- Rubella, also known as German measles, is a viral infection that can cause birth defects if a pregnant woman is infected. - It is caused by the rubella virus and spreads through respiratory droplets. While it usually causes a mild illness in children, it poses risks during pregnancy. - If a pregnant woman is infected during the first trimester, the virus can cross the placenta and infect the fetus, possibly resulting in congenital rubella syndrome which can affect multiple organs and body systems in the baby.

1. In the Name of GOD
Dr. Kaveh Haratian
Department of Microbiology and Immunology
Alborz University of Medical Sciences

2. Rubella
Postnatal infections

3. Introduction
• Derived from “rubellus” meaning “reddish” refers to pink rash.
• Also called “German measles”, first described in Germany during
18th. Century.
• Predominantly an infection of children, mild febril illness.
• Potent cause of fetal abnormality.
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4. Electron micrograph of rubella virus 4

5. Rubella virus 5

6. Classification of the Rubella virus
• Belongs to the family “Togaviridae”.
• This family has two genera:
• Alphaviruses : mosquito-born and infect a wide range of vertebrates.
• Rubivirus
• Only Togavirus that is not arbovirus.
• So, Rubella has a genus all to itself, Rubivirus.
• Lack of serological cross reactions with other togaviruses.
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7. Morphology, Genome and Replication
• Enveloped , ssRNA+ : 10kb , has a high GC content at 69.5%.
• 5` end has a 7-methyl guanosine cap:encodes a polyprotein that is
cleaved into 2 NS-proteins:p150 and p90 which involved in genome
replication and transcription.
• 3` end is polyadenylated: encodes for 3 structural proteins : E1,
E2 and C translated from a subgenomic RNA.
• Has two ORFs which are separated by 123 non-coding nucleotides.
• Unidentified receptor.
• 1 serotype and 7 genotype.
• Only infects humans.
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8. Rubella in children
• Spreading from respiratory secretions : viremia : present in stool
samples.
• Slight malaise
• Fever, 38 °C
• Suffusion of the conjunctivae
• Enlargment of lymph nodes in the suboccipital region, behind ears,
neck and axillae.
• Rashes after 1-2 d after above (but is not diagnostic).
• Pinkish maculae, upto 3mm, more discrete and regular than measles.
• First on face and neck , then on trunk
• Getting better in few days, encephalitis is very rare.
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9. Rashes of rubella on skin of child 9

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11. Rubella in Adults
• The main difference is polyarthritis .
• Hand and wrist, maybe larger joints(limbs).
• Some myalgia
• Arthropathy predominantly affects post-pubertal women.
• Clears up quickly, but may persist for months or even years.
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12. Epidemiology
• Of significant in women of childbearing age.
• Presents in all countries but its distribution varies in each one.
• About 70% of women has been infected in most populations.
• Effective immunization programmes radically alter the
prevalence.
• So, rubella is now a rare infection.
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13. Pathogenesis and pathology
• The portal of entry : respiratory tract
• IP: 14-16 d (10-21d).
• Postnatal rubella is not fatal.
• Animals van not be infected.
• Fetal infection : slowed growth rate of fetal cells infected by the
virus and apoptosis induced by viral proteins.
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14. Rubella perinatal infection
• Congenital rubella : primary infection of the mother during the
first 16 weeks of pregnancy:
• Absence of maternal antibody
• Virus readily crosses the placenta
• Event time is an important factor in outcome determination.
• During the 1st. Month, infection rate is about 100%.
• In full-blown congenital syndrome(expanded rubella syndrome)
has common features with other congenital infections (HSVs, CMV,
Toxoplasmosis…).
• Many systems are affected and prognosis is very poor.
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15. Modes of intrauterine and perinatal viral infections
Virus Trans placental During birth Shortly after birth
Rubella ++ - -
CMV + ++ ++ BM
HSV + ++ +
VZV ++ + +
Parvovirus ++ - -
Enteroviruses + late ++ ++
HIV + ++ + BM
HBV + ++ ++
HPV - ++ -
Influenza A(H1N1) + - +
++most frequent route, +less frequent route, BM: can be transmitted via breast milk
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16. Possible adverse outcomes of intrauterine and
perinatal viral infections
Virus Death of embryo/fetus Clinically apparent disease at or
soon after birth
Long-term persistence of
infection, with or without
clinical signs
Rubella + + +
CMV ? + +
HSV + + +
VZV + + +
Parvovirus + - -
Coxsackie B,
echovirus
+ + -
HIV ? + +
HBV - - +
HPV - - +
Influenza A(H1N1) + - -
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17. Most frequent physical signs of severe congenital
rubella, CMV and HSV.
Defects Rubella syndrome CMV HSV
Low birth weight + +
Hepatosplenomegaly,jaundice + + +
Thrombocytopenia,petechiae +
Purpurae +
Skin rashes +
Microcephaly + +
Intracranial calcification +
Meningitis, encephalitic +
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18. Most frequent physical signs of severe congenital rubella,
CMV and HSV.
Defects Rubella syndrome CMV HSV
Cataracts +
Choroidorethinitis + +
Lesions of pulmonary artery
and aorta
+
Bone defects +
Sensorineural deafness + +
Diabetes melitus +
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19. Immune response
• Specific IgM appears within a few days of rash, next IgG.
• IgM titer increases rapidly , peak about 10 days after onset.
• Diclining to undetectable amounts after several weeks.
• Specific IgM unvaluable for diagnostic purposes.
• IgG peaks at a same time and persists for many years.
• IgA also appears in the serum and nasopharyngeal secretion.
• CMI appears before antibodies and is detectable for many years.
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20. The course of postnatal rubella 20

21. Laboratory Diagnosis
• Often difficult to diagnose on purely clinical grounds.
• Lab diagnosis is important.
• RT-PCR on throat swab.
• Test for rubella infection:
• Screening test for rubella antibody to ascertain the immune status of
women in childbirth age
• Test for acute infection in pregnancy
• Test on infants for congenital infections.
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22. Screening teats on women
• Antenatal clinics for routin screening of rubella antibody.
• Negative result : immunization soon after the birth : preotect
subsequent pregnancies.
• Screening is also advised for women of childbearing age of
particular risk of infection : teachers, clinical and hospital staff
(irrespective of a history of past infection/immunization which
may be unreliable).
• ELISA test for IgG antibody is commonly available .
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23. Rubella vs. some other rash diseases 23

24. Immunization
• The only vaccine not given primarily for the benefit of the
recipient, but to protect another (=fetus).
• First dose : 12-15 months.
• Second dose : before school entry (3-5 years).
• Non-immune women : before pregnancy or after delivery (single
dose).
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25. Contraindications to vaccine
• Main subjects (like other live vaccines) are :
• Febrile illness
• Allergy to one of the constituents (rare)
• Defective immunity
• The importance is : early pregnancy : not before 1 month after
receiving rubella vaccine.
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