CMV (includes congenital) Flashcards
In europe, how many cCMV infections are secondary to primary (as opposed to re-infection of reactivation)
50%
Describe possible approaches of identifying primary CMV infection in pregnancy (using serology only)
Discuss pros and cons
1) Do CMV IgG and IgM, do avidity only if IgM is detected
- Note: This is what is recommended in SMI
(this is probably based on old data, where the sensitivity of first gen avidity assays were poor)
2) Do CMV avidtiy on all IgG positives
Sensitivty of IgM decreases over time (good at picking up within one month)
Using IgM alone to decide on whether you will do avidity could miss peri-conception infection
IgM positivity lacks specificity
A low level of CMV IgG may lead to an indeterminate or falsley low level of avidity
Where is CMV latent?
CD32+ myeloid progenitor cells
Factors leading to pathogenesis of CMV
Latency in CD32+ myeloid progenitor cells
Dissemination across several host cell compartments
Virus exhibits high intra-host genetic diversity , which leads to infection of many cell types and
modulation of immune system
In retinitis and gastroenteritis CMV upregulates chemokines associated with inflammatory response
Immunohistochemistry staining of CMV
pp65, IE1/2
Write comment for
CMV IgM detected (S/CO 1.3)
CMV IgG Not detected
Any further tests
CMV IgM detected at low level. May be non-specific reactivity of the assay.
- Repeat CMV IgG testing in 1 to 3 weeks to further
- investigate possible CMV infection
Check EBV serology
Note SMI says to consider NAAT in cases of IgM +ve IgG -ve, but in this case it is close to cut off
Other option; for a “proper” IgM
CMV IgM detected, CMV IgG not detected. Repeat CMV
IgG testing in 1 to 3 weeks to further investigate possible
CMV infection
1) Write comment for
CMV IgM reactive
CMV IgG reactive
2) Further tests
CMV IgM detected, CMV IgG detected. Supportive of recent CMV infection.
(as per UKSMI note that recent infection includes primary infection or reinfection)
2) CMV avidity
When does SMI for CMV indicate sending a NAAT?
When CMV
IgM detected
IgG not detected
For congential CMV diagnosis: i.e. amnio, saliva, urine or Guthrie card
Sensitivity of NAAT from guthrie card?
70-80%
Comments for below
CMV detected in amnio fluid
CMV
Confirmed intrauterine infection
Comments for below
CMV detected in mouth swab/urine of baby (under three weeks)
Confirmed congenital CMV infection
Comments for below
CMV detected in mouth swab between 3-12 weeks of age, not found on guthrie card
Congenital infection cannot be excluded
Child 6 weeks old, suspect congential CMV- what do you do
Mouth swab/urine from child
- If neg repeat
- if positive- do guthrie
From 12 months serology can be helpful to exclude congenital CMV
Check mums booking bloods
Note: Viral excretion in urine and saliva lasts for several years with a steep decline after 5 years
Serology from 4 month old infant
CMV IgG detected
Comment
Passively acquired maternal IgG may be present
