Schistosomiasis laboratory findings: Difference between revisions

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{{Schistosomiasis}}
{{Schistosomiasis}}
{{CMG}}
{{CMG}} ; {{AE}} {{ADG}}


==Overview==
==Overview==
Microscopic identification of eggs in [[feces|stool]] or [[urine]] is the most practical method for diagnosis. The stool exam is the more common of the two. For the measurement of eggs in the feces of presenting patients the scientific unit used is [[epg]] or [[eggs per gram]].  Stool examination should be performed when infection with ''S. mansoni'' or ''S. japonicum'' is suspected, and urine examination should be performed if ''S. haematobium'' is suspected.
Methods for diagnosing schistosomiasis include visualization of Schistosoma eggs in [[stool]], [[urine]], and crushed [[Biopsy|biopsy tissues]]. [[Serological testing|serologic assays]] and urinary antigen testing have also been used. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating [[antibodies]] to schistosomes and schistosomal [[antigen]] in [[serum]].


==Laboratory Findings==
==Laboratory Findings==
Visualization of schistosoma eggs in stool, urine, and crushed biopsy tissues is diagnostic of schistosomiasis. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating antibodies to schistosomes and schistosomal antigen in serum. Diagnostic tests for schistosomiasis include the following:
Visualization of Schistosoma eggs in [[stool]], [[urine]], and [[Biopsy|crushed biopsy tissues]] is diagnostic of schistosomiasis. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating [[antibodies]] to schistosomes and schistosomal [[antigen]] in [[serum]]. Diagnostic tests for schistosomiasis include the following:<ref name="pmid21633040">{{cite journal |vauthors=Ibironke OA, Phillips AE, Garba A, Lamine SM, Shiff C |title=Diagnosis of Schistosoma haematobium by detection of specific DNA fragments from filtered urine samples |journal=Am. J. Trop. Med. Hyg. |volume=84 |issue=6 |pages=998–1001 |year=2011 |pmid=21633040 |pmc=3110375 |doi=10.4269/ajtmh.2011.10-0691 |url=}}</ref><ref name="urlCDC - DPDx - Schistosomiasis Infection - Laboratory Diagnosis">{{cite web |url=https://www.cdc.gov/dpdx/schistosomiasis/dx.html |title=CDC - DPDx - Schistosomiasis Infection - Laboratory Diagnosis |format= |work= |accessdate=}}</ref><ref name="pmid26224883">{{cite journal |vauthors=Weerakoon KG, Gobert GN, Cai P, McManus DP |title=Advances in the Diagnosis of Human Schistosomiasis |journal=Clin. Microbiol. Rev. |volume=28 |issue=4 |pages=939–67 |year=2015 |pmid=26224883 |pmc=4548261 |doi=10.1128/CMR.00137-14 |url=}}</ref>
*Microscopic examination of stool
*[[Microscopic examination]] of [[stool]]
*Urine testing for schistosome eggs
*[[Urinalysis|Urine testing]] for schistosome eggs
*Serologic testing
*[[Serological testing|Serologic testing]]
*Schistosomal antigen testing (urine or serum)
*Schistosomal [[antigen]] testing ([[urine]] or [[serum]])
*Microscopic examination of tissue
*[[Microscopic examination]] of [[Tissue (biology)|tissue]]
*PCR to detect schistosomal DNA
*[[PCR]] to detect schistosomal [[DNA]]
===Microscopic examination of stool===
*The classic and most commonly used method for identification of schistosome eggs in [[stool]] is a modified [[Kato-Katz thick smear]].<ref name="pmid19772859">{{cite journal |vauthors=Tarafder MR, Carabin H, Joseph L, Balolong E, Olveda R, McGarvey ST |title=Estimating the sensitivity and specificity of Kato-Katz stool examination technique for detection of hookworms, Ascaris lumbricoides and Trichuris trichiura infections in humans in the absence of a 'gold standard' |journal=Int. J. Parasitol. |volume=40 |issue=4 |pages=399–404 |year=2010 |pmid=19772859 |pmc=2829363 |doi=10.1016/j.ijpara.2009.09.003 |url=}}</ref>
*Testing should be done on formed [[stool]], as schistosomiasis typically does not cause [[diarrhea]].
*Several areas of a [[Stool examination|stool specimen]] should be evaluated independently, as eggs are not deposited uniformly throughout. In addition, eggs are not deposited uniformly throughout the day, and, thus, three different [[Stool examination|stool specimens]] should be evaluated.
*One to 99 eggs/g is suggestive of mild infection, 100 to 299 eggs/g indicate moderate infection, and more than 300 eggs/g are indicative of high-intensity infection.
*[[Kato-Katz thick smear|Kato Katz smears]] are not sufficiently [[Sensitive Skin|sensitive]] for detection of low-intensity [[infections]]. Other techniques may be superior but often are unavailable or more difficult to use.
{{#ev:youtube|WpcZejHa_jM}}


'''Other laboratory tests'''


Eggs can be present in the stool in infections with all ''Schistosoma'' species.  The examination can be performed on a simple smear (1 to 2 mg of fecal material).  Since eggs may be passed intermittently or in small amounts, their detection will be enhanced by repeated examinations and/or concentration procedures (such as the formalin-ethyl acetate technique).  In addition, for field surveys and investigational purposes, the egg output can be quantified by using the [[Kato-Katz technique]] (20 to 50 mg of fecal material) or the Ritchie technique.
Other diagnostic tests that are helpful in diagnosis of schistosomiasis include:
 
*[[Urinalysis]], including [[Dipsticks|dipstick]] testing and [[Microscope image processing|microscopic analysis]] for [[leukocytes]], [[erythrocytes]], and [[Urinary casts|casts]].
Eggs can be found in the urine in infections with  (recommended time for collection: between noon and 3 PM) S. japonicum' and with S. intercalatum. Detection will be enhanced by [[centrifugation]] and examination of the sediment.  Quantification is possible by using filtration through a [[nucleopore]] membrane of a standard volume of urine followed by egg counts on the membrane. Investigation of ''S. haematobium'' should also include a pelvic x-ray as bladder wall calcificaition is highly characteristic of chronic infection.
*Measurement of [[blood urea nitrogen]] ([[Blood urea nitrogen|BUN]]) and [[serum creatinine]] to test [[renal function]].
 
*[[Liver function tests]]
Recently a field evaluation of a novel handheld microscope was undertaken in Uganda for the diagnosis of intestinal schistosomiasis by a team led by Dr. Russell Stothard who heads the Schistosomiasis Control Iniative at the Natural History Museum, London. His report abstract may be found here: [http://looksmall.com/news.asp]
*[[Complete blood count|Complete blood count (]]CBC)
 
**[[Anemia]]  
**[[Eosinophilia]]
[[Image:Schistosoma bladder histopathology.jpeg|thumb|center|Photomicrography of bladder in ''S. hematobium'' infection, showing clusters of the parasite eggs with intense eosinophilia, Source: CDC]]
[[Image:Schistosoma bladder histopathology.jpeg|thumb|center|Photomicrography of bladder in ''S. hematobium'' infection, showing clusters of the parasite eggs with intense eosinophilia, Source: CDC]]
Tissue [[biopsy]] (rectal biopsy for all species and biopsy of the bladder for ''S. haematobium'') may demonstrate eggs when stool or urine examinations are negative.
The eggs of ''S. haematobium'' are ellipsoidal with a terminal spine, ''S. mansoni'' eggs are also ellipsoidal but with a lateral spine, ''S. japonicum'' eggs are spheroidal with a small knob.


==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
[[Category:Disease]]
[[Category:Water-borne diseases]]
[[Category:Parasitic diseases]]
[[Category:Zoonoses]]
[[Category:Tropical disease]]
[[Category:Hepatology]]
[[Category:Neglected diseases]]
[[Category:Infectious disease]]

Latest revision as of 12:46, 23 August 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Methods for diagnosing schistosomiasis include visualization of Schistosoma eggs in stool, urine, and crushed biopsy tissues. serologic assays and urinary antigen testing have also been used. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating antibodies to schistosomes and schistosomal antigen in serum.

Laboratory Findings

Visualization of Schistosoma eggs in stool, urine, and crushed biopsy tissues is diagnostic of schistosomiasis. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating antibodies to schistosomes and schistosomal antigen in serum. Diagnostic tests for schistosomiasis include the following:[1][2][3]

Microscopic examination of stool

  • The classic and most commonly used method for identification of schistosome eggs in stool is a modified Kato-Katz thick smear.[4]
  • Testing should be done on formed stool, as schistosomiasis typically does not cause diarrhea.
  • Several areas of a stool specimen should be evaluated independently, as eggs are not deposited uniformly throughout. In addition, eggs are not deposited uniformly throughout the day, and, thus, three different stool specimens should be evaluated.
  • One to 99 eggs/g is suggestive of mild infection, 100 to 299 eggs/g indicate moderate infection, and more than 300 eggs/g are indicative of high-intensity infection.
  • Kato Katz smears are not sufficiently sensitive for detection of low-intensity infections. Other techniques may be superior but often are unavailable or more difficult to use.

{{#ev:youtube|WpcZejHa_jM}}

Other laboratory tests

Other diagnostic tests that are helpful in diagnosis of schistosomiasis include:

Photomicrography of bladder in S. hematobium infection, showing clusters of the parasite eggs with intense eosinophilia, Source: CDC

References

  1. Ibironke OA, Phillips AE, Garba A, Lamine SM, Shiff C (2011). "Diagnosis of Schistosoma haematobium by detection of specific DNA fragments from filtered urine samples". Am. J. Trop. Med. Hyg. 84 (6): 998–1001. doi:10.4269/ajtmh.2011.10-0691. PMC 3110375. PMID 21633040.
  2. "CDC - DPDx - Schistosomiasis Infection - Laboratory Diagnosis".
  3. Weerakoon KG, Gobert GN, Cai P, McManus DP (2015). "Advances in the Diagnosis of Human Schistosomiasis". Clin. Microbiol. Rev. 28 (4): 939–67. doi:10.1128/CMR.00137-14. PMC 4548261. PMID 26224883.
  4. Tarafder MR, Carabin H, Joseph L, Balolong E, Olveda R, McGarvey ST (2010). "Estimating the sensitivity and specificity of Kato-Katz stool examination technique for detection of hookworms, Ascaris lumbricoides and Trichuris trichiura infections in humans in the absence of a 'gold standard'". Int. J. Parasitol. 40 (4): 399–404. doi:10.1016/j.ijpara.2009.09.003. PMC 2829363. PMID 19772859.