Parvovirus – Serology

Testing Indications

To determine acute/recent infection, during pregnancy in suspected cases of hydrops fetalis, to assess immune status following exposure to a known active case or during an outbreak investigation, during investigation of patients with aplastic crisis, and for public health purposes.

Timing of Specimen Collection

In suspected acute infection, IgM antibodies are detected 10-12 days after infection, and IgG antibodies are detected at 2 weeks. 90% of patients with classic erythema infectiosum rash have IgM antibodies detected at initial presentation and IgG antibodies by day 7.  IgM remains detectable for months and IgG for life following recovery from acute infection.  In pregnant women exposed to parvovirus B19, obtain IgG and IgM serology as soon as possible following exposure - Negative IgG and IgM results indicate that the mother is not immune and that no evidence of acute infection is noted. In this case, repeat the tests in 3 weeks.  In patients with clinically significant anemia or transient aplastic crisis, IgM antibodies are usually present by day 3 of illness.

Limitations

Grossly haemolyzed or lipaemic samples as well as samples containing particulate matter or exhibiting obvious microbial contamination are not recommended for testing.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and shipped to PHO laboratory on ice packs.

Test Frequency and Turnaround Time (TAT)

Parvovirus serology (IgG and IgM) testing is performed daily Monday to Friday. 

Turnaround time is up to 5 days from receipt by PHO laboratory.

The parvovirus testing is performed using the Biotrin Parvovirus B19 assay. The test uses chemiluminescence immunoassay (CLIA) technology for the qualitative determination of specific IgG and IgM antibodies to Parvovirus B19 in human serum or plasma samples.

Interpretation

Results for Parvovirus IgG and IgM are reported as either ‘Positive’ or ‘Negative’.  Results may be interpreted as follows:

• Positive IgG and negative IgM indicate past infection
• Positive IgG and IgM indicate infection within the last 7-120 days
  
• Negative IgG and positive IgM indicate acute/recent infection 
  
• Negative IgG and IgM indicate that the patient is not immune and that no evidence of acute/recent infection is identified

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

References

LAB-SD-008, Blood Collection using Serum Separator Tubes