Mobiliviruses Flashcards
what are morbilliviruses?
RNA viruses in the family Paramyxoviridae
what are some morbilliviruses?
- measles
- rinderpest
- peste des petits ruminants (PPR)
- canine distemper virus (CDV)
- phocine distemper virus
what does measles cause?
a rash of the skin
what is rinderpest?
cattle plague - eradicated by global vaccination
what is PPR?
the ovine rinderpest
what is the CDV?
hard pad disease
what are the parts of a morbillivirus?
- fusion proteins
- haemagglutinin
- matrix protein
- nucleoprotein
- genome
who does measles infect?
Is restricted to humans
what is the incubation period of measles?
10-12 days
what does measles cause?
- red blotches on the skin 7-18 days post-exposure, starting at the hairline then spreading across the body
- appearance of “Koplik’s spots”
- fever, sneezing and coughing
what are other consequences of measles?
- ear infections (1/10)
- diarrhoea and pneumonia (1/20)
- febrile convulsions (1/200)
- encephalitis (1/1000)
- fatalities (1/500)
how transmissible is measles?
it has the highest transmissible
what is the global impact of measles?
one of the leading causes of death among young children even though a safe and cost-effective vaccine is available
how many deaths do measles cause?
122,000 in 2012
330 deaths/day; 14 deaths/h
how much did measles vaccines reduced deaths?
78%
when is the first dose of measles vaccine administered?
children 12 months or older
when is the second dose of the measles vaccine administered?
at least 4 weeks after the first dose
intended to catch the 5% of the vaccinates who failed to respond to the first dose
why do children have to be 12 months or older in order to receive the firs dose?
because the immune system has to be developed
what are the adverse reactions of the measles vaccines?
- fever 5-10%
- rash 5%
- joint symptoms 25%
- thrombocytopenia 1/25,000 doses
- parotitis rare
- encephalopathy 1/1,000,000 doses
what does the vaccine have?
ATTENUVAX, MUMPSVAX, MERUVAX
what is ATTENUVAX?
attenuated derivative of Edmonton strain (1954) of measles (passaged 40 times in chick embryo cells)
1968
what is MUMPSVAX?
attenuated derivative of the Jeryl Lynn strain of mumps passaged in chick embryo cells
1967
what is MERUVAX?
Wistar RA 27/3 strain of rubella virus passaged in human cells
1965
how do you make a mumps vaccine?
- take a throat swab form a patient with mumps
- inoculate into nutrient broth and use to infect embryonate hen’s egg
- after several passages in eggs, remove embryo and culture cells
- passage virus in chick embryo cells five times
- test virus for attenuation and immunogenicity in humans
how many hen’s eggs are required to make 300 million doses of influenza vaccine?
900 million
what is the acute phase of the canine distemper virus?
- transient fever 3-6 days post-infection with lymphopenia/leukopenia
- second round of fever, nasal and ocular discharges, lethargy and anorexia
- GI and respiratory signs, secondary bacterial infections
may develop encephalomyelitis
what can dog surviving the acute phase develop?
hyperkeratosis fot he footpads and nasal plans, enamel hypoplasia in incompletely erupted teeth
what may prolonged illness of cDV result in?
neurological signs: circling, head tilting, nystagmus, paresis/paralysis, seizures, involuntary muscle twitching, convulsions characterised by salivation, chewing movements
why is CDV dangerous?
it has a high potential for zoonotic spread
what happens if CDV is introduced into a population immune to measles?
infection fails to propagate (cross-protection from MeV to CDV)
what happens id CDV is introduced into an immunologically naïve population?
infection propagates rapidly
what is rubulavirus?
a genus within the family Paramyxoviridae
what is the incubation period of Human Parainfluenza virus (HPIV)?
2-7 days
what do HPIV-1 and HPIV-2 cause?
75% of croup (laryngotracheobronchitis), upper and lower respiratory tract illnesses, cold like symptoms
what does HPIV-3 cause?
bronchiolitis, bronchitis, and pneumonia
what does HPIV-4 cause?
mild to severe respiratory tract illness
how are children protected against HPIV?
most children 5 years of age and older have antibodies against HPIV-3 and approx. 75% have antibodies against HPIV-1 and HPIV-2
what is henopavirus?
a genus within the family Paramyxoviridae
what is pneumovirus?
a genus within the family Paramyxoviridae
what is the most important cause of bronchiolitis in children under 1 year of age?
Respiratory syncytial virus (RSV)
by when should children have a RSV vaccination?
by the age of 2
what does Metapneumovirus account for?
10% of respiratory tract infections that are not related to previously know aetiologies agents
how is metapneumovirus distributed?
worldwide and seasonal
who are at risk of severe disease and hospitalisation by metapneumovirus?
children, elderly, immunocompromised people
