Under-notification of cryptosporidiosis by routine clinical and laboratory practices among non-hospitalised children with acute diarrhoea in Southern Spain

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.

Occurrence and genetic diversity of Cryptosporidium and Giardia in urban wastewater treatment plants in north-eastern Spain

This study was designed to investigate the presence and removal efficiency of Cryptosporidium and Giardia in wastewater treatment plants at the 20 most populated towns in Aragón (north-eastern Spain). Samples of influent and effluent wastewater and dewatered sewage sludge were collected seasonally from 23 plants and processed according to USEPA Method 1623. All samples from raw and treated wastewater tested positive for Giardia, at an average concentration of 3247±2039cysts/l and 50±28cysts/l, respectively. Cryptosporidium was identified in most samples from both raw (85/92) and treated (78/92) wastewaters in a concentration significantly lower than Giardia, at both influent (96±105oocysts/l) and effluent samples (31±70oocysts/l) (P<0.001). The (oo)cyst counts peaked in summer in most plants. The removal efficiency was higher for Giardia (1.06-log to 2.34-log) than Cryptosporidium (0.35-log to 1.8-log). Overall, high removal efficiency values were found for Giardia after secondary treatment based on activated sludge, while tertiary treatment (microfiltration, chlorination and/or ultraviolet irradiation) was needed to achieve the greatest removal or inactivation of Cryptosporidium. Most samples of treated sludge were positive for Giardia (92/92) and Cryptosporidium (45/92), at an average concentration of 20-593cysts/g and 2-44oocyst/g, respectively. The molecular characterization of Cryptosporidium oocysts and Giardia cysts were attempted at the SSU rRNA/GP60 and bg/tpi loci, respectively. G. duodenalis sub-assemblage AII was identified in all plants, with a large proportion of samples (15/47) harboring mixed assemblages (AII+B). Nine Cryptosporidium species and six subtypes were identified, with C. parvum IIaA15G2R1 being the most prevalent. The presence of significant numbers of (oo)cysts in samples of final effluents and treated sludge reveals the limited efficacy of conventional treatments in removing (oo)cysts and highlights the potential environmental impact and public health risks associated with disposal and reclamation of wastewater.

Epidemiology of Cryptosporidium in Pediatric Diarrheal Illnesses

CONTEXT

Cryptosporidium spp. is a zoonotic infection, now being recognized as a significant cause of diarrhea in both immunocompetent and immunocompromised hosts. However, there still exist significant knowledge gaps in its estimated global burden, epidemiology, diagnosis and management.

EVIDENCE ACQUISITION

A semi-systematic search was performed across PubMed to select studies on epidemiological burden of cryptosporidium diarrhea using the following keywords- ['crytosporidiosis' OR 'cryptosporidium'] AND ['diarrhea' OR 'diarrhoea']. Articles were included if participants were 'Humans', belonged to pediatric (0-18 y) age group, and were published after 1990. The results were compiled separately for acute and persistent diarrhea.

RESULTS

Cryptosporidium spp is commonly detected in stools of both cases (acute/ persistent diarrhea) and asymptomatic controls. The prevalence is higher in children with diarrhea than non-diarrheal controls (1.7-35% vs 0.3-15%); varying widely across different studies. The positivity rate is higher in younger children (<2 years) suffering from diarrhea. The main symptoms associated with cryptosporidiosis include fever, vomiting and abdominal pain with propensity for prolonged duration of diarrhea. It predisposes to malnutrition, which is also a risk factor for cryptosporidiosis. The prevalence is higher in HIV positive patients; certain socio-demographic factors play a more important role than mere geographical distribution for infection.

CONCLUSION

The high positivity rates during both acute and persistent diarrhea highlights the need to suspect this infection even in immunocompetent children.

Occurrence of Cryptosporidium and Giardia in raw and finished drinking water in north-eastern Spain

This paper collects the first large-sample-size study on the presence of Cryptosporidium oocysts and Giardia cysts in drinking water plants at the 20 most populated towns in Aragón (north-eastern Spain). Samples of influent raw water and effluent finished water were collected from each plant during different seasons and processed according to USEPA Method 1623. Cryptosporidium oocysts and Giardia cysts were detected in samples collected from 55% and 70% plants, respectively, with nine plants being positive for both protozoa and only four plants being negative over the study period. Both parasites were identified in the raw water throughout the year, with a lower frequency in autumn and a peak in winter, at a mean concentration of 67±38 oocysts per 100l and 125±241 cysts per 100l. The turbidity of raw water was not related to the presence or concentration of (oo)cysts, and the (oo)cyst removal efficiency was not related to the type of water treatment. One or both pathogens were identified in the finished water in 7 out of 11 plants with a conventional treatment process (coagulation, flocculation, sedimentation, filtration, and disinfection processes) compared to 4 out of 9 plants that did not apply one of the pre-chlorination treatment steps. Protozoa were detected in the finished water of positive plants at a mean concentration of 88±55 oocysts per 100l and 37±41 cysts per 100l, and most of them excluded propidium iodide so were considered potentially viable. The ubiquity of these parasites in the drinking water sources and the inefficiency of conventional water treatment in reducing/inactivating them may present a serious public health issue in this geographical area.

Modulation of the immune response by infection with Cryptosporidium spp. in children with allergic diseases

It has been demonstrated that the allergic response can be ameliorated by the administration of pathogen derivatives that activate Toll-like receptors and induce a Th1-type immune response (IR). Cryptosporidium is a parasite that promotes an IR via Toll-like receptors and elicits the production of Th1-type cytokines, which limit cryptosporidiosis. The aim of this study was to investigate allergy-related immune markers in children naturally infected with Cryptosporidium. In a cross-sectional study, 49 children with or without clinical diagnosis of allergies, oocysts of Cryptosporidium spp. in the faeces were screened microscopically. We microscopically screened for leucocytes, examined T and B cells for allergy-related activation markers using flow cytometry and evaluated serum for total IgE using chemiluminescence. Children with allergies and Cryptosporidium in the faeces had significantly lower levels of total IgE, B cells, CD19(+) CD23(+) and CD19(+) CD124(+) cells as well as a greater percentage of interferon-gamma (IFN-γ(+) ) and IL-4(+) CD4(+) cells than children with allergies without Cryptosporidium. This is the first description of the modulation of the IR in children with allergic diseases in the setting of natural Cryptosporidium infection. Our findings suggest the involvement of CD4(+) cells producing IL-4 and IFN-γ in the IR to Cryptosporidium in naturally infected children.

Assessment of microscopic and molecular tools for the diagnosis and follow-up of cryptosporidiosis in patients at risk

Cryptosporidiosis is an important though underreported public health concern. Molecular tools might be helpful in improving its diagnosis. In this study, ZR Fecal DNA MiniPrep™ Kit (ZR) and NucliSens® easyMAG® (EM) were compared using four Cryptosporidium-seeded feces and 29 Cryptosporidium-positive stools. Thereafter, ZR was selected for prospective evaluation of Cryptosporidium detection by 18S rDNA and LAXER quantitative PCR (qPCR) in 69 stools from 56 patients after Cryptosporidium detection by glycerin, modified Ziehl-Neelsen (ZN) and auramine-phenol (AP) stainings. The combination of any of the two extraction methods with 18S qPCR yielded adequate detection of Cryptosporidium in seeded stools, but the ZR kit showed the best performance. All 29 Cryptosporidium-positive samples were positive with 18S qPCR, after both ZR and EM extraction. However, false-negative results were found with LAXER qPCR or nested PCR. Cryptosporidiosis was diagnosed in 7/56 patients. All the microscopic methods enabled the initial diagnosis, but Cryptosporidium was detected in 12, 13, and 14 samples from these seven patients after glycerin, ZN, and AP staining respectively. Among these samples, 14 and 12 were positive with 18S and LAXER qPCR respectively. In two patients, Cryptosporidium DNA loads were found to be correlated with clinical evolution. Although little known, glycerin is a sensitive method for the initial detection of Cryptosporidium. When combined with 18S qPCR, ZR extraction, which had not been evaluated so far for Cryptosporidium, was an accurate tool for detecting Cryptosporidium and estimating the oocyst shedding in the course of infection.

Prevalence of Cryptosporidium parvum/hominis, Entamoeba histolytica and Giardia lamblia among Young Children with and without Diarrhea in Dar es Salaam, Tanzania

Background

Although enteroparasites are common causes of diarrheal illness, few studies have been performed among children in Tanzania. This study aimed to investigate the prevalence of Cryptosporidium parvum/hominis, Entamoeba histolytica and Giardia lamblia among young children in Dar es Salaam, Tanzania, and identify risk factors for infection.

Methodology/Principal Findings

We performed an unmatched case-control study among children < 2 years of age in Dar es Salaam, recruited from August 2010 to July 2011. Detection and identification of protozoans were done by PCR techniques on DNA from stool specimens from 701 cases of children admitted due to diarrhea at the three study hospitals, and 558 controls of children with no history of diarrhea during the last month prior to enrollment. The prevalence of C. parvum/hominis was 10.4% (84.7% C. hominis), and that of G. lamblia 4.6%. E. histolytica was not detected. The prevalence of Cryptosporidium was significantly higher in cases (16.3%) than in controls (3.1%; P < 0.001; OR = 6.2; 95% CI: 3.7–10.4). G. lamblia was significantly more prevalent in controls (6.1%) than in cases (3.4%; P = 0.027; OR = 1.8; 95% CI: 1.1–3.1). Cryptosporidium infection was found more often in HIV-positive (24.2%) than in HIV-negative children (3.9%; P < 0.001; OR = 7.9; 95% CI: 3.1–20.5), and was also associated with rainfall (P < 0.001; OR = 2.41; 95% CI: 1.5–3.8). Among cases, stunted children had significantly higher risk of being infected with Cryptosporidium (P = 0.011; OR = 2.12; 95% CI: 1.2–3.8). G. lamblia infection was more prevalent in the cool season (P = 0.004; OR = 2.2; 95% CI: 1.3–3.8), and more frequent among cases aged > 12 months (P = 0.003; OR = 3.5; 95% CI: 1.5–7.8). Among children aged 7–12 months, those who were breastfed had lower prevalence of G. lamblia infection than those who had been weaned (P = 0.012).

Conclusions

Cryptosporidium infection is common among young Tanzanian children with diarrhea, particularly those living with HIV, and infection is more frequent during the rainy season. G. lamblia is frequently implicated in asymptomatic infections, but rarely causes overt diarrheal illness, and its prevalence increases with age.

Diarrheal diseases are a leading cause of disease and deaths among young children. In Africa they contribute to more than one tenth of childhood deaths. Parasites like Cryptosporidium, Entamoeba histolytica and Giardia lamblia are all common causes of diarrheal illness, but there are few studies on these enteroparasites among Tanzanian children. In this case-control study, we included 701 cases and 558 controls, all < 2 years of age, in Dar es Salaam, Tanzania. We assessed the prevalence of C. parvum/hominis, E. histolytica and G. lamblia by PCR, and the association with potential risk factors such as demographic data, clinical symptoms, HIV status and seasonality. One or more parasites were found in 14.9% of the samples. C. parvum/ hominis and G. lamblia were found in 10.4% and 4.6%, respectively, while E. histolytica was not found in any of the samples. The prevalence of Cryptosporidium was high, particularly in children with HIV, and its prevalence increased during the rainy season. Among cases, Cryptosporidium was found more frequently in stunted children, although any causal association could not be established in the current study. G. lamblia was more often implicated in asymptomatic infections than in overt diarrheal illness. The prevalence of G. lamblia increased with age, and breastfeeding seemed to protect the children from G. lamblia. This study presents relevant information about the prevalence and clinical characteristics of these intestinal parasites in Tanzanian children.

Gastrointestinal pathogens detected by multiplex nucleic acid amplification testing in stools of pediatric patients and patients returning from the tropics

BACKGROUND

Gastrointestinal infections are caused by a broad spectrum of pathogens. Conventional diagnostic procedures are resource and time consuming due to single pathogen testing, often in different laboratories.

METHOD

We analyzed 312 consecutive stool samples from pediatric patients (n = 127) with gastroenteritis or from adult travelers returning from the tropics with suspected parasite infestation (n = 185) using commercial multiplex nucleic acid amplification testing (NAT) (xTAG gastrointestinal pathogen panel, Luminex) covering 15 diarrhea-causing pathogens. The results of the positive samples and a representative number of negative samples were compared to standard methods, including NAT, direct antigen detection (DAD), bacterial culture and microscopy.

RESULTS

Of the 185 samples from adult travelers, 21 (11 %) were multiplexNAT-positive, with enterotoxigenic Escherichia coli (4 %) being the predominant pathogen. Microscopic examination revealed Blastocystis hominis in 23 % not covered by the panel. MultiplexNAT scored positive in 66 pediatric samples (52 %), with rotavirus (27 %) being the most prevalent. All adenovirus-, rotavirus-, Clostridium difficile- and Cryptosporidium-positive samples were confirmed in external laboratories, but only 40 % of norovirus- and 29 % of Giardia-positive samples. Analysis of frozen specimens by bacterial culture showed the highest discrepancies with the multiplexNAT.

CONCLUSION

Our study demonstrates broad detection of relevant gastroenteritis pathogens by multiplexNAT with a short turnaround time. This is important for diagnosis, infection control and empiric management of gastroenteritis patients, but may be selectively complemented by bacterial culture and resistance testing.

Measuring underreporting and under-ascertainment in infectious disease datasets: a comparison of methods

BACKGROUND

Efficient and reliable surveillance and notification systems are vital for monitoring public health and disease outbreaks. However, most surveillance and notification systems are affected by a degree of underestimation (UE) and therefore uncertainty surrounds the 'true' incidence of disease affecting morbidity and mortality rates. Surveillance systems fail to capture cases at two distinct levels of the surveillance pyramid: from the community since not all cases seek healthcare (under-ascertainment), and at the healthcare-level, representing a failure to adequately report symptomatic cases that have sought medical advice (underreporting). There are several methods to estimate the extent of under-ascertainment and underreporting.

METHODS

Within the context of the ECDC-funded Burden of Communicable Diseases in Europe (BCoDE)-project, an extensive literature review was conducted to identify studies that estimate ascertainment or reporting rates for salmonellosis and campylobacteriosis in European Union Member States (MS) plus European Free Trade Area (EFTA) countries Iceland, Norway and Switzerland and four other OECD countries (USA, Canada, Australia and Japan). Multiplication factors (MFs), a measure of the magnitude of underestimation, were taken directly from the literature or derived (where the proportion of underestimated, under-ascertained, or underreported cases was known) and compared for the two pathogens.

RESULTS

MFs varied between and within diseases and countries, representing a need to carefully select the most appropriate MFs and methods for calculating them. The most appropriate MFs are often disease-, country-, age-, and sex-specific.

CONCLUSIONS

When routine data are used to make decisions on resource allocation or to estimate epidemiological parameters in populations, it becomes important to understand when, where and to what extent these data represent the true picture of disease, and in some instances (such as priority setting) it is necessary to adjust for underestimation. MFs can be used to adjust notification and surveillance data to provide more realistic estimates of incidence.

A year-long study of Cryptosporidium species and subtypes in recreational, drinking and wastewater from the central area of Spain

A year-long longitudinal study was undertaken to evaluate the presence of Cryptosporidium spp. in drinking water treatment plants (DWTPs), wastewater treatment plants (WWTPs) and freshwater bathing beaches (FBBs) from the central area of Spain. Water samples were collected according to USEPA Method 1623, and concentrated by the IDEXX Filta-Max® system. Cryptosporidium species were detected based on PCR-restriction fragment length polymorphism and sequence analyses of the ssuRNA gene. C. hominis and/or C. parvum isolates were subtyped by DNA sequencing of the Gp60 gene. Among 150 samples, 23 (15.3%) were positive by IFAT and 40 (26.7%) by PCR. Cryptosporidium spp. was more frequent in WWTPs (26.2 and 50.8%) and FBBs (12.5 and 17.5%) by IFAT and PCR respectively. Effluent waters from DWTPs were negative for this parasite suggesting that they are suitable for public use. Tertiary treatment in the WWTPs demonstrated a high removal efficiency of Cryptosporidium in the samples evaluated. Cryptosporidium species identified included C. hominis, C. parvum, C. ubiquitum, C. andersoni and C. muris. Subtyping analysis revealed C. hominis IbA10G2 and IeA11G3T3 alleles, which is the first report of the latter in water samples. Cryptosporidium highest frequency was observed in winter and spring. Our data provide information about the occurrence and diversity of Cryptosporidium in water of human use from the central area of Spain.