Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia and Cryptosporidium parvum in human fecal specimens.

It is well known that Giardia lamblia and Cryptosporidium parvum can cause severe symptoms in humans, particularly those who are immunologically compromised. Immunoassay procedures offer both increased sensitivity and specificity compared to conventional staining methods. These reagents are also helpful when screening large numbers of patients, particularly in an outbreak situation or when screening patients with minimal symptoms. The data obtained by using 9 diagnostic kits were compared: direct fluorescent-antibody assay (DFA) kits (TechLab Giardia/Crypto IF kit, TechLab Crypto IF kit, and Meridian Merifluor Cryptosporidium/Giardia) and enzyme immunoassay (EIA) kits (Alexon ProSpecT Giardia EZ Microplate Assay, Alexon ProSpecT Cryptosporidium Microplate Assay, Cambridge Giardia lamblia Antigen Microwell ELISA, Meridian Premier Giardia lamblia, Meridian Premier Cryptosporidium, TechLab Giardia CELISA, Trend Giardia lamblia EIA). The test with the Meridian Merifluor Cryptosporidium/Giardia kit was used as the reference method. In various combinations, 60 specimens positive for Giardia, 60 specimens positive for Cryptosporidium, 40 specimens positive for a Giardia-Cryptosporidium mix, and 50 negative fecal specimens were tested. Different species (nine protozoa, three coccidia, one microsporidium, five nematodes, three cestodes, and one trematode) were included in the negative specimens. The sensitivity of EIA for Giardia ranged from 94% (Alexon) to 99% (Trend and Cambridge); the specificity was 100% with all EIA kits tested. The sensitivity of EIA for Cryptosporidium ranged from 98% (Alexon) to 99% (Meridian Premier); specificities were 100%. All DFA results were in agreement, with 100% sensitivity and specificity; however, the TechLab reagents resulted in fluorescence intensity that was generally one level below that seen with the reagents used in the reference method. In addition to sensitivity and specificity, factors such as cost, simplicity, ease of interpretation of results (color, intensity of fluorescence), equipment, available personnel, and number of tests ordered are also important considerations prior to kit selection.     

Comparison of Nine Commercially Available Enzyme-Linked Immunosorbent Assays for Detection of Giardia lamblia in Fecal Specimens

Overall performance, including ease of use, total hands-on time, incubation and processing times, sensitivity, and specificity, of each of nine enzyme-linked immunosorbent assays (ELISAs) were compared by using 222 individual fecal samples submitted for the detection of Giardia lamblia. The assays evaluated were manufactured by Alexon, Inc., Cambridge Biotech Corp., Meridian, Inc., and Trend Scientific, Inc. All assays used polyclonal antibodies except the “new and improved” Microplate (direct and diluted methods) by Alexon, which is a monoclonal antibody assay. Seventy specimens were positive for G. lamblia by ELISA, ova and parasite test, and/or direct fluorescent-antibody assay. One hundred fifty two were negative by all three methods. Sensitivities and specificities ranged from 88.6 to 100% and 99.3 to 100%, respectively. The total hands-on time needed to run one specimen ranged from 1 min to 2 min 17 s per specimen. All except one commercially available ELISA were found to be rapid, sensitive, and specific for the detection of G. lamblia in fecal specimens.     

Performance of three enzyme immunoassays and two direct fluorescence assays for detection of Giardia lamblia in stool specimens preserved in ECOFIX

ECOFIX is a single-vial stool preservative that is both formalin- and mercury-free. We evaluated the abilities of three commercial Giardia lamblia-specific enzyme immunoassays (EIAs) (ProSpecT Giardia Microplate Assay [Alexon-Trend Inc.], Giardia Test [Techlab], and Premier Giardia lamblia [Meridian Diagnostics, Inc.]) and two commercial direct fluorescent-antibody (FA) assays for G. lamblia (Crypto/Giardia IF Test [Techlab] and Merifluor Cryptosporidium/Giardia [Meridian Diagnostics, Inc.]) to detect G. lamblia in 34 G. lamblia-positive and 44 G. lamblia-negative stool specimens (determined by traditional examination for ova and parasites) preserved in ECOFIX compared to their abilities to detect G. lamblia in the same specimens preserved in formalin as the "gold standard" for each assay. Of the 34 formalin-fixed positive specimens, the number detected by each assay was as follows:, Alexon EIA, 34; Meridian EIA, 27; Techlab EIA, 29; Meridian FA assay, 31; and Techlab FA assay, 28. Both FA tests and the Alexon EIA performed well with ECOFIX, but the other two EIAs detected fewer positive specimens (the difference was statistically significant with the Techlab EIA) when ECOFIX was the preservative. Use of G. lamblia cyst antigen from cultured organisms preserved in formalin and ECOFIX demonstrated that the Alexon EIA could detect smaller amounts of antigen in ECOFIX than the other two EIAs could and suggested that cyst antigen is more stable in formalin. We recommend that laboratories use an FA assay or the Alexon EIA if they plan to use ECOFIX as their stool preservative.     

Clinical and Analytical Evaluation of a Single-Vial Stool Collection Device with Formalin-Free Fixative for Improved Processing and Comprehensive Detection of Gastrointestinal Parasites

Microscopic examination of feces is a standard laboratory method for diagnosing gastrointestinal parasite infections. In North America, the ovum and parasite (O&P) examination is typically performed using stool that is chemically fixed in polyvinyl alcohol (PVA) and formalin, after which the stool is concentrated by filtration to enhance sensitivity. Mini Parasep solvent-free (SF) tubes allow collection and concentration within a single collection vial. The goal of the study was to determine whether consolidated processing and concentration with the Parasep tubes using an alcohol-based fixative (Alcorfix) provide O&P examinations equivalent to or better than those done by processing of PVA-formalin-fixed stool using a SpinCon concentration device. Parasep tubes revealed filtration performance equivalent to that of the SpinCon concentration device using PVA-formalin-fixed stool containing protozoa. Specimens cocollected in Parasep tubes containing PVA-formalin and Alcorfix revealed comparable morphology and staining for various protozoa. Alcorfix effectively fixed live Cryptosporidium and microsporidia such that morphology and staining were conserved for modified acid-fast and modified trichrome stains. A work flow analysis revealed significant time savings for batches of 10 or 30 O&P specimens in tubes with Alcorfix compared to the amount of time that it took to analyze the same number of specimens in tubes with PVA-formalin. The direct hands-on time savings with Mini Parasep tubes were 17 min and 41 s and 32 min and 1 s for batches of 10 and 30 specimens, respectively. Parasep tubes containing Alcorfix provide significant work flow advantages to laboratories that process medium to high volumes of O&P specimens by streamlining processing and converting to a single tube. These improvements in work flow, reduction of the amount of formalin used in the laboratory, and equivalent microscopy results are attractive advancements in O&P testing for North American diagnostic parasitology laboratories.     

Stool diagnosis of giardiasis using a commercially available enzyme immunoassay to detect Giardia-specific antigen 65 (GSA 65).

A commercially available enzyme immunoassay for the diagnosis of giardiasis was evaluated in a clinical trial. The ProSpecT/Giardia diagnostic test (Alexon, Inc., Mountain View, Calif.) was compared with the standard ova and parasite (O&P) microscopic examination. Additionally, several widely used stool fixatives and a commonly used transport medium were assessed for compatibility with the immunoassay. A total of 325 stool specimens were collected and used to evaluate assay performance. Of those, 93 specimens were collected from symptomatic Giardia O&P-positive patients and 232 specimens were randomly collected from patients as part of a routine health screening procedure. All 93 Giardia O&P-positive stool specimens were strongly positive by visual and spectrophotometric examination using the immunoassay. Of the 232 randomly collected specimens, 16 were positive by O&P examination and immunoassay, 6 were negative by O&P examination but positive by immunoassay, and 1 was positive by O&P examination and negative by immunoassay. There was substantial supportive evidence that indicated that the six immunoassay-positive, O&P-negative specimens were true-positives. When these six specimens were accepted as true-positives, the immunoassay detected almost 30% more cases of Giardia infection than did O&P examination. Its sensitivity and specificity were 96 and 100%, respectively, while the sensitivity and specificity of O&P examination were 74 and 100%, respectively. The immunoassay also performed well on specimens treated with 10% neutral Formalin, sodium acetate-Formalin fixative, and Cary-Blair transport medium. However, the test was not compatible with polyvinyl alcohol-treated specimens. Overall, the ProSpecT/Giardia test was a sensitive, specific immunoassay which was easy to run and interpret. It offers a simple solution to traditional difficulties encountered in diagnosing Giardia infection.     

Tritiation of protein antigens of Plasmodium knowlesi schizont-infected erythrocytes using pyridoxal phosphate-sodium boro[3H]hydride

The protein antigens of Plasmodium knowlesi schizont-infected red blood cells (SI-RBCs) and normal RBCs were compared using the pyridoxal phosphate/NaB³H₄ method. Permeation of the outer SI-RBC membrane by the pyridoxal phosphate anion was enhanced since unlike normal RBCs it was not possible to exclusively label surface membrane proteins without concurrent haemoglobin labelling. Under conditions of minimal haemoglobin labelling a subset of total susceptible SI-RBC proteins (M_r 125 000, 50 000, 45 000 and 30 000) were labelled that were absent from normal RBCs and which may be surface proteins. The M_r 125 000 band labels much more readily than Band 3, the normal anion transporter, suggesting that it may be a new anion transporter in the SI-RBC membrane. At higher pyridoxal phosphate concentrations additional bands (M_r 230 000, 180 000, 165 000, 145 000, 107 000 and 72 000) were labelled exclusively with SI-RBCs. The new pyridoxal phosphate-labelled proteins had altered electrophoretic mobility and reduced Coomassie Blue staining, both properties assisting in their identification. Antigen analysis using Protein A-Sepharose and sera from infected monkeys demonstrated that all new ³H-labelled proteins were SI-RBC-specific antigens. One very high M_r antigen (> 250 000) recognized only by homologous strain antisera may represent a strain-specific antigen.     

Evaluation of a Screening Test for Detection of Giardia and Cryptosporidium Parasites

The Giardia/Cryptosporidium Chek test (TechLab, Inc.), a screening test for Giardia and Cryptosporidium, was evaluated with 136 fecal samples. Using the results of the Giardia II test and Cryptosporidium II test as gold standards, it was 98.4% sensitive and 100% specific and had positive and negative predictive values of 98.7% and 99.3%.     

Contemporary testing for enteric pathogens: the potential for cost, time, and health care savings.

We sent a questionnaire to 79 clinical microbiology laboratories seeking information on contemporary practices when investigating for bacterial and protozoan enteric pathogens. Data from the 67 respondents (response rate of 85%) showed that a minority of laboratories (40% for stool culture and 45% for ova and parasite [O&P] examinations) had restrictions for testing in place and that fewer laboratories (24% for stool culture and 19% for O&P examinations) rejected specimens from patients who had been in the hospital for > 3 days. Using two estimates, 15 and 40%, for the proportion of all specimens received from patients in the hospital for > 3 days, we calculated savings for the average hospital in this survey. Reagent savings of $4,000 to $10,000 and time savings of 274 to 731 h per year might have been realized. Moreover, between $26,000 and $71,000 in patient charges could have been prevented. On the basis of this survey, wider application of rejection criteria when testing for enteric pathogens appears possible. If implemented, savings to the nation's health care system could be between $27 and $73 million a year.     

Large-scale isolation of the two major polypeptides of the hepatitis B surface antigen (HBsAg) by gel filtration in 6 M guanidinium chloride

Purified hepatitis B surface antigen (HBsAg) of subtype ay was solubilized in guanidinium chloride and submitted to chormatography on Sepharose 4B in the presence of guanidinium chloride. The polypeptides P1 (M_r = 24,000) and P2 (M_r = 29,000) were eluted in the same fraction with a minor contaminant (M_r = 40,000). Large amounts of these two polypeptides were obtained in a single step. This technique which constitutes a method for large-scale purification of the P1 and P2 polypeptides should permit more complete characterization of the P1 and P2 polypeptides and of their antigenic determinants.     

Comparison of PCR, Isoenzyme Analysis, and Antigen Detection for Diagnosis of Entamoeba histolytica Infection

The diagnosis of amebiasis by microscopic identification of the parasite in stool is insensitive and unable to distinguish the invasive parasite Entamoeba histolytica from the commensal parasite E. dispar. In this study, we have tested a PCR technique for the detection of E. histolytica and compared it with isoenzyme analysis and the TechLab E. histolytica-specific antigen detection test. The nested-PCR test we used is based on amplification of the small subunit rRNA gene of E. histolytica and E. dispar followed by restriction digest analysis of the PCR product. Single stool samples were obtained from 98 patients from Dhaka, Bangladesh, with diarrhea: 88 patients diagnosed by microscopy and/or culture with E. histolytica and/or E. dispar infection and 10 patients without infection. Isoenzyme analysis identified 53 of the infections as E. histolytica and 28 as E. dispar. PCR and isoenzyme identification of E. histolytica agreed in 96% (51 of 53) of amebic cultures. PCR for E. histolytica was negative in all 10 samples that were negative for E. histolytica by isoenzyme and antigen detection. PCR and antigen detection had comparable sensitivities when performed directly on fresh stool specimens, identifying 87% (46 of 53) and 85% (45 of 53), respectively, of E. histolytica infections identified by isoenzyme analysis. The correlation of results by antigen detection and PCR for identification of E. histolytica in stool was 93% (45 of 48 cases). Mixed infections with E. histolytica and E. dispar were detected by PCR in 14% (12 of 88) of cases. In conclusion, all three techniques for specific identification of E. histolytica in fresh stool showed excellent correlation. Only the TechLab E. histolytica antigen detection test was both rapid and technically simple.     

The structure and protein kinase activity of proteins encoded by nonconditional mutants and back mutants in the sec gene of avian sarcoma virus

We have characterizedsrc proteins encoded by approximately 30 nonconditional transformation-defective mutants of avian sarcoma virus (ASV) and by several back mutants which reestablish a transformed phenotype. We used gel electrophoresis of immunoprecipitated proteins labeled with³²PO₄ or [³⁵S]methionine to assess size, stability, and phosphorylation; partial digestion with staphylococcal V8 protease to determine structure; and an immune complex assay to measure protein kinase activity. The mutants were all isolated as phenotypic revertants of the B31 line of B77-ASV transformed rat cells, each revertant cell bearing a single provirus without appreciable deletions, as described in the accompanying report (Varmuset al., 1980). In several instancesm the mutant proteins were examined both in the revertant rat cells and in chicken cells infected with transformation-defective viruses rescued from the nonpermissive rat cells. In addition, secondary mutations to restore a transformed phenotype (back mutations) occurred in some cases, in the original rat cells and/or chicken cells infected with rescued viruses. Three categories of mutants were identified by this survey. The largest group (Class I) encodedsrc proteins of normal size (60,000M_r); these proteins were hypophosphorylated and exhibited little or no protein kinase activity.Class II mutants displayed immunoprecipitablesrc proteins of less than normal size. In three cases, the shortsrc related proteins were mapped to the amino terminus of wild-type pp60^src and may be the result of nonsense mutations; in two cases, the short proteins were mapped to the car?yl terminus. Most of Class II mutants lacked protein kinase activity, but the 45,000M_r protein in line 000 exhibited moderate levels of activity, thereby mapping the enzymatically active site to the car?yl terminal three-fourths of pp60^src. The smallest group of mutants (Class III) did not produce detectablesrc proteins. Some of the mutant proteins behaved differently in permissive and nonpermissive hosts; in particular, the product of mutant L produced fusiform transformation and was highly phosphorylated and associated with wild-type levels of protein kinase activity in chicken cells, but was nontransforming, hypo-phosphorylated, and associated with low levels of protein kinase activity in rat cells. In all cases, back mutation to a transformed phenotype was accompanied by a restoration of wild-type (or near wild type) levels of protein kinase activity, further documenting the functional significance of the enzymatic activity. Some of the back mutants, however, encoded proteins of atypical size, either smaller or larger than pp60^src. The active proteins larger than pp60^src ranged up to 68,000M_r in size and were altered at or near the amino terminus. In one case (a retransformed derivative of the Class II revertant 000), the generation of a functionalsrc protein of 68,000M_r coincided with the appearance of an insert of ca. 200 base pairs into the ASV provirus, within or adjacent to the coding region for the amino terminus ofsrc. The diversity of reagents, both mutants and back mutants, derived from the single provirus in B31 cells indicates that this system will be useful for correlation of functional and structural attributes ofsrc.     

Physician use of parasite tests in the United States from 1997 to 2006 and in a Utah Cryptosporidium outbreak in 2007

Parasitic infection is uncommon in the United States, but surveys suggest that physicians test when the presence of parasites is unlikely and fail to order appropriate testing when suspicion is high. Numerous studies confirm that immunoassays are more sensitive for Giardia and Cryptosporidium detection, but our experience was that physicians preferentially used ovum and parasite examination (O&P). We conducted a retrospective study of fecal parasite testing at a referral laboratory nationally (1997 to 2006) and during a Cryptosporidium outbreak (Utah, 2007) to correlate physician use of O&P and enzyme immunoassays (EIAs) with the yield of parasites detected. Nationally, of 170,671 episodes, 76.0% (n = 129,732) included O&P, 27.9% (n = 47,666) included Giardia EIA, and 5.7% (n = 9,754) included Cryptosporidium EIA. Most pathogens were Giardia or Cryptosporidium. More episodes were positive when EIA was performed (n = 1,860/54,483 [3.4%]) than when O&P only was performed (n = 1,667/116,188 [1.4%]; P < 0.001), and EIA was more sensitive than O&P. However, more O&P results were positive among patients with both O&P and EIA performed (2.5%) than among those with O&P only performed (1.4%; P < 0.001), suggesting that patients tested by O&P only may have been at lower risk. During the first 10 weeks of the outbreak, physicians also preferentially used O&P over EIA, but no Cryptosporidium cases were detected by O&P. We conclude that clinicians frequently use O&P testing when test performance and epidemiology support the use of immunoassays or no testing. We recommend that stool O&P be limited to patients with negative immunoassay results and persistent symptoms or individuals at increased risk for non-Giardia, non-Cryptosporidium infection. An evidence-based algorithm for the evaluation of patients with suspected intestinal parasitic infection is proposed.     

Translation of tick-borne encephalitis virus (flavivirus) genome in vitro: Synthesis of two structural polypeptides

RNA isolated from tick-borne encephalitis virus (TBEV) was translated in an mRNA-dependent cell-free system derived from Krebs-2 cells, producing a set of polypeptides with M_r ranging from ca. 13,000 to 160,000 and higher. Two of these polypeptides with M_r of 13,000 (p13) and 53,000 (p53) were identified as TBEV core polypeptide V2 and the polypeptide moiety of envelope glycoprotein, V3, respectively. The amino acid sequences of p13 and p53 were also shown to be contained in a high-molecular-weight polypeptide (M_r ～ 118,000). The label from the initiator tRNA species, f-[³⁵S]Met-tRNA_f^Met, could be incorporated into p13 but not into p53, suggesting that p13 is encoded in a region of the viral genome immediately adjacent to the site at which the translation in vitro is initiated; on the other hand, the p53 coding segment appears to be located further from the initiation point. The two structural polypeptides of TBEV were accumulated in vitro with dissimilar kinetics and both differed from the majority of other translation products in that their synthesis was relatively resistant to an increase in KCl concentration in the incubation mixture. Possible modes of synthesis of TBEV structural proteins and post-translational processing of their precursor are discussed.     

Evaluation of Four Enzyme Immunoassays for the Detection of Giardia lamblia Antigen in Stool Specimens

 Four enzyme immunoassays for the detection of Giardia lamblia antigen in stool specimens were evaluated: the ProSpecT Giardia Microplate Assay (Alexon, USA), the Giardia CELISA (Cellabs, Australia), the DSl-Giardia-ELISA (DSL, Germany), and the Melotest Giardiasis Ag (Melotec, Spain). Microscopic examination and enzyme immunoassays were performed on 168 stool specimens collected from 168 patients suspected to have giardiasis. All assays were easy to perform. The ProSpecT Giardia assay had the highest sensitivity of the assays evaluated (91%), and its interpretation was the easiest. The sensitivity of the three other assays ranged from 63 to 81%. The ProSpecT Giardia assay can be useful to detect Giardia lamblia and may replace microscopic examination in areas of high endemicity.     

The oxygen consumption of mammalian non-myelinated nerve fibres at rest and during activity

1. A study has been made of the oxygen consumption of non-myelinated nerve fibres of rabbit desheathed cervical vagus nerves at rest and during activity.2. The average resting oxygen consumption (Q_r) was 0·0924 μmole/g. min at 21° C. Stimulation for 1-3 min at 3/sec caused an extra oxygen consumption (Q_s) of 816 p-mole/g.shock.3. When the frequency of stimulation was increased, to 10/sec and 30/sec, Q_s fell. When the frequency was decreased, to 1/sec and 0·3/sec, Q_s increased slightly.4. When the temperature was decreased, Q_r fell; when the temperature was increased, Q_s also increased. Temperature similarly affected Q_s with high frequencies of stimulation, but had relatively little effect on Q_s at low frequencies of stimulation.5. An isolated single shock seemed to produce an increase in oxygen consumption of about 1200 p-mole/g, and this value was largely independent of temperature.6. When part of the sodium in the Locke solution was replaced by barium, Q_r decreased (by 12%) whereas Q_s increased (by 87%).7. Veratrine (1 μg/ml.) increased both Q_r (by 142%) and Q_s (by 361%).8. Acetylcholine (1·7 mM) increased Q_r (by 32%).9. When nerves were transferred to potassium-free solutions there was little change in Q_r, and Q_s fell slightly (by 8%).10. When the potassium concentration in the Locke solution was increased 4-fold, Q_r increased (by 27%).11. Salicylate (1-10 mM) increased Q_r (by 24%) and abolished Q_s.12. When the sodium of Locke solution was replaced by lithium, Q_r decreased (by 19%) and Q_s was abolished.13. In sodium-Locke solution ouabain (100 μM) decreased Q_r (by 26%) and abolished Q_s. In lithium-Locke solution ouabain also decreased Q_r (by 28%).14. All or nearly all of the oxygen consumed at rest or during activity seemed to be used to pump potassium ions into, and sodium ions out of, the axoplasm.15. The K/O₂ ratio during pumping was about 5·0.     

Further characterization of proteins assembled by vesicular stomatitis virus from human tumor cells

Vesicular stomatitis virus (VSV), when reproduced in human tumor cell lines, assembled a specific subset of cell-derived proteins. These were detected by [³⁵S]methionine labeling of cells prior to infection and subsequent immunoprecipitation of VSV grown in these cells, as well as by direct immunoprecipitation of labeled cell extracts with antiserum directed against the VSV-assembled proteins. Their molecular weight (M_r) ranged between 15K and 180K; the larger proteins were glycosylated. Two of the major protein species (gp88 and gp130) were common to all four cell lines used (HeLa—cervical carcinoma, T47D—breast carcinoma, and HMB2 and SK1477—two melanoma cell lines). Proteins of other molecular weights were detected only in one or two of the cell lines. The melanoma cell lines (even in the absence of VSV) shed large particulate material which had contained the same spectrum of proteins that were assembled by VSV. The major protein component had an M_r of 30K. Some of the VSV-assembled proteins might possibly serve as specific tumor markers. It is also conceivable that the proteins assembled by VSV as well as the large particulate material might be products of defective endogenous human retroviruses.     

Use of an enzyme immunoassay does not eliminate the need to analyze multiple stool specimens for sensitive detection of Giardia lamblia

The relative sensitivities of a commercially available enzyme immunoassay (EIA) (ProSpecT Giardia; Alexon-Trend Inc., Ramsey, Minn.) and conventional ovum-and-parasite (O&P) examination for the detection of Giardia lamblia in preserved stool specimens were determined. Paired stool samples collected independently within a 7-day period from 103 patients were analyzed by both methods. A total of 54 specimens from 30 patients (18 asymptomatically infected with G. lamblia and 12 with symptoms consistent with intestinal giardiasis) were determined to be positive for G. lamblia, of which 48 (88.9%) were positive by microscopy and 52 (96.3%) were positive by EIA. Both specimens submitted were positive for G. lamblia by O&P examination for 66.7% (20 of 30) of the positive patients; for 26.7% (8 of 30) a single specimen was positive by O&P examination, and for 6.7% (2 of 30) of those determined to be infected with G. lamblia, both samples were negative by microscopy. The sensitivity of conventional O&P examination was somewhat higher in symptomatically infected individuals, with 75% (9 of 12) of patients in this category having G. lamblia detected in both samples, compared with 61% (11 of 18) of asymptomatic patients. A total of 24 positive patients (80%) had G. lamblia antigen detected by EIA in both submitted samples, 4 positive patients (13.3%) had one specimen positive by EIA, and the EIA was negative in both specimens from 2 infected individuals (6.5%), the sensitivity of EIA was substantially equivalent in asymptomatic and symptomatic individuals (77 versus 83% of patients with positive results on both specimens). Although the sensitivity of EIA for the detection of G. lamblia on a single stool specimen was somewhat higher than that of conventional O&P examination in symptomatic patients (83 versus 75%), in asymptomatic patients (77 versus 61%), and overall (80 versus 67%), examination of two specimens by either EIA or microscopy was necessary to achieve a diagnostic sensitivity of greater than 90%.     

Evaluation of rapid commercial enzyme immunoassay for detection of Giardia lamblia in formalin-preserved stool specimens.

Two hundred twenty-three formalin-preserved stool specimens were evaluated by using ProSpecT Giardia Rapid Assay (membrane bound) (Alexon, Inc., Sunnyvale, Calif.). Enzyme immunoassay (EIA) results were compared with those by conventional microscopic examination. Two hundred four specimens were negative by both methods, and 13 (6.3%) were positive. Five specimens were negative by initial microscopic exam and positive by EIA; three of these specimens were found to be positive upon extensive microscopic reexamination. The remaining two specimens were from patients who previously tested positive and who had recurrent symptoms of or responded to therapy for giardia. Therefore, we consider both cases to be true positives. One specimen exhibited a single cyst by microscopic exam and was negative by EIA Resolved results yielded a relative sensitivity of 95%, a relative specificity of 100%, a positive predictive value of 99.6%, and a negative predictive value of 100%, compared with a sensitivity of 74% for conventional microscopy.     

Serological diagnosis of canine leishmaniosis: comparison of three commercially available tests

Quantitative serology is an important tool in canine leishmaniosis diagnostics from clinical and epidemiological points of view. Serologic diagnosis in laboratories is traditionally carried out by immunofluorescent antibody test (IFAT), but enzyme-linked immunosorbent assays (ELISA) are being increasingly employed. Two commercially available ELISAs (LEISHMANIA-ELISA DOG® [LED] and INGEZIM LEISHMANIA® [IL]) for the detection of Leishmania infantum infection in dogs were compared with the classical IFAT technique. Ninety-two canine serum samples covering a broad range of IFAT titers were chosen for evaluation. Titers ranged from negative (<1:50) to high (>1:3,200). Statistical analysis showed high correlation between all three assays for both negative and positive IFAT-tested samples as described by respective Spearman’s rank correlation coefficient (r _s), but results varied for samples with inconclusive IFAT titers (1:50–1:100) with IL stating samples predominantly negative. The highest accordance was found between LED and IFAT (percentage of identical results?=?83.7 %; r _s?=?0.90, p?<?0.0001). IL showed higher analogy with LED (accordance?=?81.5 %; r _s?=?0.88, p?<?0.0001) than with IFAT (73.9 %; r _s?=?0.80, p?<?0.0001). The distribution of the different ELISA scores is discussed and grouped according to correspondent IFAT titers to familiarize practitioners with the range of these tests since antibody levels play an important role in clinical management of canine patients with L. infantum infection.