Postnatal infections

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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