Evaluation of the ImmunoCardSTAT! rotavirus assay for detection of group A rotavirus in fecal specimens

Evaluating the Diagnostic Accuracy of Rapid Immuno-chromatographic Tests for Early Detection of Rotavirus in Fecal Samples from Children Less than Five Years with Acute Watery Diarrhea

Acute diarrheal illness is a serious public health issue in developing and developed economies, with high morbidity and mortality rates. Children below five years are the most vulnerable, with one in every six dying from diarrhea. Diarrhea may be caused by various viruses, protozoa, and bacteria. Rotavirus, in particular, is often associated with diarrhea in children. Early detection of rotavirus infection reduces the need for medication and the spread of the virus and helps determine the optimal treatment strategies. In this study, we compared the efficacy of the rapid immunochromatography technique (ICT) with that of enzyme-linked immunosorbent assay (ELISA) to detect rotavirus antigens in stool samples. Overall, 361 stool samples were obtained from hospitalized children under five-years-old, with acute watery diarrhea symptoms and were tested by both rapid ICT and ELISA. Among these samples, 104 (28.81%) tested positive by ICT and 109 (30.19%) by ELISA. Furthermore, the specificity and sensitivity of ICT were assessed using ELISA, the gold standard test. ICT had a 95.41% sensitivity and a 100% specificity. Thus, during emergency testing, ICT may be utilized as an alternative test for quick diagnosis with high specificity and sensitivity in patients with rotavirus diarrhea.

Evaluation of the Field Performance of ImmunoCard STAT!® Rapid Diagnostic Test for Rotavirus in Dadaab Refugee Camp and at the Kenya-Somalia Border

Rotavirus commonly causes diarrhea in children, leading to hospitalization and even death. Rapid diagnostic tests are feasible alternatives for determining rotavirus outbreaks in refugee camps that have inadequate laboratory capacity. We evaluated the field performance of ImmunoCard STAT!^® Rotavirus (ICS-RV) in Dadaab Refugee Camp and at the Kenya–Somalia border. From May to December 2014, we prospectively enrolled children aged < 5 years hospitalized with acute diarrhea, defined as ≥ 3 episodes of loose stool in 24 hours for < 7 days. Stool samples were collected and tested by trained surveillance clerks using ICS-RV per manufacturer's instructions. The field performance characteristics of ICS-RV were evaluated against the gold standard test, Premier^™ Rotaclone^® enzyme immunoassay. The operational characteristics were evaluated using World Health Organization (WHO) ASSURED criteria to determine whether ICS-RV is appropriate as a point-of-care test by administering a standard questionnaire and observing surveillance clerks performing the test. We enrolled 213 patients with a median age of 10 months (range = 1–48); 58.2% were male. A total of 71 (33.3%) and 60 (28.2%) patients tested positive for rotavirus infection by immunoassay and ICS-RV, respectively. The sensitivity, specificity, and positive and negative predictive values of ICS-RV compared with the immunoassay were 83.1% (95% confidence interval [CI] = 72.3–91.0), 99.3% (95% CI = 96.1–100), 98.3% (95% CI = 91.1–100), and 92.1% (95% CI = 86.6–95.5), respectively. The ICS-RV fulfilled the WHO ASSURED criteria for point-of-care testing. ICS-RV is a field-ready point-of-care test with good field performance and operational characteristics. It can be useful in determining rotavirus outbreaks in resource-limited settings.

Gastrointestinal Infections

Establishing a specific etiology for gastrointestinal infections can be challenging because of the common clinical features and wide variety of causative microorganisms. In many cases, the etiologic agent cannot be determined using traditional diagnostic methods and may result in unnecessary antibiotic use or prolonged periods of illness. Molecular tests provide many advantages over traditional laboratory methods but, with the exception of a few analytes, are still largely in the developmental phase for gastrointestinal pathogens and are not widely used. The main advantages of molecular tests include increased sensitivity and the ability to detect agents which will not grow in culture. To test for all possible gastrointestinal pathogens at one time would require a large panel that would include a variety of bacterial, viral and parasitic agents. Challenges inherent in developing diagnostic molecular panels include ensuring that all variants of a particular microorganism can be detected as well as the rapid evolution of pathogens. In this chapter, the diagnostic merit of molecular tests as well as available tests will be presented for the major groups of gastrointestinal pathogens.

Comparison of two commercial kits and an in-house ELISA for the detection of equine rotavirus in foal feces

Group A rotaviruses (RVA) are important infectious agents associated with diarrhea in the young of several animal species including foals. Currently, a variety of diagnosis methods are commercially available, like ELISA, latex agglutination and immunochromatographic assays. These commercial tests are mainly designed for the detection of human RVA; its applicability in veterinary diagnosis has been poorly studied. The aim of this study was to compare the sensitivity and specificity of two commercial diagnostic kits, Pathfinder™ Rotavirus and FASTest Rota® strip, with an in-house KERI ELISA, for the detection of equine RVA. A total of 172 stool samples from Thoroughbred foals with diarrhea were analyzed. The presence of equine RVA in samples in which only one of the three methods showed positive results was confirmed by RT-PCR. A sample was considered "true positive" when RVA was detected by at least two of the methods, and "true negative" when it tested negative by the three assays. Following these criteria, 50 samples were found positive and 122 were found negative, and were handled as reference population for the assay validation. Pathfinder™ Rotavirus assay showed 32% sensitivity and 97% specificity, FASTest Rota® strip, 92% sensitivity and 97% specificity, and KERI ELISA, 76% sensitivity and 93% specificity. Pathfinder™ Rotavirus showed 77%, FASTest Rota® strip 95%, and KERI ELISA 88% accuracy to correctly classify the samples as equine RVA positive or negative. Pathfinder failed specifically to detect equine RVA G3P12I6 genotype; such performance might be related to the specificity of the monoclonal antibody included in this kit. According to our results, differences among VP6 genotypes could influence the sensitivity to detect equine RVA in foal feces, and thus assay validation of diagnostic kits for each species is necessary. In conclusion, FASTest Rota® strip is more suitable than ELISA Pathfinder™ Rotavirus for the screening of rotavirus infection in foals. The KERI ELISA showed an acceptable performance, and could be considered a proper economic alternative for equine RVA diagnosis.

Laboratory diagnosis of viral infection

Since the last Handbook of Clinical Neurology volume on this topic, viral diagnosis has made tremendous strides, moving from the margin to the mainstream of clinical care. For many years, conventional virus isolation was the mainstay of viral diagnosis since it was sensitive and “open-minded.” However, growth in conventional cell culture entails an inherent delay that limits its clinical impact. Although rapid culture and viral antigen methods detect fewer pathogens and are less sensitive than conventional culture, both require less expertise and have greatly reduced time to result. Polymerase chain reaction has ushered in a new era in virology, especially in the diagnosis of neurologic diseases. Molecular amplification methods are rapid, highly sensitive, can be automated, quantitative, and detect viruses not amenable to routine culture. User-friendly, walk-away tests with results in an hour, as well as multiplex tests that can detect 20 viruses in a single reaction, are now a reality. As the variety of test methods and commercial products proliferate, the challenges for clinicians and laboratories are selecting which tests to utilize in which clinical scenarios, and understanding how to interpret the results. The advantages and limitations of each method are discussed in this chapter, with special attention to neurologic disease.

Point of care testing: diagnosis outside the virology laboratory

Numerous point-of-care tests (POCTs) are available to diagnose viral infections in both hospital and community settings. The ideal POCT is rapid, sensitive, specific, and simple to perform. This chapter will describe the benefits of POCTs, factors that can influence the accuracy of POCTs and highlight some limitations of POCT strategies. The sensitivity, specificity, and turn-around time of available POCTs are included for common conditions including respiratory viral infections (e.g. influenza, RSV) and blood-borne viral infections (e.g. HIV).

Effectiveness of rotavirus vaccine in preventing hospitalization due to rotavirus gastroenteritis in young children in Connecticut, USA

Rotavirus vaccine was recommended for use in US infants to prevent rotavirus gastroenteritis (RGE) in February 2006. This matched case control study assessed the effectiveness of rotavirus vaccine in preventing hospitalization of young. Cases were vaccine-eligible children 8 weeks-3 years of age, hospitalized due to laboratory-confirmed RGE. Cases (n=42) were matched to 2 control groups: (a) hospitalized controls (n=80): children hospitalized for reasons other than RGE, matched to the cases by age and time of presentation and (b) community controls (n=73): non-hospitalized children matched by age and medical practice. Adjusted vaccine effectiveness against hospitalization with RGE in vaccine eligible children receiving at least one dose of vaccine was 94.3% (95% C.I.: 55.4%-99.3%; p=0.006) for hospitalized controls and 96.9% (95% C.I.: 59.4%-99.8%; p=0.008) for community controls.

[Comparisons of latex agglutination, immunochromatography and enzyme immunoassay methods for the detection of rotavirus antigen]

BACKGROUND

Rotavirus is the most common cause of childhood gastroenteritis during winter season. Rapid, accurate diagnosis is essential for preventing severe complications of rotaviral gastroenteritis. The sensitivity and specificity of five detection test kits for rotavirus including latex agglutination (LAT), enzyme immunoassay (EIA) and three immunochromatographic methods (ICG) were evaluated in this study.

METHODS

A total of 95 stool samples collected from patients with acute gastroenteritis were studied. The test kits were as follows: LAT (Slidex latex, bioMerieux Vitek, France); three kinds of ICG (Dipstick ROTA, Eiken, Japan; SAS Rota Test, SA Scientific, Inc., USA; and ASAN Easy Test Rota strip, ASAN Pharmaceutical., Korea); and EIA (VIDAS Rotavirus, bioMerieux Vitek). The samples showing discordant results were reevaluated by reverse-transcription (RT) PCR and clinical manifestations.

RESULTS

Of a total of 95 cases, 56 (58.9%) were positive and 39 (41.1%) were negative. Thirteen cases showed discordant results. Sensitivity and specificity were, respectively, 85.7% and 100% for LAT, 100% and 95% for both of Dipstick ROTA and SAS Rota, 86.7% and 87.5% for ASAN Rota strip and 98.1% and 97.3% for EIA.

CONCLUSIONS

LAT was rapid and easy to perform and showed the lowest sensitivity among the five test kits. ICG showed a good agreement with EIA and RT-PCR. EIA was the best in respect of sensitivity and specificity, but difficulty in interpretations of equivocal results and time-consuming procedures were limitations. In conclusion, ICG, which is easy to perform at a low cost, may be an optimal method in place of LAT for the detection of rotavirus.

Field evaluation of a rota- and adenovirus immunochromatographic assay using stool samples from children with acute diarrhea in Ghana

We evaluated the Rida Quick rotavirus/adenovirus Combi rapid immunochromatographic test (ICT) under field conditions with Ghanaian children with acute diarrhea. Compared to PCR results, sensitivities and specificities were 75% and 95% for rotavirus and 22% and 84% for adenovirus. In resource-poor settings, ICTs may help to overcome difficulties in the diagnosis of rotavirus infection.

Évaluation de sept réactifs d'immunochromatographie pour détecter les rotavirus humains dans les selles

Seven commercially available immunochromatographic assays were tested for the rapid detection of group A rotaviruses in fecal samples compared to a enzyme immunoassay (Argene). Detection of rotaviruses in 80 ELISA positive frozen stool samples showed rates superior to 90% for three reagents (Rota Strip (Cypress Diagnostics), 98.8%; Rotascreen (Microgen), 95.0%; VIKIA Rota/Adeno (bioMérieux), 92.5%); from 82.5% to 88.8% for three others (Diarlex with centrifugation (Orion Diagnostica), 88.8%; Combo Rota/Adeno (All Diag), 87.5%; Rota/Adeno Combi Stick (bmd), 82.5%) and only 70.0% for Diarlex with filtration vial (Orion Diagnostica). The evaluation of the specificity, performed on one hundred fresh rotavirus negative stools, did not show any false positives with any assay. Analysis of the different technical features of these tests showed that they are quick and suitable for a clinical laboratory and do not require expensive equipment.

Childhood diarrhoea in Ankara, Turkey: epidemiological and clinical features of rotavirus-positive versus rotavirus-negative cases

Published reports dealing with rotavirus infections in Turkey are very scarce. This study included 1099 consecutive paediatric patients with diarrhoea, who sought care at 3 hospitals in Ankara, Turkey between 1999 and 2002 and were investigated for the presence of rotavirus antigen in faeces. Rotavirus antigen was detected by an immunochromatographic test, Simple Rotavirus (Operon, Spain). Other clinical and laboratory data were extracted from patient journals. A total of 404 (36.8%) patients were positive for rotavirus antigen. Rotavirus antigen was more frequently detected in boys than girls (40.8 vs 31.8%) and in children younger than 2 y (62.7%). The proportion of rotavirus-positive children was higher in the winter season (49.6%; November to April) and the highest proportion was observed in December (55.4%). Rotavirus-associated diarrhoea had a more severe clinical presentation than non-rotaviral diarrhoea; 55.3% of all patients who required hospitalization were rotavirus-positive. The seasonal and epidemiological characteristics of rotavirus diarrhoea in Ankara were similar to those in the USA and Europe. For reliable nationwide information about the epidemiology of rotavirus-associated disease in Turkey, more individual studies and reliable official statistics of gastroenteritis cases are needed.

Viruses causing gastroenteritis

Acute gastroenteritis is one of the most common diseases in humans worldwide. Viruses are recognized as important causes of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has steadily increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Astrovirus, calicivirus and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses, such as toroviruses, coronaviruses, picobirnaviruses and pestiviruses, are increasingly being identified as causative agents of diarrhea. In recent years, the availability of diagnostic tests, mainly immunoassays or molecular biology techniques, has increased our understanding of this group of viruses. The future development of a safe and highly effective vaccine against rotavirus could prevent, at least, cases of severe diarrhea and reduce mortality from this disease.

[Severe diarrhea due to rotavirus infection in a Belgian hospital 1981-2002]

Rotavirus infections are a major cause of severe diarrhea in children younger than 2 years. In Belgium they cause many hospitalizations because of dehydration. A study of the laboratory diagnosis of rotavirus infections in 28.251 stool samples at a university teaching hospital in Belgium during a twenty-year period (1981-2002) showed a marked seasonality. The virus was most often diagnosed during the winter months: 54% of the rotavirus isolates were found in the first three months of the year, with 21% of the positive samples occurring in February. Recently, rotaviruses can be genotyped based on differences in the viral outer capsid protein VP7. Vaccines are currently being developed against the four most prevalent genotypes G1, G2, G3 and G4. During the last three epidemic seasons (1999-2002) in Belgium, G1 was the most prevalent genotype and accounted for 62% of the rotavirus isolates recovered. G2, G3 and G4 were also isolated, and other emerging types need to be carefully monitored too, since G9 (45%) was co-dominant with G1 (42%) in the 2000-2001 rotavirus season in Belgium. The future development of an efficient rotavirus vaccine will need to take the diversity of the rotavirus genotypes into account.

Evaluation of a human group a rotavirus assay for on-site detection of bovine rotavirus

Neonatal diarrhea induced by bovine group A rotavirus causes significant economic loss in the dairy and beef industry due to increased morbidity and mortality, treatment costs, and reduced growth rates. The objective of this study was to evaluate a human group A rotavirus assay (ImmunoCardSTAT Rotavirus [ICS-RV]) as an on-site diagnostic test for bovine rotavirus. When used with a collection of bovine diarrhea samples submitted to the Virology Section of the Diagnostic Center for Population and Animal Health at Michigan State University and compared to a bovine group A rotavirus-specific reverse transcription-PCR (RT-PCR), the ICS-RV assay had a sensitivity and specificity of 87.0 and 93.6%, respectively. A commercially available group A rotavirus enzyme-linked immunosorbent assay (ELISA) (Pathfinder; Sanofi Diagnostics, Redmond, Wash.), when used with the same fecal sample collection and compared to the same RT-PCR, had a sensitivity and specificity of 78.3 and 67.7%, respectively. Subsequently, the ICS-RV assay, RT-PCR, and a different commercially available group A rotavirus ELISA (Rotaclone; Meridian Diagnostics, Cincinnati, Ohio) were used to evaluate fecal samples collected from neonatal calves experimentally infected with bovine rotavirus. When diarrheic fecal samples that were positive for bovine rotavirus by RT-PCR were evaluated, the ICS-RV assay and the Rotaclone assay detected bovine rotavirus 85 and 95% of the time, respectively. Based on these studies, the ICS-RV assay appears to be an excellent test for detecting group A bovine rotaviruses. This assay may be useful as an on-site diagnostic test for veterinarians as an aid in the management of bovine neonatal diarrhea.

Gastrointestinal infections

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Evaluation of two current generation enzyme immunoassays and an improved isolation-based assay for the rapid detection and isolation of rotavirus from stool

BACKGROUND

Rapid and accurate rotavirus testing is important in decisions involving patient care and management. Quality assurance testing needs to be periodically performed, especially among widely used assays having a direct impact on patient care.

OBJECTIVES

To evaluate the current generation Kallestad Pathfinder Direct antigen Detection system (PTH), and the widely used Rotaclone(R) Rotavirus EIA Diagnostic Kit (RTC), in comparison with an improved cell culture amplification-antigen detection (CCA-Ag) isolation-based assay.

STUDY DESIGN

Two hundred stool specimens (specimen stored at > or =-75 degrees C), which had been previously tested by PTH, were tested by RTC and CCA-Ag. Discordant specimens were retested by PTH, blocking assay, polyacrylamide gel electrophoresis (PAGE), and/or electron microscopy (EM).

RESULTS

Among 200 stool specimens, 197 were in accord by PTH, RTC and CCA-Ag. The sensitivity, specificity, positive and negative predictive values for RTC, PTH and CCA-Ag were, 100, 99, 99, 100, 100, 99, 99, 100; and 98, 100, 100, 98%, respectively. Among five initially discordant specimens, two required a period of 10 days to affect isolation. A non-cultivatable (CCA-Ag negative) but true positive specimen, was identified as rotavirus group A serotype G2 by RT-PCR. Four true positive but discordant specimens were blocking assay negative using one or both EIA kits.

CONCLUSIONS

PTH and RTC are excellent rotavirus detection system. However, PTH is more expensive (ca. $3.50 vs. $2.00 per test), mandates a slightly longer turn-around time (ca. 1 vs. 1.5 h), and necessitates slightly more hands-on manipulative/preparative steps. Blocking assay was not a reliable confirmatory test for the resolution of specimen discordancy. A combination of CCA-Ag, PAGE, EM, and/or perhaps RT-PCR, is recommended as an appropriate test panel for the resolution of discordant results during assay evaluation. The newly modified and simplified 48-h rotavirus isolation-based assay may serve as a base line methodology in laboratory evalaution studies, as a laboratory support methodology during drug/vaccine efficacy trials, or for the testing of sources (e.g., biopsy/autopsy tissues) not approved for assay by commercial rotavirus kits.

Viral infections of the gastrointestinal tract

Viral gastroenteritis is a major public health problem worldwide, and the number of identified pathogens continuously increases. Investigators have made considerable progress toward understanding both the epidemiology and the mechanisms of virus-cell interactions, host responses, and pathogenesis. A vaccine for the most important pathogen, rotavirus, has been approved by the US Food and Drug Administration, but possible complications have temporarily curbed the use of this vaccine.