Viruses of Childhood Flashcards
Describe the MMR vaccine. How effective is it, and why?
The MMR vaccine contains live-attenuated versions of measles, mumps and rubella. It is highly effective, as each virus has only 1 antigenic type.
Measles
How is it transmitted? Describe its pathogenesis.
How does measles present on exam?
How prevalent is it today?
Measles
Inhalation of infected droplets; there is infection in the respiratory tract which spreads via lymphatics to viremia.
A characteristic rash (vesicular, maybe with petechiae or purpura), potentially croup, otitis media, pneumonia, blindness, and encephalitis.
There are only a few hundreds of cases per years, mostly outbreaks involving unvaccinated children.
Mumps
What type of virus is it? Describe its pathogenesis.
How does mumps present?
How prevalent is it today?
Mumps
It is a paramyxovirus that first infects the upper RT and then spreads via lymphatics (same as measles).
Usually asymptomatically, but more characteristically with parotitis and swelling of other glands. May have some meningeal involvement.
It is slightly more common than Measles–a few thousand per year.
Rubella
What type of virus is it? Describe its pathogenesis.
How does rubella present on exam?
How prevalent is it today?
Rubella
It is a togavirus. Infects the upper RT then spreads via lymphatics.
Often asymptomatic, but sometimes a rash. Adults experience more severe illness and arthralgia, while congenital infections have many problematic symptoms (failure to thrive, cataracts, heart defects…)
Nearly eliminated; only a few cases per year.
Parvovirus
Describe its structure, shape, and baltimore type.
Describe its pathogenesis.
How does it present?
Parvovirus
Icosahedral, naked, and type II (ssDNA).
Starts in the upper RT. It infects blood cell precursors expressing the group P antigen (globoside). Replication requires the host cell to be in S phase, as the virus does not express polymerases.
Usually asymptomatic, but sometimes causes erythema infectiosum. May cause anemia (aplastic crisis). Nasty when transmitted to fetus (stillbirth, edema…)
What is bocavirus?
Bocavirus is a relatively new parvovirus that causes respiratory and GI infections.
How are viruses like Rotavirus, Norovirus, Poliovirus and Enteroviruses spread?
Which involve viremia in their pathogenesis?
Fecal-oral route.
Polioviruses and Enteroviruses (rota/noro stay in the GI, usually).
Rotavirus
Describe its structure, shape, and baltimore type. What about its antigenic groups?
Describe its protein products. Which are antigenic?
Rotavirus
It is a naked icosahedral dsRNA (type III) virus. It has A-E groups, of which A is a major human pathogen.
VP4 (P serotype) and VP7 (G serotype) are possible antigens for neutralization. VP6 too, and it is the antigen for which A-E grouping is assigned. NSP4 is an enterotoxin that increases [Ca2+]i, damaging junctions.
Rotavirus
Describe the two current vaccines.
How widespread are rotavirus infections now?
Rotavirus
RotaTeq is a maxture of 5 different live-attenuated (human-bovine) viruses. Rotarix is just 1 (human), with a shorter regimen.
On great decline; 2011-2012 had no true rotavirus season.
Norovirus
Describe its pathology.
What makes it particularly contagious?
Describe its structure. What are some targets of antiviral therapy?
Norovirus
Major cause of foodborne illness. Worse in winter seasons.
A low inoculum, prolonged asymptomatic shedding period, and environmental stability.
Like picornavirus–ssRNA+, makes a polyprotein. So, target the protease, and viral polymerase.
Enteroviruses
Describe their pathogenesis.
What symptoms do they all share?
What season is worst for enteroviruses?
Enteroviruses
Pharyngeal or fecal-oral transmission, involves viremia and can hit many different targets depending on the virus…
All enteroviruses cause undifferentiated fever and RTI, and potentially meningitis and paralytic disease.
Summer & fall.
Describe the symptoms of viral meningitis.
What virus most often causes this?
In infants: Fever, irritability, anorexia and difficulty to be awoken.
In adults: Headache, fever/chilld, N/V, stiff neck, photophobia.
Enteroviruses are the leading cause.
Coxsackie A virus
What type of virus is it?
What symptoms does it cause?
Coxsackie A virus
An enterovirus (so, a picornavirus).
Herpangina (mouth blisters), fever, sore throat, fatigue, loss of appetite, and vesicular lesions.
(“Hand/foot/mouth disease”)
