rubella

 

Pathogenesis

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Transmission:

• Rubella is spread via respiratory droplets in the air from person to person.
  • A person is most contagrious 1 week after the onset of symtpoms, and one week after the rash appears.
• Transplacental infection of fetus during pregnancym may result in Congenital Rubella Syndrome (CRS) in infants which is a  group of  physical abnormailities experiencd by the infant.

Incubation Period:

• The incubation period of Rubella is anywhere from 12-23 days. 
• The virus replicates in the upper respiratory tract and the cervical lymph nodes.
• After incubation, characteristic signs and symptoms appear (see signs and symptoms).

Duration:

• Rubella usually lasts (with rash) 1-3 days.
• Lymph nodes may be swollen for up to 2 weeks after the illness occurs.
• In unimmunized adults, the disease can last up to 1 week.

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Signs and Symptoms

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Symptoms in the general population:

• Erythematous
• Maculopapular rash on face, trunk, and extremities (resolves within 3 days)
• Low grade fever (99-100ºC)
• Malaise (feeling of discomfort)
• Swelling of lymph glands
• Upper respiratory infection (lasting 5 days)
  • Including coughing, sneezing, and runny nose.
• 25-50% of patients with Rubella infection appear asymptomatic!

Image of typical Rubella rash on the abdomen
Image Courtesy http://www.nlm.nih.gov/medlineplus/rubella.html

Symptoms in pregnant women:

• Arthralgias and arthritis (acute forms)
• Encephalitiis (inflammation of the brain)
• Thrombocytopenia (few platelets in the blood)
• Myocarditis (very infrequent)
• Birth defects in the fetus
• 20% damage to fetus if acquired in early pregnancy
• Affects on fetus include: 
  • Congenital Rubella Syndrome (CRS): deafness, mental retardation, microcephaly (small brain size), cataracts, heart defects, liver, and spleen damage
  • Miscarriage
  • Stillbirth

Images of Congenital Rubella Syndrome in infants after birth.
Image courtesy of http://www.nlm.nih.gov/medlineplus/ency/imagepages/17253.htm