Lecture on Ruby Virus and Rubella

Overview

• Ruby Virus is the causative agent of rubella, formerly known as German measles.
• The disease is rare today due to the widespread use of a vaccine.
• Ruby Virus is a type of toga virus but unlike other toga viruses, it is not an arbovirus (not spread by arthropods).
• Rubella is spread person-to-person via aerosols, not vectors.

Characteristics of Toga Viruses

• Enveloped viruses.
• Positive-sense single-stranded RNA genomes.
• With the exception of ruby virus, other toga viruses are arboviruses.

Transmission and Epidemiology

• Before vaccination, rubella was common and spread through aerosols (coughing, sneezing).
• Humans are the only reservoir.
• Last pandemic occurred in 1964-1965.
• Over 90% of adults are now seropositive due to vaccination or past exposure.
• Vaccination is through MMRV or MMR vaccine, which includes measles, mumps, rubella, and varicella.

Importance of Vaccination

• Recent declines in MMR and MMRV vaccination rates have led to outbreaks of measles and mumps.
• Rubella is a concern particularly for pregnant women and their babies.

Impact on Pregnant Women and Fetuses

• Rubella can spread transplacentally from mother to fetus.
• Risk of congenital infection depends on the month of gestation.
  • Months 1-3: 18% risk
  • Month 4: 6% risk
  • Month 5: <2% risk
• After the fifth month, transplacental infections are rare.

Congenital Rubella Syndrome

• Infection can persist in infants for months or years if untreated.
• Symptoms include:
  • Neonatal purpura, cataracts, glaucoma (first two months)
  • Congenital heart disease (first trimester)
  • Cognitive deficits and deafness (first four months)
  • Retinopathy and cataracts (five months)
• "Blueberry muffin baby" syndrome refers to specific skin lesions.
• Congenital cataracts are more associated with rubella than CMV.

Diagnosis and Treatment

• Diagnosis primarily through PCR, especially important for vaccine-eligible diseases.
• Check titers in pregnant women to ensure immunity.
• No specific antiviral treatment for rubella.
• Highly effective vaccine available.

Comparison with Other Diseases

• German measles vs.
  • Roseola (human herpes virus): Rash after fever, not pruritic.
  • Measles: Rash starts at hairline, three C's (cough, coryza, conjunctivitis).
• Rubella rash: Starts on face, may be pruritic.

TORCHES Infections

• Rubella is part of the TORCHES acronym:
  • T: Toxoplasma
  • O: Other (includes Zika, parvovirus, varicella)
  • R: Rubella
  • C: Cytomegalovirus (CMV)
  • H: Herpes
  • S: Syphilis
• These are infections that cause significant congenital issues.