Measles Virus

Categorization
Class: Paramyxoviruses
Genome: RNA Virus, Negative ssRNA Virus Structure: Enveloped Virus
Transmission
  • Measles Virus is transmitted via inhalation of contaminated respiratory droplets and is highly contagious.
Pathogenesis
  • Like all paramyxoviruses, measles virus first infects cells of the upper respiratory tract following inhalation of infective respiratory droplets. From there the virus spreads hematogenously and infects cells of the immune system which then disseminate the virus to a wide variety of organs resulting in the characteristic skin rash and possible complications.
Clinical Consequences
  • A viral prodrome is typical of measles infection and is characterized by constitutional symptoms including a high fever along with cough, coryza, and conjunctivitis. Soon afterwards, pathognomonic "Koplik Spots", small bluish-white lesions on a red oral mucosa, appear only to disappear following the development of the skin rash. The characteristic skin rash of measles, consisting of pink non-pruritic maculo-papules, first appears on the head and face and progresses down the entire body to the feet only to disappear in the same sequence.
Complications
  • Most cases of measles resolve spontaneously within 7-10 days; however, in some individuals complications can arise due to dissemination of the virus via immune cells to specific organs.
  • Otitis Media: Frequently occurs in infected children
  • Pneumonia: Termed a "Giant-cell Pneumonia" due to the viral F Protein-mediated development of multi-nucleated syncytial cells
  • Acute Encephalitis: Infection of the CNS can be potentially life-threatening or cause long-term neurological damage
  • Subacute Sclerosing Pan-Encephalitis (SSPE): Is an extremely slow form of progressive encephalitis which can have a course of months to years, leading to the insidious onset of mental deterioration.
Prevention
  • Attenuated live measles virus is part of the MMR Vaccine and results in excellent immunity for nearly a life-time.