Viral RTIs Flashcards
How are viral RTIs transmitted?
Droplet (not aerosol transmission) and then contact (inoculation) with the eyes or nose
- can survive on fomites and non porous surfaces for hours
in what types of places are outbreaks of viral RTIs common?
daycares, long term care facilities, in the community in general
based on the study discussed, what is the relative role of hands in the transmission of parainfluenza virus? what about rhinovirus?
relatively low for parainfluenza but high for rhinovirus
is it easy or difficult to transmit rhinovirus by kissing?
difficult actually
Cold viruses can linger on hotel room surfaces for how long after contamination…
18 hours
In the rhinovirus/hotel room study, what were common locations to be contaminated?
door handles, light switches, faucets, telephones and TV remote controls
What two viral and two host characteristics controbute to the severity of a RTI?
virus: inoculum size and virulence traits
host: immune system and any comorbidities
What is the most common viral cause of an RTI? which one is #2
- rhinovirus
2. coronavirus
What are a couple other common viral causes of RTIs? which two cause severe disease?
Coronavirus, parainfluenza virus, adenovirus
Respiratory syncytial virus (RSV) and Influenza virus (FluA and FluB) cause severe illness
What type of viruses can cause RTIs in immunocompromised individuals?
Herpes virus family (HSV, VZV, CMV, EBV)
What predisposes immunocompromised patients to developing antiviral resistance?
prolonged periods of virus shedding
What is the best form of specimen collection for upper respiratory tract infections ?
Nasopharyngeal swabs or aspirates
What is the best form of specimen collection for lower respiratory tract infections?
Bronchial alveolar lavages (BAL)
What kind of swab is the best to use? what kind of media is required?
a flocked swab is best
transport media (doesn’t support growth) is required
What is the best laboratory diagnostic technique for detecting respiratory viruses?
Molecular methods like quantitative RT-PCR
What trio of diseases can quantitative RT-PCR be used to quickly diagnose? How long does it take?
FluA/B/RSV
about 45 min
What is conventional multiplex RT-PCR used for? how long does it take?
used if the typical RT-PCR does not detect Flu A/B or RSV then it can be used to screen for 15 different RTI causing viruses simultaneously
About 6 hours
what family of viruses does rhinovirus belong to? what type of genome does it have? what morphology?
Picornaviridae family
ssRNA(+), non-enveloped
How many different serotypes of rhinovirus are there?
> 100 serotypes
what family of viruses does coronavirus belong to? what type of genome does it have? what morphology?
Coronaviridae family
ssRNA(+), enveloped
What are two coronaviruses that have caused more severe illness?
SARS and MERS-CoV
what family of viruses does enterovirus belong to? what type of genome does it have? what morphology?
Picornaviridae family
ssRNA(+), non-enveloped
How many species and how many serotypes of enterovirus are there?
12 species
> 100 serotypes
Enterovirus typically causes mild respiratory illness but has been linked with more sever cases of…
aseptic meningitis*, myocarditis, acute flaccid paralysis (polio type illnesses with paralysis)
what family of viruses does Respiratory Syncytial Virus (RSV) belong to? what type of genome does it have? what morphology?
Paramyxoviridae family
ssRNA-, enveloped
RSV is the most common cause of…
bronchitis in children
Do people have longterm immunity to RSV?
no, this is why adults can get it from children relatively easily
What is the name of the preformed monoclonal antibody used to treat RSV? what type of antibody and what type of immunization is this?
Palivizumab
IgG
Passive immunization
what family of viruses does Parainfluenza virus belong to? what type of genome does it have? what morphology? How many types are there?
Paramyxoviridae family
ssRNA(-), enveloped
4 types (1 to 4)
What is an example of a DNA virus we discussed?
Adenovirus
Is adenovirus enveloped or non-enveloped
Enveloped
How many types of adenovirus have been identified?
over 60
What are 4 symptomatic presentations of an adenovirus infection?
URTIs or LRTIs
Conjunctivitis
Hemorrhagic cystitis
Diarrhea
What two types of adenovirus cause diarrhea?
40 and 41
what family of viruses does Influenza virus belong to? what type of genome does it have? what morphology? How many types are there?
Orthomyxoviridae
ssRNA- , enveloped
**Segmented genome
How many types of Flu are there?
3 - A, B, and C (C is very rare)
Which of the types of flu has pandemic potential? Which causes more severe disease?
Flu A does both
What two surface structures are used to subtype the different flus?
Hemagglutinin (HA)
Neuraminidase (NA)
What symptoms are common for the flu but rare for other respiratory infections?
Flu: headache, fever, malaise, fatigue, weakness, muscle aches
Others: nasal congestion and discharge
What are the two classes of antiviral treatments of influenza? what is an example of each?
- M2 inhibitors - Amantidine
2. Neuraminidase inhibitors -oseltamivir and zanamivir
How does amantidine work?
prevents the formation of M2 proteins which are required to make proton channels for the virus to uncoat
Why isn’t amantidine used anymore?
- All Flu B strains are resistant naturally because they don’t have M proteins
- All H3N2 Flu A human strains are resistant naturally
- Pandemic H1N1 is resistant
What is the issue with the neuraminidase inhibitors?
need to be used within 48 hours of infection which is very difficult to manage clinically
What are the trivalent/quadrivalent flu vaccines effective against?
Influenza A (pH1N1)
Influenza A (H3N2)
Influenza B
- Victoria and Yamagata lineages
Why does the flu vaccine need to be updated every year ?
because of antigenic drift
What is antigenic drift? in what strains does it occur?
can occur in both Flu A and Flu B
Due to mutation over time in surface glycoproteins
What is the role of hemaggluttinin (HA) ? what does it bind?
Hemagglutinin (HA) binds sialic acid receptors on cells to facilitate entry
What is the role of neuraminidase (NA)?
Neuraminidase (NA) cleaves HA/sialic acid = vial release
What is antigenic shift? in what strains does it occur ?
Genetic reassortments between avian/swine/human
Only in Flu A
What is the result of antigenic shift?
pandemics due to no existing immunity to the viral antigens
What is the natural reservoir of influenza?
Aquatic birds
which animal acts as the “mixing ground” for flu viruses? why?
pigs because they have both avian and human Flu receptors
how many different HA and NA types are there naturally in birds?
18 HA and 9 NA in birds naturally
which strain of pandemic flu was a triple reassortment?
H1N1
- avian, human, and swine
What strain of flu is avian flu?
H5N1
How is avian flu transmitted ? When are people most likely to be exposed?
direct contact with infected poultry, or objects contaminated by their feces
Exposure is most likely during poultry slaughter and cooking preparation
Can avian flu be transmitted from human to human?
NO
What is the difference in disease severity and spread between H1N1 and H5N1?
H1N1 spreads quickly but rarely fatal
H5N1 spreads very minimally but tends to be fatal
What is H7N9?
An avian flu that was first reported in humans in March 2013, in China – linked to 144 cases; 46 deaths
H7N9 vaccine developed in Oct 2013
