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Lect 6 a measles, mumps and rubella

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Lect 6 a measles, mumps and rubella

  1. 1. Measles, Mumps & Rubella (MMR(
  2. 2. • Infections with measles, mumps and rubella viruses are confined to man and occur worldwide. • Spread primarily via the aerosol route. • Each of these viruses exists as a single serotype • MMR vaccine contains all three of these viruses • .Measles & Mumps belong to family Paramyxovirus • RNA enveloped viruses Measles & Mumps
  3. 3. MEASLES (RUBEOLA) PATHOGENESIS AND DISEASE • The word measles is derived from German word for blister • Respiratory droplet infection. • Virus replicates in the upper/lower respiratory tract and lymphoid tissues leading to viremia and then growth in a variety of epithelial sites. • The virus is very contagious: maximum contagiousness is 2 to 3 days before onset of the rash. • The disease develops 1 - 2 weeks after infection.
  4. 4. Clinical Features • Measles is still a major killer in underdeveloped countries • Fever of 101o F (38.3o C) or above • Running nose (coryza) and cough • Conjunctivitis • Koplik's spots on mucosal membranes - small (1 - 3mm), irregular, bright red spots, with bluish-white speck at center.
  5. 5. • Maculopapular rash which extends from face to the extremities. • The infection is prostrating but recovery is usually rapid Clinical Features
  6. 6. Complications of Measles • Secondary bacterial infections: otitis media and bacterial pneumonia. • Pneumonia accounts for 60% of deaths from measles • Encephalitis (1 in 1000 cases) a few days after the rash disappears.
  7. 7. Subacute Sclerosing Pan encephalitis • Very rare (7 in 1,000,000 cases) • Develops 1 to 10 years after the initial infection. • Behavioral changes. • Impaired speech, vision and swallowing • A progressive, usually fatal disease • SSPE is associated with defective forms of the virus in the brain Complications of Measles
  8. 8. • Measles can cause temporary defects in the immune response; e.g. tuberculin- positive individuals may temporarily give a negative response. Complications of Measles
  9. 9. LAB DIAGNOSIS • The clinical picture • Serodiagnosis o IgM & IgG levels • Virus isolation in cell culture o The large syncytia, or multinucleated giant cells, result from fusion of cell membranes o Inclusion bodies, eosinophilic areas of altered staining in the cytoplasm
  10. 10. EPIDEMIOLOGY • Almost all infected individuals show signs of disease. • Only one serotype of measles and a single natural infection gives life-long protection.
  11. 11. MMR Vaccine • Is a live, attenuated combined vaccine to prevent measles, mumps and rubella. • Two doses are given to pre-school children: o The first dose at 12-15 months o The second booster dose at 3-5 years PREVENTION
  12. 12. PREVENTION & TREATMENT • Immune serum globulin: for at risk patients during an outbreak i.e. those <1 year with impaired cellular immunity o No antiviral therapy available for primary disease. Complications should be treated appropriately
  13. 13. MUMPS • The name comes from the British word "to mump", that is grimace • Clinically, mumps is an acute unilateral or bilateral parotid gland swelling that lasts for more than two days with no other apparent cause.  Other agents can also cause parotitis
  14. 14. Mumps Pathogenesis
  15. 15. Mumps Epidemiology Reservoir Human Transmission Respiratory droplet infection Communicability 7 days before to 9 days after onset of active disease • Worldwide distribution •Many (30%) infections are sub-clinical •No 'carrier state'.
  16. 16. Clinical Aspects of Mumps • Fever • Parotitis • Meningitis & encephalitis • Orchitis • Pancreatitis • Myocarditis • Nephritis • Arthritis
  17. 17. Mumps Complications CNS involvement 15% of clinical cases Orchitis 20-50% in post-pubertal males Pancreatitis 2-5% Deafness 1/20,000 Death 1-3/10,000
  18. 18. MMR Vaccine • Is a live, attenuated combined vaccine to prevent measles, mumps and rubella. • Two doses are given to pre-school children: o The first dose at 12-15 months o The second booster dose at 3-5 years PREVENTION & TREATMENT
  19. 19. Rubella (German Measles( History 1881Rubella accepted as a distinct disease 1941Associated with congenital disease Rubella virus first isolated 1961 1967Serological tests available 1969Rubella vaccines available
  20. 20. Rubella Virus RNA enveloped virus Member of the togavirus family Spreads by respiratory droplets In the pre-vaccination era, 80% of women were already infected by childbearing age
  21. 21. Clinical Features Rubella: Latin “little red” Maculopapular rash Lymphadenopathy Fever Arthropathy (up to 60% of cases(
  22. 22. Rash of Rubella
  23. 23. Risks of Rubella Infection During Pregnancy Preconception :Minimal risk 0-12weeks: 100% risk of fetus being congenitally infected  resulting in major congenital abnormalities. Spontaneous abortion occurs in 20% of cases. 13-16weeks: Deafness and retinopathy 15% After 16 weeks: Normal development, slight risk of deafness and retinopathy
  24. 24. Congenital Rubella Syndrome Classical triad consists of: Cataracts Heart defects Sensorineural deafness.
  25. 25. Transient Low birth weight, hepatosplenomegaly, thrombocytopenic purpura, meningoencephalitis, hepatitis, haemolytic anemia, pneumonia, lymphadenopathy Permanent Sensorineural deafness, Heart defects, Eye defects (retinopathy, cataract, microopthalmia, glaucoma), diabetes mellitis Developmental Sensorineural deafness, Mental retardation Congenital Rubella Syndrome
  26. 26. Outcome 1/3rd will lead normal independent lives 1/3rd will live with parents 1/3rd will be institutionalised The only effective way to prevent CRS is to terminate the pregnancy
  27. 27. Laboratory Diagnosis Diagnosis of acute infection Presence of rubella-specific IgM Rising titres of antibody (mainly IgG(
  28. 28. Typical Serological Events following acute rubella infection Note that in reinfection, IgM is usually absent or only present transiently at a low level
  29. 29. Prevention Antenatal screening Screening of all pregnant women attending antenatal clinics for immune status against rubella. Non-immune women are vaccinated in the immediate post partum period.
  30. 30. Prevention Since 1968, a highly effective live attenuated vaccine has been available with 95% efficacy Universal vaccination is now offered to all infants as part of the MMR regimen in the USA, UK and a number of other countries. Vaccination of schoolgirls before they reach childbearing age.