Rubella

Question 1

Rubella structure & classification & receptor

Answer 1

Family: Matonaviridae (previously togaviridae)
Genus: Rubivirus

(+)ss RNA Enveloped

Baltimore: IV

Genotypes 1E & 2B are the most common.

Exclusive host - humans

Replicates in cytoplasm. Myelin oligodendrocyte glycoprotein is a potential receptor.

Question 2

Rubella incubation & infectious period

Answer 2

Incubation: 14 to 21 days

Infectious: 7 days before to 10 days after rash.

Question 3

Rubella clinical syndromes

Answer 3

Asymptomatic in up to 50%

Rash in children

Arthralgia in 70% adults - remember previous classification as Togaviridae

Question 4

Rubella diagnostics

Answer 4

IgM - 4 days after rash for 6-8 weeks
IgG 4-fold increase and avidity
RT-PCR

Question 5

Rubella in pregnancy

Answer 5

Congenital rubella syndrome

Congenital infection:

1st trimester - 80%
2nd trimester - 25%
3rd trimester- 35%
>36 weeks - 100%

Foetal malformations in 1st 16 weeks of pregnancy - SNHL, Cardiac abnormalities, IUGR, abortion, stillbirth

Intervention- only monitoring, NO IVIG