B2 G&D Lec 4: Transplacental infections Rubella virus & listeria monocytogenes Flashcards
What diseases are caused by Rubella virus?
This virus causes:
- Rubella
- Congenital rubella malformations
How is rubella transmitted?
transmitted via respiratory droplets.
• From mother to fetus transplacentally.
Mention the important properties of rubella virus
- A member of the Togavirus family
— Composed of single-stranded RNA, an icosahedral nucleocapsid and a lipoprotein envelope. - has a positive-strand RNA and therefore has no virion polymerase
- surface spikes contain hemagglutinin.
- single antigenic type.
- Human is the natural host
Where does the Initial replication of rubella occurs?
in the nasopharynx and local lymph
nodes.
How is rubella spread?
via the blood to the internal organs and skin
What is the origin of the rubella rash?
The origin of the rash is unclear; it may be due to antigen antibody
mediated vasculitis
What is the immunity against rubella virus?
• Natural infection leads to lifelong immunity. Second cases of rubella do not occur.
• Antibody crosses the placenta and protects the newborn.
Rubella is a milder, shorter disease than ________
measles
What is the incubation period of rubella virus?
14 to 21 days
What are the clinical findings of rubella?
- Brief prodromal period with fever and malaise
- Maculopapular rash, which starts on the face and progresses downward to involve the extremities.
-Posterior auricular lymphadenopathy is characteristic.
-When rubella occurs in adults especially women, polyarthritis caused by immune complexes often occurs.
How long does the rubella rash lasts ?
Typically 3 days
What is the cause of Congenital Rubella Syndrome?
teratogen ; significance of rubella virus is not as a cause of mild childhood disease
When does the pregnant women get infected by rubella?
First trimester
What happens when a non-immune pregnant woman is infected by rubella early gestation?
significant congenital malformations can occur as a result of maternal viremia and fetal infection.
• The increased rate of abnormalities during the early weeks of pregnancy is attributed to the very sensitive organ development that occurs at that time.
What are the manifestations of Congenital Rubella Syndrome?
Some congenital shedders are asymptomatic and
without malformations
The malformations are widespread and involve primarily the heart (e.g., patent ductus arteriosus), the eyes (e.g., cataracts), and the brain (e.g., deafness and mental retardation).