Scrub typhus laboratory findings
|
Scrub typhus Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Scrub typhus laboratory findings On the Web |
|
American Roentgen Ray Society Images of Scrub typhus laboratory findings |
|
Risk calculators and risk factors for Scrub typhus laboratory findings |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
In endemic areas, diagnosis is generally made on clinical grounds alone. Where there is doubt, the diagnosis may be confirmed by a laboratory test such as serology.
Laboratory Findings
The choice of laboratory test is not straightforward, and all currently available tests have their limitations.[1] The cheapest and most easily available serological test is the Weil-Felix test, but this is notoriously unreliable.[2] The gold standard is indirect immunofluorescence,[3] but the main limitation of this method is the availability of fluorescent microscopes, which are not often available in resource-poor settings where scrub typhus is endemic. Indirect immunoperoxidase (IIP) is a modification of the standard IFA method that can be used with a light microscope,[4] and the results of these tests are comparable to those from IFA.[2][5] Rapid bedside kits have been described that produce a result within one hour, but the availability of these tests are severely limited by their cost.[2] Serological methods are most reliable when a fourfold-rise in antibody titre is looked for. If the patient is from a non-endemic area, then diagnosis can be made from a single acute serum sample.[6] In patients from endemic areas, this is not possible because antibodies may be found in up to 18% of healthy individuals.[7]
Other methods include culture and PCR, but these are not routinely available[8] and the results do not always correlate with serological testing,[9][10][11] and are affected by prior antibiotic treatment.[12] The currently available diagnostic methods have been summarised.[1]
Acute scrub typhus appears to improve viral loads in patients with HIV.[13] This interaction is refused by an in vitro study.[14]
References
- ↑ 1.0 1.1 Koh GCKW, Maude RJ, Paris DH, Newton PN, & Blacksell SD (2010). "Diagnosis of Scrub Typhus". Am J Trop Med Hyg. 82 (3): 368&ndash, 370. doi:10.4269/ajtmh.2010.09-0233. PMC 2829893. PMID 20207857.
- ↑ 2.0 2.1 2.2 Pradutkanchana J; Silpapojakul K; Paxton H; et al. (1997). "Comparative evaluation of four serodiagnostic tests for scrub typhus in Thailand". Trans R Soc Trop Med Hyg. 91 (4): 425–8. doi:10.1016/S0035-9203(97)90266-2. PMID 9373640. Unknown parameter
|author-separator=ignored (help) - ↑ Bozeman FM & Elisberg BL (1963). "Serological diagnosis of scrub typhus by indirect immunofluorescence". Proc Soc Exp Biol Med. 112: 568–73. PMID 14014756.
- ↑ Yamamoto S & Minamishima Y (1982). "Serodiagnosis of tsutsugamushi fever (scrub typhus) by the indirect immunoperoxidase technique". J Clin Microbiol. 15 (6): 1128–l. PMC 272264. PMID 6809786.
- ↑ Kelly DJ, Wong PW, Gan E, Lewis GE Jr (1988). "Comparative evaluation of the indirect immunoperoxidase test for the serodiagnosis of rickettsial disease". Am J Trop Med Hyg. 38 (2): 400–6. PMID 3128129.
- ↑ Blacksell SD; Bryant NJ; Paris; DH; et al. (2007). "Scrub typhus serologic testing with the indirect immunofluorescence method as a diagnostic gold standard: a lack of consensus leads to a lot of confusion". Clin Infect Dis. 44 (3): 391–401. doi:10.1086/510585. PMID 17205447. Unknown parameter
|author-separator=ignored (help) - ↑ Eamsila C; Singsawat P; Duangvaraporn A; et al. (1996). "Antibodies to Orientia tsutsugamushi in Thai soldiers". Am J Trop Med Hyg. 55 (5): 556–9. PMID 8940989. Unknown parameter
|author-separator=ignored (help) - ↑ Watt G, Parola P (2003). "Scrub typhus and tropical rickettsioses". Curr Opin Infect Dis. 16 (5): 429–436. doi:10.1097/00001432-200310000-00009. PMID 14501995.
- ↑ Tay ST, Nazma S, Rohani MY (1996). "Diagnosis of scrub typhus in Malaysian aborigines using nested polymerase chain reaction". Southeast Asian J Trop Med Public Health. 27 (3): 580–3. PMID 9185274.
- ↑ Kim, DM; Yun, NR; Yang, TY; Lee, JH; Yang, JT; Shim, SK; Choi, EN; Park, MY; Lee, SH (2006). "Usefulness of nested PCR for the diagnosis of scrub typhus in clinical practice: A prospective study". Am J Trop Med Hyg. 75 (3): 542–545. PMID 16968938.
- ↑ Sonthayanon P; Chierakul W; Wuthiekanun V; et al. (2006). "Rapid diagnosis of scrub typhus in rural Thailand using polymerase chain reaction". Am. J. Trop. Med. Hyg. 75 (6): 1099–102. PMID 17172374. Unknown parameter
|month=ignored (help); Unknown parameter|author-separator=ignored (help) - ↑ Kim DM, Byun JN (2008). "Effects of Antibiotic Treatment on the Results of Nested PCRs for Scrub Typhus". J Clin Microbiol. 46 (10): 3465–. doi:10.1128/JCM.00634-08. PMC 2566087. PMID 18716229.
- ↑ Watt G; Kantipong P; de Souza M; et al. (2000). "HIV-1 suppression during acute scrub-typhus infection". Lancet. 356 (9228): 475–479. doi:10.1016/S0140-6736(00)02557-5. PMID 10981892. Unknown parameter
|author-separator=ignored (help) - ↑ Moriuchi M, Tamura A, Moriuchi H. (2003). "In vitro reactivation of human immunodeficiency virus-1 upon stimulation with scrub typhus rickettsial infection". Am J Trop Med Hyg. 68 (5): 557–561. PMID 12812345.