MEASLES VIRUS

Structure & Property	Transmission	Pathogenesis	Clinical findings	Laboratory diagnosis	Treatment	
Family: paramyxovirus

Genome: single-strand RNA, negative polarity.

Size: 120-250nm

Helical nucleocapsid

Lipoprotein envelope:
- hemagglutinin
- fusion protein

Single serotype.

Hemagglutinin is the antigen against which neutralizing antibody is directed.	Transmitted via respiratory droplets produced by coughing and sneezing.

Infectivity: prodromal period and for a few days after the rash appears.

Humans are the natural host.	Infects cells lining the upper respiratory tract.

Enters blood and infects reticuloendothelial cells, where it replicates again. 

Spreads via blood to the skin.

Immunity to measles is lifelong.

Has a suppressive effect on cell-mediated immunity.

Maternal antibody passes the placenta, and infants are protected during the first 6 months of life.

	Incubation period: 10-14 days

Prodromal syndromes:
- nasal discharge
- suffusion of eyes

Main illness:
- fever
- maculopapular rash lasting 2-5 days.
- Koplik’s spots on buccal mucosa. (diagnostic feature)

Complications:
Respiratory: bronchitis, bronchiolitis, croup, bacterial otitis media.

Giant cell pneumonia:
- invasion of lungs by measles virus.
- usually fatal.

Subacute sclerosing panencephalitis (SSPE):
- personality changes, intellectual impairment.
- convulsions, myoclonic movements.
- coma and death.

Post-infectious encephalitis: drowsiness, vomiting, headache, and convulsions.
	Haemagglutinates and hemolyzes monkey erythrocytes.

Grows in human embryo lung cells and primary monkey kidney cells with syncytial CPE of multinucleated giant cells.

Serology:
- complement fixation.
- immunofluorescence to detect measles IgM.

SSPE: demonstration of measles antibody in CSF.

Direct demonstration of viral antigen by immunofluorescence in nasopharyngeal aspirates.	No antiviral therapy available.

Immunization with live, attenuated vaccine:
- given to children at 15 months of age.
- should not be given prior to 15 months as maternal antibody in child can neutralize virus.
- contraindicated in immunodeficient individuals and pregnant women. 

Immunoglobulin contains measles antibody and can be used to confer immediate immunity to infants and to other vulnerable individuals exposed to measles.