Gold (SST - Clot activator & gel)
2 ml blood
1 ml serum
If multiple viral serologies are being requested from the same specimen, the general rule is to collect a total of 2-4 ml of blood for every 2-3 tests ordered. A single serum specimen is required to determine the immune status of an individual or to test for viral-specific IgM antibodies. Paired sera specimens, collected two to three weeks apart, are required for the diagnosis of a current or recent viral infection when examining specimens for IgG antibody. Obtain the acute phase serum as soon as possible after the onset of illness. The most useful results are obtained by submitting acute and convalescent phase sera together to be tested simultaneously. Evaluation of serum for antibodies to TORCH (Toxoplasma, Rubella, CMV, HSV, etc) agents can be used to detect congenital and perinatal infections in newborns. Two serum specimens should be submitted for testing; one from the mother and the other from her infant. Serological testing is not usually available for body fluids other than serum. However, in patients with viral neurologic disease, cerebrospinal fluid (CSF) may be tested for viral antibody if paired with a serum specimen from the same date.
<0.9 - No varicella-zoster virus (VZV) IgG antibody detected
0.9-1.10 - Equivocal for varicella-zoster virus (VZV) IgG antibody
>1.10 - Positive for varicella-zoster virus (VZV) IgG antibody
Negative or no varicella-zoster virus (VZV) IgG antibody detected
Clinical Utility: Serological assays provide an indirect diagnostic approach by detecting specific antibody responses to viral infections. Detection of virus-specific IgM in a single serum sample or demonstration of a seroconversion from a negative to a positive IgG antibody response between acute and convalescent sera collected 2-3 weeks apart can be diagnostic of primary viral infection. Detection of virus-specific IgG in a single serum specimen indicates exposure to a virus at some time in the past or a response to vaccination. Negative antibody titers may exclude viral infection. Results of serological tests must be interpreted with caution, as measurements of antibody responses to viral infections can be complicated by numerous factors. For most viral infections in the acute phase of illness,rapid antigen and/or nucleic acid detection methods or viral isolation are also available and may yield results in a more sensitive and timely manner.