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__NOTOC__ | __NOTOC__ | ||
{{Scrub typhus}} | {{Scrub typhus}} | ||
{{CMG}} | |||
==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.<ref name="Koh2010">{{cite journal|author=Koh GCKW, Maude RJ, Paris DH, Newton PN, & Blacksell SD|title=Diagnosis of Scrub Typhus|journal=Am J Trop Med Hyg|year=2010|volume=82|pages=368–370|pmid= 20207857|doi=10.4269/ajtmh.2010.09-0233|issue=3|pmc=2829893}}</ref> The cheapest and most easily available serological test is the [[Weil-Felix test]], but this is notoriously unreliable.<ref name="Pradutkanchana">{{cite journal | |||
|author=Pradutkanchana J | |||
|title=Comparative evaluation of four serodiagnostic tests for scrub typhus in Thailand | |||
|journal=Trans R Soc Trop Med Hyg | |||
|volume=91 | |||
|issue=4 | |||
|pages=425–8 | |||
|year=1997 | |||
|pmid=9373640 | |||
|doi=10.1016/S0035-9203(97)90266-2 | |||
|author-separator=, | |||
|author2=Silpapojakul K | |||
|author3=Paxton H | |||
|display-authors=3 | |||
|last4=Pradutkanchana | |||
|first4=Sukone | |||
|last5=Kelly | |||
|first5=Daryl J. | |||
|last6=Strickman | |||
|first6=Daniel}}</ref> The gold standard is [[indirect immunofluorescence]],<ref>{{cite journal | |||
|author=Bozeman FM & Elisberg BL | |||
|title=Serological diagnosis of scrub typhus by indirect immunofluorescence | |||
|journal=Proc Soc Exp Biol Med | |||
|volume=112 | |||
|pages=568–73 | |||
|year=1963 | |||
|pmid=14014756}}</ref> 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,<ref>{{cite journal | |||
|author=Yamamoto S & Minamishima Y | |||
|year=1982 | |||
|title=Serodiagnosis of tsutsugamushi fever (scrub typhus) by the indirect immunoperoxidase technique | |||
|journal=J Clin Microbiol | |||
|volume=15 | |||
|issue=6 | |||
|pages=1128–l | |||
|pmid=6809786 | |||
|pmc=272264}}</ref> and the results of these tests are comparable to those from IFA.<ref name="Pradutkanchana"/><ref>{{cite journal | |||
|author=Kelly DJ, Wong PW, Gan E, Lewis GE Jr | |||
|title=Comparative evaluation of the indirect immunoperoxidase test for the serodiagnosis of rickettsial disease | |||
|journal=Am J Trop Med Hyg | |||
|year=1988 | |||
|volume=38 | |||
|issue=2 | |||
|pages=400–6 | |||
|pmid=3128129}}</ref> 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.<ref name="Pradutkanchana"/> 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.<ref>{{cite journal|author=Blacksell SD|title=Scrub typhus serologic testing with the indirect immunofluorescence method as a diagnostic gold standard: a lack of consensus leads to a lot of confusion|journal=Clin Infect Dis|volume=44|issue=3|pages=391–401|year=2007|doi=10.1086/510585|pmid=17205447|author-separator=,|author2=Bryant NJ|author3=Paris|author4=DH|display-authors=4|last5=Sakoda|first5=Y.|last6=Day|first6=N. P. J.}}</ref> In patients from endemic areas, this is not possible because antibodies may be found in up to 18% of healthy individuals.<ref>{{cite journal|title=Antibodies to ''Orientia tsutsugamushi'' in Thai soldiers|journal=Am J Trop Med Hyg|volume=55|issue=5|pages=556–9|year=1996|pmid=8940989|author=Eamsila C|author-separator=,|author2=Singsawat P|author3=Duangvaraporn A|display-authors=3|last4=Strickman|first4=D}}</ref> | |||
Other methods include culture and [[polymerase chain reaction|PCR]], but these are not routinely available<ref>{{cite journal | |||
|author=Watt G, Parola P | |||
|title=Scrub typhus and tropical rickettsioses | |||
|journal=Curr Opin Infect Dis | |||
|volume=16 | |||
|issue=5 | |||
|year=2003 | |||
|pages=429–436 | |||
|pmid=14501995 | |||
|doi=10.1097/00001432-200310000-00009}}</ref> and the results do not always correlate with serological testing,<ref>{{cite journal|author=Tay ST, Nazma S, Rohani MY|title=Diagnosis of scrub typhus in Malaysian aborigines using nested polymerase chain reaction|journal=Southeast Asian J Trop Med Public Health|year=1996|volume=27|issue=3|pages=580–3|pmid=9185274}}</ref><ref>{{cite journal|title=Usefulness of nested PCR for the diagnosis of scrub typhus in clinical practice: A prospective study|journal=Am J Trop Med Hyg|volume=75|issue=3|year=2006|pages=542–545|pmid=16968938|last1=Kim|first1=DM|last2=Yun|first2=NR|last3=Yang|first3=TY|last4=Lee|first4=JH|last5=Yang|first5=JT|last6=Shim|first6=SK|last7=Choi|first7=EN|last8=Park|first8=MY|last9=Lee|first9=SH}}</ref><ref>{{cite journal |author=Sonthayanon P |title=Rapid diagnosis of scrub typhus in rural Thailand using polymerase chain reaction |journal=Am. J. Trop. Med. Hyg. |volume=75 |issue=6 |pages=1099–102 |year=2006 |month=December |pmid=17172374 |doi= |url= |author-separator=, |author2=Chierakul W |author3=Wuthiekanun V |display-authors=3 |last4=Blacksell |first4=SD |last5=Pimda |first5=K |last6=Suputtamongkol |first6=Y |last7=Pukrittayakamee |first7=S |last8=White |first8=NJ |last9=Day |first9=NP}}</ref> and are affected by prior antibiotic treatment.<ref>{{cite journal|author=Kim DM, Byun JN|title=Effects of Antibiotic Treatment on the Results of Nested PCRs for Scrub Typhus|journal=J Clin Microbiol|year=2008|volume=46|issue=10|pages=3465–|pmid=18716229|doi=10.1128/JCM.00634-08|pmc=2566087}}</ref> The currently available diagnostic methods have been summarised.<ref name="Koh2010"/> | |||
Acute scrub typhus appears to improve viral loads in patients with [[HIV]].<ref>{{cite journal | |||
|author=Watt G|title=HIV-1 suppression during acute scrub-typhus infection|journal=Lancet|year=2000|volume=356|issue=9228|pages=475–479|doi=10.1016/S0140-6736(00)02557-5|pmid=10981892 | |||
|author-separator=, | |||
|author2=Kantipong P | |||
|author3=de Souza M | |||
|display-authors=3 | |||
|last4=Chanbancherd | |||
|first4=Penprapa | |||
|last5=Jongsakul | |||
|first5=Krisada | |||
|last6=Ruangweerayud | |||
|first6=Ronnatrai | |||
|last7=Loomis-Price | |||
|first7=Lawrence D | |||
|last8=Polonis | |||
|first8=Victoria | |||
|last9=Myint | |||
|first9=Khin Saw}}</ref> This interaction is refused by an in vitro study.<ref>{{cite journal | |||
|author=Moriuchi M, Tamura A, Moriuchi H.|title=In vitro reactivation of human immunodeficiency virus-1 upon stimulation with scrub typhus rickettsial infection|journal=Am J Trop Med Hyg|year=2003|volume=68|issue=5|pages=557–561|doi= | |||
|pmid=12812345}}</ref> | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
[[Category:Rickettsioses]] | [[Category:Rickettsioses]] | ||
[[Category:Bacterium-related cutaneous conditions]] | [[Category:Bacterium-related cutaneous conditions]] | ||
[[Category:Zoonoses]] | [[Category:Zoonoses]] | ||
[[Category:Disease]] | |||
{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} | ||
Latest revision as of 15:09, 2 January 2013
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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.