Measles, Mumps, Rubella Flashcards
(46 cards)
What is the structure of the paramyxoviruses (measles, mumps)?
Single stranded RNA in a helical nucleocapsid
Surrounded by lipid bilayer (wimpy) envelope
Envelope studded with virus encoded glycoproteins
How is measles spread?
Respiratory droplets
What is the pathogenesis of measles?
Infects respiratory epithelial cells of susceptible hosts
Incubates (virus replicates) and spreads to lymph nodes
Primary viremia infects respiratory epithelium and T cells
How long is the incubation period of measles?
10 days (until fever, rash appears day 14)
What are the first clinical manifestations of a measles infection?
3 C’s: Cough, coryza (runny nose), and conjunctivitis
Fever
What clinical manifestations of measles infection appear later on?
Koplik spots on buccal mucosa
Rash appears 4 days after fever
What are the characteristics of a measles rash?
Erythematous, maculopapular, coalesces to become confluent
Begins at hairline and spreads downwards
What makes measles such a deadly illness?
Causes transient but profound immunosuppression, making hosts susceptible to secondary infections
Also causes encephalitis
(sub acute scleroising panencephalitis can appear years later)
What is the most common cause of death in someone with a measles infection?
Pneumonia
What increases the severity of the measles infection?
Malnutrition Immunodeficiencies (HIV) Vitamin A deficiency
How is measles diagnosed?
Clinical
Serology (IgM, paired acute-convalescent IgG)
Viral culture (difficult, can tell you if strains are related)
PCR
When is the measles vaccine given?
Given combined with mumps and rubella as MMR+/-V
Two doses given after 1 yo
(in endemic countries, vaccine given once at 9 mo)
What is the pathogenesis of mumps?
Infection in upper respiratory tract epithelium
Spreads to local lymph nodes
Viremia infects various sites (salivary glands, cochlea, seminiferous tubules)
CMI controls infection but also causes most of symptoms
How is mumps transmitted?
Respiratory droplets
When is someone with measles most infectious?
Before the rash appears (1-14 days after exposure)
When is someone with mumps most infectious?
2 days before salivary swelling to 5 days afterwards
What are clinical features of mumps?
1/3 asymptomatic
Characterized by swelling of salivary glands, particularly parotid
Can get swelling of other glandular tissue (testes)
What are complications of mumps infection?
Encephalitis
Deafness
Infertility
How is mumps diagnosed?
Clinical
Serology: IgM, IgG
Culture (saliva, CSF)
PCR (Can be positive after vaccine)
What family and genus is Rubella in?
Togavirus family, Rubivirus genus (only member)
What is the structure of Rubella?
Single stranded RNA
Lipid envelope (wimpy)
Glycoprotein spikes on surface
How is Rubella spread?
Respiratory droplets
Vertical transmission
What is the pathogenesis of Rubella?
NOT cytolytic
Infects upper respiratory tract
Spreads to local lymph nodes
Antibody develops and CMI eliminates infection
How long is the incubation period of mumps?
2-3 weeks
