Flashcards in Paramyxoviridae Deck (53):
What are the five viruses in the paramyxoviridae family?
Measles, mumps, parainfluenza, RSV, and human metapneumovirus
Of measles, mumps, and rubella, which are paramyxoviridae?
Measles and mumps, rubella is togaviridae
What is measles virus also known as?
What is rubella virus also known as?
What are Koplik's spots?
Small bluish-white elevations on a red, erythematous mucosa
Characteristic of measles virus before the rash appears
What are the four main symptoms of measles virus?
Does measles virus lead to congenital birth defects?
No, but mumps and rubella do
Of measles, mumps, and rubella, which can cause congenital birth defects?
Rubella and Mumps
Rubella causes major congenital defects, mumps can possibly cause congenital defects
Measles virus does not cause congenital defects
What types of vaccines are available for MMR?
The 4 major characteristics of paramyxoviruses? (pos/neg, ss/ds, env/non-env, RNA/DNA)
enveloped (-) ssRNA
Name a virulence factor common to all paramyxoviruses
F or fusion protein
This protein forms syncytia, the F must be cleaved by proteases into F1 and F2, which act to fuse the host membrane to the virus lipid envelope that allows the nucleocapsid to enter the cytoplasm
Measles (morbillivirus) virus has which virulence factor(s)?
H and F
hemagglutinin and fusion
Mumps and parainfluenza (paramyxovirus) have which virulence factor(s)?
H, N, and F
hemagglutinin, neuraminidase, and fusion protein
RSV and human metapneumovirus have which virulence factor(s)?
F (fusion) and G
G is a large viral attachment protein that is neither hemagglutinin nor neuraminidase
How is measles (morbillivirus transmitted)?
Virus is shed from the respiratory tract before the rash even begins.
How are young infants protected from measles (morbillivirus)?
Maternal antibody is transplacentally acquired during gestation
What are the four major clinical symptoms of measles (morbillivirus), and when do they appear?
cough, conjunctivitis, coryza, and Koplik's spots.
CCC + photophobia are the prodrome.
K + rash are later
What does the measles rash look like and how does it progress?
a blotchy, purplish, generalized rash -- usually in a child with a runny nose and sore eyes
The rash is red, flat to slightly maculopapular
The rash spreads from the forehead to the face, neck, and torso and reaches the feet by the third day.
How do we diagnose measles (morbillivirus)?
Usually by physical symptoms.
In stained smears, multinucleated giant cells can be seen.
In serologic tests, hemagglutination assays or viral neutralization assays can be done.
What is the treatment of measles (morbillivirus)?
Passive immunization may help to lessen infection, otherwise supportive care
What are some complications of measles virus?
10-20% of measles infections have severe consequences:
- otitis media and pneumonia 2dary to bacterial infection are the most common
- encephalitis = worst complication
- giant cell pneumonia
- infection during pregnancy does not lead to birth defects but may lead to spontaneous abortion
- SSPE = a slowly progressive, degenerating neurologic disorder with scarring and demyelination of brain tissue (subacute sclerosing panencephalitis)
What is SSPE and how do patients get it?
Subacute sclerosing panencephalitis is a slowly progressive, degenerating neurologic disorder with scarring and demyelination of brain tissue. Untreatable.
Patients may get this secondary to measles infection.
What is the vaccine for measles (morbillivirus)?
MMR, live-attenuated, given at 12-15 months
Is Rubella a paramyxovirus?
No, it's a member of the toga virus family. We speak about it with paramyxoviridae due to it's comparisons to measles virus
The 4 major characteristics of Rubella virus? (pos/neg, ss/ds, env/non-env, RNA/DNA)
Who is the MMR vaccine contraindicated in?
How is Rubella spread?
respiratory aerosols or maternal-fetal transmission due to viremia
What are the clinical symptoms of Rubella?
Lymphadenopathy first, fever and rash later
The lymphadenopathy coincides with viremia
Describe the rubella rash?
Discrete rash begins on the face and neck, then spreads to the trunk and extremities, similar to measles rash
How do we diagnose Rubella?
A physical diagnosis is unreliable, so we do serology with viral neutralization, HAI, or ELISA tests
Rubella has which virulence factor(s)?
What are some clinical findings in Congenital Rubella Syndrome?
cataracts/ocular deficits, heart defects, deafness, intrauterine growth retardation, failure to thrive, mortality within the first year, microcephaly, mental retardation
When would a Rubella infection be most dangerous for a fetus?
30% of infections in the first trimester result in fetal illness and fatality, infections after 3-4 months are less severe
What virulence factors does mumps have?
HN, NA, and F
What are some clinical symptoms of mumps?
inflammation of salivary glands, unilateral epididymoorchitis, aseptic meningitis (relatively frequent), encephalitis (rare)
What is the most common cause of aseptic meningitis?
Does mumps cause congenital defects?
It may occur if mumps is acquired during pregnancy
How do we diagnose mumps?
Mostly by clinical signs, but we have a viral detection assay and serology (ELISA or indirect immunofluorescence)
Do we have a mumps vaccine?
MMR - three live-attenuated viruses, very effective
Is there any treatment for mumps?
No acute treatment or antiviral therapy :(
What does the parainfluenza virus cause?
mild cold-like symptoms in adults, more serious LRTI or URTI in children (croup)
How prevalent is croup, and what virus causes it?
Croup is caused by parainfluenza virus.
2-3% of parainfluenza cases in children will cause croup.
50% of all cases of croup are caused by parainfluenza virus
What is the leading cause of LRTI in children under 3? Second leading cause?
2. Type 1, 2, and 3 parainfluenza viruses
How do we diagnose parainfluenza virus?
Isolation of virus from nasal or respiratory secretions, check for CPE like cyncytia, hem adsorption
Immunofluorescence with labeled anti-viral antibodies or RT-PCR to detect virus
What is the treatment for parainfluenza virus?
Supportive treatment, no vaccine or antivirals
What is the most frequent cause of fatal acute respiratory infection in infants and young children?
What virulence factors does parainfluenza virus have?
Just G (glycoprotein without HA, NA, or F)
What is special about virulence factor G that makes re-infection possible?
G protein undergoes antigenic changes, which makes vaccine development difficult
What are some clinical symptoms of RSV?
- can range from the common cold to pneumonia
- bronchiolitis, wheezing, lung hyperinflation
- mucous/fibrin/tissue plugs in small airways
How do we diagnose RSV?
detection of the viral antigen by immunofluorescence or enzyme immunoassays
How do we treat RSV?
- supportive care
- Ribavirin for premature or immunocompromised patients
- passive immunization with anti-RSV IgG
What is human metapneumovirus?
a paramyxovirus that produces similar symptoms to RSV