Flea-borne Typhus Testing
Information for Medical Professionals
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Providers should consider a diagnosis of flea-borne typhus in patients with a non-specific febrile illness with headache, myalgia, rash and laboratory abnormalities including leukopenia, thrombocytopenia and elevation of hepatic transaminases,
without alternate identifiable etiology.
As symptoms are non-specific and laboratory testing is
unreliable in acute phases of infection, treatment
decisions should be based on clinical presentation and
exposure history. Treatment for patients with suspected
flea-borne typhus should not be delayed pending
diagnostic tests.
Laboratory diagnosis can be conducted through serologic testing for
R.typhi IgG and IgM antibodies. As there can be cross-reactivity with other rickettsiae, LAC DPH also recommends testing for antibodies against
R. rickettsii, the causative agent of Rocky Mountain Spotted Fever. Serology performed on samples collected within the first week of onset can often be false-negative. Confirmation of
R. typhi infection requires paired serology of acute and convalescent samples (drawn 2 weeks later) demonstrating a four-fold increase in IgG titers. However, as not all patients return for additional testing, a probable diagnosis can be made with a single positive sample plus supportive clinical and laboratory criteria. Serological tests for both
R. typhi and
R. rickettsia are available at most commercial laboratories.
Testing at the LAC DPH
Public Health Laboratory
The LAC DPH
Public Health Laboratory
(PHL) provides both serological and PCR testing for
Rickettsia.
R. typhi and
R. rickettsii serum
testing is available and PCR whole blood testing can
detect all Rickettsia species. Select the
Rickettsia IgM & IgG IFA option
under the Immunoserology/Virology section on the
submittal form to request serological testing. To
request Rickettsia PCR testing, list it in the
Title 17/Other text box. Whole blood submitted
for PCR testing must be preserved with purple top EDTA
tube. Deteailed specimen collection instructions can be
found in the
PHL test catalog. PHL does not charge the submitter for these services.
A
standard
laboratory submittal form must be completed and
accompany the specimen(s). Each specimen must be labeled
with the patient name and a second identifier (date of
birth or medical record number), date of collection, and
specimen type. Include a copy of previous test results
and any pertinent patient history with the specimen
including onset date. Send specimens by courier or
overnight shipper using the appropriate transport
conditions for the specimen type. Ship packages
Monday-Thursday to avoid weekend deliveries. Frozen
specimens should be shipped on dry ice.
Reporting
Flea-borne typhus and other rickettsial infections are reportable in California. Reporting of cases guides the Los Angeles County Department of Public Health to target surveillance activities and health education. A standard
Confidential Morbidity Report (CMR) can be used to file a report; the CMR may be faxed to the DPH Morbidity Unit at (888) 397-3778 or (213) 482-5508. You may also report cases by telephone during normal business hours from 8:00 a.m. to 5:00 p.m. to (888) 397-3993. For cases among residents of the cities of
Long Beach or
Pasadena, please contact their local health departments.
PHL TEST CATALOG:
2020 Catalog of Laboratory Tests
LABORATORY SUBMITTAL FORM:
PHL Test Request Form (v2 10-4-2021)
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To receive the free weekly emailed West Nile Virus and Other
Arboviral Diseases Report (published during WNV season) email:
ACDC2@ph.lacounty.gov
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