Evaluation of a combination rapid immunoassay for detection of Giardia and Cryptosporidium antigens

The Gut-Wrenching Effects of Cryptosporidiosis and Giardiasis in Children

Cryptosporidium species and Giardia duodenalis are infectious intestinal protozoan pathogens that cause alarming rates of morbidity and mortality worldwide. Children are more likely to have clinical symptoms due to their less developed immune systems and factors such as undernutrition, especially in low- and middle-income countries. The severity of the symptoms and clinical manifestations in children may vary from asymptomatic to life-threatening depending on the Cryptosporidium species/G. duodenalis strains and the resulting complex stepwise interactions between the parasite, the host nutritional and immunologic status, and the gut microbiome profile. Structural damages inflicted by both parasites to epithelial cells in the large and small intestines could severely impair children's gut health, including the ability to absorb nutrients, resulting in stunted growth, diminished neurocognitive development, and other long-term effects. Clinically approved cryptosporidiosis and giardiasis drugs have broad antimicrobial effects that have incomprehensible impacts on growing children's gut health.

Antigen-Based Diagnosis of Human Giardiasis: A Systematic Review and Meta-Analysis

Background

We aimed to present a systematic review and meta-analysis of studies that used antigen-based assays for the diagnosis of human giardiasis.

Methods

All the related published literature cited within PubMed, ISI web of science, Google Scholar, Embase, and Scopus, were searched up to December 2021. The search terms, both as MeSH terms and text words, were "Giardia", "Giardia lamblia", "Giardia intestinalis", "giardiasis", combined with "diagnosis", "antigen detection", serodiagnosis, or serological diagnosis. The required data was extracted from the papers. Pooled estimates of sensitivity and specificity were obtained and forest plots and summary receiver operating characteristics (SROC) plots were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Results

The search of databases found 1683 papers, of which 46 articles fulfilled our eligibility criteria. The sensitivity of antigen-based methods for the diagnosis of human giardiasis ranged from 45% (95% CI: 31-59%) to 100% (95% CI: 100-100%) and the pooled estimate of sensitivity was 92% (95% CI: 90-93%). The pooled estimated specificity was 97% (95% CI: 96-98%), ranged from 81% (95% CI: 68-89%) to 100% (95% CI: 98-100%). The summary estimate of PPV and NPV were 92 % (95% CI: 90-93%) and 97% (95% CI: 96-98%) respectively. Comparing the performance of the antigen detection assays by region revealed a significant difference in the assay's performances in different regions of the world.

Conclusion

The antigen-based detection methods have acceptable and satisfactory performance in the diagnosis of human giardiasis. The task ahead is to identify more specific target antigens and design simpler, cheaper, and more sensitive methods for the diagnosis of this common worldwide-distributed parasitic infection.

Cryptosporidium spp. diagnosis and research in the 21st century

The protozoan parasite Cryptosporidium has emerged as a leading cause of diarrhoeal illness worldwide, posing a significant threat to young children and immunocompromised patients. While endemic in the vast majority of developing countries, Cryptosporidium also has the potential to cause waterborne epidemics and large scale outbreaks in both developing and developed nations. Anthroponontic and zoonotic transmission routes are well defined, with the ingestion of faecally contaminated food and water supplies a common source of infection. Microscopy, the current diagnostic mainstay, is considered by many to be suboptimal. This has prompted a shift towards alternative diagnostic techniques in the advent of the molecular era. Molecular methods, particularly PCR, are gaining traction in a diagnostic capacity over microscopy in the diagnosis of cryptosporidiosis, given the laborious and often tedious nature of the latter. Until now, developments in the field of Cryptosporidium detection and research have been somewhat hampered by the intractable nature of this parasite. However, recent advances in the field have taken the tentative first steps towards bringing Cryptosporidium research into the 21st century. Herein, we provide a review of these advances.

A review of Cryptosporidium spp. and their detection in water

Cryptosporidium spp. are one of the most important waterborne pathogens worldwide and a leading cause of mortality from waterborne gastrointestinal diseases. Detection of Cryptosporidium spp. in water can be very challenging due to their low numbers and the complexity of the water matrix. This review describes the biology of Cryptosporidium spp. and current methods used in their detection with a focus on C. parvum and C. hominis. Among the methods discussed and compared are microscopy, immunology-based methods using monoclonal antibodies, molecular methods including PCR (polymerase chain reaction)-based assays, and emerging aptamer-based methods. These methods have different capabilities and limitations, but one common challenge is the need for better sensitivity and specificity, particularly in the presence of contaminants. The application of DNA aptamers in the detection of Cryptosporidium spp. oocysts shows promise in overcoming these challenges, and there will likely be significant developments in aptamer-based sensors in the near future.

Giardia lamblia infection: review of current diagnostic strategies

Giardiasis has a global distribution and it is a common cause of diarrhea in both children and adults and is transmitted via the fecal-oral route through direct or indirect ingestion of cysts. The laboratory diagnosis of Giardia spp. is mainly based on demonstration of microscopic cyst or trophozoite in stool samples but several immunological-based assays and molecular methods are also available for giardiasis diagnosis. The aim of this study was to conduct a review of the applied methods in medical laboratory and to highlight pitfalls and challenges of them for diagnosis of giardiasis. In this article we have evaluated the Giardia diagnostic methods with a broad review of literature, electronic databases and books. The search has covered the articles and some textbooks that have published up to 2018. It has been concluded that traditional microscopy combination with stool concentration method should still be held in the routine medical laboratory due to economical and high sensitivity and immunological-based assay and molecular methods which are recommended to use as a complementary test to the traditional technique.

Laboratory diagnosis of cryptosporidiosis

Cryptosporidiosis is a major etiology of persistent and chronic diarrhea in children and immunocompromised patients. In addition, it is also one of the important pathogens causing zoonotic or waterborne outbreaks. A number of conventional and molecular tests are available, but each test is riddled with few limitations. Further, there is a need to develop point of care tests and multiplexed tests for simultaneous detection of multiple pathogens.

Evaluation of ImmunoCard STAT test and ELISA versus light microscopy in diagnosis of giardiasis and cryptosporidiosis

This study was designed to evaluate ImmunoCard STAT Cryptosporidium/Giardia rapid assay and ELISA copro-antigen assays in detecting Giardia lamblia and Cryptosporidium species in fecal samples in comparison to microscopy. Both ImmunoCard STAT and ELISA assays were evaluated with 90 stool specimens that were tested by the standard ova and parasite examination including staining with both iron hematoxylin stain and modified Ziehl Neelson stains. Counting the number of Giardia cysts and Cryptosporidia oocysts in the positive stool samples was done in order to quantify the lower limit of parasite number that was able to be detected by all included assays. Both ImmunoCard STAT and ELISA assays were compared on the basis of the attributes which are number of detected cases, sensitivity, specificity, time required for the procedure and screening, ease of performance and interpretation, and cost. Microscopic examination revealed that 13.3% of the samples were positive for Giardia and 2.2% for Cryptosporidium. By ELISA, 16.7% of the samples were infected with Giardia and 3.3% with Cryptosporidium, while by ImmunoCard STAT, 17.8 and 4.45% of the samples were positive for Giardia and Cryptosporidium, respectively. There is no statistically significant difference between the results of ELISA and ImmunoCard STAT assays. The lowest concentration detected in the stool samples was 10.50 ± 1.05 Giardia cysts and 2.83 ± 1.72 Cryptosporidium oocysts. The ImmunoCard STAT was extremely easy to read, thus requiring much less time, but its cost was much higher than ELISA. We concluded that although the overall ranking of both assays was high, the ImmunoCard STAT rapid assay was a more desirable test despite its higher cost.

Comparison of diagnostic techniques for the detection of Cryptosporidium oocysts in animal samples

While a large number of laboratory methods for the detection of Cryptosporidium oocysts in faecal samples are now available, their efficacy for identifying asymptomatic cases of cryptosporidiosis is poorly understood. This study was carried out to determine a reliable screening test for epidemiological studies in livestock. In addition, three molecular tests were compared to identify Cryptosporidium species responsible for the infection in cattle, sheep and horses. A variety of diagnostic tests including microscopic (Kinyoun's staining), immunological (Direct Fluorescence Antibody tests or DFAT), enzyme-linked immunosorbent assay (ELISA), and molecular methods (nested PCR) were compared to assess their ability to detect Cryptosporidium in cattle, horse and sheep faecal samples. The results indicate that the sensitivity and specificity of each test is highly dependent on the input samples; while Kinyoun's and DFAT proved to be reliable screening tools for cattle samples, DFAT and PCR analysis (targeted at the 18S rRNA gene fragment) were more sensitive for screening sheep and horse samples. Finally different PCR primer sets targetedat the same region resulted in the preferential amplification of certain Cryptosporidium species when multiple species were present in the sample. Therefore, for identification of Cryptosporidium spp. in the event of asymptomatic cryptosporidiosis, the combination of different 18S rRNA nested PCR primer sets is recommended for further epidemiological applications and also tracking the sources of infection.

Evaluation of an immunoassay-based algorithm for screening and identification of giardia and cryptosporidium antigens in human faecal specimens from saudi arabia

An immunoassay-based algorithm, involving three commercial kits, was introduced and evaluated for screening and identification of Giardia/Cryptosporidium antigens in human stool specimens. Initially, Giardia/Cryptosporidium Chek kit (TechLab), an enzyme-linked immunosorbent assay (ELISA), was adopted for screening. The ELISA-positive reactions were subsequently characterised by RIDA Quick Giardia and RIDA Quick Cryptosporidium immunochromatographic kits (R-Biopharm). A gold standard test comprising PCR and microscopy was used for preparing control samples. Performance of individual kits was tested against these samples which included 50 Giardia-positive, 40 Cryptosporidium-positive, and 70 Cryptosporidium/Giardia-negative. For Cryptosporidium, specificities of the ELISA and RIDA Quick Cryptosporidium kits were 95.71% and 100%, respectively. Both kits demonstrated sensitivity of 95%. For Giardia, the ELISA and RIDA Quick Giardia kits showed sensitivities of 100% and 97.5%, respectively. Specificities obtained by the ELISA and RIDA Quick Giardia were 95.7% and 100%, respectively. Based on the results of two reference PCRs, on 250 random samples, the algorithm exhibited sensitivity, specificity, positive predictive value, and negative predictive value of 97.06%, 100.00%, 100.00%, and 98.91%, respectively. In conclusion, this immunoassay-based algorithm can be used as routine test in diagnostic laboratories for screening and identification of a large number of samples.

Diagnostic testing for Giardia infections

The traditional method for diagnosing Giardia infections involves microscopic examination of faecal specimens for Giardia cysts. This method is subjective and relies on observer experience. From the 1980s onwards, objective techniques have been developed for diagnosing Giardia infections, and are superseding diagnostic techniques reliant on microscopy. Detection of Giardia antigen(s) by immunoassay is the basis of commercially available diagnostic kits. Various nucleic acid amplification techniques (NAATs) can demonstrate DNA of Giardia intestinalis, and have the potential to become standard approaches for diagnosing Giardia infections. Of such techniques, methods involving either fluorescent microspheres (Luminex) or isothermal amplification of DNA (loop-mediated isothermal amplification; LAMP) are especially promising.

Epidemiological characteristics of the first water-borne outbreak of cryptosporidiosis in Seoul, Korea

The first case of human cryptosporidiosis was reported in Korea in 1995; however, an outbreak of Cryptosporidium has not been reported in Korea until now. This paper describes the first outbreak of cryptosporidiosis in Korea. On May 24, 2012, a local public health center filed a report on 126 residents with gastrointestinal symptoms in an old apartment complex in Seoul. Epidemiological investigations were implemented on 125 of the 126 patients. The patients were reported continuously over a period of 22 days. Diarrhea was the most common clinical symptom, and lasted for 5 days on average. The tap water was the only common exposure of the patients. During the environmental investigation it was discovered that the water and septic tanks were situated closely and that the waste water pipes were corroded where they passed over the water pipes. Cryptosporidium parvum was detected in 3 of the 7 stool specimens by PCR-RFLP. A number of Cryptosporidium oocysts were also detected in the water specimens from the water tank. In conclusion, Cryptosporidium parvum was the key causal pathogen of this outbreak. It is presumed that the tap water was contaminated by a sewage leak from the aged pipelines.

ImmunoCard STAT! cartridge antigen detection assay compared to microplate enzyme immunoassay and modified Kinyoun's acid-fast staining technique for detection of Cryptosporidium in fecal specimens

Cryptosporidium species infect humans and a wide range of animals worldwide; outbreaks of cryptosporidiosis have been reported in several countries. Routine diagnostic methods may be insufficient to demonstrate the presence of these organisms. The study assessed the diagnostic accuracy of the antigen detection immuno-cartridge test, ImmunoCard STAT! (Meridian Bioscience Inc., Cincinnati, OH, USA), compared to the combined gold standard: modified Kinyoun's acid-fast technique confirmed with the microplate enzyme immunoassay (EIA) for the detection of Cryptosporidium in fecal specimens. Three hundred fifteen formalin-fixed stool specimens were submitted for testing. The Kinyoun's acid-fast-stained smear revealed 24 positive samples for Cryptosporidium (of which 23 specimens were confirmed by the EIA) and 291 negative samples (of which 289 were negative by EIA). Agreement between the three used tests was shown in 22 positive and 288 negative samples for Cryptosporidium. Kappa score of agreement between the immuno-cartridge test and EIA was 0.957, p = 0.000. The sensitivity of the immuno-cartridge test was 96% (95% confidence interval (CI), 87% to 104%) and the total accuracy of the test was 97% (95% CI, 93-103). The ImmunoCard STAT! Cryptosporidium cartridge assay is easy to use and does not require specialized training or equipment and is useful in routine diagnosis and screening for Cryptosporidium especially where rapid, point of care testing is needed or where other reliable tests are unfeasible with a performance comparable to the EIA and acid-fast technique.

Evaluation of four commercial rapid immunochromatographic assays for detection of Cryptosporidium antigens in stool samples: a blind multicenter trial

In a multicenter study, potassium dichromate-preserved stools from patients infected with Cryptosporidium parvum (n = 20), C. hominis (n = 20), and other Cryptosporidium species (n = 10) and 60 controls were examined using four immunochromatographic assays. Assay sensitivity ranged between 50.1% and 86.7% for C. parvum and C. hominis but was <35% for other species.

Development and laboratory evaluation of a lateral flow device (LFD) for the serodiagnosis of Theileria annulata infection

Several DNA-based and serological tests have been established for the detection of Theileria annulata infection, including polymerase chain reaction, reverse line blot and loop-mediated isothermal amplification, indirect enzyme-linked immunosorbent assay (ELISA), and competitive ELISA. In this study, we have applied knowledge from the development and application of a recombinant protein-based indirect ELISA and competitive ELISA to establish a rapid test for point-of-care diagnosis of T. annulata infection in the field to be used by the veterinarian. For the development of a lateral flow test, the recombinantly expressed T. annulata surface protein (TaSP) was applied as the test antigen and anti-TaSP antiserum as the control line. TaSP antigen conjugated to colloidal gold particles was used as the detection system for visualization at the test line for the binding of anti-TaSP antibody present in the serum of infected animals. The developed test specifically detected antibodies in the serum of animals experimentally infected with T. annulata and showed no cross-reactivity with serum from animals infected with other tested bovine pathogens (Trypanosoma brucei, Anaplasma marginale, Babesia bigemina, Babesia bovis, and Theileria parva). Testing of field samples was compared to results obtained by other serological tests, resulting in a sensitivity and specificity of 96.3% and 87.5% compared to indirect fluorescence antibody test, 98.7% and 81.8% compared to indirect ELISA, and 100% and 47.6% compared to competitive ELISA. In conclusion, a rapid test for the detection of T. annulata infection (T. annulata lateral flow device, Ta-LFD) has been developed, which is easy to perform, delivers results to be read by the naked eye within 10 min, and is suitable for the detection of infection in field samples.

Clinical significance of enteric protozoa in the immunosuppressed human population

Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4(+) cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.

Emerging pathogens: challenges and successes of molecular diagnostics

More than 50 emerging and reemerging pathogens have been identified during the last 40 years. Until 1992 when the Institute of Medicine issued a report that defined emerging infectious diseases, medicine had been complacent about such infectious diseases despite the alarm bells of infections with human immunodeficiency virus. Molecular tools have proven useful in discovering and characterizing emerging viruses and bacteria such as Sin Nombre virus (hantaviral pulmonary syndrome), hepatitis C virus, Bartonella henselae (cat scratch disease, bacillary angiomatosis), and Anaplasma phagocytophilum (human granulocytotropic anaplasmosis). The feasibility of applying molecular diagnostics to dangerous, fastidious, and uncultivated agents for which conventional tests do not yield timely diagnoses has achieved proof of concept for many agents, but widespread use of cost-effective, validated commercial assays has yet to occur. This review presents representative emerging viral respiratory infections, hemorrhagic fevers, and hepatitides, as well as bacterial and parasitic zoonotic, gastrointestinal, and pulmonary infections. Agent characteristics, epidemiology, clinical manifestations, and diagnostic methods are tabulated for another 22 emerging viruses and five emerging bacteria. The ongoing challenge to the field of molecular diagnostics is to apply contemporary knowledge to facilitate agent diagnosis as well as to further discoveries of novel pathogens.

Cryptosporidium--biotechnological advances in the detection, diagnosis and analysis of genetic variation

Cryptosporidiosis is predominantly a gastrointestinal disease of humans and other animals, caused by various species of protozoan parasites representing the genus Cryptosporidium. This disease, transmitted mainly via the faecal-oral route (in water or food), is of major socioeconomic importance worldwide. The diagnosis and genetic characterization of the different species and population variants (usually recognised as "genotypes" or "subgenotypes") of Cryptosporidium is central to the prevention, surveillance and control of cryptosporidiosis, particularly given that there is presently no broadly applicable treatment regimen for this disease. Although traditional phenotypic techniques have had major limitations in the specific diagnosis of cryptosporidiosis, there have been major advances in the development of molecular analytical and diagnostic tools. This article provides a concise account of Cryptosporidium and cryptosporidiosis, and focuses mainly on recent advances in nucleic acid-based approaches for the diagnosis of cryptosporidiosis and analysis of genetic variation within and among species of Cryptosporidium. These advances represent a significant step toward an improved understanding of the epidemiology as well as the prevention and control of cryptosporidiosis.

Development of two immunochromatographic tests for the serodiagnosis of bovine babesiosis

In this study, we developed two immunochromatographic tests (ICTs), which are nitrocellulose membrane-based immunoassays for the convenient and rapid serodiagnosis of bovine babesiosis caused by Babesia bovis (BoICT) and Babesia bigemina (BiICT). The efficacy of two ICTs was evaluated using 13 positive sera from experimentally infected cattle with B. bovis or B. bigemina. Clear results showed that the BoICT and ELISA detected antibodies in sera collected from 14 to 93 days post-infection, while BiICT and ELISA detected from 13 to 274 days post-infection. In additon, non-infected cattle, Neospora caninum, and Cryptosporidium parvum were negative in two ICTs. To evaluate the field utility of the ICTs, we tested 186 field bovine sera collected from cattle living in Yanbian (China) and Mato Grosso do Sul (Brazil). The results of ICTs were compared to those of classical serodiagnostic methods, enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence assay (IFAT). The overall concordances of BoICT were determined as 92.5 and 90.3% when the results of ELISA and IFAT were set as the reference standards, respectively. In contrast, those of BiICT showed 96.8 and 92.5% relative to the results of standard ELISA and IFAT, respectively. Conventional and rapid diagnosic devices for bovine babesiosis may provide a valuable tool in clinical and field applications.

Detection of Giardia lamblia antigens in human fecal specimens by a solid-phase qualitative immunochromatographic assay

The SIMPLE-READ Giardia rapid assay (Medical Chemical Corporation) is a solid-phase qualitative immunochromatographic assay that detects Giardia lamblia in aqueous extracts of human fecal specimens. Testing 106 Giardia-positive and 104 Giardia-negative stool specimens yielded a sensitivity of 97.2% and a specificity of 100% for the SIMPLE-READ Giardia rapid assay.

Evaluation of seven commercial antigen detection tests for Giardia and Cryptosporidium in stool samples

Stool samples from patients with abdominal symptoms were used to evaluate different copro-diagnostic assays for the detection of Giardia and Cryptosporidium. Results from microscopical examination following conventional stool concentration and direct fluorescent-antibody methods were compared with various commercially available immunochromatographic and enzyme immunoassays. Of 220 samples, 45 were positive for Giardia and 17 for Cryptosporidium. For Giardia, the sensitivities obtained by Ridascreen Giardia, Rida Quick Giardia, Rida Quick Combi and Giardia-Strip were 82%, 80%, 80% and 44%, respectively. For Cryptosporidium, the sensitivities obtained by Rida Quick Cryptosporidium, Ridascreen Cryptosporidium, Rida Quick Combi and Cryptosporidium-Strip were 88%, 82%, 82% and 75%, respectively. The specificity of all tests was > or = 98%. Other intestinal parasites were present in 68 samples, but cross-reactions with other protozoan or helminthic parasites were not observed. Overall, the copro-antigen assays were less time-consuming and easier to perform, but were less sensitive than conventional microscopical methods. Thus, these tests might be a useful addition to, but not a substitute for microscopical methods in the diagnosis of travel-associated giardiasis and cryptosporidiosis.

An updated review on Cryptosporidium and Giardia

Cryptosporidium and Giardia are two of the most commonly occurring enteric protozoans. They are responsible for diarrheal diseases that may lead to nutritional deficiencies and significant morbidity and mortality, especially among children in developing countries and patients who have immune defects. Both are difficult to diagnose with microscopic techniques. This article provides an updated review of the epidemiology, pathogenesis, clinical manifestations, and treatment of Cryptosporidium and Giardia.

Cryptosporidium infection: diagnostic techniques

The aim of this study was to compare a rapid immunological test and a PCR method with the conventional morphological technique for the identification of Cryptosporidium in faecal samples. Cryptosporidium was found in five samples by Kinyoun acid-fast stain. Five samples yielded positive results on immunoassay, three of which yielded negative results on microscopy. Thus, only two patients were positive for Cryptosporidium according to both methods. PCR analysis confirmed only one sample as positive. Non-homogeneous distribution of parasites in stool samples, lack of oocysts in the tested sample and antigenic diversity among Cryptosporidium species may explain the poor agreement among the three tests. Based on our experience, microscopy test with Kinyoun stain is the best and cheapest way to detect Cryptosporidium spp. in faecal samples. With this method, we have found a 5.4% prevalence of Cryptosporidium infection in our area, similar to those reported for other regions of Italy and Europe.

Development of a practical immunochromatographic test with recombinant P50 for the diagnosis of Babesia gibsoni infection in dogs

An immunochromatographic test (ICT), using recombinant truncated P50 (P50t), for the detection of antibodies to Babesia gibsoni was developed and evaluated. Whereas all sera from specific pathogen-free dogs were clearly negative, all sera from dogs experimentally infected with B. gibsoni were clearly positive in the ICT. In addition, the ICT detected no cross-reactivity with sera from dogs experimentally infected with closely related parasites, B. canis canis, B. canis vogeli, and B. canis rossi, or with Neospora caninum, and Leishmania infantum. Sequential sera from a dog experimentally infected with B. gibsoni were tested with the ICT; it was shown that the specific antibodies are detectable as early as 6 days post-infection (p.i.) and that strong antibody responses remained until the end of the experiment (144 days p.i.). To evaluate the clinical application of the ICT, a total of 54 serum samples collected from domestic dogs that had been identified as having signs of anaemia at veterinary hospitals in Japan, were tested with the ICT, the previously established enzyme-linked immunosorbent assay (ELISA) and with the indirect fluorescent antibody test (IFAT). Twenty-four of the tested samples (44.4%) were positive in both ICT and ELISA, and (51.8%) in IFAT. The concordance between ELISA and ICT was found to be 100%, and 85.7% with IFAT. Taken together, the results above suggest that the ICT using P50t is rapid, simple, accurate, and suitable for use at clinical sites for the diagnosis of B. gibsoni infection in dogs.

A review of the biology and epidemiology of cryptosporidiosis in humans and animals

The epidemiology of cryptosporidiosis, an infection caused by several genotypically and phenotypically diverse Cryptosporidium species, has been dynamically changing over the past decade from that of a rare, largely asymptomatic infection to an acute enteric disease of animals and humans. In this review, the current understanding of factors (biology and epidemiology) contributing to the emergence of cryptosporidiosis in animals, including parasite biology, genetic diversity, environmental spread, livestock production trends, presence of the parasite in livestock and companion animals, and potential risk of transmission from animals to humans is highlighted. Potential control measures and the role of veterinary and medical professionals in the prevention of cryptosporidiosis are also discussed.

Evaluation of two rapid assays for detecting Cryptosporidium parvum in calf feces

OBJECTIVE

To evaluate 2 rapid, patient-side assays for detection of Cryptosporidium parvum in feces from neonatal calves with diarrhea.

DESIGN

Diagnostic test evaluation Sample Population-Fecal samples from 96 neonatal (1 to 30 days old) calves with diarrhea.

PROCEDURE

Results of the rapid assays were compared with results of microscopic examination of fecal smears that had been stained with diamant fuchsin stain.

RESULTS

One of the rapid assays correctly identified 56 of 62 (90%) fecal samples positive for C. parvum oocysts and 33 of 34 (97%) fecal samples negative for oocysts. The other assay correctly identified 53 of 62 (85%) fecal samples positive for oocysts and 33 of 34 (97%) fecal samples negative for oocysts.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that these 2 rapid assays are accurate when used to detect C. parvum in fecal samples from neonatal calves with diarrhea.

Evaluation of three commercial assays for detection of Giardia and Cryptosporidium organisms in fecal specimens

There is an increasing demand for diagnostic testing for Giardia intestinalis (G. lamblia) and Cryptosporidium parvum, with a priority being placed on obtaining diagnostic results in an efficient and timely manner. Several commercial companies have developed rapid diagnostic tests that are simple to perform and can be completed in less time than traditional methods for detecting Giardia and Cryptosporidium: We compared one of these rapid tests, the ImmunoCard STAT! (Meridian Bioscience, Inc.) lateral-flow immunoassay, with the MERIFLUOR direct fluorescent-antibody (DFA) test, the ProSpecT EZ microplate assay for Giardia and the ProSpecT microplate assay for Cryptosporidium, and modified Kinyoun's acid-fast stained smears for the detection of Cryptosporidium using 246 specimens. The MERIFLUOR DFA (Meridian Bioscience, Inc.) test detected the largest number of cases (32 Giardia and 37 Cryptosporidium) infections and was used to calculate the sensitivity and specificity of the other tests. For Giardia, the sensitivities of the ImmunoCard STAT! and the ProSpecT Giardia EZ microplate assay (Alexon-Trend, Inc.) were 81 and 91%, respectively. For detection of Cryptosporidium, the sensitivities of the ImmunoCard STAT!, the ProSpecT Cryptosporidium microplate assay (Alexon-Trend, Inc.), and modified Kinyoun's acid-fast stained smears were 68, 70, and 78%, respectively. Test specificities were equal to or greater than 99%. Specimens with very small numbers of organisms were not detected by the ImmunoCard STAT!, the ProSpecT microplate assay or modified Kinyoun's acid-fast stained smears.

Commercial assay for detection of Giardia lamblia and Cryptosporidium parvum antigens in human fecal specimens by rapid solid-phase qualitative immunochromatography

The ImmunoCard STAT! Cryptosporidium/Giardia rapid assay (Meridian Bioscience, Inc.) is a solid-phase qualitative immunochromatographic assay that detects and distinguishes between Giardia lamblia and Cryptosporidium parvum in aqueous extracts of human fecal specimens (fresh, frozen, unfixed, or fixed in 5 or 10% formalin or sodium acetate-acetic acid-formalin). By using specific antibodies, antigens specific for these organisms are isolated and immobilized on a substrate. After the addition of appropriate reagents, a positive test is detected visually by the presence of a gray-black color bar (regardless of the intensity) next to the organism name printed on the test device. A control is included in the device. Steps include tube preparation (buffer, patient specimen, conjugates A and B), testing (addition of sample onto the test device), and visual reading (total time, 12 min). Test performance was evaluated with known positive and negative stool specimens (170 specimens positive for Giardia and 231 specimens negative for Giardia) (85 specimens positive for Cryptosporidium and 316 specimens negative for Cryptosporidium); they were tested with trichrome, iron-hematoxylin, or modified acid-fast stains or the Meridian Bioscience, Inc., Giardia/Cryptosporidium Merifluor combination reagent; specimens with discrepant results were retested by using the Merifluor combination reagent. On the basis of the results of the reference methods, the sensitivities, specificities, and positive and negative predictive values were as follows: for G. lamblia, 93.5, 100, 100, and 95.5%, respectively; for C. parvum, 98.8, 100, 100, and 99.7%, respectively. False-negative results for G. lamblia were obtained with specimens with low parasite numbers (n = 7) or specimens containing trophozoites only (n = 3); one specimen with a false-negative result contained numerous cysts. The one specimen false negative for C. parvum was confirmed to be positive by immunofluorescence. No cross-reactivity was seen with 10 different protozoa (152 challenges), nine different helminths (35 challenges), or human cells (4 challenges) found in fecal specimens. This rapid test system may be very beneficial in the absence of trained microscopists; however, for patients who remain symptomatic after a negative result, the ova and parasite examination and special stains for other coccidia and the microsporidia should always remain options.