Rubella Virus

Question 1

Classification

Answer 1

Family: Togaviridae

Genus: Rubivirus

Species: Rubella virus

Question 2

Characteristics

Answer 2

• Enveloped virus
• +ssRNA
• No virion polymerase
• cytoplasmic replication
• one serotype

Question 3

Transmission

Answer 3

• Respiratory droplets

- Across the placenta from mother to fetus = “TORCHES infection”

Question 4

Pathogenesis

Answer 4

• initial site of infection: the nasopharynx
• spreads to local lymph nodes
• it then disseminated to the skin via the blood stream
• cause rash

The rash is attributed to both viral replication and immune injury

During maternal infection, the virus replicates in the placenta and then spreads to fetal tissue

• if the infection occurs during the first trimester, a higher risk of congenital malformations

Question 5

Disease

Answer 5

Rubella (aka German measles or three day measles)

Can either occur in childhood or adulthood

• congenital rubella syndrome = congenital malformations
  [[[especially affecting the cardiovascular and CNS]]]

> the incidence of congenital rubella has been greatly reduced by the widespread use of the vaccine

Question 6

Microbiological diagnosis

Answer 6

• Detection&raquo_space;> PCR assay

To determine whether an adult woman is immune:

> > > detection of IgG antibody in hemagglutination inhibition test

To determine whether recent infection has occurred:

Detection of IgM antibody in serum

or

Detection of IgG antibody by a set of acute- and convalescent phase sera

Question 7

Treatment and prevention

Answer 7

Treatment:
- no antiviral therapy

Prevention:

• live attenuated vaccine (for children)
• usually given in combination with measles and mumps vaccine (trimovax)