Rubella Virus: Structure, Multiplication, and Symptoms

• Rubella virus is the sole member of the genus Rubivirus and resides in the family Togaviridae
• Rubella is also known as German measles or third-day measles

Rubella Virus Structure

• Rubella virus is a spherical, positive-sense, single-stranded RNA virus
• It is 40-80 nm in size
• It exhibits spike-like, hemagglutinin-containing surface projections
• The virus contains an electron-dense 30 to 35 nm core surrounded by a lipoprotein envelope

Rubella Multiplication

• Rubella virus is Group IV
• • strand parental RNA creates non-structural proteins such as RNA polymerase via ribosome
• Minus strand parental RNA is created by + strand parental RNA
• • mRNA is created by - strand parental RNA via RNA pol
• Structural protiens like Capsids are created by + mRNA via ribosome
• • strand progeny RNA is created by - strand parental RNA

Symptoms

• Symptoms typically manifest within 14 to 21 days post-infection
• The characteristic rash initiates on the face, progresses to the trunk and limbs, and generally fades within 3 to 5 days, and may be itchy
• Other symptoms include a stuffy or runny nose, headache, mild fever, red or inflamed eyes, nerve inflammation, enlarged and tender lymph nodes, and aching joints
• Rubella rarely affects young infants or adults over 40, the infection can occur at any age
• Adults affected by Rubella may have more severe symptoms

Congenital Rubella Syndrome (CRS)

• CRS occurs when a pregnant woman contracts the rubella virus, it passes through the placenta to the unborn child
• The rubella virus can traverse the placenta and move throughout the fetal circulation, potentially destroying cells or preventing their division
• CRS can result in pregnancy loss, stillbirth, or severe damage to the developing fetus
• Effects on the infant can include eye problems, hearing problems, and heart damage
• 90% of babies are born with CRS
• 20% of pregnancies can result in spontaneous abortion and stillbirth/foetal death

Conditions of Congenital Rubella Syndrome (CRS)

• Deafness
• Hearing impairment
• Cataracts
• Congenital heart disease
• Conjunctivitis
• Anemia
• Hepatitis
• Developmental delay
• Damage to the retina (retinopathy)
• Unusually small head, lower jaw, or eyes
• Liver, spleen, or bone marrow issues
• Low birth weight
• Autism.
• Schizophrenia
• Learning difficulties
• Type 1 diabetes

Diagnosis

• Diagnosis may be suggested by the presence of a typical rash and lymph node enlargement
• Laboratory diagnosis typically involves serologic studies
• Detection of IgM and/or fourfold antibody rises
• The presence of specific IgM antibodies indicates recent rubella infection
• Congenital rubella is diagnosed in neonates through virus isolation or blood testing
• Affected neonates have circulating antibodies, including transplacentally acquired maternal IgG and actively produced fetal and neonatal IgM
• Persistence of IgG antibody beyond 6 months or detection of IgM antibody is diagnostic for CRS

MMR Vaccination

• Vaccination is the only way to prevent contraction
• Includes measles and mumps vaccination
• The vaccine is live attenuated and delivered at 12-15 months, includes a second dose at 4-6 years
• All adults who have not had the MMR vaccine should receive it

Side Effects of the MMR Vaccine

• Side effects are minimal
• Approximately 15% of people will develop a mild fever 7-12 days post-injection
• 5% develop a minor rash
• Teenagers and adult women may experience joint aches
• Severe reactions occur in fewer than 1 in 1,000,000 cases
• There is no link between the MMR vaccination and autism