Cryptosporidiosis

Cryptosporidium and irritable bowel syndrome

Cryptosporidium is an apicomplexan parasite that causes gastrointestinal disease in a wide variety of hosts and is associated with waterborne outbreaks. Nonetheless, the parasite is underdiagnosed. Cryptosporidium has been proposed as an etiological cause of irritable bowel syndrome (IBS) in several studies. However, the exact mechanism of pathogenesis is unknown, and no direct link has been discovered. This review will discuss several parasite-induced modifications, such as immunological, microbiome, and metabolite modifications, as well as their interactions. To summarize, Cryptosporidium causes low inflammation, dysbiosis, and unbalanced metabolism, which leads to a lack of homeostasis in the intestine in a comparable pattern to postinfectious IBS.

Complications of Cryptosporidium infection after pediatric liver transplantation: Diarrhea, rejection, and biliary disease

BACKGROUND

Cryptosporidium enteritis can be devastating in the immunocompromised host. In pediatric liver transplant recipients, infection may be complicated by prolonged carriage of the parasite, rejection, and biliary tree damage and fibrosis. Herein, we report on six patients and their long-term outcomes following cryptosporidiosis.

METHODS

We reviewed all cases of cryptosporidiosis in a pediatric liver transplant population over a 17-year period at a single center. Six patients with infection were identified, and their outcomes were analyzed.

RESULTS

Infection was associated with significant diarrhea and dehydration in all cases, and led to hospitalization in one-half of patients. Four of the six patients developed biopsy-proven rejection following infection, with three of those patients developing rejection that was recalcitrant to intravenous steroid treatment. Additionally, three patients developed biliary tree abnormalities with similarity to sclerosing cholangitis. In one patient, those biliary changes led to repeated need for biliary drain placement and advancing fibrotic liver allograft changes.

CONCLUSIONS

Cryptosporidiosis in pediatric liver transplant recipients may lead to significant complications, including recalcitrant episodes of rejection and detrimental biliary tree changes. We advocate for increased awareness of this cause of diarrheal disease and the allograft injuries that may accompany infection.

Review of Cryptosporidium and Giardia in the eastern part of Europe, 2016

This paper reviews the current knowledge and understanding of Cryptosporidium spp. and Giardia spp. in humans, animals and the environment in 10 countries in the eastern part of Europe: Bosnia and Herzegovina, Croatia, Czech Republic, Estonia, Hungary, Latvia, Poland, Romania, Serbia and Slovenia. Methods: Published scientific papers and conference proceedings from the international and local literature, official national health service reports, national databases and doctoral theses in local languages were reviewed to provide an extensive overview on the epidemiology, diagnostics and research on these pathogens, as well as analyse knowledge gaps and areas for further research. Results: Cryptosporidium spp. and Giardia spp. were found to be common in eastern Europe, but the results from different countries are difficult to compare because of variations in reporting practices and detection methodologies used. Conclusion: Upgrading and making the diagnosis/detection procedures more uniform is recommended throughout the region. Public health authorities should actively work towards increasing reporting and standardising reporting practices as these prerequisites for the reported data to be valid and therefore necessary for appropriate control plans.

Modelling Cryptosporidium infection in human small intestinal and lung organoids

Stem-cell-derived organoids recapitulate in vivo physiology of their original tissues, representing valuable systems to model medical disorders such as infectious diseases. Cryptosporidium, a protozoan parasite, is a leading cause of diarrhoea and a major cause of child mortality worldwide. Drug development requires detailed knowledge of the pathophysiology of Cryptosporidium, but experimental approaches have been hindered by the lack of an optimal in vitro culture system. Here, we show that Cryptosporidium can infect epithelial organoids derived from human small intestine and lung. The parasite propagates within the organoids and completes its complex life cycle. Temporal analysis of the Cryptosporidium transcriptome during organoid infection reveals dynamic regulation of transcripts related to its life cycle. Our study presents organoids as a physiologically relevant in vitro model system to study Cryptosporidium infection.

Modification of the Alere GIARDIA Ag TEST immunochromatography KIT methodology for its use in frozen fecal sediment of dogs and cats

Giardia duodenalis is a worldwide intestinal parasite and is one of the most frequent protozoa species infecting dogs and cats. This study aimed to modify the methodology of Alere GIARDIA Ag TEST KIT for its use in frozen fecal sediments with different storage times in a freezer (-20°C), thus expanding the range of use of this methodology. One hundred fecal sediments from dogs (n=50) and cats (n=50) previously examined by optical microscopy for Giardia cysts were selected for this study. The agreement between the modified immunochromatography and microscopy results was calculated by Kappa coefficient. To evaluate the performance of the modified immunochromatography assay on samples with different storage time, the fecal sediments were divided into three groups according to the time of storage in a freezer: (a) ≤ 1 year (n=37); (b) > 1 year and ≤ 3 years (n=39); (c) > 10 years (max. 13 years) (n=24). The results obtained by the modified immunochromatography assay demonstrates a higher sensitivity of this technique when compared with microscopy, regardless of the frozen storage time. These results allow for the use of this methodology in a greater scope of analysis, especially in frozen fecal sediment triage in sample collections, enabling epidemiological and comparative analysis along different decades.

Impact of confinement housing on study end-points in the calf model of cryptosporidiosis

BACKGROUND

Diarrhea is the second leading cause of death in children < 5 years globally and the parasite genus Cryptosporidium is a leading cause of that diarrhea. The global disease burden attributable to cryptosporidiosis is substantial and the only approved chemotherapeutic, nitazoxanide, has poor efficacy in HIV positive children. Chemotherapeutic development is dependent on the calf model of cryptosporidiosis, which is the best approximation of human disease. However, the model is not consistently applied across research studies. Data collection commonly occurs using two different methods: Complete Fecal Collection (CFC), which requires use of confinement housing, and Interval Collection (IC), which permits use of box stalls. CFC mimics human challenge model methodology but it is unknown if confinement housing impacts study end-points and if data gathered via this method is suitable for generalization to human populations.

METHODS

Using a modified crossover study design we compared CFC and IC and evaluated the impact of housing on study end-points. At birth, calves were randomly assigned to confinement (n = 14) or box stall housing (n = 9), or were challenged with 5 x 107 C. parvum oocysts, and followed for 10 days. Study end-points included fecal oocyst shedding, severity of diarrhea, degree of dehydration, and plasma cortisol.

FINDINGS

Calves in confinement had no significant differences in mean log oocysts enumerated per gram of fecal dry matter between CFC and IC samples (P = 0.6), nor were there diurnal variations in oocyst shedding (P = 0.1). Confinement housed calves shed significantly more oocysts (P = 0.05), had higher plasma cortisol (P = 0.001), and required more supportive care (P = 0.0009) than calves in box stalls.

CONCLUSION

Housing method confounds study end-points in the calf model of cryptosporidiosis. Due to increased stress data collected from calves in confinement housing may not accurately estimate the efficacy of chemotherapeutics targeting C. parvum.

Cryptosporidium and Giardia in Danish organic pig farms: Seasonal and age-related variation in prevalence, infection intensity and species/genotypes

Although pigs are commonly infected with Cryptosporidium spp. and Giardia duodenalis, including potentially zoonotic species or genotypes, little is known about age-related infection levels, seasonal differences and genetic variation in naturally infected pigs raised in organic management systems. Therefore, the current study was conducted to assess seasonal and age-related variations in prevalence and infection intensity of Cryptosporidium and Giardia, evaluate zoonotic potential and uncover correlations between species/genotypes, infection intensity and faecal consistency. Shedding of oocysts and cysts ((oo-)cysts) was monitored at quarterly intervals (September 2011-June 2012) in piglets (n = 152), starter pigs (n = 234), fatteners (n = 230) and sows (n = 240) from three organic farms in Denmark. (oo-)Cysts were quantified by immunofluorescence microscopy; and 56/75 subsamples from Cryptosporidium infected pigs were successfully analysed by PCR amplification and partial sequencing of the small subunit (SSU) 18S rRNA and hsp70genes, while 13/67 Giardia subsamples were successfully analysed by amplification and partial sequencing of the 18S rRNA and the gdh genes. Altogether, Cryptosporidium or Giardia infections were observed in 40.9% (350/856) and 14.0% (120/856) of the pigs, respectively, including 8.2% (70/856) infected with both parasites. Prevalence, intensity of infections and presence of Cryptosporidium species varied significantly between age-groups; 53.3% piglets, 72.2% starter pigs, 40.4% fatteners and 2.9% sows were infected with Cryptosporidium, whereas 2.0% piglets, 27.4% starter pigs, 17.8% fatteners and 5.0% sows were infected with Giardia. The overall prevalence was stable throughout the year, except for dual-infections that were more prevalent in September and December (p < 0.05). The infection intensity was age-related for both parasites, and dual-infected pigs tended to excrete lower levels of oocysts compared to pigs harbouring only Cryptosporidium. Likewise, pigs infected with Cryptosporidium scrofarum excreted fewer oocysts (mean CPG: 54,848 ± 194,508CI: 9085-118,781) compared to pigs infected with Cryptosporidium suis (mean OPG: 351,035 ± 351,035CI: 67,953-634,117). No correlation between faecal consistency and (oo-)cyst excretion levels was observed. Of the successfully genotyped isolates, 38/56 (67.9%) were C. scrofarum and 18/56 (32.1%) were C. suis, while the livestock specific G. duodenalis Assemblage E was detected in 11/13 (84.6%) isolates and the potentially zoonotic Assemblage A was identified in 2/13 (15.4%) isolates. Piglets exclusively hosted C. suis, with one exception, while starter pigs and fatteners predominantly hosted C. scrofarum. As organic pigs are partly reared outdoors, environmental contamination with Cryptosporidium and Giardia is inevitable. Nevertheless, the present data indicate that the potential public health risk associated with both of these parasites in Danish organic pig production seems to be negligible.

Heparin interacts with elongation factor 1α of Cryptosporidium parvum and inhibits invasion

Cryptosporidium parvum is an apicomplexan parasite that can cause serious watery diarrhea, cryptosporidiosis, in human and other mammals. C. parvum invades gastrointestinal epithelial cells, which have abundant glycosaminoglycans on their cell surface. However, little is known about the interaction between C. parvum and glycosaminoglycans. In this study, we assessed the inhibitory effect of sulfated polysaccharides on C. parvum invasion of host cells and identified the parasite ligands that interact with sulfated polysaccharides. Among five sulfated polysaccharides tested, heparin had the highest, dose-dependent inhibitory effect on parasite invasion. Heparan sulfate-deficient cells were less susceptible to C. parvum infection. We further identified 31 parasite proteins that potentially interact with heparin. Of these, we confirmed that C. parvum elongation factor 1α (CpEF1α), which plays a role in C. parvum invasion, binds to heparin and to the surface of HCT-8 cells. Our results further our understanding of the molecular basis of C. parvum infection and will facilitate the development of anti-cryptosporidial agents.

[Cryptosporidium and Giardia as water contaminant pathogens in Hungary]

INTRODUCTION

Many species of Cryptosporidium, and two assemlages of Giardia duodenalis cause typically acute diaorrhoea in human. The oocysts and cysts of these parasites excreted in faeces are capable of infecting other hosts and those are environmentally stable.

AIM

The aims of the study were to evaluate the prevalence and genotypes of Cryptosporidium and Giardia species from different water sources as well as to monitor and characterize the (oo)cyst contamination sources in watersheds. In addition, an epidemiological study was performed in three selected settlements.

METHOD

Wide range of modern epidemiological and molecular detection methods have been applied.

RESULTS

(Oo)cysts densities were associated with water receiving effluents of sewage treatment plants or originating from a forest environment. It was confirmed, that cattle can be a source of Cryptosporidium oocysts at watersheds and aquatic birds can play a role in the environmental dissemination of these protozoa. The epidemiological study demonstrated a specific epidemiological situation, giving essential evidence about giardiasis in asymptomatic carriers. The applied novel detection technology was found to be cost effective and simple procedure for screening catchments to identify those that require further treatment and more detailed microscopic counts.

CONCLUSIONS

The presented results contribute to a better understanding the epidemiology and relevance of waterborne parasites, their surveillance and performance of future control measures to prevent waterborne infections in Hungary.

Intestinal parasitic infections in an industrialized country; a new focus on children with better DNA-based diagnostics

In recent years, the isolation of parasitic DNA from faecal samples and PCR techniques, have been improved and simplified. Moreover, the introduction of real-time PCR has made it possible to multiplex different targets into one reaction. These new technical possibilities make it feasible to introduce PCR with its unsurpassed sensitivity and specificity in a routine laboratory setting for the diagnosis of intestinal parasites. Detection rates of the parasitic infections included in the PCR are increased significantly compared with microscopy. Molecular diagnostics, especially in children, reveal a possible cause of the gastrointestinal complaints in many more cases compared with conventional methods. Usually in GP patients no other pathogenic parasites are detected using microscopy and in the returning travellers additional parasites are found with microscopy in a minority of cases only. Multiplex real-time PCR offers a highly sensitive and specific diagnostic alternative for labour intensive microscopy in clinical laboratory practice. Additional diagnostic methods for the detection of parasitic infections that are not included as PCR target can be limited to a selected group of patients.

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

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

Antibody response of healthy adults to recombinant thrombospondin-related adhesive protein of cryptosporidium 1 after experimental exposure to cryptosporidium oocysts

Thrombospondin-related adhesive protein of Cryptosporidium 1 (TRAP-C1) belongs to a group of proteins that are also found in Toxoplasma gondii, Eimeria tenella, and Plasmodium species. TRAP-related proteins are needed for gliding motility, host-cell attachment, and invasion. The objective of this study was to characterize the antibody response to recombinant TRAP-C1 (rTRAP-C1) in healthy volunteers exposed to C. parvum and their association with clinical illness. A total of 31 healthy adult volunteers participated. Seven volunteers received the C. parvum TAMU isolate (inocula, 10 to 300 oocysts), and 24 volunteers received the C. parvum UCP isolate (500 to 10(5) oocysts). The total antibody (immunoglobulin M [IgM], IgG, and IgA) response to rTRAP C-1 was measured by enzyme-linked immunosorbent assays prior to and after exposure to Cryptosporidium parvum (days 0 to 45). Results of this study showed that individuals who were uninfected demonstrated higher reactivity at baseline compared to those who became infected. After challenge, increases in antibody reactivity were seen on days 30 and 45 compared to the results seen on days 0 to 5. The increases in antibody reactivity were statistically significant in subjects with diarrhea and with or without detectable oocysts compared to the results seen with those who were uninfected and asymptomatic. These findings suggest that increases in antibody reactivity to rTRAP-C1 occur after recent exposure to C. parvum.

Study of 18S rRNA and rDNA stability by real-time RT-PCR in heat-inactivatedCryptosporidium parvumoocysts

The public health problem posed by Cryptosporidium parvum has led the water supply industry to develop analytical tools for detecting viable oocysts in water. In this study, we report on a TaqMan real-time reverse transcription-polymerase chain reaction (RT-PCR) method that targets and quantifies C. parvum 18S rRNA. To study the suitability of 18S rRNA as an indicator of Cryptosporidium oocyst viability, the stability of 18S rRNA and rDNA was monitored by real-time RT-PCR following various Cryptosporidium heat treatments. Decay of 18S rRNA was first observed after a 20-min treatment of C. parvum oocysts at 95 degrees C and was still detectable after 4 h. In contrast, rDNA was more heat resistant. The stability of 18S rRNA and rDNA was also studied after oocyst lysis by thermal shocks in the presence and absence of Chelex-100. In the former case, both rRNA and rDNA were degraded whereas in the presence of Chelex-100 both molecules were protected from heat degradation and were still detected after 4 h at 95 degrees C following thermal shocks. Our results indicate that 18S rRNA detection may not be directly associated with viability following heat inactivation of Cryptosporidium oocysts even if in all the experiments 18S rRNA was less stable than rDNA.

An immunomagnetic separation-real-time PCR method for quantification of Cryptosporidium parvum in water samples

The protozoan parasite Cryptosporidium parvum is known to occur widely in both raw and drinking water and is the cause of waterborne outbreaks of gastroenteritis throughout the world. The routinely used method for the detection of Cryptosporidium oocysts in water is based on an immunofluorescence assay (IFA). It is both time-consuming and nonspecific for the human pathogenic species C. parvum. We have developed a TaqMan polymerase chain reaction (PCR) test that accurately quantifies C. parvum oocysts in treated and untreated water samples. The protocol consisted of the following successive steps: Envirochek capsule filtration, immunomagnetic separation (IMS), thermal lysis followed by DNA purification using Nanosep centrifugal devices and, finally, real-time PCR using fluorescent TaqMan technology. Quantification was accomplished by comparing the fluorescence signals obtained from test samples with those from standard dilutions of C. parvum oocysts. This IMS-real-time PCR assay permits rapid and reliable quantification over six orders of magnitude, with a detection limit of five oocysts for purified oocyst solutions and eight oocysts for spiked water samples. Replicate samples of spiked tap water and Seine River water samples (with approximately 78 and 775 oocysts) were tested. C. parvum oocyst recoveries, which ranged from 47.4% to 99% and from 39.1% to 68.3%, respectively, were significantly higher and less variable than those reported using the traditional US Environmental Protection Agency (USEPA) method 1622. This new molecular method offers a rapid, sensitive and specific alternative for C. parvum oocyst quantification in water.

Development of a TaqMan quantitative PCR assay specific for Cryptosporidium parvum

A rapid detection method that is both quantitative and specific for the water-borne human parasite Cryptosporidium parvum is reported. Real-time polymerase chain reaction (PCR) combined with fluorescent TaqMan technology was used to develop this sensitive and accurate assay. The selected primer-probe set identified a 138-bp section specific to a C. parvum genomic DNA sequence. The method was optimized on a cloned section of the target DNA sequence, then evaluated on C. parvum oocyst dilutions. Quantification was accomplished by comparing the fluorescence signals obtained from test samples of C. parvum oocysts with those obtained from standard dilutions of C. parvum oocysts. This real-time PCR assay allowed reliable quantification of C. parvum oocysts over six orders of magnitude with a baseline sensitivity of six oocysts in 2 h.

Cryptosporidial infections after solid organ transplantation in children

The diagnosis and treatment of moderate-to-severe diarrhea in solid organ transplant recipients is often a challenge because of the variety of infectious and non-infectious causes. The morbidity associated with this clinical condition is of particular significance in the pediatric population where malnutrition may lead to poor growth and development. Rarely, Cryptosporidium has been identified as the cause of clinically significant diarrhea in pediatric solid organ transplant patients. A retrospective review identified cases of cryptosporidiosis among the 1160 non-renal, abdominal organ transplant recipients cared for at the Children's Hospital of Pittsburgh between 1981 and June 1998. Four cases of clinically significant diarrhea were identified in three liver transplant recipients and one small bowel transplant recipient. Endoscopy and biopsy with histologic confirmation diagnosed three cases; ova and parasitic examination of stool specimens identified the fourth case. Therapy varied among the patients depending on when they had been diagnosed as, over the years, different and newer agents have been indicated for the treatment of cryptosporidiosis. All four patients resolved their infections. Hence, endoscopy and biopsy is recommended for pediatric transplant patients who present with chronic diarrhea of unknown etiology. The patients who may be at a higher risk for cryptosporidial infections include those with an increased immunosuppressive state (i.e. pre-existing immunodeficiency, malignancy, re-transplantation, and those receiving higher doses of immunosuppressive therapy). While cryptosporidiosis is a non-lethal complication, it allows the clinician to gain further insight into the degree of immunosuppression of their patient.

Diarrheal diseases associated with HIV infection

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.