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51 Cards in this Set

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  • Back
What kinds of infection orthomyxovirus and paramyxovirus normally cause?
Nonviremic infections
True or False:
Paramyxoviruses do not cause systemic infection
False- Mumps and measles are paramyxoviruses that cause systemic infections with viremia as an essential step in pathogenesis.
True or False:
Mumps and measles have a short incubation period.

Why or why not?
False: Incubation periods of mumps and measles viruses are longer because veremia is an essential step in their pathogenesis, and thus, they require cycles of multiplication in several sites.
If one recovers from mumps or measles, would he/she acquire life-long immunity?
What about subclinical infection?
Yes, becaues mumps and measles require viremia, neutralization by IgG and thus life-long immunity will be induced. This is true for subclinical infection as well.
Which virus is antigenically related to the parainfluenza viruses?
1) mumps virus
2) influenza virus
3) measles virus
4) none of the above
mumps virus - mumps and measles are typical paramyxoviruses with helical nucleocapsid contaiing munius stranded RNA and an envelope containing virus-specified glycoproteins.
Do paramyxoviruses contain H-antigens as their glycoproteins? I.e. can we titre the relative concentration of the virus in the sample using hemagglutination inhibition?
Yes, paramyxoviurses, including mumps and measles contain a minus-stranded RNA in a helical nucleocapsid and an envelope with H-antigens.
Is it likely to see an antigenic-variation in mumps and measles viruses?
No, because the viral RNA is in one piece, recombination is very rare.
How long is an incubation period of mumps virus?
What follows the incubation period?
Three weeks;
1) Parotiditis
2) a prodromal period of fever, malaise and anorexia
What is the usual presenting symptom of mumps?
Mumps virus grows in the enlarged painful parotid salivary glands and is excreted in saliva several days before and after swelling of the salivary gland beings.
Are there subclinical infections of mumps?
~30% of infections are subclinical.
What causes pain on the face when one is infected with mumps?
Pressure within the parotid gland capsules cause the pain.
What is orchitis mumps?
A mumps infection in the testis.
What is the incidence rate of orchitis due to mumps?
10% of infected males past puberty show orchitis but it rarely results in sterility.
What organs are affected by mumps virus?
parotid glands and meninges (aseptic meningitis)-common
pancreas, ovary - uncommon

All have a generally benign course.
What is kind of vaccine used to immunize against mumps infection?
A live-attenuated vaccine grown in chick embryo culture.
Is a single subcutaneous dose of mumps vaccine sufficient to provide life-long infection?
It works for ~80% to 90% of times, but to be sure you ought to get a second vaccination of mumps virus. e.g. 2005 epidemics on college campus. Majority of the students infected with mumps have been previously vaccinated only once.
Is the live mumps vaccine a component of the MMR pediatric vaccine?
Is world-wide eradication of mumps a high priority? Why or why not?
World-wide eradication of mumps is a low priority because the morbidity and mortality are low with this infection.
Describe the transmission route of mumps.
1) Saliva droplets from an mumps-infected person infect the upper respiratory tract
2) Primary multiplication in respiratory epithelium and local lymph nodes
3) Viremia
4) Infection of the salivary glands to the Stensen's duct
4) 18 days after the initial infection, swelling and fever begins. (incubation period)
What is the most contagious diseases known?
Measles: No asymptomatic infection. No one escapes!
True or false:
Measles almost never causes subclinical infections.
Describe the typical cycle of epidemics prior to the vaccine era.
The epidemics followed an increase in the number of susceptibles. When the concentration of children under the age of 3 rises high enough to break down herd immunity, measles virus is disseminated and an epidemic occurs.
List some prodromal symptoms of measles virus.
Cold-like symptoms
Koplik spots (lesions on the buccal mucosa)
What would be the specific symptom alerting measles infection?
Rash accompanied by various prodromal symptoms. Rash moves down from the head to lower extremities.
How long is the incubation period of the measles?
14 days- precisely timed event
What is thought to cause the rash due to mealsles virus infection?
The pathogenesis is not confirmed, but widely agreed that: After infecting the cells lining the upper respiratory tract, the virus enters the blood and infects reticloendothelial cells. Then, cytotoxic T cells attacking the measles virus-infected vascular endothelial cells in the skin cause rash.
True or false:
Virus excretion from repiratory tract and in tears and urine occurs primarily after the appearance of the rash.
Virus excretion from repiratory tract and in tears and urine occurs for a few days before and after appearance of the rash.
True or false:
Immune response eliminates viral excretion and generally confers life-long immunity only if IgA immunity has been solicited.
Immune response to measles virus eliminates viral excretion and generally confers life-long immunity. Cell-mediated immunity is more potent form of immunity against measles.
True or false:
Shortly after the rash appears, the virus can no longer be recovered and the patient can no longer spread the virus to others.
What would you expect a child who was positive for tuberculin test to show in the same test when contracted with measles?
The child is likely to have a negative result in the tuberculin test due to the transient loss of cell-mediated immunity called "ANERGY." In measles-infected patients, the suppression of cell-mediated immunity is shown.
What does measles virus require to survive?
a large, concentrated human population
What are common complications of measles in the developed countries?
(1) encephalitis
(2) Pneumonia
(3) Rare giant-cell pneumonia without rash
What are common complications of measles in the developing countries?
(1) high mortality(5~25%)
(2) severe hemorrhagic rash

*death commonly results from a fatal synergism of measles and MALNUTRITION.
What is the type of measles vaccine used nowadays?
An injected live-attenuated vaccine is now used as a component of the MMR pediatric vaccine which is given several times. A killed vaccine resulted in "atypical measles," which is more severe than ordinary measles.
Which is the age group the most susceptible to measles?
The disease is common in all ages but it tends to start with infants and young children under 3.
Describe the typical symptoms/ progression of SSPE.
An insidious onset of intellectual deterioration, psychological disturbances with slow decline interrupted by remission. It is generally fatal with terminal paralysis and blindness.
In which age group is SSPE observed?
SSPE is a disease seen in school-age children but is rare.
All with SSPE had an uncomplicated case of measles 4 to 17 years earlier (LONG INCUBATION PERIOD). Many had measles at a very early age (age 2 and younger).
What is unusual about the serum sample of SSPE patients?
SSPE patients have very high antibody titers to measles virus. Their CNS contains measles viral antigen.
Is it possible to contract SSPE with the live measles vaccine?
Yes, but the incidence of SSPE due to vaccine (< 1 per million) is lower than the incidence following natural measles (one per 100,000).
What are four characteristics of slow viruses?
a. long incubation period (months or usually years)
b. relentless progressive abnormalities
c. generally localized to a single organ
d. genetic constitution of the host often critical
Fill in the blank:
The study of the scrapie agent in adult sheeps led to the discovery of ( ).
What are prions?
Prions are proteins that are highly resistant to proteolytic enzymes. They are remarkably resistant to UV irradiation, formaldehyde, alkylating agents, etc unike viruses we know of.
True or false:

The agent that caused scrapie can be transferred to mice with incubation period of less than a year.
The "slow viruses" are a hetrogeneous group.
Explain the above statment and give an example.
Some are likely to be conventional (like measles virus and SSPE), while other are atypical (like prions and Scrapie)
What is kuru?
Kuru is a progressive degenerative disorder of the CNS, especially the cerebellum. It is limited to a small stone-age tribe in new Guinea Fore people.
What is the symptom/ neuropathology of kuru?
Spongiform encephalopathy
Is it possible to reproduce symptoms of kuru from human to chimps? How?
It is possible to reproduce in chimps by the intracerebral injection of brain material from human cases.
The most common human spongiform encephalopathy is....
Creutzfeld-Jacob disease.
Can CJ disease be transmitted to primates?
What are some causes of Creutzfeld-Jacob disease?
a. inherited mutation (rare)
b. spontaneous mutation with no established cause (most)
c. Iatrogenic (inadvertently caused by physicians in transplants from a donor with undiagnosed diseases or contaminated surgical instruments)
True or false:
Atypical human Creuzfeld-Jacob disease and "mad cow disease" (a spongiform encephalopathy of cows) has been linked epidemiologically.