Unit 4 - Viral Infections of the Upper Respiratory Tract Flashcards
what are the most frequent, occasional, and infrequent respiratory syndromes of rhinovirus?
MF: common cold
O: excerbation of chronic bronchitis and asthma
I: pneumonia in children
what are the most frequent, occasional, and infrequent respiratory syndromes of coronavirus?
MF: common cold
O: exacerbation of chronic bronchitis and asthma
I: pneumonia and bronchiolitis
what are the most frequent, occasional, and infrequent respiratory syndromes of human respiratory syncytial virus?
MF: pneumoia and bronchiolitis in young children
O: common cold in adults
I: pneumonia in elderly and immunosuppressed patients
what are the most frequent, occasional, and infrequent respiratory syndromes of parainfluenxa viruses?
MF: croup and lower RT disease in young children
O: pharyngitis and common cold
I: tracheobronchitis in adults, lower RT disease if immunosuppressed
what are the most frequent, occasional, and infrequent respiratory syndromes of adenovirus?
MF: common cold and pharyngitis in children
O: outbreaks of acute respiratory disease in military recruits
I: pneumoia in children, lower RTand disseminated disease in immunosuppressed patients
what are the most frequent, occasional, and infrequent respiratory syndromes of influenza A?
MF: influenza
O: pneumonia and excess mortality in high-risk patients
I: pneumonia in healthy individuals
what are the most frequent, occasional, and infrequent respiratory syndromes of influenza B?
MF: influenza
O: rhinitis or pharyngitis alone
I: pneumonia
what are features of viral respiratory infections?
- virions reach RT by fomites or aerosol transmission
- epithelial cells are first site of virus host interaction
- infected epithelial cells release cytokines that cause typical viral symptoms (fever, aches)
explain the temperature differential in viruses?
different temps in upper and lower RT have pathogenic consequences
- rhinovirus replicate preferentially in URT
- differential basis for attenuated viral vaccines like FluMist
explain the age effect of viruses
infants and elderly have more severe respiratory i infections
what are patterns of virus replication in RT for acute infection?
confined to respiratory mucosal surface
- picornavirus (rhinovirus)
- coronavirus
- paramyxovirus (parainfluenza and RSV)
- orthomyxovirus (influenza)
what are patterns of virus replication in RT for persistent infection?
on respiratory mucosal surface
- EBV
- adenovirus
- papillomavirus
what are patterns of virus replication in RT for systemic infection?
dissemination after primary replication in RT
- paramyxovirus (mumps, measles)
- herpesvirus (EBV, VZV, HHV6, CMV)
- rubella
- picornavirus (polio)
- other viruses: bunya, arena, parvo, pox, reo
what are details about coronavirus?
named for “crown” of spikes
- (-)ssRNA virus
- most strains cause cold-like symptoms
- rare new strains cause lethal respiratory diseases
- -SARS, MERS (animal-human barrier)
naming between orthomyxovirus and paramyxovirus
myxovirus = mucus; bind to mucin protein on RBCs
- ortho: straight, proper, right (influenza is the “right” one)
- para: beside, resembling (measles is like orthomyxovirus, but not the same)
orthomyxoviridae
- representatives
- replication
- genome
- structure
- 1 genus (influenza) and 3 types (influenza A, B, C)
- nuclear replication
- segmented -ssRNA (easier rearrangement –> more serotypes)
- enveloped
paramyxoviridae
- representatives
- replication
- genome
- structure
- 3 genera
- -paramyxovirus: mumps, parainfluenza virus 1-4, newcastle disease virus
- -morbillivirus: measles, rinderpest, canine distemper
- cytoplasmic replication
- non-segmented -ssRNA (harder rearrangement –>less serotypes)
what causes the “influenza syndrome” of respiratory viral diseases?
viral replication in RT causes a T cell response and interferon induction
-this along with the desquamation of (dying) mucus-secreting and ciliated cells causes the symptoms
what is treatment for flu?
antiviral drugs Tamiflu (oseltamivir) and Relenza (zanamivir) for influenza A and B
what is prevention for flu?
- Fluzone (trivalent infactivated vaccine)
- Flumist (live attenuated vaccine)
explain what croup is
- what causes it
- when it starts, and in who
- treatments and complications
laryngotracheobronchitis caused by parainfluenza virus and RSV
- peak incidence in winter
- starts like a cold in adults and infants (latter may develop distinctive barking cough)
- commonly treated at home with steam and humidifiers
- complications include pneumonia and respiratory distress
explain the morphology of adenovirus, and who it affects
icosahedral, naked DNA virus with 100 serotypes,47 of which infect humans
- widespread in nature, infecting birds, mammals, humans
- most people infected by at least 1 type by age 15
- adenovirus infections are very common, most are asymptomatic
- most infections involve RT, GIT, or eye
explain the diseases that come from adenovirus
- respiratory diseases
- febrile UT infection
- pharyngoconjunctival fever
- acute disease
- pertussis-like disease
- pneumonia - acute hemorrhagic cystitis
- epidermic keratoconjunctivitis
- gastroenteritis
what are disease mechanisms for adenovirus?
- transmitted by aerosol, close contact, fecal-oral route, fingers, and ophthalmologic instruments (eye infections)
- virus infects mucoepithelial cells of RT and GIT, conjunctiva, cornea
- virus persists in lymphoid tissue (tonsils, adenoids, Peyer’s patches)
- Ab is essential for recovery from infection
what is the transmission of adenovirus?
- respiratory droplets, fecal matter, fomites
- close contact
- poorly sanitized swimming pools
what is the distribution of adenovirus?
ubiquitous, w/o seasonal incidence
what are the at risk or risk factors for adenovirus?
- children < 14 years
- day care centers, military camps, swimming clubs
what are the vaccines or antiviral drugs for adenovirus?
live, attenuated vaccine used only for military (serotypes 4 and 7)
