Clinical features of different viruses Flashcards
What type of virus is varicella zoster?
Herpes virus, DNA virus
How is varicella zoster spread?
By close contact and droplets
How is varicella zoster virus transmitted in pregnancy
Maternal infection> maternal viraemia> virus transferred across the placenta> fetus recovers from initial infection> virus reactivates and acts like Zoster attacking the dermatomes
What are the physical consequences of varicella embryopathy?
Skin - scarring, hypopigmentation, hyperpigmentation
Limbs - hypoplasia and rudimentary digits
eyes - chorioretinitis, eye defects, cataracts
brain - cortical atrophy
Head - microcephaly
When should the varicella vaccination be given?
Pre natally or postpartum not antenatally as it is a live attenuated vaccination
What type of vaccination is the varicella zoster vaccine?
Live attenuated
When should VZIG be given?
Within 10 days of significant exposure in a patient that has not had chickenpox
When should VZIG not be given?
When a chickenpox rash is present
When should acyclovir be given to treat chickenpox in pregnancy?
Within 24 hours of a rash and after 20 weeks gestation
How long is a pregnant patient with chickenpox infectious for?
8-28 days (if they received VZIG)
8-21 days (if they did not receive VZIG)
What is the incubation period for Varicella Zoster?
14 days (10-21)
Which viruses are part of the herpes family?
Varicella zoster, herpes simplex, cytomegalovirus
What is the rate of fetal transmission of VZV in the first trimester?
0.4%
What is the rate of fetal transmission of VSV in the second trimester?
2%
What is the rate of transmission after 20 weeks?
0%
What are the maternal consequences of varicella zoster infection?
High risk of pneumonitis (10%)
Hepatitis, encephalitis
How do fetal transmission rates for CMV throughout pregnancy?
Fetal transmission rates increase
How does gestation affect the risk of CMV infection affecting the neonate?
The risk of a fetus being affected decreases with gestation
What are the ultrasound findings of a CMV infected fetus?
IUGR, microcephaly, ventriculomegaly, ascites, hydrops, intracerebral calcifications, echogenic bowel
How many affected babies with CMV will be symptomatic at birth?
7-10%
What are the clinical features of congenital CMV at birth?
Microcephaly, jaundice, SGA, petechiae, hepatosplenomegaly, jaundice, seizures, visual impairment, cerebral palsy
What proportion of babies with congenital CMV are asymptomatic at birth?
approximately 90% (approx. 10% will develop symptoms in later life)
What are the clinical features of late stage congenital CMV?
Sensorineural deafness and mental retardation (10%), failure to thrive, failure to reach milestones
How is CMV transmitted?
Body fluids (including breast milk)
Who is most at risk of developing a CMV infection?
Nursery workers, pregnancy women with nursery age children, teenage pregnant women
Can you develop immunity to CMV
No
What types of CMV infections are there?
Primary (first infection) vs. non-primary (reactivation or new infection on previously infected)
What is the risk of fetal transmission in a primary infection?
40%
What is the risk of fetal transmission in a secondary infection?
1%
Why is IgG avidity used in CMV testing in pregnancy?
It tells how tightly the IgG binds to the antigen, higher avidity increases the likelihood that the infection is a non-primary infection and therefore is at lower risk of being transmitted to fetus
What does negative IgM and IgG for CMV mean?
No active or previous CMV infection
What does positive IgM and IgG for CMV mean?
May be either a primary or non-primary infection therefore IgG avidity needs to be performed.
What is the incubation period for CMV?
3-12 weeks
What are the maternal symptoms of CMV in pregnancy?
Most women are asymptomatic. May be flu like symptoms, general malaise or lethargy
When should amniocentesis be performed for CMV?
At least 6 weeks after maternal infection, more than 21 weeks (baby needs to be producing urine)
Is there a treatment for CMV?
No
What is a retrovirus (+example)?
HIV - RNA virus that uses host DNA for replication
What type of virus is rubella?
A togavirus, single stranded RNA. Family = rubibvirus
What kind of vaccine is the rubella vaccine?
Live attenuated
Incubation period for Rubella
12-23days
What are the symptoms of rubella?
25% asymptomatic
Joint pain
Fever, malaise coryzal symptoms
Maculopapular all body rash
What are the features of congenital rubella syndrome
80% sensorineural deafness
60% neurological deficit (neurodevelopmental delay, microcephaly)
60% cardiac defect
30% eye defect - cataracts, glaucoma
What is the significance of gestation with rubella syndrome infection?
In first trimester - High risk of mortality and morbidity
20% miscarry, 80% affected by the disease
In second trimester - 15-20% sensorineural deafness
In third trimester - low risk of impact to baby
What does Gardasil vaccinate against?
4 Human Papilloma viruses
16 and 18 - responsible for 70% of cervical cancer
6 and 11 - cause anogenital warts
What type of virus is HIV?
A retrovirus, Family = lentivirus, single stranded RNA
What type of virus is polio
Enterovirus, single stranded RNA virus
What type of virus is the zika virus?
Flavirus, single stranded RNA virus
Which organism causes scarlet fever?
Streptococcus pyogenes
What percentage of women develop antibodies to HPV infection?
50-60%
