Rubella
Rubella / German measles
- post natal rubella
- congenital rubella
- differential diagnosis : Measles , Scarlet fever
- 1941 – Australian ophthalmologist
retrospective study , “ Congenital cataract following
German measles in the mother”
German Measles
- acute febrile illness characterized by – rash,
posterior auricular & suboccipital lymphadenopathy
* children and young adults
* pregnancy – congenital abnormalities
- mental retardation
Causal organism
Etiological agent - Rubella virus
Family - Togaviridae
genus - Rubivirus
Rubella virus
- (+) ssRNA virus
- 60 nm in diameter
- nucleocapsid – 30 nm , double membranes
- Icosahedral symmetry
- Envelop with projection
- haemagglutination activity present
Reaction to physical and chemical agents
- relatively labile, ether sensitive, can be stored at –70º C.
Host range and cultivation
Animals-Rhesus monkey,Hamster,Guinea pigs,ferret & rabbit
Chick embryo – hen egg, duck eggs
Cell culture – human amnion, rabbit kidney,
Cell lines-Monkey(Vero),Rabbit(RK13),African green
monkey kidney
POST NATAL RUBELLA
Pathogenesis
- Incubation–2-3 weeks
- Natural host – human
- MOT-air borne
- Organism enters through mucous membrane of URT
replication occur in cervical lymph nodeviraemia
(after 5-7 days), viraemia last 13-15 days
- when rash appearsvirus detectable only in nasopharynx
for several weeks
- 25% - subclinical infection
Clinical findings
• malaise, low grade fever
• morbilliform rash – appear on the same day
• start on the face, extends over the trunk and extremeties,
• rash usually - 3 days(3 days measles)
• Lymph node – post-auricular and sub occipital
• transient arthralgia, arthritis in women
• thrombocytopenic purpura,
•Pharyngeal viral excretion 1 week before and 1 week after
onset of rash
• Patient is potentially infectious for a long period
Rubella rash
Rubella rash
Immunity
- development of Ab as the appearnce of rash
-initial Ab – IgM – last for 6 months
IgG – persist for life
-One attack confer lifelong immunity
- only one antigenic type
Laboratory Diagnosis
*Specimens – nasopharyngeal and throat swabs
taken 2-3 days after symptoms appear
- Amniotic fluid during pregnancy
*Isolation and identification of virus
Tissue culture
cell lines - rabbit (RK-13, SIRC) ,
- primary African green monkey cultures
Serology
HI test - standard test
ELISA - specific IgM
IgM in a single specimen
Recent infection -rise in titre between 2 serum sample
10 days apart
Epidemiology
World wide distribution
Epidemic – 6-10 years, Pandemic – 20-25 yrs
Mode of transmission
Respiratory route
Congenital Rubella Syndrome
Pathogenesis
- Rubella infection during pregnancy
- infection of placenta and fetus
- growth rate of infected cells is reduced
- fewer numbers of cells in affected organs at birth
- deranged and hypoplastic organ development
- structural abnormalities in newborn
Out come of infection
• the earlier in pregnancy infection occurs, the greater the
damage to the fetus
• 1st month of pregnancy – abnormalities in 50% of cases
• 2nd month of pregnancy – abnormalities in 20% of cases
• 3rd month of pregnancy – abnormalities in 4% of cases
•
Clinical Findings
Congenital Rubella Syndrome
1. Transient effects in infants
- growth retardation, failure to thrive, hepatosplenomegaly,
thrombocytonic purpura, osteitis and meningoencephalitis
2. Permanent manifestations
- Congenital heart diseases- PDA, AS, PS, VSD, ASD
- Eyes - total or partial blindness- cataract, glaucoma,
chrioretinitis
- Neurosensory deafness
3. Developmental abnormalities – appear and progress
during childhood and adolescence
- mental retardation, psychiatric disorders, behavioral
manifestations in preschool and school going age children,
significant learning deficits ,poor balance, muscle weakness,
deficits in tactile perception
- 20% mortality rate - in symptomatic infant at birth
- progressive rubella panencephalitis-develop in the 2nd
decade of life
Congenital Rubella
Papular & purpurotic rash Sequelae: cataract & deafness
Immunity
- maternal Ab – transplacentally –immunity for
6 months
- in infant infected in utero, persistence of
Rubella virus causes arising titre of Rubella
specific IgM and IgG level
- IgG persists long after the fall in maternal IgG
LABORATORY DIAGNOSIS
- Large amount of virus shed in pharyngeal secretion
- Other body fluid – CSF ,Blood,Urine for up to 18
months of age
- Demonstration of IgM Rubella in infant
- Children with congenital Rubella
TREATMENT
Abnormalities corrected by surgery or medical therapy
PREVENTION AND CONTROL
-Active immunization – induces life long immunity in at
least 95% of recipients
-Live attenuated vaccine
-MMR vaccine(at 15 months of age)
-Vaccine induces some respiratory IgA interrupting the
spread of virulent virus by nasal carriage
Indications
- 1 to 12 years children, adolescent & women
of child bearing age
- Prepubertal girls
- Women in the immediate post partum period
- Non pregnant women vaccinees should be
advised to delay conception for at least 3
months
CONTRAINDICATIONS
- Pregnant women
- Immunocompromised host
Passive immunization
-High titre rubella Ig (IGIV-immune globulin IV) not
protect fetus against rubella infection
