Febrile Antibodies Panel

Typhi, Typhus, Typhoid, Febrile Agglutinins

Test Codes

EPIC: LAB1231997, Beaker: FABPNL, Quest: 91121

Department

Send Outs

Instructions

Includes:

• Rickettsia (RMSF) Antibodies (IgG, IgM) with Reflex to Titers.
• Rickettsia (Typhus Fever) Antibodies (IgG, IgM) with Reflex to Titers.
  
• Salmonella, Total Antibody, EIA (Salmonella H Type a, Salmonella H Type b, Salmonella H Type d, Salmonella O Type Vi, Salmonella O Type D).
  
• Brucella Antibodies (IgG, IgM), EIA with Reflex to Agglutination.
• If Rickettsia (RMSF) screen is Detected, IgG or IgM, then the appropriate Titer will be performed at an additional charge (CPT code(s) 86757 per titer performed).
• If Rickettsia (Typhus Fever) screen is Detected, IgG or IgM, then the appropriate Titer will be performed at an additional charge (CPT code(s) 86757 per titer performed).
• If Brucella IgM is ≥1.10, then Brucella Antibody Agglutination will be performed at an additional charge (CPT code(s): 86622).

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube. (Minimum: 5.0 mL)
Also acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: 3.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 0.8 mL)

Rejection Criteria

Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Transport: 3.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 0.8 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Information not available.

Reference Range

RMSF IgG                             Not detected.
RMSF IgM                            Not detected.

R. typhi IgG                         Not detected.
R. typhi IgM                        Not detected.

Salmonella H, Type a        Negative.
Salmonella H, Type b        Negative.
Salmonella H, Type d        Negative.
Salmonella O, Type Vi       Negative.
Salmonella O, Type D        Negative.

Brucella IgG       <0.80
Brucella IgM      <0.80

Test Methodology

Semi-Quantitative Agglutination/Semi-Quantitative Indirect Fluorescent Antibody/Qualitative Immunoblot.

Clinical Utility

This panel comprises antibody testing for infections caused by Ricketssia rickettsii, Richetssia typhi, Salmonella, and Brucella in patients with fever. A 4-fold change in titers of antibodies between acute and convalescent sera confirms the infection. This panel provides targeted identification of antibodies, which supports differential diagnosis and can provide evidence of exposure.

R rickettsii causes Rocky Mountain spotted fever (RMSF), the most severe rickettsial disease in the United States. RMSF is transmitted via several species of ticks and occurs most commonly in North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma. Fever and headache along with other nonspecific symptoms begin 3 to 12 days after the bite. Serious complications that affect multiple systems may develop quickly and can lead to death in days, especially in children under 10 years old. Thus, early diagnosis and treatment are critical to survival [1].

R typhi causes flea-borne (murine) typhus. The geographic distribution of murine typhus extends throughout tropical and subtropical areas worldwide; it is rare in the United States, occurring mainly in Southern California, Hawaii, and Texas. Fever begins with chills and can last about 12 days. Severe complications can happen, if the infection is not treated, but are unusual [2].

Salmonella infection can be caused by eating contaminated foods including vegetables, eggs, chicken, pork, and fruits. It can also spread between people and from animals to people. Common symptoms, such as diarrhea, fever, and stomach cramps, are usually self-limiting. However, children under 5 years old, adults over 65, and people with compromised immune systems may develop serious or fatal complications [3]. This panel can detect antibodies to 5 Salmonella antigens: H type A, B, and D; O type Vi and D.

Brucella infections are commonly acquired from farm animals and raw dairy products in countries without effective public health and domestic animal health programs. Fever and other nonspecific symptoms of brucellosis start suddenly and later may become remittent. Recurrent brucellosis affects multiple systems with endocarditis as one of the most severe complications [4].

Clinical false-negative results for IgG- and IgM-based serologic tests can occur due to compromised immunity, testing before antibody response has started, or the presence of interfering substances in host serum. A 4-fold change in titers of antibodies between acute and convalescent sera confirms the infection [1,2,4].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

Reference

1. Rocky Mountain spotted fever (RMSF). Centers for Disease Control and Prevention. Accessed September 25, 2021. https://www.cdc.gov/rmsf/index.html
2. Flea-borne (murine) typhus. Centers for Disease Control and Prevention. Accessed September 25, 2021. 
   https://www.cdc.gov/typhus/murine/index.html
3. Salmonella. Centers for Disease Control and Prevention. Accessed September 25, 2021. https://www.cdc.gov/salmonella/
4. Brucellosis. Centers for Disease Control and Prevention. Accessed September 25, 2021. https://www.cdc.gov/brucellosis/

Test Resources
Algorithm

An Approach to the Differential Diagnosis of Tick-borne Diseases

Clinical Focus
Tick-borne Diseases: Laboratory Support of Diagnosis and Management

CPT Codes

86622(x2), 86757(x4), 86768(x5).

Contacts

Last Updated

11/19/2025