Rubella, caused by the rubella virus, primarily affects older children and young adults, with its incidence peaking during spring. The disease features a 14-day incubation period, a characteristic rash, and complications such as arthritis and fetal damage in pregnant women. Diagnosis involves lab confirmation and serology, while management focuses on vaccination and monitoring, as no specific treatment is required.

1. Viral Exanthem Part III:
Rubella:

2. Introduction:
Well recognized Exanthem caused by the Rubella virus of the genus
Rubiviris and Family of Togaviridae.

3. Epidemiology:
Incidence and prevalence
 Epidemics occur during the spring.
 Transmission via droplets from the nasopharynx.
 Infectivity is greatest at the end of the incubation period and falls
rapidly during the 4 days after the appearance of the rash.
Age
 Infection is most common amongst older children and young adults.

4. Pathophysiology:
Causative organisms
 Rubella virus is a member of the Rubivirus genus of the family
Togaviridae.
 Four types (1E, 1G, 1J and 2B) account for over 70% of infections.

5. Clinical features:
 Incubation period of about 14 days (range 12–21 days).
 Children rarely experience prodromal symptoms
 Adults have a brief prodromal illness lasting 1–5 days:
 Fever up to 39°C,
 Headache and malaise,
 sore throat without coryza and
 suffusion of the conjunctivae with a gritty sensation.
 The symptoms subside as the rash develops.
 Forschheimer sign: An enanthem of dull‐red macules or petechiae confined to the soft
palate is present in up to 20% of patients during the prodromal period or on the first day of
the rash.

6. Lymphadenopathy:
 Begins 5–7 days before the rash appears and reaches a maximum on the first or second
day of the rash.
 Lymphadenopathy is generalized but characteristically involves the suboccipital,
postauricular and cervical glands.
 The tenderness of the glands subsides after a day or two but palpable enlargement may
continue for several weeks.

7. Rash:
 Appears towards the end of the Incubation period.
 Appears first on the face and spreads rapidly downwards to the trunk and limbs.
 Consists of pink macules, at first discrete, but soon becoming confluent leading to a diffuse
erythema.
 On the second day, the face begins to clear and the macules on the trunk show some
coalescence, those on the limbs remaining discrete.

8. Complications and co‐morbidities
 In older children and adults:
 Arthritis affects up to 70% of females and 5% of males.
 Arthritis usually resolves within a month.
 Purpura – thrombocytopaenic or non‐thrombocytopaenic
 Encephalitis
 Haemophagocytic syndrome

9. Rubella in pregnancy:
First 11 weeks:
 The overall risk of fetal damage and multiple birth defects: 85%.
 Most of the defects are of neurological nature.
 Heart and eye damage is most frequent in embryos infected under 6 weeks;
Between weeks 12 and 16:
 The risk defect: 35% and is principally that of deafness.
 Mental deficiency occurs in embryos of all ages up to about 16 weeks.
After 16 weeks:
 Although fetal infection occurs it does not result in damage.
During the neonatal period:
 Congenital rubella may give rise to a number of manifestations which are self‐limiting
 The most frequent is thrombocytopenic purpura, which may manifest as a transient purpuric rash.
 Jaundice
 Bone lesions

10. Disease course and prognosis:
By the third day:
 The rash on the trunk has cleared
By the fourth day:
 The eruption on the limbs has also faded.
The rash may be absent in some 40% of cases.

11. Investigations:
 Labs must be carried out to confirm a diagnosis in pregnancy or immunosuppression.
 Serology remains the gold standard method.
 First clotted blood to be taken immediately upon the appearance of the rash as the antirubella
antibodies can be detected from the time when the rash appears.
 A second blood sample is taken after 7–10 days.
 IgM antibodies suggest acute or recent rubella infection.
 IgG antibodies appear 2–3 weeks later or may indicate prior exposure and immunity.
 In neonates, the presence of IgM and continued antibody production are
indicative of congenital infection.
 RT‐PCR amplification of viral RNA from saliva and throat swabs can also be done.
 Complete Blood Count:
 Normal or
 Leukopenia with an inconstant increase in Plasma Cells.

12. Management
Prophylaxis:
 Active immunization: with live attenuated rubella virus as part of MMR vaccine is offered to
infants aged 1–2 years old,
 A preschool booster of MMR is also recommended.
 At risk women for e.g. Medical or nursing staff and school teachers can also be given the
rubella vaccine.
 A quadruple vaccine including varicella is also available but there has been concern, but not
confirmation, that this combination leads to a slight increase in convulsions.
 Pregnancy is a contraindication to vaccine and should be avoided for 4 weeks after its
administration.
 Arthralgia is common in adult women 2–4 weeks after vaccination and in children a rubelliform
rash may occur.
 Encephalitis has been reported
Treatment:
 No specific treatment is needed.

13. Prodrome:
1-5 days
Forscheimer Spot:
Either in the prodrome
or the first day of rash
Day 1:
Rash Appears Day 2:
Day 3:
Rash on trunk clearedIncubation Period:
10-14 days
Lymphadenopathy:
5-7 days before rash appears
Face begins to
clear. Macules
on trunk begin to
coalesce. Limbs
show discrete
macules
Day 4:
Rash on
limbs
cleared
Rubella Timeline:

14. Topic to be Discussed in Future:
Erythema Infectiosum.
Previously Discussed:
Measles
Roseola Infantum