Cysticercosis laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
There is no single gold standard for diagnosing cysticercosis (except for biopsy which is rarely done). Diagnosis is made by | There is no single [[Gold standard (test)|gold standard]] for diagnosing cysticercosis (except for [[biopsy]] which is rarely done). Diagnosis is made by combining data from various investigations and suspecting the disease. | ||
A set of diagnostic criteria was proposed in 2001 based on combination of epidemiological factors, clinical manifestations, laboratory and radiological investigations. | A set of [[diagnostic criteria]] was proposed in 2001 based on combination of [[Epidemiology|epidemiological]] factors, clinical manifestations, laboratory and radiological investigations. | ||
==Diagnostic criteria == | ==Diagnostic criteria == | ||
A set of diagnostic criteria were proposed by Del Brutto et al based on the laboratory and imaging tests. The criteria were modified in 2001 to be: (22) | A set of [[diagnostic criteria]] were proposed by Del Brutto et al based on the laboratory and imaging tests. The criteria were modified in 2001 to be: (22) | ||
{| class="wikitable" | {| class="wikitable" | ||
!Categories | !Categories | ||
| Line 21: | Line 21: | ||
|Major | |Major | ||
| | | | ||
* Positivity of [[serum]] [[Antibodies|anticysticercal antibodies]] using enzyme-linked immunoelectrotransfer blot assay (EITB) | * Positivity of [[serum]] [[Antibodies|anticysticercal antibodies]] using [[Immunoblot|enzyme-linked immunoelectrotransfer blot assay (EITB)]] | ||
* Highly suggestive [[lesions]] of neurocysticercosis on [[neuroimaging]] | * Highly suggestive [[lesions]] of neurocysticercosis on [[neuroimaging]] | ||
| Line 65: | Line 65: | ||
* It is 100% [[Specificity (tests)|specific]] and has a [[sensitivity]] superior to that of any other test yet evaluated. Serum specimens from 97% of parasitologically confirmed cases of cysticercosis have detectable [[antibodies]]. No serum samples from patients with other microbial infections react with any of the [[Taenia solium|T. solium-]]<nowiki/>specific [[antigens]]. | * It is 100% [[Specificity (tests)|specific]] and has a [[sensitivity]] superior to that of any other test yet evaluated. Serum specimens from 97% of parasitologically confirmed cases of cysticercosis have detectable [[antibodies]]. No serum samples from patients with other microbial infections react with any of the [[Taenia solium|T. solium-]]<nowiki/>specific [[antigens]]. | ||
* The most important factors identified as determining positive [[immunoblot]] reactions are the numbers and stage of development of cysticerci. Cumulative clinical experience has confirmed that in patients with multiple (more than two) lesions, the test has more than 95% [[sensitivity]]. [[Seropositivity]] in biopsy-confirmed patients with single, enhancing [[parenchymal]] cysts was <50%; in clinically defined patients with a single cyst but who were not biopsied, [[sensitivity]] was 70%. [[Seropositivity]] in [[serum]] and [[CSF]] of patients with multiple but only [[Calcification|calcified]] cysts was 82 and 77%, respectively. | * The most important factors identified as determining positive [[immunoblot]] reactions are the numbers and stage of development of cysticerci. Cumulative clinical experience has confirmed that in patients with multiple (more than two) lesions, the test has more than 95% [[sensitivity]]. [[Seropositivity]] in biopsy-confirmed patients with single, enhancing [[parenchymal]] cysts was <50%; in clinically defined patients with a single cyst but who were not biopsied, [[sensitivity]] was 70%. [[Seropositivity]] in [[serum]] and [[CSF]] of patients with multiple but only [[Calcification|calcified]] cysts was 82 and 77%, respectively. | ||
* In all patients, regardless of their clinical presentation, the [[immunoblot]] assay is slightly more [[Sensitivity (test)|sensitive]] in [[serum]] than in [[CSF]] specimens: consequently, there is no need to obtain CSF solely for use in the immunoblot assay. | * In all patients, regardless of their clinical presentation, the [[immunoblot]] assay is slightly more [[Sensitivity (test)|sensitive]] in [[serum]] than in [[CSF]] specimens: consequently, there is no need to obtain [[CSF]] solely for use in the [[Immunoblot|immunoblot assay]]. | ||
* [[Immunoblot|CDC's immunoblot]] is both more specific and more sensitive than enzyme immunoassay (EIA) systems with which it has been compared. Lack of specificity has been a major problem in most EIAs because of cross-reacting components in crude antigens derived from cysticerci; these components react with antibodies specific for other helminthic infections, especially echinococcosis and filariasis. Most partially purified fractions evaluated in an EIA appear to have lower sensitivity than crude antigens and do not necessarily achieve higher specificity. Assays employing crude antigens for the detection of antibody are not reliable for the identification of this disease; all positives and any negative strongly suspected of cysticercosis should be confirmed by immunoblot. Currently available antibody detection tests for cysticercosis do not distinguish between active and inactive infections and thus have not been useful in evaluating the outcomes and prognoses of medically treated patients. Both the CDC immunoblot and an EIA are commercially available in the United States. | * [[Immunoblot|CDC's immunoblot]] is both more [[Specificity|specific]] and more [[Sensitivity (tests)|sensitive]] than [[Enzyme immunoassay|enzyme immunoassay (EIA)]] systems with which it has been compared. Lack of [[specificity]] has been a major problem in most [[Immunoassay|EIAs]] because of cross-reacting components in crude [[antigens]] derived from cysticerci; these components react with [[antibodies]] specific for other [[Helminthiasis|helminthic infections]], especially [[echinococcosis]] and [[filariasis]]. Most partially purified fractions evaluated in an [[Immunoassay|EIA]] appear to have lower [[sensitivity]] than crude [[antigens]] and do not necessarily achieve higher [[specificity]]. Assays employing crude [[antigens]] for the detection of [[antibody]] are not reliable for the identification of this disease; all positives and any negative strongly suspected of cysticercosis should be confirmed by [[immunoblot]]. Currently available [[antibody]] detection tests for cysticercosis do not distinguish between active and inactive infections and thus have not been useful in evaluating the outcomes and prognoses of medically treated patients. Both the CDC [[immunoblot]] and an [[Immunoassay|EIA]] are commercially available in the United States. | ||
* CDC's immunoblot assay with purified Taenia solium antigens has been acknowledged by the World Health Organization and the Pan American Health Organization as the immunodiagnostic test of choice for confirming a clinical and radiologic presumptive diagnosis of neurocysticercosis. | * CDC's [[immunoblot]] assay with purified [[Taenia solium]] [[antigens]] has been acknowledged by the World Health Organization and the Pan American Health Organization as the immunodiagnostic test of choice for confirming a clinical and radiologic presumptive diagnosis of neurocysticercosis. | ||
[[Image:CysticerWB.jpg|center|200 px|frame|Cysticercosis immunoblot]] | [[Image:CysticerWB.jpg|center|200 px|frame|Cysticercosis immunoblot]] | ||
* Typical antibody reactions in CDC's immunoblot for cysticercosis. Individual sera from patients with either cysticercosis or echinococcosis were analyzed using the immunoblot for cysticercosis. | * Typical [[antibody]] reactions in CDC's [[immunoblot]] for cysticercosis. Individual sera from patients with either cysticercosis or [[echinococcosis]] were analyzed using the [[immunoblot]] for cysticercosis. | ||
* Cysticercosis-specific antibodies react with glycoproteins derived from T. solium cysts. The positions of the seven diagnostic glycoproteins are marked and designated according to their relative mobilities in SDS-PAGE. Sera from patients with cysticercosis react with at least one of the cysticercosis-specific proteins, whereas sera from patients with echinococcosis do not react with any of the seven diagnostic proteins. | * [[Antibodies|Cysticercosis-specific antibodies]] react with [[glycoproteins]] derived from [[Taenia solium|T. solium]] cysts. The positions of the seven diagnostic [[glycoproteins]] are marked and designated according to their relative mobilities in SDS-PAGE. [[Serum|Sera]] from patients with cysticercosis react with at least one of the cysticercosis-specific proteins, whereas sera from patients with [[echinococcosis]] do not react with any of the seven diagnostic proteins. | ||
===Using monoclonal antibodies to detect parasitic antigen=== | ===Using monoclonal antibodies to detect parasitic antigen=== | ||
Can be used for following the response to treatment but less sensitive than EITB in detecting the disease. (23) | Can be used for following the response to treatment but less [[Sensitivity (tests)|sensitive]] than [[Immunoblot|EITB]] in detecting the disease. (23) | ||
===Stool Examination=== | ===Stool Examination=== | ||
Microscopic identification of eggs and [[proglottid]]s in feces is diagnostic for taeniasis; however, eggs and proglottids are not released into the feces until approximately 2 to 3 months after the adult tapeworm is established in the upper [[jejunum]]. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Examination of 3 stool samples collected on different days is recommended to increase the sensitivity of microscopic methods. Eggs of Taenia spp. cannot be differentiated; a species determination may be possible if mature, gravid proglottids (or, more rarely, examination of the scolex) are present. | Microscopic identification of eggs and [[proglottid]]s in feces is diagnostic for [[taeniasis]]; however, eggs and [[Proglottid|proglottids]] are not released into the feces until approximately 2 to 3 months after the adult [[Tapeworms|tapeworm]] is established in the upper [[jejunum]]. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Examination of 3 stool samples collected on different days is recommended to increase the [[sensitivity]] of microscopic methods. Eggs of [[Taenia (tapeworm)|Taenia spp]]. cannot be differentiated; a species determination may be possible if mature, [[Proglottid|gravid proglottids]] (or, more rarely, examination of the scolex) are present. | ||
===CSF analysis=== | ===CSF analysis=== | ||
*Analysing CSF for parasitic antigens is one of the minor criteria for diagnosing cysticercosis. (23) | *Analysing [[CSF]] for [[Antigen|parasitic antigens]] is one of the minor criteria for diagnosing cysticercosis. (23) | ||
*Lumbar puncture is contraindicated if there are signs of increased ICP (to avoid brain stem herniation) | *[[Lumbar puncture]] is contraindicated if there are signs of [[increased ICP]] (to avoid [[brain stem]] herniation) | ||
*Positive changes in CSF analysis as Increased cells (mainly eosinophils), increased proteins, decreased glucose in additiion to positive immunoassays in CNS analysis (ELISA and complement fixation) are almost only present in extraparenchymal NCC in the ventricles and choroidal plexus. (24) | *Positive changes in [[CSF]] analysis as Increased cells (mainly [[eosinophils]]), [[Proteins|increased proteins]], [[Glucose|decreased glucose]] in additiion to positive [[immunoassays]] in CNS analysis ([[ELISA]] and [[complement fixation]]) are almost only present in extraparenchymal NCC in the [[ventricles]] and [[Choroidal|choroidal plexus]]. (24) | ||
==References== | ==References== | ||
Revision as of 19:12, 18 April 2017
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2]
Overview
There is no single gold standard for diagnosing cysticercosis (except for biopsy which is rarely done). Diagnosis is made by combining data from various investigations and suspecting the disease. A set of diagnostic criteria was proposed in 2001 based on combination of epidemiological factors, clinical manifestations, laboratory and radiological investigations.
Diagnostic criteria
A set of diagnostic criteria were proposed by Del Brutto et al based on the laboratory and imaging tests. The criteria were modified in 2001 to be: (22)
| Categories | Details |
|---|---|
| Absolute |
|
| Major |
|
| Minor |
|
| Epidemiologic |
|
| Certainty of diagnosis after applying the criteria | |
| certainty of diagnosis | Details |
| Definitive |
|
| Probable |
|
Laboratory Findings
The definitive diagnosis consists of demonstrating the cysticercus in the tissue involved. Demonstration of Taenia Solium eggs and proglottids in the feces diagnoses taeniasis and not cysticercosis. While suggestive, it does not necessarily prove that cysticercosis is present. Persons who are found to have eggs or proglottids in their feces should be evaluated serologically since autoinfection resulting in cysticercosis can occur.
Enzyme-linked immunoelectrotransfer blot (EITB)
- CDC's immunoblot is based on detection of antibody to one or more of 7 lentil-lectin purified structural glycoprotein antigens from the larval cysts of Taenia solium in an immunoblot format. (25)
- It is 100% specific and has a sensitivity superior to that of any other test yet evaluated. Serum specimens from 97% of parasitologically confirmed cases of cysticercosis have detectable antibodies. No serum samples from patients with other microbial infections react with any of the T. solium-specific antigens.
- The most important factors identified as determining positive immunoblot reactions are the numbers and stage of development of cysticerci. Cumulative clinical experience has confirmed that in patients with multiple (more than two) lesions, the test has more than 95% sensitivity. Seropositivity in biopsy-confirmed patients with single, enhancing parenchymal cysts was <50%; in clinically defined patients with a single cyst but who were not biopsied, sensitivity was 70%. Seropositivity in serum and CSF of patients with multiple but only calcified cysts was 82 and 77%, respectively.
- In all patients, regardless of their clinical presentation, the immunoblot assay is slightly more sensitive in serum than in CSF specimens: consequently, there is no need to obtain CSF solely for use in the immunoblot assay.
- CDC's immunoblot is both more specific and more sensitive than enzyme immunoassay (EIA) systems with which it has been compared. Lack of specificity has been a major problem in most EIAs because of cross-reacting components in crude antigens derived from cysticerci; these components react with antibodies specific for other helminthic infections, especially echinococcosis and filariasis. Most partially purified fractions evaluated in an EIA appear to have lower sensitivity than crude antigens and do not necessarily achieve higher specificity. Assays employing crude antigens for the detection of antibody are not reliable for the identification of this disease; all positives and any negative strongly suspected of cysticercosis should be confirmed by immunoblot. Currently available antibody detection tests for cysticercosis do not distinguish between active and inactive infections and thus have not been useful in evaluating the outcomes and prognoses of medically treated patients. Both the CDC immunoblot and an EIA are commercially available in the United States.
- CDC's immunoblot assay with purified Taenia solium antigens has been acknowledged by the World Health Organization and the Pan American Health Organization as the immunodiagnostic test of choice for confirming a clinical and radiologic presumptive diagnosis of neurocysticercosis.
- Typical antibody reactions in CDC's immunoblot for cysticercosis. Individual sera from patients with either cysticercosis or echinococcosis were analyzed using the immunoblot for cysticercosis.
- Cysticercosis-specific antibodies react with glycoproteins derived from T. solium cysts. The positions of the seven diagnostic glycoproteins are marked and designated according to their relative mobilities in SDS-PAGE. Sera from patients with cysticercosis react with at least one of the cysticercosis-specific proteins, whereas sera from patients with echinococcosis do not react with any of the seven diagnostic proteins.
Using monoclonal antibodies to detect parasitic antigen
Can be used for following the response to treatment but less sensitive than EITB in detecting the disease. (23)
Stool Examination
Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis; however, eggs and proglottids are not released into the feces until approximately 2 to 3 months after the adult tapeworm is established in the upper jejunum. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Examination of 3 stool samples collected on different days is recommended to increase the sensitivity of microscopic methods. Eggs of Taenia spp. cannot be differentiated; a species determination may be possible if mature, gravid proglottids (or, more rarely, examination of the scolex) are present.
CSF analysis
- Analysing CSF for parasitic antigens is one of the minor criteria for diagnosing cysticercosis. (23)
- Lumbar puncture is contraindicated if there are signs of increased ICP (to avoid brain stem herniation)
- Positive changes in CSF analysis as Increased cells (mainly eosinophils), increased proteins, decreased glucose in additiion to positive immunoassays in CNS analysis (ELISA and complement fixation) are almost only present in extraparenchymal NCC in the ventricles and choroidal plexus. (24)
References