, immunocompromised
RSV passive immunoprophylaxis
palivizumab (monoclonal anti-RSV antibody) injected monthly for 5 mo during RSV season
prophylaxis of infants in first year if premature, chronic lung dz, or heart dz
up to 2nd year if immunocompromised
influenza symptoms
-myalgia
-headache
-fever
-shaking chills
-cough
-fatigue, general weakenss
inc severity during pandemic outbreaks
peak during winter
risk complications influenza
kids under 2,
adults over 65,
preg women or up to 2 weeks post partum
certain med conditions (anything that affects respiratory, metabolic disorders)
pneumonia
inflamm of lung parenchyma > abnormal gas exchange
fever + chills + cough + pleuritic chest pain + inc respir rate + wheezes/crackles
primary influenza virus pneumonia
usually influ A
-inc cough, tachypnea, dyspnea, acute respir distress
-sputum gram stain shows abundant pmn cells, not much bacteria
-radiograph shows lung infiltrtion with interstitial pattern of opacities
bacterial influenza associated pneumonia
onset a week after influ symptoms begin
-biphasic pattern so symps lessen for little while then progress worse (cough, fever, respir distress)
gram stain may show bacteria (S. pneumoniae, S. aureus, H influenze)
influ virus
segmented -ssRNA orthomyxovirus enveloped
agglutinates RBCs (hemagglutinin) + neuraminidase (virion release and spread)
antigenic drift
influ
small changes in H and N driven by point muts (from polymerase during rep)
epidemiological significant changes every 2-3 years
antigenic shift
influ
large changes in H and N driven by reassortment of two viruses
co-infection of same cell by diff virus strains, risk for pandemics
reassortment barriers
-specialize for the host so human strains spread in humans but not thru animals and v/v
-mixing vessel animals that can support infection from diff species (avian and human can infect swine) allow transmission b/t species
anti-virals for influenza
- ion channel blockers-block rep prior to genome release
- neuraminidase inhibitors- inhib virion release and spread of A and B
- endonuclease inhibitor- target cap dependent endonuclease to cleave, single oral dose vs A and B
types of neuramindase
- zanamivir- inhalation admin
- oseltamivir- oral admin
- peramivir- IV admin
ion channel blockers
amantadine or rimantadine, was only effective vs A but now A has resistance,
when to use antivirals
-if no risk factors and within 48 hours otherwise limited effectiveness
-if yes risk factors then at anytime
influenza vaccines
- inactivated-dead virus via intramuscular injection
- live attenuated- intranasal inhalation
- recombinant - hemagglutinin protein instead of virus, intramuscular
production methods of vaccine influ
- classic- chicken eggs
- novel- mammalian cells (faster than eggs) like MDCK cells
recombinant made by purifying baculovirus that infects a fermenter (faster and egg free)
vaccine components
2 influ A + 2 influ B strains
dosing and timing
offer vaccine by late october
-antibody resp within 2 weeks
-1 dose per/year except under 9 then 2
COVID diagnosis
- nucleic acid detection/PCR, most sensitive
- antigen test
COVID antivirals
- remdesivir- targets RdRp of CoV, peds and adults can recieve if pos, hospitalized pts
- ritonavir boosted nirmatrelvir/paxlovid- inhibits cyctochrome enzymes, mild to moderate symptoms, oral, not for hospitalized
- molnupiravir- induces hypermutation so interrupt normal fxn, oral deilvery, not for preg or hospitalized
COVID vaccines
- mRNA based, intramuscular, invoke antibodies vs spike protein, Phizer and Moderna
- rep defective adenovirus vector encodes spike, J and J
- recombinant spike protein, Novavax, has adjuvant
cytomegalovirus
respir illness in immunocomp indivs
measles and varicella
