Threshold of detection of Cryptosporidium oocysts in human stool specimens: evidence for low sensitivity of current diagnostic methods

Prevalence of Cryptosporidium spp. infection in a working horse population in Egypt

Working horses support the livelihoods of smallholder farmers in Egypt. No previous study has investigated the prevalence of cryptosporidiosis in working horses in Egypt. Faecal samples were collected from 607 working horses recruited from thirty-seven villages/areas in two Egyptian governorates and examined for Cryptosporidium spp. infection using the modified Zielh-Neelsen staining technique. Data on signalment, history of recent diarrhoea, and strongyle burden were collected. The prevalence of Cryptosporidium spp. infection was calculated using a bootstrap method and potential risk factors for infection were investigated using mixed-effects logistic regression models that included sampling location as a random-effects variable. The prevalence of Cryptosporidium spp. infection was 28.7% (95% confidence interval = 23.5-33.9). None of the variables investigated, which include age, sex of the animals, and strongyle burden, were associated with risk of infection. This study provided evidence-based information on the prevalence of Cryptosporidium spp. infection in the study area. However, the potential zoonotic risk of Cryptosporidium cannot be confirmed until further studies are conducted to genotype these parasites.

Epidemiology of Cryptosporidium Infection in Romania: A Review

Since 1983, when the first report of a human Cryptosporidium spp. infection was published in Romania, and until now, many studies on cryptosporidiosis have been published in our country, but most of them are in the Romanian language and in national journals less accessible to international scientific databases. Although the infection was first recognized as a problem in children or immunocompromised people or more of a problem in low-income or underdeveloped global countries, we have shown in this review that it can also occur in people with normal immunological function and that the epidemiology of our country can provide a theoretical basis for the formulation of a Cryptosporidium spp. prevention strategy. In addition, 9.1% of healthy children and 73% of immunocompromised children were observed to have Cryptosporidium spp. infections. Higher rates have also been reported in immunocompromised adults (1.8-50%). Analyzing the prevalence of Cryptosporidium spp. infection in animals, we found values of 28.52% in cattle, 18% in buffalo calves, between 27.8 and 60.4% in pigs, 52.7% in dogs, and 29.4% in cats. Furthermore, in Romania, the burden of cryptosporidiosis, including acute infections and long-term sequelae, is currently unknown.

Advances in paper based isothermal nucleic acid amplification tests for water-related infectious diseases

Water-associated or water-related infectious disease outbreaks are caused by pathogens such as bacteria, viruses, and protozoa, which can be transmitted through contaminated water sources, poor sanitation practices, or insect vectors. Low- and middle-income countries bear the major burden of these infections due to inadequate hygiene and subpar laboratory facilities, making it challenging to monitor and detect infections in a timely manner. However, even developed countries are not immune to these diseases, as inadequate wastewater management and contaminated drinking water supplies can also contribute to disease outbreaks. Nucleic acid amplification tests have proven to be effective for early disease intervention and surveillance of both new and existing diseases. In recent years, paper-based diagnostic devices have made significant progress and become an essential tool in detecting and managing water-associated diseases. In this review, we highlight the importance of paper and its variants as a diagnostic tool and discuss the properties, design modifications, and various paper-based device formats developed and used for detecting water-associated pathogens.

Enteric protozoal infections in camels: Etiology, epidemiology, and future perspectives

Camels have great potential as a safety valve for current and future food security for pastoralists, agropastoralists, and urban populations. Enteric protozoal diseases are important causes of economic losses in camels; however, they are poorly concerned globally. The most common members of enteric protozoa are Balantidium, Eimeria, Giardia, and Cryptosporidium. Some of them threaten human health as humans can be infected by consuming food or water contaminated with camel feces, particularly in poor communities with inadequate sanitation and low-quality healthcare facilities. For these reasons, a comprehensive and careful investigation was conducted on some enteric protozoal diseases of camels to present an updated insight into the etiology, epidemiology, and future trends in diagnosing and controlling camel enteric protozoa. Future studies on the camel enteric protozoa should be carried out to develop advanced diagnostic approaches in diverse farm animal species. Moreover, the protozoan zoonotic potential should be considered to secure human health.

Prevalence of Cryptosporidium spp. infection in working horses in Egypt.. [DOI: 10.21203/rs.3.rs-2363022/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Working horses support the livelihoods of smallholder farmers in Egypt but can pose potential zoonotic risk to their handlers such as cryptosporidiosis. Working horses were recruited into the study from 37 villages/areas in two Egyptian governorates. Faecal samples were collected from 607 horses and were examined for Cryptosporidium spp. infection using modified Zielh-Neelsen staining technique. Data about signalment, concurrent disease and level of strongyle infection were collected. The prevalence of Cryptosporidium spp. infection was calculated using a bootstrap method and potential risk factors for the infection were investigated using mixed-effects logistic regression models that included the sampling location as a random-effects variable. The prevalence of Cryptosporidium spp. infection was 28.7% (95% confidence interval = 23.5–33.9). None of the variables investigated including age and sex of the animals were associated with the risk of the infection. The study identified greater prevalence of Cryptosporidium spp. infection in the study area and further studies may be required to genotype these parasites. Personal hygiene such as hand sanitation should be practiced when managing these horses.

Cryptosporidium spp. during chemotherapy: a cross-sectional study of 94 patients with malignant solid tumor

BACKGROUND

Cryptosporidium spp. is a protozoan parasite that infects many vertebrate animals, including humans. Since Cryptosporidium spp. can cause chronic life-threatening diarrhea and severe malabsorption in immunocompromised patients, we investigated the prevalence of this parasite among patients undergoing chemotherapy for malignant solid tumors.

OBJECTIVE

Investigate the prevalence of Cryptosporidium spp. in stool samples.

DESIGN

Cross-sectional.

SETTING

Tertiary care.

PATIENTS AND METHODS

Stool samples were collected from adult patients with malignant solid tumors receiving chemotherapy and diarrhea. Cryptosporidium spp. prevalence was determined using Ziehl-Neelsen staining, ELISA, and real-time PCR targeting of the COWP gene.

MAIN OUTCOME MEASURE

The prevalence of Cryptosporidium spp. in patients undergoing chemotherapy for malignant solid tumors.

SAMPLE SIZE

94 RESULTS: The prevalence was 2.1% (2/94), 5.3% (5/94), and 5.3% (5/94) as detected by Ziehl-Neelsen staining, real-time PCR and ELISA, respectively. The prevalence reached 8.5% (8/94) using all results obtained from the three methods. Among eight positive stool samples, four were positive by at least two different methods (Ziehl-Neelsen staining-ELISA or ELISA-real-time PCR) whereas the remaining four were positive by either ELISA or real-time PCR.

CONCLUSION

These findings show the risk of cryptosporidiosis in cancer patients and the necessity to use at least two diagnostic methods during the diagnosis of cryptosporidiosis to reach more accurate and trustworthy results.

LIMITATIONS

Further studies with a larger sample size are recommended.

CONFLICT OF INTEREST

None.

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.

Cryptosporidiosis is predominantly an urban, anthroponotic infectious disease among Zambian children

BACKGROUND

Cryptosporidium species are leading causes of diarrhoea in children and immunocompromised individuals. This study aimed to characterise Cryptosporidium species from children in rural and urban settings of Zambia.

METHODS

Stool samples collected from 490 children aged <5 y with diarrhoea were assessed for Cryptosporidium oocysts microscopically. A structured questionnaire was used to collect demographic and socioeconomic characteristics. Positive samples were subjected to PCR and gp60 sequence analysis.

RESULTS

The overall prevalence was 10% (50/490, 95% CI 7.8 to 13.2) with a peak in March, the late rainy season. Children who came from households where boiling water was not practised (OR=2.5, 95% CI 1.29 to 5.17; p=0.007) or who had experienced recurrent episodes of diarrhoea (OR=9.31, 95% CI 3.02 to 28.73; p=0.001) were more likely to have Cryptosporidium infection. Genotyping of 16 positive samples (14 from urban and 2 from rural sources) revealed Cryptosporidium hominis (14/16) and Cryptosporidium parvum (2/16). The Cryptosporidium hominis subtypes identified were Ia, Ib and Ie with subtype families IeAIIG3 (1), IbA9G3R2 (2), IaA31R3 (3), IbA9G3 (5), IaA27R3 (1), IaA30R3 (1) and Ia (1). Subtypes IbA9G3 and Ia were identified in children from a rural area. Cryptosporidium parvum subtypes were IIcA5G3R2 (1) and IIcA5G3a (1).

CONCLUSIONS

All isolates successfully genotyped were C. hominis or anthroponotic C. parvum, suggesting that anthroponotic transmission dominates in Lusaka and the surrounding countryside.

Global prevalence of Cryptosporidium spp. in cats: A systematic review and meta-analysis

The One-Health approach highlights that the health of human populations is closely connected to the health of animals and their shared environment. Cryptosporidiosis is an opportunistic zoonotic disease considering as global public health concern. Cats are considered as one of potential host for transmitting the Cryptosporidium spp. infection to humans. A random-effects meta-analysis model was used to estimate the overall and the subgroup-pooled prevalence of Cryptosporidium spp. across studies, and the variance between studies (heterogeneity) were quantified by I² index. Eighty articles (including 92 datasets), from 29 countries met eligibility criteria for analysis. The pooled global prevalence (95% CI) of Cryptosporidium spp. in cats was 6% (4-8%), being highest in Africa 14% (0-91%) and lowest in South and Central America 4% (3-7%) countries. Considering the detection methods, the pooled prevalence was estimated to be 26% (1-67%) using serological detection methods, 6% (3-10%) using coproantigen detection methods, 5% (3-7%) using molecular detection methods, and 4% (3-7%) using microscopic detection methods. The highest prevalence of Cryptosporidium spp. was found in stray cats 10% (5-17%), while pet (domestic) cats 4% (3-7%) had the lowest prevalence. These results emphasize the role of cats as reservoir hosts for human-infecting Cryptosporidium spp. Prevention and control of this zoonosis in cats should receive greater attention by health officials and health policymakers, especially in countries where prevalence are highest.

Prevalence of, and Factors Associated with Intestinal Parasites in Multinational Expatriate Workers in Al Ain City, United Arab Emirates: An Occupational Cross-Sectional Study

To estimate the prevalence of, and identify factors associated with intestinal parasites (IPs) in expatriate workers in the United Arab Emirates (UAE). All expatriate workers (N = 115) in a conveniently selected workplace in the industrial district of Al Ain city were invited to participate in a cross-sectional study. Consenting workers completed an interviewer-led questionnaire and self-collected stool samples. Stool samples were microscopically and molecularly screened for the presence of IPs. Univariate and multivariate analyses were conducted. Overall, 102 (88.7%) workers participated in the survey and 84.3% provided stool samples. Over three-quarters (79.4%) of workers were living in labour accommodation, 76.0% were sharing a bedroom with ≥ 4 workers, 80.2% were sharing a toilet with > 5 other people. Fifteen species of IPs were identified. Microscopically, 17.4% of the screened stool samples were positive for at least one parasite. Entamoeba species was the most common (8.1%) followed by Cryptosporidium species (3.5%). Thirty-six (41.8%) of the tested stool samples were positive for at least one parasite by molecular testing. The most prevalent parasite was Cryptosporidium species (16.3%) followed by Enterobius vermicularis (14.0%) and Ascaris lumbricoides (5.8%). Overall, 47.8% of the tested expatriate workers were positive for at least one IP, microscopically or molecularly. Educational attainment was negatively associated with being positive for at least one IP. IPs were very common amongst expatriate workers in Al Ain city. Efficacious and cost-effective public health interventions are required to reduce the burden of, and prevent the onward transmission of IPs in the UAE.

Safety and Ethics in Endoscopic Studies in Children: Evidence From the BEECH Study in Zambia

BACKGROUND

Environmental enteropathy is an example of a poorly-understood intestinal disorder affecting millions of children worldwide, characterized by malabsorption and stunting. Although there is increasing interest in non-invasive means of assessing intestinal structure and function, the potential value of intestinal biopsy for histology, immunostaining, RNA sequencing and epigenetic work means that endoscopic biopsy remains extremely valuable. We here report our experience in the BEECH (Biomarkers of Environmental Enteropathy in CHildren) study of stunting in Zambia, in the belief that it may help address the knowledge gap regarding the safety of endoscopic biopsy in vulnerable young children.

METHODS

We report our experience of safety in 119 children undergoing endoscopic biopsy in the BEECH study in Lusaka Children's Hospital, Lusaka, and discuss ethical considerations in this light.

RESULTS

Upper gastrointestinal endoscopy was performed on children with stunting (length-for-age z score -2 or less) not responsive to nutritional interventions. Conscious sedation was provided by anaesthetists. Of 119 children, 5 (4%) developed transient desaturation, but no serious adverse events were experienced; no clinical, demographic or anaesthetic characteristics were identified as predictive of desaturation. Two children derived clinically useful information from the endoscopy, one life-saving. Of 105 lactase tests, 59 (54%) showed hypolactasia.

DISCUSSION

Children with stunting underwent endoscopy safely, and some derived clinical benefit. Safety and the possibility of clinical benefit are usually felt to be preconditions for the ethical justification for endoscopy for research in children, and we believe that these conditions were met in this study.

Multicenter Comparative Study of Six Cryptosporidium parvum DNA Extraction Protocols Including Mechanical Pretreatment from Stool Samples

BACKGROUND

Nowadays, many commercial kits allow the detection of Cryptosporidium sp. in stool samples after deoxyribonucleic acid (DNA) extraction. Protocols of stool pretreatment have been proposed to optimize oocysts' DNA extraction. Among them, mechanical grinding was reported to improve the performance of Cryptosporidium oocysts' DNA extraction.

METHODS

A multicenter comparative study was conducted within the framework of the French National Reference Center-Expert Laboratory for Cryptosporidiosis. Six extraction systems (i.e., manual or automated) associated with various mechanical pretreatment protocols, were compared for the Cryptosporidium parvum oocyst' DNA extraction, before amplification using the same real-time PCR method targeting.

RESULTS

The sensitivity of real-time PCR assay was unequally impacted by the pretreatment/extraction protocol. We observed significant differences for the lowest concentrations of C. parvum oocysts (i.e., 0-94.4% and 33.3-100% respectively for 10 and 50 oocysts/mL). All in all, the protocol using Quick DNA Fecal/Soil Microbe-Miniprep® manual kit showed the best performances. In addition, optimal performances of mechanical pretreatment were obtained by combining a grinding duration of 60 s with a speed of 4 m/s using Fastprep24® with Lysing Matrix E®.

CONCLUSIONS

Sample pretreatment, as well as the extraction method, needs to be properly adapted to improve the diagnostic performances of the C. parvum DNA amplification methods.

Outbreak of cryptosporidiosis in African penguins Spheniscus demersus

Cryptosporidium spp. are parasitic intracellular protozoa that infect the digestive, respiratory, and urinary tracts of vertebrates. The disease affects many different avian species across all continents, and >25 species and genotypes of Cryptosporidium have been documented infecting birds. We report on an outbreak of cryptosporidiosis in African penguin Spheniscus demersus chicks admitted to a rehabilitation center in South Africa from February 2012 to October 2013. Eighteen cases were confirmed through histopathology. The most frequent clinical signs were regurgitation (78%), dyspnea (72%), decreased weight gain or weight loss (72%), and lethargy (50%). Clinical signs began 8-46 d after hatching or admission (median: 13 d), and death followed 1-41 d after the onset of clinical signs (median: 13.5 d). The most frequent necropsy findings were stomach distended with undigested food or gas (78%), mildly reddened lungs (56%), spleen petechial hemorrhage (44%), and kidney congestion (39%). The most frequent histopathological findings were necrotic bursitis (89%), necrotic enteritis (83%), and bursal atrophy (67%). Small round or oval basophilic bodies (3-5 µm diameter) consistent with Cryptosporidium sp. were closely associated with the surface of the epithelial cells or in the lumen of the bursa (89%), large intestine (61%), small intestine (44%), trachea (22%), and ventriculus (6%). Transmission electron microscopy of 1 case confirmed that these organisms were Cryptosporidium sp. To our knowledge, this is the first report of cryptosporidiosis in penguins, raising concern of the potential implications for the conservation of these species.

Inverse association between dengue, chikungunya, and Zika virus infection and indicators of household air pollution in Santa Rosa, Guatemala: A case-control study, 2011-2018

BACKGROUND

Dengue, chikungunya, and Zika viruses are increasingly important public health problems. Burning vegetation, leaves, and other plant products have been shown to be effective mosquito repellents for their vector, Aedes spp., but there has been scant research on whether firewood cooking smoke in households influences mosquito populations or mosquito-borne diseases. About 2.9 billion people worldwide use biomass fuel for household cooking and heating, resulting in an estimated 1.6 million deaths annually from household air pollution (HAP)-related diseases. Global health agencies now encourage households to transition from biomass to clean fuels, but it is unclear whether such interventions may actually increase risk for mosquito-borne diseases. This retrospective case-control study evaluated associations between arboviral infections and cooking with firewood in Santa Rosa, Guatemala.

METHOD

Vigilancia Integrada Comunitaria (VICo) was a prospective public health surveillance system for bacterial, parasitic, and viral causes of diarrheal, neurological, respiratory, and febrile illnesses in hospitals and clinics in the department of Santa Rosa, Guatemala. Enrolled VICo in-patients and out-patients during 2011-2018 were interviewed using standardized questionnaires on demographics and household characteristics. Blood and stool specimens were collected and tested to identify the etiologies presenting symptoms. Cases were defined as laboratory-positive for dengue, chikungunya, or Zika virus infections. Controls were laboratory-positive for bacterial and viral diarrheal illnesses (e.g., Salmonella, Shigella, Campylobacter, Escherichia coli, rotavirus, norovirus, sapovirus, or astrovirus). Cooking with firewood, kitchen location, stove type, and firewood cooking frequency were the independent exposure variables. Logistic regression models were used to analyze unadjusted and adjusted associations between arboviral infections and exposures of interest.

RESULT

There were 311 arboviral cases and 1,239 diarrheal controls. Arboviral infections were inversely associated with cooking with firewood in the main house (AOR: 0.22; 95% CI: 0.08-0.57), cooking with firewood on an open hearth (AOR: 0.50; 95% CI: 0.33-0.78), and cooking with firewood ≥5 times per week (AOR: 0.54; 95% CI: 0.36-0.81), adjusting for age, sex, ethnicity, socioeconomic status index, number of people per household, community population density, community elevation, recruitment location, season, and admission year.

CONCLUSION

Several primary determinants of HAP exposure were inversely associated with arboviral infections. Additional studies are needed to understand whether interventions to reduce HAP might actually increase risk for mosquito-borne infectious diseases, which would warrant improved education and mosquito control efforts in conjunction with fuel interventions.

Socio-ecological Factors of Zoonotic Diseases Exposure in Colorado Dairy Workers

Objectives: Zoonotic pathogens on dairy farms are a known risk for people who work and live there. Exposure and/or transmission of Salmonella serovars, E. coli (O157; H7), Campylobacter jejuni, and Cryptosporidium parvum have been documented to occur in the dairy farm environment. Social ecological factors have been identified as determinants of preventive behaviors of people at risk of infectious diseases.Methods: This study described the effect of socio-ecological factors on selected zoonotic bacterial and protozoal diseases in 42 workers of two dairy farms.Results: Occupational exposure to Salmonella ser. Dublin, E. coli, and Campylobacter spp. was confirmed. Self-efficacy and negative workplace perceptions were risk factors for Salmonella Dublin exposure (OR = 1.43[95% CI 1.11-2.22] & 1.22 [95% CI 1.02-1.53] respectively,). Additionally, safety knowledge and risk perceptions were protective factors of exposure (OR = 0.90 [95% CI 0.79-1.00]). Positive perceptions of supervisors and coworkers was a protective factor of Campylobacter exposure (OR = 0.89 [95% CI 0.79-0.98]).Conclusion: Results indicated that the presence of a supporting organizational environment, good communication with supervisors and coworkers, and training on prevention of zoonotic diseases would potentially reduce occupational exposures to zoonotic diseases on these farms.

First report of Cryptosporidium viatorum and Cryptosporidium occultus in humans in China, and of the unique novel C. viatorum subtype XVaA3h

BACKGROUND

Cryptosporidium is a genus of common intestinal protozoa, members of which cause diarrhea in a wide variety of hosts. Previous studies on Cryptosporidium in China have mainly focused on diarrhea sufferers, children, and immunodeficient individuals such as HIV/AIDS patients. However, the epidemiological characteristics of Cryptosporidium in the population in rural areas remain unclear. Herein, we investigated the prevalence of, and risk factors for, Cryptosporidium in rural areas of Binyang County, Guangxi Zhuang Autonomous Region, China, and genetically characterized the Cryptosporidium isolates we obtained.

METHODS

From August to December 2016, two villages in Binyang County, Guangxi, were sampled using a random cluster sampling method. Fresh fecal samples were collected from all eligible residents (residence time > 6 months). Molecular characterization of Cryptosporidium was carried out based on its SSU rRNA, gp60, actin and hsp70 gene sequences. Fisher's exact test were conducted to assess the risk factors for Cryptosporidium infection.

RESULTS

A total of 400 fecal samples were collected from 195 males (48.8%) and 205 females (51.2%). Two samples (0.5%) were positive for Cryptosporidium and were identified as C. viatorum and C. occultus respectively. Moreover, a new C. viatorum subtype XVaA3h was identified based on the sequence of the gp 60 gene.

CONCLUSIONS

To our knowledge, this is the first report of C. viatorum and C. occultus infections in humans in China and of C. viatorum subtype XVaA3h. The findings provide important information on the prevalence of Cryptosporidium in the Chinese population, and expand the range of Cryptosporidium species known to infect people in China.

A novel detection method of Cryptosporidium parvum infection in cattle based on Cryptosporidium parvum virus 1

Cryptosporidium parvum is an important zoonotic parasite that causes significant economic loss in the animal husbandry industry, especially the cattle industry. As there is no specific vaccine or drug against Cryptosporidium, a rapid and accurate method for the detection of C. parvum is of great significance. In this study, colloidal gold strips were developed based on Cryptosporidium parvum virus 1 (CSpV1) for the detection of C. parvum infection in cattle fecal samples. The colloidal gold solution was prepared by reducing trisodium citrate and the CSpV1 #5 monoclonal antibody was labeled with colloidal gold. A polyclonal antibody against the CSpV1 capsid protein and an anti-mouse IgG antibody were coated on the colloidal gold strips for use in the test and control lines, respectively. Our results showed that the detection sensitivity in fecal samples was up to a 1:64 dilution. There was no cross-reaction with Cryptosporidium andersoni or Giardia in the fecal samples. The different preservation conditions (room temperature, 4°C, and 37°C) and preservation time (7, 30, 60, and 90 days) were analyzed. The data showed that the strips could be preserved for 90 days at 4°C and for 60 days at room temperature or 37°C. The colloidal gold strips were used to detect the samples of 120 clinical fecal in Changchun, China. The results indicated that the rate of a positive test was 5% (6/120). This study provides a rapid and accurate method for detecting C. parvum infection in cattle and humans.

Comparison of current methods used to detect Cryptosporidium oocysts in stools

In this review all of the methods that are currently in use for the investigation of Cryptosporidium in stool material are highlighted and critically discussed. It appears that more qualifications and background knowledge in this field regarding the diagnosis of the Cryptosporidium parasite is required. Furthermore, there is no standardization for the protocols that are commonly used to either detect oocysts in faeces or to diagnose the Cryptosporidium infection. It is therefore necessary to initiate further education and research that will assist in improving the accuracy of the diagnosis of Cryptosporidium oocysts in the faecal micro-cosmos. Where ambient concentrations of oocysts are low in stool material, detection becomes a formidable task. Procedures for ring tests and the standardization of multi-laboratory testing are recommended. It is also necessary to enhance the routine surveillance capacity of cryptosporidiosis and to improve the safety against it, considering the fact that this disease is under diagnosed and under reported. This review is intended to stimulate research that could lead to future improvements and further developments in monitoring the diagnostic methodologies that will assist in harmonizing Cryptosporidium oocysts in stool diagnosis.

Infectious helminth ova in wastewater and sludge: A review on public health issues and current quantification practices

Raw and partially treated wastewater has been widely used to maintain the global water demand. Presence of viable helminth ova and larvae in the wastewater raised significant public health concern especially when used for agriculture and aquaculture. Depending on the prevalence of helminth infections in communities, up to 1.0 × 10³ ova/larvae can be presented per litre of wastewater and 4 gm (dry weight) of sludge. Multi-barrier approaches including pathogen reduction, risk assessment, and exposure reduction have been suggested by health regulators to minimise the potential health risk. However, with a lack of a sensitive and specific method for the quantitative detection of viable helminth ova from wastewater, an accurate health risk assessment is difficult to achieve. As a result, helminth infections are difficult to control from the communities despite two decades of global effort (mass drug administration). Molecular methods can be more sensitive and specific than currently adapted culture-based and vital stain methods. The molecular methods, however, required more and thorough investigation for its ability with accurate quantification of viable helminth ova/larvae from wastewater and sludge samples. Understanding different cell stages and corresponding gene copy numbers is pivotal for accurate quantification of helminth ova/larvae in wastewater samples. Identifying specific genetic markers including protein, lipid, and metabolites using multiomics approach could be utilized for cheap, rapid, sensitive, specific and point of care detection tools for helminth ova and larva in the wastewater.

Advancements in Parasite Diagnosis and Challenges in the Management of Parasitic Infections: A Mini Review

Intestinal parasitic infections (IPIs) remain a widespread public health concern causing severe implications in both developed and developing countries. Globally, numerous studies have been carried out ranging from various communities to schoolchildren as well as indigenous communities. The infections are commonly caused by helminths (e.g. Ascaris lumbricoides, Trichuris trichiura and hookworm) and protozoa (e.g. Blastocystis hominis, Cryptosporidium sp., Entamoeba histolytica and Giardia duodenalis). Poor sanitation and poverty are some of the factors associated with IPIs. With the ever-increasing impact of IPIs, newer detection approaches have been developed and studied. The efficacy of diagnostic method is crucial to give an accurate identification of these parasites. Recent developments of diagnostic tools such as serology- and molecular-based assays are assisting the conventional method of microscopy in detecting and further confirming current or past infections and the specific species of parasites. Ongoing investigations in parasitic infections using these advanced tools will provide useful information that will enable the evaluation of the effectiveness of the current control program and thus, assist future planning for improved strategies in eradicating these parasitic infections.

Practical Guidance for Clinical Microbiology Laboratories: Laboratory Diagnosis of Parasites from the Gastrointestinal Tract

This Practical Guidance for Clinical Microbiology document on the laboratory diagnosis of parasites from the gastrointestinal tract provides practical information for the recovery and identification of relevant human parasites. The document is based on a comprehensive literature review and expert consensus on relevant diagnostic methods. However, it does not include didactic information on human parasite life cycles, organism morphology, clinical disease, pathogenesis, treatment, or epidemiology and prevention. As greater emphasis is placed on neglected tropical diseases, it becomes highly probable that patients with gastrointestinal parasitic infections will become more widely recognized in areas where parasites are endemic and not endemic. Generally, these methods are nonautomated and require extensive bench experience for accurate performance and interpretation.

Cryptosporidium in humans and animals-a one health approach to prophylaxis

Cryptosporidium is a major cause of moderate-to-severe diarrhoea in humans worldwide, second only to rotavirus. Due to the wide host range and environmental persistence of this parasite, cryptosporidiosis can be zoonotic and associated with foodborne and waterborne outbreaks. Currently, 31 species are recognized as valid, and of these, Cryptosporidium hominis and Cryptosporidium parvum are responsible for the majority of infections in humans. The immune status of the host, both innate and adaptive immunity, has a major impact on the severity of the disease and its prognosis. Immunocompetent individuals typically experience self-limiting diarrhoea and transient gastroenteritis lasting up to 2 weeks and recover without treatment, suggesting an efficient host antiparasite immune response. Immunocompromised individuals can suffer from intractable diarrhoea, which can be fatal. Effective drug treatments and vaccines are not yet available. As a result of this, the close cooperation and interaction between veterinarians, health physicians, environmental managers and public health operators is essential to properly control this disease. This review focuses on a One Health approach to prophylaxis, including the importance of understanding transmission routes for zoonotic Cryptosporidium species, improved sanitation and better risk management, improved detection, diagnosis and treatment and the prospect of an effective anticryptosporidial vaccine.

Sensitivity, specificity and comparison of three commercially available immunological tests in the diagnosis of Cryptosporidium species in animals

The study was conducted to compare the specificity of immunological diagnostic methods used for the diagnosis of Cryptosporidium species capable of causing life-threatening infection in both immunosuppressed and immunocompetent patients. For the detection of Cryptosporidium species in 79 animals with diarrhoea, we used three Copro-antigen tests: RIDASCREEN^®Cryptosporidium test, Cryptosporidium 2nd Generation (ELISA) and RIDA^®QUICK Cryptosporidium. For immunoassays we used positive and negative samples detected by means of polymerase chain reaction and validated by sequencing and nested polymerase chain reaction to confirm the presence six different species of Cryptosporidium species. Prevalence of cryptosporidiosis in the entire group determined by enzyme immunoassay, enzyme linked immunosorbent assay, immuno-chromatographic test and polymerase chain reaction was 34.17%, 27.84%, 6.33% and 27.84%, respectively. Sensitivity of animal samples with enzyme immunoassay, enzyme linked immunosorbent assay, and immuno-chromatographic test was 63.6%, 40.9% and 22.7%, resp., when questionable samples were considered positive, whereas specificity of enzyme immunoassay, enzyme linked immunosorbent assay and immuno-chromatographic test was 75.9%, 78.9% and 100%, respectively. Positive predictive values and negative predictive values were different for all the tests. These differences results are controversial and therefore reliability and reproducibility of immunoassays as the only diagnostic method is questionable. The use of various Cryptosporidium species in diagnosis based on immunological testing and different results obtained by individual tests indicate potential differences in Copro-antigens produced by individual Cryptosporidium species.

Dramatic enhancement of the detection limits of bioassays via ultrafast deposition of polydopamine

The ability to detect biomarkers with ultrahigh sensitivity radically transformed biology and disease diagnosis. However, owing to incompatibilities with infrastructure in current biological and medical laboratories, recent innovations in analytical technology have not received broad adoption. Here, we report a simple, universal ‘add-on’ technology (dubbed EASE) that can be directly plugged into the routine practices of current research and clinical laboratories and that converts the ordinary sensitivities of common bioassays to extraordinary ones. The assay relies on the bioconjugation capabilities and ultrafast and localized deposition of polydopamine at the target site, which permit a large number of reporter molecules to be captured and lead to detection-sensitivity enhancements exceeding 3 orders of magnitude. The application of EASE in the enzyme-linked-immunosorbent-assay-based detection of the HIV antigen in blood from patients leads to a sensitivity lower than 3 fg ml⁻¹. We also show that EASE allows for the direct visualization, in tissues, of the Zika virus and of low-abundance biomarkers related to neurological diseases and cancer immunotherapy.

Comparison of culture-based, vital stain and PMA-qPCR methods for the quantitative detection of viable hookworm ova

Accurate quantitative measurement of viable hookworm ova from environmental samples is the key to controlling hookworm re-infections in the endemic regions. In this study, the accuracy of three quantitative detection methods [culture-based, vital stain and propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR)] was evaluated by enumerating 1,000 ± 50 Ancylostoma caninum ova in the laboratory. The culture-based method was able to quantify an average of 397 ± 59 viable hookworm ova. Similarly, vital stain and PMA-qPCR methods quantified 644 ± 87 and 587 ± 91 viable ova, respectively. The numbers of viable ova estimated by the culture-based method were significantly (P < 0.05) lower than vital stain and PMA-qPCR methods. Therefore, both PMA-qPCR and vital stain methods appear to be suitable for the quantitative detection of viable hookworm ova. However, PMA-qPCR would be preferable over the vital stain method in scenarios where ova speciation is needed.

Diagnostic biomarkers in murine Cryptosporidiosis: dose- and age-related infection

Increasing prevalence of Cryptosporidium raises the importance to explore different aspects of its infection. In the absence of reproducible in vitro culturing, animal model is the only experimental method to study Cryptosporidium. Our study evaluated Cryptosporidium infection using coproscopy, copro-antigen and copro-DNA for early detection of murine cryptosporidiosis. Hundred and forty albino mice (neonates and adult) were divided into two groups, control group received sterile PBS solution, and infected groups were inoculated with molecularly characterized Cryptosporidium parvum oocysts and further subdivided into three subgroups for infectious dose response detection. Mice fecal samples were collected every 4 h on the first day and then daily and examined for fecal oocysts, copro-antigen and copro-DNA. Four mice from each subgroup were killed at 12, 24 and 48 h post-infection (P-I), and their intestines were examined for cryptosporidial mucosal DNA. Cryptosporidium copro-antigen and copro-DNA were detected 4 and 8 h P-I in infected neonatal and adult mice, respectively, and intestinal mucosal DNA was detected after 12 h in both. Microscopy was able to detect oocysts 48 h P-I. Inoculated C. parvum oocysts were recovered in feces of infected mice without genotypic changes. Neonate mice showed higher susceptibility for cryptosporidial infection than adults without statistical differences for the given infectious doses. Both copro-immunoassay and copro-nPCR assays can early detect Cryptosporidium infection; however, nPCR was able to identify Cryptosporidium species, making nPCR a reliable biomarker for early detection in murine model.

The Impact of Different Copro-preservation Conditions on Molecular Detection of Cryptosporidium Species

BACKGROUND

We aimed to evaluate different copro-preservation conditions along the duration of one month for a better outcome of molecular diagnosis of Cryptosporidium species.

METHODS

Ten samples out of 380 fresh stool samples collected from patients with diarrhea proved positive after direct examination, concentration, staining and confirmed by immunochromatographic test. The study was conducted at the Diagnostic and Research Unit of Parasitic diseases, Faculty of Medicine, Ain Shams University at the time interval from July 2014 to December 2015. Each stool sample was preserved in five different conditions; freezing at -20 °C, 70% ethyl alcohol, 10% formalin, 2.5% potassium dichromate (K dichromate) at 4 °C and 2.5% K dichromate at room temperature (RT). Then DNA extraction and nested PCR, with Cryptosporidium oocyst wall protein (COWP) gene were done from each sample at zero time (fresh specimens) as a standard for comparison with the preservation conditions at 10, 20 and 30 d.

RESULTS

Sensitivity of studied preservative conditions along the whole study duration showed best outcome from freezing at -20 °C (80%) then K dichromate (4 °C) (73.3%) followed by K dichromate (RT) (66.7%), then alcohol (33.3%), while formalin was the worst (0%) with a highly significant comparative outcome between the different conditions. Along the three extraction intervals, K dichromate (RT), unlike all the rest of conditions lacks the consistent preservative action.

CONCLUSION

Our study highlights freezing at -20 °C to be the most suitable condition for preservation followed by K dichromate at 4 °C, K dichromate at RT, then 70% ethyl alcohol. Formalin (10%) is better to be avoided.

Quantitative detection of viable helminth ova from raw wastewater, human feces, and environmental soil samples using novel PMA-qPCR methods

In this study, we have evaluated the efficacy of propidium monoazide quantitative polymerase chain reaction (PMA-qPCR) to differentiate between viable and non-viable Ancylostoma caninum ova. The newly developed method was validated using raw wastewater seeded with known numbers of A. caninum ova. Results of this study confirmed that PMA-qPCR has resulted in average of 88 % reduction (P < 0.05) in gene copy numbers for 50 % viable +50 % non-viable when compared with 100 % viable ova. A reduction of 100 % in gene copies was observed for 100 % non-viable ova when compared with 100 % viable ova. Similar reductions (79-80 %) in gene copies were observed for A. caninum ova-seeded raw wastewater samples (n = 18) collected from wastewater treatment plants (WWTPs) A and B. The newly developed PMA-qPCR method was applied to determine the viable ova of different helminths (A. caninum, A. duodenale, Necator americanus and Ascaris lumbricoides) in raw wastewater, human fecal and soil samples. None of the unseeded wastewater samples were positive for the above-mentioned helminths. N. americanus and A. lumbricoides ova were found in unseeded human fecal and soil samples. For the unseeded human fecal samples (1 g), an average gene copy concentration obtained from qPCR and PMA-qPCR was found to be similar (6.8 × 10(5) ± 6.4 × 10(5) and 6.3 × 10(5) ± 4.7 × 10(5)) indicating the presence of viable N. americanus ova. Among the 24 unseeded soil samples tested, only one was positive for A. lumbricoides. The mean gene copy concentration in the positively identified soil sample was 1.0 × 10(5) ± 1.5 × 10(4) (determined by qPCR) compared to 4.9 × 10(4) ± 3.7 × 10(3) (determined by PMA-qPCR). The newly developed PMA-qPCR methods were able to detect viable helminth ova from wastewater and soil samples and could be adapted for health risk assessment.

Prevalence of Cryptosporidium and Giardia in the water resources of the Kuang River catchment, Northern Thailand

A catchment-scale investigation of the prevalence of Cryptosporidium and Giardia in the Kuang River Basin was carried out during the dry and rainy seasons. Water samples were collected from the Kuang River and its tributaries as well as a major irrigation canal at the study site. We also investigated the prevalence of gastrointestinal parasitic infection among dairy and beef cattle hosts. Cryptosporidium and/or Giardia were detected in all the rivers considered for this study, reflecting their ubiquity within the Kuang River Basin. The high prevalence of Cryptosporidium/Giardia in the upper Kuang River and Lai River is of a particular concern as both drain into the Mae Kuang Reservoir, a vital source of drinking-water to many local towns and villages at the research area. We did not, however, detected neither Cryptosporidium nor Giardia were in the irrigation canal. The frequency of Cryptosporidium/Giardia detection nearly doubled during the rainy season compared to the dry season, highlighting the importance of water as an agent of transport. In addition to the overland transport of these protozoa from their land sources (e.g. cattle manure, cess pits), Cryptosporidium/Giardia may also be re-suspended from the streambeds (a potentially important repository) into the water column of rivers during storm events. Faecal samples from dairy and beef cattle showed high infection rates from various intestinal parasites - 97% and 94%, respectively. However, Cryptosporidium and Giardia were only detected in beef cattle. The difference in management style between beef (freeranging) and dairy cattle (confined) may account for this disparity. Finally, phylogenetic analyses revealed that the Cryptosporidium/Giardia-positive samples contained C. ryanae (non-zoonotic) as well as Giardia intestinalis assemblages B (zoonotic) and E (non-zoonotic). With only basic water treatment facilities afforded to them, the communities of the rural area relying on these water supplies are highly at risk to Cryptosporidium/Giardia infections.

Serum Anti-Cryptosporidial gp15 Antibodies in Mothers and Children Less than 2 Years of Age in India

Little is known about the type and longevity of the humoral response to cryptosporidial infections in developing countries. We evaluated serum antibody response to Cryptosporidium gp15 in 150 sets of maternal, preweaning and postinfection/end-of-follow-up sera from children followed up to 2 years of age to determine the influence of maternal and preweaning serological status on childhood cryptosporidiosis. Fifty two percent (N = 78) of mothers and 20% (N = 30) of children were seropositive preweaning. However, most positive preweaning samples from children were collected early in life indicating transplacental transfer and subsequent rapid waning of antibodies. Although 62% (N = 94) of children had a parasitologically confirmed cryptosporidial infection (detected by stool polymerase chain reaction) during the follow-up, only 54% (N = 51) of children were seropositive postinfection. Given there were striking differences in seropositivity depending on when the sample was collected, even though Cryptosporidium was detected in the stool of the majority of the children, this study indicates that antibodies wane rapidly. During follow-up, the acquisition or severity of cryptosporidial infections was not influenced by maternal (P = 0.331 and 0.720, respectively) as well as the preweaning serological status of the child (P = 0.076 and 0.196, respectively).

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.

Rapid microfluidic immunoassay for surveillance and diagnosis of Cryptosporidium infection in human immunodeficiency virus-infected patients

Cryptosporidiosis has been reported to be associated with HIV/acquired immune deficiency syndrome, which greatly reduces the quality of life and shortens the life expectancy of HIV-infected patients. In order to properly treat the infected patients, accurate and automatic diagnostic tools need to be developed. In this study, a novel microfluidic immunochip system was presented for the surveillance and the rapid detection of Cryptosporidium infection in 190 HIV-infected patients from Guangxi, China, using the P23 antigen of Cryptosporidium. The procedure of detection can be completed within 10 min with 2 μl sample consumption. The system also was evaluated using the standard ELISA method. Among 190 HIV-infected individuals, the rate of P23 positivity was 13.7%. Seropositivity in HIV-infected individuals was higher in female patients. The seropositivity to P23 was higher in HIV-infected individuals with high viral load, although the difference was statistically insignificant. Significantly higher Cryptosporidium seropositivity was observed in HIV-infected individuals with a CD4(+) T-cell count of <200 cells/μl than in those with ≥200 cells/μl. Our results also demonstrate that a lower CD4(+) T-cell count may reflect an increased accumulated risk for cryptosporidiosis. The detection system was further validated using the standard ELISA method and good correlation between the two methods was found (r = 0.80). Under the same sensitivity, this new microfluidic chip device had a specificity of 98.2%. This developed system may provide a powerful platform for the fast screening of Cryptospordium infection in HIV-infected patients.

Diagnosis of Parasitic Infections

Methods for the diagnosis of parasitic infections have stagnated in the past three decades. Labor-intensive methods such as microscopy still remain the mainstay of several diagnostic laboratories. There is a need for more rapid tests that do not sacrifice sensitivity and that can be used in both clinical settings as well as in poor resource field settings. The fields of diagnostic medical parasitology, treatment, and vaccines are undergoing dramatic change. In recent years, there has been tremendous effort to focus research on the development of newer diagnostic methods focusing on serological, molecular, and proteomic approaches. This article examines the various diagnostic tools that are being used in clinical laboratories, optimized in reference laboratories, and employed in mass screening programs.

Retroreflective imaging system for optical labeling and detection of microorganisms

A retroreflective imaging system for imaging microscopic targets over macroscopic sampling areas is introduced. Detection of microorganism-bound retroreflector (RR) targets across millimeter-scale samples is implemented according to retroreflection directionality, collimation, and contrast design characteristics. Retroreflection directionality is considered for corner-cube (CC) and spherical geometries. Spherical-RRs improve directionality and reliability. Retroreflection collimation is considered for spherical-RRs. Retroreflective images for micro-CC-RRs and micro-spherical-RRs with varying refractive indices show optimal results for high refractive index BaTiO3 micro-spherical-RRs. A differential imaging technique improves retroreflection contrast by 35 dB. High refractive index micro-spherical-RRs and differential imaging, together, can detect microscopic RR targets across macroscopic areas.

Performance evaluation of point-of-care test for detection of Cryptosporidium stool antigen in children and HIV infected adults

Background

Gastro-enteritis is associated with significant morbidity and mortality in patients with HIV/AIDS and children, and Cryptosporidium is the most important parasite implicated. To date, several commercial companies have developed simple and rapid point-of-care tests for the detection of Cryptosporidium infection; however, information is scarce regarding their diagnostic significance in Ethiopia. This study aimed at evaluating the performance of a rapid diagnostic test (RDT) for the detection of Cryptosporidium stool antigen.

Methods

A hospital-based cross-sectional study was conducted in Hawassa University Hospital, southern Ethiopia from May to November 2013. Faecal samples were collected from a total of 100 children and 250 HIV infected individuals with diarrhea or CD4 T-cell count lower than 200 cells/μl. Specimens were processed using direct, formol-ether concentration and modified Ziehl-Neelsen techniques for diagnosis of Cryptosporidium and other parasites. One hundred faecal samples (50 positives for Cryptosporidium, 35 positives for other parasites and 15 negatives for any intestinal parasites) were tested using the CoproStrip™Cryptosporidium kit (Savyon Diagnostics Ltd, Israel). Test parameters were calculated using microscopy of the modified Ziehl-Neelsen stained stool smear as reference method.

Results

The performance of the RDT was first compared to routine microscopic analysis (examination ≤10 min). The CoproStrip™Cryptosporidium RDT correctly detected 31 of 42 positive samples and 49 of 50 negative samples (i.e., 11 false negatives and 1 false positive). Sensitivity, specificity, PPV, NPV and accuracy were calculated to be 74, 98, 97, 84 and 88%, respectively. Upon thorough microscopic analysis (examination >10 min), 8 more samples with very low oocyst density were found. However, these were missed by the kit and lower the sensitivity and NPV to 62 and 72%, respectively. No cross-reactivity was observed with any of the helminthic or other protozoan parasites including Isospora and Cyclospora species.

Conclusion

Based on the results described herein, the CoproStrip™Cryptosporidium test could be used as an alternative to conventional microscopy especially where diagnosis of Cryptosporidium is limited due to time constraints, lack of experienced microscopists or unavailability of appropriate equipment/electricity.

Comparative diagnostic techniques for cryptosporidium infection

Diarrhoea caused by Cryptosporidium is usually mild in immune competent individuals but severe in the young and those with underlying disease leading to compromised immunity. The conventional diagnosis of Cryptosporidium requires observation of the infective oocysts however, their tiny size yields indistinct results, thus limiting the effectiveness of the conventional diagnostic technique, modified Ziehl-Neelsen (ZN) differential staining. Consequent to the abovementioned limitation, ZN staining, sandwich antigen detection enzyme linked immunosorbent assay (sad-ELISA) and a direct polymerase chain reaction (PCR) assay techniques were evaluated for diagnostic efficacy. Stool samples were collected from 180 consenting adult patients attending outpatient and inpatient clinics at Victoria Hospital, Alice, Eastern Cape Province of South Africa. Subjects were stratified as; 35 HIV-positive and diarrhoeagenic, 125 HIV-negative diarrhoeagenic and 20 apparently healthy controls. Cryptosporidium incidence following diagnostic techniques were 13 (37.1%; ZN staining), 26 (74.3%; sad-ELISA) and 23 (65.7%; PCR), respectively, among HIV-positive diarrhoeagenic patients and 34 (27.2%; ZN staining), 96 (76.8%; sad-ELISA) and 89 (71.2%; PCR) among HIV-negative diarrhoeagenic patients. Sensitivity, specificity and predictive values of the diagnostic techniques’ efficiency were: sensitivity: 46.2% (HIV-positive) and 32.3% (HIV-negative) against the ZN technique and 96.9% against sad-ELISA and PCR, respectively, for both HIV-positive and -negative patients; specificity was 88.9% (HIV-positive) and 96.6% (HIV-negative) against the ZN technique. Lastly, the predictive values were 92.3% (HIV-positive) and 96.9% (HIV-negative), respectively, following ZN staining. The sad-ELISA technique proved more suitable for the determination of the presence of Cryptosporidium oocysts. The high incidence of Cryptosporidium in HIV-positive subjects as compared to the HIV-negative population accentuates the significance of cryptosporidiosis diagnosis in the treatment and management of HIV cases.

Nucleic acid test to diagnose cryptosporidiosis: lab assessment in animal and patient specimens

Diarrheal diseases cause more morbidity and mortality around the world than human immunodeficiency virus (HIV), malaria, or tuberculosis. Given that effective treatment of persistent diarrheal illness requires knowledge of the causative organism, diagnostic tests are of paramount importance. The protozoan parasites of the genus Cryptosporidium are increasingly recognized to be responsible for a significant portion of diarrhea morbidity. We present a novel nucleic acid test to detect the presence of Cryptosporidium species in DNA extracted from stool samples. The assay uses the isothermal amplification technique recombinase polymerase amplification (RPA) to amplify trace amounts of pathogen DNA extracted from stool to detectable levels in 30 min; products are then detected visually on simple lateral flow strips. The RPA-based Cryptosporidium assay (RPAC assay) was developed and optimized using DNA from human stool samples spiked with pathogen. It was then tested using DNA extracted from the stool of infected mice where it correctly identified the presence or absence of 27 out of 28 stool samples. It was finally tested using DNA extracted from the stool of infected patients where it correctly identified the presence or absence of 21 out of 21 stool samples. The assay was integrated into a foldable, paper and plastic device that enables DNA amplification with only the use of pipets, pipet tips, and a heater. The performance of the integrated assay is comparable to or better than polymerase chain reaction (PCR), without requiring the use of thermal cycling equipment. This platform can easily be adapted to detect DNA from multiple pathogens.

A comparison of nested PCR assay with conventional techniques for diagnosis of intestinal cryptosporidiosis in AIDS cases from northern India

Cryptosporidiosis is a very important opportunistic infection and is responsible for significant morbidity and mortality in HIV/AIDS patients. Although current laboratory methods are generally considered adequate to detect high concentrations of oocysts, they fail to detect cases of cryptosporidiosis in many immunocompromised patients. The present study was done to determine the diagnostic efficacy of modified Ziehl-Neelsen (ZN), antigen detection ELISA, and a nested PCR assay for detection of Cryptosporidium in 58 adult AIDS cases with diarrhea from the ART clinic of Lok Nayak Hospital, New Delhi. Cryptosporidium was detected in 17 (29.4%), 39 (67.3%), and 45 (77.5%) cases by modified ZN staining, antigen ELISA, and nested PCR assay, respectively. Taking nested PCR as the gold standard, specificity of both modified ZN staining and Cryptosporidium antigen detection ELISA was 100% while the sensitivity of the tests was 37.8% and 86.6%, respectively. PCR was more sensitive than the other two diagnostic modalities but required a more hands-on time per sample and was more expensive than microscopy. PCR, however, was very adaptable to batch analysis, reducing the costs considerably. This assay can therefore have considerable advantages in the treatment of immunosuppressed individuals like AIDS patients, allowing their early diagnosis and decreasing the morbidity and the mortality.