Thursday, 9 July 2015

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Infectious Disease Serology



Introduction


Diagnostic and immune status serologic assays are performed for various viral, rickettsial, bacterial, fungal, chlamydial and mycoplasmal agents. The assay methods vary depending upon the specific agent for which testing is requested. For specific agents and assay methods refer to Chart V - 1 SEROLOGICAL TESTS AVAILABLE FROM TDH LABORATORY.
Serological testing for infectious agents that are not performed by the Tennessee Department of Health (TDH) Laboratory may be available at the Centers for Disease Control and Prevention (CDC). Consult with the appropriate section at the Nashville laboratory before submitting specimens for testing. According to CDC's guidelines, all specimens submitted to the CDC must come through the state laboratory or receive the state laboratory's approval for direct shipment from the provider to the CDC.

Specimen Acceptance Policy

HIV-1
 Serological testing for HIV-1 is available only in support of counseling and testing sites established by the TDH Sexually Transmitted Diseases/HIV (STD/HIV) Control Program.
Other agents -- serological testing is available to all public and private health care providers.
Type of Specimen Required
Immunity Screening
 Immunity screening for rubella is intended for prenatal and family planning patients. Immunity screening for measles and mumps is not routinely available. Arrangements may be made with the TDH Laboratory to perform this screening on a case-by-case basis. A single, whole clotted blood or serum is required for rubella, measles, or mumps immunity screening.
Diagnostic Testing
As a rule, acute and convalescent sera must be submitted for serological testing. The acute serum should be collected as soon after the onset of illness as possible. For the majority of the serological testing offered by the TDH Laboratory, the convalescent serum should be collected 14 days from the time the acute specimen was collected. In most cases, the laboratory requests that the acute and convalescent sera be submitted at the same time. For those agents for which IgM is available, submit the acute specimen when it is collected. See Chart V - 1 SEROLOGICAL TESTS AVAILABLE FROM THE TDH LABORATORY.

 Infectious Disease Serology (Continued)

Chart V - 1
Serological Tests Available from the TDH Laboratory
Testing for infectious agents not listed in this chart may be available at the CDC.

Consult with the TDH Laboratory concerning testing not listed. Agent or Disease Suspected
Specimen Needed
Test Method
Normal Reference Range1
Turn Around Time (days)2
Eastern Equine encephalitis virus
Acute and convalescent(14 days) sera
IFA IgG
IFA IgM
<1:16
<1:16
5
5
Ehrlichia chaffeensis

Acute and convalescent(28 days) sera
IFA, IgG
<1:128
5
Human immunodeficiency virus Type 1 (HIV-1)3
Whole, clotted blood or serum
Screening - EIA
Confirmation - WB
Non-Reactive
Non-Reactive
7
7
LaCrosse (California encephalitis group) virus
Acute and convalescent(14 days) sera
IFA IgG
IFA IgM
<1:16
<1:16
5
5
Legionella pneumoniae (Type 1-specific)
Acute and convalescent(28 days) sera
IFA, IgG
<1:128
5
Measles virus4 (Rubeola)
Immunity Screening -- Whole clotted blood or serum
EIA (IgG)
Positive (Immune)
5
Measles virus (Rubeola)4
Diagnostic -- Acute and convalescent (14 days) sera
EIA (IgG)
EIA (IgM)
Negative
Negative
1
1
Mumps virus4
Immunity Screening -- Whole clotted blood or serum
EIA (IgG)
Positive
(Immune)
5
Mumps virus
Diagnostic -- Acute and convalescent (14 days) sera
EIA (IgG)
Negative
1
Mycoplasma pneumoniae
Acute and convalescent(14 days) sera
EIA IgM
EIA IgG
Negative
Negative
5
5
Q Fever (Coxiella burnetii) Phases 1 and 2
Acute and convalescent(28 days) sera
IFA, IgG
<1:256
5
Rocky Mountain Spotted Fever (Rickettsia rickettsii)
Acute and convalescent(28 days) sera
IFA, IGG
<1:128
5
Rubella virus
Immunity Screening -- Whole clotted blood or serum
EIA (IgG)
Positive
(Immune)
5
Infectious Disease Serology (Continued)
Chart V - 1 (continued)

Blood

Infectious Disease Serology (Continued)
Specimen Collection
1. Collect an acute serum as soon after the onset of the illness as possible. A convalescent serum should be collected 14 days after the collection of the acute serum. Exceptions to this general rule of collection of specimens are noted in Chart V - 1 SEROLOGICAL TESTS AVAILABLE FROM TDH LABORATORY
2. Draw at least 5 to 7 ml of blood into a red-top vacuum tube allowing the tube to fill completely. Allow the tube to stand at room temperature to ensure complete clotting of blood. Blood should not be taken for 1 hour after a meal to avoid chylous serum.
3. Store the specimen in a refrigerator until it is sent to the laboratory. If a sample of serum is to be sent to the laboratory, separate the serum from the blood clot by centrifuging the whole clotted blood at 1,500 to 2,000 rpm at room temperature for 10 minutes. Pipette the serum into a new red-top vacuum tube or a sterile plastic screw-capped vial. A minimum of 1 ml of serum should be sent to the laboratory for testing.
Serum-separating tubes may be used to collect the specimens for serological testing. These specimens should be sent to arrive in the testing laboratory within 48 to 72 hours of collection to avoid having the red blood cells hemolyze and "spill" into the upper portion of the tube.
4. Acute serum that is held until the collection of a convalescent serum should be separated from the blood clot and stored frozen until collection of the convalescent serum. Acute serum will not be tested routinely unless the TDH Laboratory offers testing for the IgM class of antibody for the analytic testing requested. Convalescent specimens may be run as stand alone specimens in limited situations. Consultation with the supervisor of the Serology Unit is required before the convalescent serum will be tested singly.
Spinal Fluid
Prior arrangement must be made with the TDH Laboratory before cerebrospinal fluid (CSF) specimens are submitted for serologic testing. The VDRL test for syphilis is routinely performed on CSF. The EIA test for West Nile Virus (WNV) IgM is performed on CSF seasonally.
Specimen Identification
1. Use the appropriate form for the test requested: Rubella
Rubella Form PH-1917
HIV-1
HIV-1 Serology Form PH-3173
Other non-syphilis serology
Immunoserology Form PH-1589


Infectious Disease Serology (Continued)
2. Using indelible ink, label each specimen with the patient's first and last name and the date of collection. Attach the tear strip number from the test request form to the specimen and secure it with transparent tape. Those providers submitting electronic test requests should affix a label produced by Laboratory Order Entry (LOE) to the associated specimen. Unlabeled specimens or specimens containing information that does not exactly match the information on the accompanying test request form or electronic record will not be tested.
Shipment of Specimens
1. Packing and shipping specimens to the state public health laboratory requires personnel trained in current regulations. Follow the shipping guidelines of your current carrier or shipping method.
2. Affix the mailing label (PH-0838), return address and other labeling required by pertinent regulations to the outer container.
1.     Ship to the Tennessee Department of Health Laboratory Services.





Syphilis Serology


Introduction
Syphilis is a disease caused by infection with the spirochete Treponema pallidum. Serological tests greatly aid in the diagnosis of syphilis. Serologic assays used to screen patients for syphilis are non-treponemal tests. The non-treponemal test performed by the Tennessee Department of Health (TDH) Laboratory is the Rapid Plasma Reagin test (RPR). Quantitative RPR results may be used to monitor therapy for T. pallidum infections.
Confirmation of reactive RPR screening test results is obtained with specific treponemal tests for syphilis. The Treponema pallidum-Particle Agglutination test (TP-PA) is the TDH Laboratory's primary confirmatory test for T. pallidum-specific antibody. Suspected biologically false-positive results sometimes produced in the RPR test may be investigated with a TP-PA test. The Fluorescent Treponemal Antibody-Absorption-Double Stain Test (FTA-ABS-DS) also detects T. pallidum-specific antibody. It is available in limited circumstances. The TP-PA and FTA-ABS-DS are not screening procedures and are only performed when required for proper patient management.
The Venereal Disease Research Laboratory (VDRL) test is a non-treponemal test used to test cerebrospinal fluids (CSF). Positive test results are quantitated to aid in monitoring therapy for neurosyphilis. The RPR, TP-PA and FTA-ABS-DS tests are not performed on CSF.
Specimen Acceptance Policy
The TDH Laboratory performs serological procedures for syphilis in support of:
                The state prenatal law.
                The TDH Sexually Transmitted Disease Control Program.
                The private medical community for which the state laboratories serve as reference laboratories.
                Other State agencies for which the TDH Laboratory has contracted or agreed to perform tests.

Testing for syphilis, non-treponemal and treponemal-specific, is available to all health care providers.
Tennessee does not require premarital testing for syphilis.
Syphilis screening tests will be performed for persons who intend to be married in a state requiring premarital syphilis testing. The TDH Laboratory will send appropriate premarital forms for the state in which the wedding will be performed with the results of the laboratory tests. Other states may not accept premarital syphilis testing performed by laboratories other than state public heath laboratories such as the TDH Laboratory.
Type of Specimen Required

For the tests performed at the TDH Laboratory, the specimen required and the application of the test refer to Chart V - 2 SEROLOGICAL TESTS FOR SYPHILIS.