Health sequelae of human cryptosporidiosis in immunocompetent patients

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.

Host genetic backgrounds: the key to determining parasite-host adaptation

Parasitic diseases pose a significant threat to global public health, particularly in developing countries. Host genetic factors play a crucial role in determining susceptibility and resistance to infection. Recent advances in molecular and biological technologies have enabled significant breakthroughs in understanding the impact of host genes on parasite adaptation. In this comprehensive review, we analyze the host genetic factors that influence parasite adaptation, including hormones, nitric oxide, immune cells, cytokine gene polymorphisms, parasite-specific receptors, and metabolites. We also establish an interactive network to better illustrate the complex relationship between host genetic factors and parasite-host adaptation. Additionally, we discuss future directions and collaborative research priorities in the parasite-host adaptation field, including investigating the impact of host genes on the microbiome, developing more sophisticated models, identifying and characterizing parasite-specific receptors, utilizing patient-derived sera as diagnostic and therapeutic tools, and developing novel treatments and management strategies targeting specific host genetic factors. This review highlights the need for a comprehensive and systematic approach to investigating the underlying mechanisms of parasite-host adaptation, which requires interdisciplinary collaborations among biologists, geneticists, immunologists, and clinicians. By deepening our understanding of the complex interactions between host genetics and parasite adaptation, we can develop more effective and targeted interventions to prevent and treat parasitic diseases. Overall, this review provides a valuable resource for researchers and clinicians working in the parasitology field and offers insights into the future directions of this critical research area.

A novel, stain-free, natural auto-fluorescent signal, Sig M, identified from cytometric and transcriptomic analysis of infectivity of Cryptosporidium hominis and Cryptosporidium parvum

Cryptosporidiosis is a worldwide diarrheal disease caused by the protozoan Cryptosporidium. The primary symptom is diarrhea, but patients may exhibit different symptoms based on the species of the Cryptosporidium parasite they are infected with. Furthermore, some genotypes within species are more transmissible and apparently virulent than others. The mechanisms underpinning these differences are not understood, and an effective in vitro system for Cryptosporidium culture would help advance our understanding of these differences. Using COLO-680N cells, we employed flow cytometry and microscopy along with the C. parvum-specific antibody Sporo-Glo™ to characterize infected cells 48 h following an infection with C. parvum or C. hominis. The Cryptosporidium parvum-infected cells showed higher levels of signal using Sporo-Glo™ than C. hominis-infected cells, which was likely because Sporo-Glo™ was generated against C. parvum. We found a subset of cells from infected cultures that expressed a novel, dose-dependent auto-fluorescent signal that was detectable across a range of wavelengths. The population of cells that expressed this signal increased proportionately to the multiplicity of infection. The spectral cytometry results confirmed that the signature of this subset of host cells closely matched that of oocysts present in the infectious ecosystem, pointing to a parasitic origin. Present in both C. parvum and C. hominis cultures, we named this Sig M, and due to its distinct profile in cells from both infections, it could be a better marker for assessing Cryptosporidium infection in COLO-680N cells than Sporo-Glo™. We also noted Sig M's impact on Sporo-Glo™ detection as Sporo-Glo™ uses fluoroscein-isothiocynate, which is detected where Sig M also fluoresces. Lastly, we used NanoString nCounter^® analysis to investigate the transcriptomic landscape for the two Cryptosporidium species, assessing the gene expression of 144 host and parasite genes. Despite the host gene expression being at high levels, the levels of putative intracellular Cryptosporidium gene expression were low, with no significant difference from controls, which could be, in part, explained by the abundance of uninfected cells present as determined by both Sporo-Glo™ and Sig M analyses. This study shows for the first time that a natural auto-fluorescent signal, Sig M, linked to Cryptosporidium infection can be detected in infected host cells without any fluorescent labeling strategies and that the COLO-680N cell line and spectral cytometry could be useful tools to advance the understanding of Cryptosporidium infectivity.

Persisting symptoms after Cryptosporidium hominis outbreak: a 10-year follow-up from Östersund, Sweden

In late 2010, an outbreak of Cryptosporidium hominis affected 27,000 inhabitants (45%) of Östersund, Sweden. Previous research shows that abdomen and joint symptoms commonly persist up to 5 years post-infection. It is unknown whether Cryptosporidium is associated with sequelae for a longer duration, how persisting symptoms present over time, and whether sequelae are associated with prolonged infection. In this prospective cohort study, a randomly selected cohort in Östersund was surveyed about cryptosporidiosis symptoms in 2011 (response rate 69.2%). A case was defined as a respondent reporting new diarrhoea episodes during the outbreak. Follow-up questionnaires were sent after 5 and 10 years. Logistic regressions were used to examine associations between case status and symptoms reported after 10 years, with results presented as adjusted odds ratios (aOR) with 95% confidence intervals. Consistency of symptoms and associations with case status and number of days with symptoms during outbreak were analysed using X² and Mann-Whitney U tests. The response rate after 10 years was 74% (n = 538). Case status was associated with reporting symptoms, with aOR of ~3 for abdominal symptoms and ~2 for joint symptoms. Cases were more likely to report consistent symptoms. Cases with consistent abdominal symptoms at follow-up reported 9.2 days with symptoms during the outbreak (SD 8.1), compared to 6.6 days (SD 6.1) for cases reporting varying or no symptoms (p = 0.003). We conclude that cryptosporidiosis was associated with an up to threefold risk for reporting symptoms 10 years post-infection. Consistent symptoms were associated with prolonged infection.

Cryptosporidiosis: From Prevention to Treatment, a Narrative Review

Cryptosporidiosis is a water- and food-borne zoonotic disease caused by the protozoon parasite of the genus Cryptosporidium. C. hominis and C. parvum are the main two species causing infections in humans and animals. The disease can be transmitted by the fecal-oral route as well as the respiratory route. The infective stage (sporulated oocysts) is resistant to different disinfectants including chlorine. Currently, no effective therapeutic drugs or vaccines are available to treat and control Cryptosporidium infection. To prevent cryptosporidiosis in humans and animals, we need to understand better how the disease is spread and transmitted, and how to interrupt its transmission cycle. This review focuses on understanding cryptosporidiosis, including its infective stage, pathogenesis, life cycle, genomics, epidemiology, previous outbreaks, source of the infection, transmission dynamics, host spectrum, risk factors and high-risk groups, the disease in animals and humans, diagnosis, treatment and control, and the prospect of an effective anti-Cryptosporidium vaccine. It also focuses on the role of the One Health approach in managing cryptosporidiosis at the animal-human-environmental interface. The summarized data in this review will help to tackle future Cryptosporidium infections in humans and animals and reduce the disease occurrence.

Increased incidence of late-onset inflammatory bowel disease and microscopic colitis after a Cryptosporidium hominis outbreak

OBJECTIVES

In 2010, 27,000 inhabitants (45% of the population) of Östersund, Sweden, contracted clinical cryptosporidiosis after drinking water contaminated with Cryptosporidium hominis. After the outbreak, local physicians perceived that the incidence of inflammatory bowel disease (IBD), including ulcerative colitis (UC), Crohn's disease (CD), and IBD-unclassified, and microscopic colitis (MC) increased. This study assessed whether this perception was correct.

MATERIALS AND METHODS

This observational study included adult patients (≥18 years old) from the local health care region who were diagnosed with pathology-confirmed IBD or MC during 2006-2019. We collected and validated the diagnosis, date of diagnosis, age at diagnosis, and sex from the Swedish quality register SWIBREG and electronic patient records. Population data were collected from Statistics Sweden. The incidences for 2006-2010 (pre-outbreak) and 2011-2019 (post-outbreak) were evaluated by negative binomial regression analysis and presented as incidence rate ratios (IRRs). Data were analyzed for IBD, for UC and CD separately, and MC.

RESULTS

During the study period, we identified 410 patients with new onset IBD and 155 new cases of MC. Overall, we found a trend toward an increased incidence of IBD post-outbreak (IRR 1.39, confidence interval (CI) 0.99-1.94). In individuals ≥40 years old, the post-outbreak incidence significantly increased for IBD (IRR 1.69, CI 1.13-2.51) and CD (IRR 2.23, CI 1.08-4.62). Post-outbreak incidence of MC increased 6-fold in all age groups (IRR 6.43, CI 2.78-14.87).

CONCLUSIONS

The incidence of late-onset IBD and MC increased after the Cryptosporidium outbreak. Cryptosporidiosis may be an environmental risk factor for IBD and MC.

Garlic (Allium sativum Linnaeus) improved inflammation and reduced cryptosporidiosis burden in immunocompromised mice

ETHNOPHARMACOLOGICAL RELEVANCE

For thousands of years, garlic (Allium sativum Linnaeus) has been consumed in food and health by numerous civilizations. Cryptosporidium (C.) parvum is an apicomplexan parasite that causes a gastrointestinal disease, with the most common symptoms being watery diarrhea. Although several substances have been tried for its anti-cryptosporidial action, there is no effective treatment for Cryptosporidium disease, especially in immunocompromised individuals. The present study aimed firstly to characterize the bio-active compounds in Allium sativum L. and secondly to evaluate its efficacy as a therapy for cryptosporidiosis especially in immunocompromised mice.

MATERIALS AND METHODS

This was accomplished by evaluating the parasitological and histopathological parameters in the experimentally infected immunocompetent and immunocompromised mice. Also, the cytokine profile during the experimental time was recorded through the measuring of T helper (h)1, Th2 and Th17 cells cytokines. Immunosuppressed mice were given 0.25 μg/g per day of dexamethasone orally, before infection with Cryptosporidium parvum oocysts, for fourteen consecutive days. Starting 10 days post infection (PI), nitazoxanide (100 mg/kg per day) or Allium sativum (50 mg/kg per day) was given orally for fourteen consecutive days.

RESULTS

Our results showed that oocyst shedding, on the 32nd day PI, in immunocompromised infected group treated with Allium sativum (354.11, 99.35% PR) showed a significant decrease when compared to its corresponding group treated with nitazoxanide (4369.14, 92.05% PR). On the 32nd day PI, all cytokines levels have been decreased to levels that were similar to those of their uninfected corresponding control groups; also, the histopathological changes and the loss in animals' body weight had been improved. Treatment with nitazoxanide did not result in infection clearance or a reduction in the increased cytokines' levels.

CONCLUSION

Allium sativum L. displayed high efficacy as a potential therapeutic agent against Cryptosporidium, which supports its traditional usage in parasite diseases.

Outbreak of Cryptosporidium hominis in northern Sweden: persisting symptoms in a 5-year follow-up

In 2010-2011, a waterborne outbreak of the parasite, Cryptosporidium hominis, affected approximately 27,000 inhabitants in the city of Östersund, Sweden. Previous research suggested that post-infectious symptoms, such as gastrointestinal symptoms and joint pain, could persist for up to 2 years after the initial infection. In this study, we investigated whether the parasite caused post-infectious sequelae for up to 5 years after the outbreak. Prospective cohort study. A randomly selected cohort of individuals residing in Östersund at the time of the outbreak was sent a postal questionnaire in 2011. Responders were sent a follow-up questionnaire in 2016 and completed items on whether they experienced a list of symptoms. We examined whether outbreak cases were more likely than non-cases to report post-infectious symptoms 5 years later. We analysed data using logistic regression and calculated odds ratios with 95% confidence intervals. The analysis included 626 individuals. Among the 262 individuals infected during the outbreak, 56.5% reported symptoms at follow-up. Compared to non-cases, outbreak cases were more likely to report watery diarrhoea, diarrhoea, swollen joints, abdominal pain, bloating, joint discomfort, acid indigestion, alternating bowel habits, joint pain, ocular pain, nausea, and fatigue at the follow-up, after adjusting for age and sex. Our findings suggested that cryptosporidiosis was mainly associated with gastrointestinal- and joint-related post-infectious symptoms for up to 5 years after the infection.

Cross-sectional household transmission study of Cryptosporidium shows that C. hominis infections are a key risk factor for spread

BACKGROUND

Infection with the Cryptosporidium parasite causes over 4000 cases of diagnosed illness (cryptosporidiosis) in England and Wales each year. The incidence of sporadic disease has not been sufficiently established, and how frequently this arises from contact with other infected people is not well documented. This project aimed to explore potential transmission in the home and attempt to identify asymptomatic infections, which might play a role in transmission. Risk factors and characteristics associated with spread of infection in the home were described including any differences between Cryptosporidium species.

METHODS

The study identified cryptosporidiosis cases from North West England and Wales over a year and invited them and their household to take part. Each household was sent a study pack containing study information and a questionnaire, and stool sample kits to provide samples from consenting household members. Cryptosporidium-positive stool samples, identified by immunofluorescence microscopy, were characterised using molecular methods to help describe any patterns of transmission. Characteristics of households with and without additional cases were described, and compared using odds ratios (OR) and a multivariable logistic regression identified independent risk factors for household transmission. Data collection ran for one year, beginning in September 2018 with an initial pilot phase.

RESULTS

We enrolled 128 index cases and their households. Additional illness occurred in over a quarter of homes, each reporting an average of two additional cases. The majority of these were undiagnosed and unreported to surveillance. This burden was even greater in households where the index case was infected with C. hominis versus C. parvum, or the index case was under five years old, with mums and siblings most at risk of secondary infection. Only having an index case of C. hominis was independently associated with transmission in the multivariable model (OR 4.46; p = 0.01).

CONCLUSIONS

Cryptosporidium was a considerable burden in the home. At-risk homes were those where the index was less than five years old and/or infected with C. hominis. Of particular risk were female caregivers and siblings. Hygiene advice should be specifically directed here. This work provides evidence for humans as sources of C. hominis infection and that person-person is a key pathway. We recommend that all stools submitted for the investigation of gastrointestinal pathogens are tested for Cryptosporidium to better capture cases, inclusion of speciation data in routine surveillance, and the consideration of specific clinical advice on prevention for high-risk homes.

New record of parasitic infection among school children of Lower Dir Pakistan

Abstract Intestinal parasitic infections (IPIs) are a major cause of morbidity worldwide and have been described as an important public health problem. The present study aimed to determine the un usual parasitic infection and identification of risk factors among 4-12years old school age children residing in lower dir district, Pakistan from 2018- 2019. Of the 400 children studied in which the overall prevalence rate for intestinal parasitic infections was found to be 71.75%. Children infected with single parasite accounted for 67.94% and 32.05% were detected with poly-parasitism. Shistosoma japonicum (0.69%), Taxocara spp (0.69%) and cryptosporidium (0.69%), were identified in children living in studied areas. We conclude that there is a need for mass scale campaigns to create awareness regarding health and hygiene in children and the need for development of effective poverty control programmes.

Postinfectious Inflammatory Syndrome following Cryptosporidium Infection

A 38-year-old woman with a history of Crohn's disease, multiple bowel resections, and ileostomy placement presented to the hospital with symptoms of increased ileostomy output for 1 week. She reported that she was emptying her bag fifteen times a day as opposed to her normal 3–4 times a day. Upon workup, she was found to have an acute kidney injury (AKI), and stool studies were positive for Cryptosporidium. She was treated with nitazoxanide 500 mg p.o. BID for 3 days along with continued rehydration. The patient was discharged after creatinine (Cr) and electrolytes returned to baseline. She continued to have elevated ileostomy output, and 1 week later, she was readmitted for another AKI and worsening of symptoms. At this hospitalization, stool studies were negative for Cryptosporidium, and the gastroenterologist consult recommended evaluation for active Crohn's and Lomotil for possible short bowel syndrome. Eventually, her laboratory results improved, and she was discharged again before the full workup was completed. The patient's ileostomy output continued to remain high following the second hospital discharge, and she eventually returned with another AKI, her third visit in a month. The workup for active Crohn's was completed, with fecal calprotectin, serum cortisol, and small bowel follow-through all returning to normal. At this time, postinfectious inflammatory syndrome was suspected, and she was started on 60 mg of prednisone for 2 weeks. Steroid therapy elicited a significant response with normalization of her ileostomy output and return of laboratory results to baseline. The patient was discharged without return of symptoms at follow-up.

Clofazimine for Treatment of Cryptosporidiosis in Human Immunodeficiency Virus Infected Adults: An Experimental Medicine, Randomized, Double-blind, Placebo-controlled Phase 2a Trial

Background

We evaluated the efficacy, pharmacokinetics (PK), and safety of clofazimine (CFZ) in patients living with human immunodeficiency virus (HIV) with cryptosporidiosis.

Methods

We performed a randomized, double-blind, placebo-controlled study. Primary outcomes in part A were reduction in Cryptosporidium shedding, safety, and PK. Primary analysis was according to protocol (ATP). Part B of the study compared CFZ PK in matched individuals living with HIV without cryptosporidiosis.

Results

Twenty part A and 10 part B participants completed the study ATP. Almost all part A participants had high viral loads and low CD4 counts, consistent with failure of antiretroviral (ARV) therapy. At study entry, the part A CFZ group had higher Cryptosporidium shedding, total stool weight, and more diarrheal episodes compared with the placebo group. Over the inpatient period, compared with those who received placebo, the CFZ group Cryptosporidium shedding increased by 2.17 log2 Cryptosporidium per gram stool (95% upper confidence limit, 3.82), total stool weight decreased by 45.3 g (P = .37), and number of diarrheal episodes increased by 2.32 (P = .87). The most frequent solicited adverse effects were diarrhea, abdominal pain, and malaise. One placebo and 3 CFZ participants died during the study. Plasma levels of CFZ in participants with cryptosporidiosis were 2-fold lower than in part B controls.

Conclusions

Our findings do not support the efficacy of CFZ for the treatment of cryptosporidiosis in a severely immunocompromised HIV population. However, this trial demonstrates a pathway to assess the therapeutic potential of drugs for cryptosporidiosis treatment. Screening persons living with HIV for diarrhea, and especially Cryptosporidium infection, may identify those failing ARV therapy.

Clinical Trials Registration

NCT03341767.

Opportunities and Challenges in Developing a Cryptosporidium Controlled Human Infection Model for Testing Antiparasitic Agents

Cryptosporidiosis is a leading cause of moderate-to-severe diarrhea in low- and middle-income countries, responsible for high mortality in children younger than two years of age, and it is also strongly associated with childhood malnutrition and growth stunting. There is no vaccine for cryptosporidiosis and existing therapeutic options are suboptimal to prevent morbidity and mortality in young children. Recently, novel therapeutic agents have been discovered through high-throughput phenotypic and target-based screening strategies, repurposing malaria hits, etc., and these agents have a promising preclinical in vitro and in vivo anti-Cryptosporidium efficacy. One key step in bringing safe and effective new therapies to young vulnerable children is the establishment of some prospect of direct benefit before initiating pediatric clinical studies. A Cryptosporidium controlled human infection model (CHIM) in healthy adult volunteers can be a robust clinical proof of concept model for evaluating novel therapeutics. CHIM could potentially accelerate the development path to pediatric studies by establishing the safety of a proposed pediatric dosing regimen and documenting preliminary efficacy in adults. We present, here, perspectives regarding the opportunities and perceived challenges with the Cryptosporidium human challenge model.

Use-case scenarios for an anti-Cryptosporidium therapeutic

Cryptosporidium is a widely distributed enteric parasite that has an increasingly appreciated pathogenic role, particularly in pediatric diarrhea. While cryptosporidiosis has likely affected humanity for millennia, its recent "emergence" is largely the result of discoveries made through major epidemiologic studies in the past decade. There is no vaccine, and the only approved medicine, nitazoxanide, has been shown to have efficacy limitations in several patient groups known to be at elevated risk of disease. In order to help frontline health workers, policymakers, and other stakeholders translate our current understanding of cryptosporidiosis into actionable guidance to address the disease, we sought to assess salient issues relating to clinical management of cryptosporidiosis drawing from a review of the literature and our own field-based practice. This exercise is meant to help inform health system strategies for improving access to current treatments, to highlight recent achievements and outstanding knowledge and clinical practice gaps, and to help guide research activities for new anti-Cryptosporidium therapies.

Identification of Uncommon Cryptosporidium viatorum (a Novel Subtype XVcA2G1c) and Cryptosporidium andersoni as Well as Common Giardia duodenalis Assemblages A and B in Humans in Myanmar

Cryptosporidium and Giardia are two important zoonotic intestinal protozoa responsible for diarrheal diseases in humans and animals worldwide. Feces from infected hosts, water and food contaminated by Cryptosporidium oocysts and Giardia cysts as well as predictors such as poverty have been involved in their transmission. Myanmar is one of the world’s most impoverished countries. To date, there are few epidemiological studies of Cryptosporidium and Giardia in humans. To understand the prevalence and genetic characterization of Cryptosporidium spp. and Giardia duodenalis in humans in Myanmar, a molecular epidemiological investigation of the two protozoa was conducted in four villages of Shan State. 172 fecal specimens were collected from Wa people (one each) and identified for the presence of Cryptosporidium spp. and G. duodenalis by sequence analysis of their respective small subunit ribosomal RNA genes. 1.74% of investigated people were infected with Cryptosporidium spp.—C. andersoni (n = 2) and C. viatorum (n = 1) while 11.05% infected with G. duodenalis—assemblages A (n = 6) and B (n = 13). By sequence analysis of 60-kDa glycoprotein gene, the C. viatorum isolate belonged to a novel subtype XVcA2G1c. DNA preparations positive for G. duodenalis were further subtyped. Five of them were amplified and sequenced successfully: different assemblage B sequences (n = 2) at the triosephosphate isomerase (tpi) locus; sub-assemblage AII sequence (n = 1) and identical assemblage B sequences (n = 2) at the β-giardin (bg) locus. This is the first molecular epidemiological study of Cryptosporidium spp. and G. duodenalis in humans in Myanmar at both genotype and subtype levels. Due to unclear transmission patterns and dynamics of Cryptosporidium spp. and G. duodenalis, future research effort should focus on molecular epidemiological investigations of the two parasites in humans and animals living in close contact in the investigated areas, even in whole Myanmar. These data will aid in making efficient control strategies to intervene with and prevent occurrence of both diseases.

Cost-benefit analysis of point-of-use devices for health risks reduction from pathogens in drinking water

Microbial contamination of drinking water post-municipal treatment is difficult to predict as a risk factor for human health. One method to reduce morbidity or mortality from unpredictable exposures is through point-of-use (POU) treatment devices. The goal of this project was to assess the cost-benefit of POU water treatment at the tap in terms of protection from microbes in drinking water. This project estimated: (1) incidence of acute illness (AI), sequela, and mortality associated with waterborne pathogens; (2) illness reduction rates from using POU devices; and (3) healthcare cost reductions associated with POU devices. Infection rates and costs associated with 10 of the most common waterborne pathogens were identified and used to calculate national annual costs. We estimated 9M AI, 0.6M sequela, and 1,400 mortality cases that occur annually in the USA from these pathogens. The greatest cost-benefit was seen when considering the totality of disease burden reduction (AI, sequela, and mortality) including all pathogens at a national level and applying a 35% infection reduction, resulting in a total cost per averted disease case of $1,815. This study suggests that it is cost-beneficial to prevent water-related illness using POU devices.

Influence of weather and climate on cryptosporidiosis-A review

Studies have shown that climatic factors can significantly influence transmission of many waterborne diseases. However, knowledge of the impact of climate variability on cryptosporidiosis is much less certain. Associations between the incidence of cryptosporidiosis and climatic variables have been reported in several countries. Given that the identified relationships were not consistently reported across studies, it is not known whether these were country-specific observations or can be considered more globally. Variation in the disease risk in both low- and middle-income countries and high-income countries presents new challenges and opportunities to enact responsive changes in research and public health policies. Available epidemiological evidence of the influence of weather and climate on cryptosporidiosis is reviewed. Fourteen studies met the inclusion criteria, and most studies showed that the incidence of cryptosporidiosis is highly sensitive to climatic conditions, especially temperature, rainfall and relative humidity. The identified associations varied across studies, with different conditions of importance and lag times across different locations. Therefore, there is a need for countries at risk to assess Cryptosporidium transmission routes based on the spatiotemporal patterns of the disease and what role climate and other socio-ecological changes play in the transmission. Information gathering will then allow us to provide information for evidence-based control strategies and mitigation of transmission. This review offers new perspectives on the role of climate variability on Cryptosporidium transmission. It highlights different epidemiological approaches adopted and provides the potential for future research and surveillance to reduce the disease burden. By evaluating the epidemiological transmission of this organism in high-income countries, all mitigation strategies, for example filtration and water catchment management, can be used as exemplars of preventing infection in low- to middle-income countries.

Health sequelae of human cryptosporidiosis in industrialised countries: a systematic review

BACKGROUND

Cryptosporidium is a protozoan parasite which is a common cause of gastroenteritis worldwide. In developing countries, it is one of the most important causes of moderate to severe diarrhoea in young children; in industrialised countries it is a cause of outbreaks of gastroenteritis associated with drinking water, swimming pools and other environmental sources and a particular concern in certain immunocompromised patient groups, where it can cause severe disease. However, over recent years, longer-term sequelae of infection have been recognised and a number of studies have been published on this topic. The purpose of this systematic review was to examine the literature in order to better understand the medium- to long-term impact of cryptosporidiosis.

METHODS

This was a systematic review of studies in PubMed, ProQuest and Web of Science databases, with no limitations on publication year or language. Studies from any country were included in qualitative synthesis, but only those in industrialised countries were included in quantitative analysis.

RESULTS

Fifteen studies were identified for qualitative analysis which included 3670 Cryptosporidium cases; eight studies conducted in Europe between 2004-2019 were suitable for quantitative analysis, including five case-control studies. The most common reported long-term sequelae were diarrhoea (25%), abdominal pain (25%), nausea (24%), fatigue (24%) and headache (21%). Overall, long-term sequelae were more prevalent following infection with Cryptosporidium hominis, with only weight loss and blood in stool being more prevalent following infection with Cryptosporidium parvum. Analysis of the case-control studies found that individuals were 6 times more likely to report chronic diarrhoea and weight loss up to 28 months after a Cryptosporidium infection than were controls. Long-term abdominal pain, loss of appetite, fatigue, vomiting, joint pain, headache and eye pain were also between 2-3 times more likely following a Cryptosporidium infection.

CONCLUSIONS

This is the first systematic review of the long-term sequelae of cryptosporidiosis. A better understanding of long-term outcomes of cryptosporidiosis is valuable to inform the expectations of clinicians and their patients, and public health policy-makers regarding the control and prevention of this infection. Systematic review registration PROSPERO Registration number CRD42019141311.

Determining the long-term health burden and risk of sequelae for 14 foodborne infections in British Columbia, Canada: protocol for a retrospective population-based cohort study

INTRODUCTION

Over one in eight Canadians is affected by a foodborne infection annually; however, the long-term consequences, including the risks and costs of sequelae, are unclear. We aim to estimate the health burden and direct costs of 14 infections commonly transmitted by food, considering the acute illness and subsequent sequelae and mortality, for the population of British Columbia, Canada (~4.7 million).

METHODS AND ANALYSIS

We will conduct a population-based retrospective cohort study of the British Columbia provincial population, over a 10-year study period (1 January 2005 to 31 December 2014). Exposure is defined as a provincially reported illness caused by Clostridium botulinum, Campylobacter, Cryptosporidium, Cyclospora, Giardia, hepatitis A virus, Listeria, non-typhoidal Salmonella spp, Salmonella Typhi, Salmonella Paratyphi, Shiga toxin-producing Escherichia coli, Shigella, Vibrio parahaemolyticus or Yersinia (excluding pestis). We will link individual-level longitudinal data from eight province-wide administrative health and reportable disease databases that include physician visits, hospitalisations and day surgeries, deaths, stillbirths, prescription medications (except those to treat HIV) and reportable foodborne diseases. Using these linked databases, we will investigate the likelihood of various sequelae and death. Hazard models will be used to estimate the risk of outcomes and their association with the type of foodborne infection. Epidemiological analyses will be conducted to determine the progression of illness and the fraction of sequelae attributable to specific foodborne infections. Economic analyses will assess the consequent direct healthcare costs.

ETHICS AND DISSEMINATION

This study has been approved by a University of Waterloo Research Ethics Committee (no 30645), the University of British Columbia Behavioral Research Ethics Board (no H16-00021) and McGill University's Institutional Review Board (no A03-M12-19A). Results will be disseminated via presentations to academics, public health practitioners and knowledge users, and publication in peer-reviewed journals. Where such publications are not open access, manuscripts will also be available via the University of Waterloo's Institutional Repository (https://uwspace.uwaterloo.ca).

Potential therapeutic and prophylactic effects of Asafoetida in murine cryptosporidiosis

Cryptosporidium parvum is an important coccidian parasite that could infect the intestine, respiratory and biliary tracts of man and animals. This study aims to test the potential therapeutic and prophylactic effects of a natural herbal agent (Asafoetida) versus the nowadays drug of choice (Nitazoxanide). Fifty bred female, white Albino mice of CDI strain were divided into 5 groups; group I (GI): immunosuppressed, infected with C. parvum and treated with Asafoetida, group II (GII): immunosuppressed, prophylactically treated with Asafoetida for 7 days prior to infection, group III (GIII): immunosuppressed, infected and treated with Nitazoxanide, group IV (GIV): immunosuppressed and infected (Positive control), group V (GV): immunosuppressed and non infected (Negative control). Parasitological and histopatholgical examinations of the stool, ileocaecal and liver specimens were performed for the study groups. GI showed reduction of the mean oocyst count in stool with improvement of the pathological changes at the ileocaecal region with preservation of hepatic architecture. Results of GI were better than GII and GIV but not as good as GIII. GII showed the least improvement among the test groups. GIII showed the best response between the test groups. GIV show no statistical significant difference between the mean oocyst count in the mice stool at the time of infection and 7 days after infection. It was therefore concluded that Asafoetida is a promising natural therapeutic and prophylactic agent against cryptosporidiosis while, Nitazoxanide is the best chemotherapeutic agent against cryptosporidiosis.

Risk Factors for Sporadic Cryptosporidiosis in the Netherlands: Analysis of a 3-Year Population Based Case-Control Study Coupled With Genotyping, 2013-2016

Background

In 2012, cryptosporidiosis cases increased in the Netherlands, but no single source was identified. In April 2013, we began a 3-year population-based case-control study coupled with genotyping to identify risk factors for sporadic cryptosporidiosis.

Methods

Cryptosporidium cases were laboratory confirmed (by microscopy or polymerase chain reaction), and the species (ie, C. hominis or C. parvum) was determined. We analyzed data by study year, combined and by species. We performed single-variable analysis, and variables with a P value of ≤ .10 were included in a multivariable logistic regression model adjusting for age, sex, and season.

Results

The study included 609 cases and 1548 frequency-matched controls. C. parvum was the predominant species in the first 2 study years, shifting to C. hominis in the third year. Household person-to-person transmission and eating barbequed food were strongly associated with being a case. Eating tomatoes was negatively associated. When the analysis was stratified by study year, person-to-person transmission was an independent risk factor. Analysis by species identified different risk factors for cases infected with C. parvum and C. hominis.

Conclusion

This was the first case-control study examining risk factors for sporadic cryptosporidiosis in the Netherlands. Providing information about Cryptosporidium exposure during outdoor activities and improvements in hygiene within households could prevent future sporadic infections.

An evaluation of health protection practices for the investigation and management of Cryptosporidium in England and Wales

Background

Cryptosporidium is a major cause of gastroenteritis (cryptosporidiosis). Case and outbreak report rates vary geographically, which may in part reflect public health practice.

Methods

To examine the public health management of cryptosporidiosis, an online questionnaire was administered to the 28 Health Protection Teams (HPTs) in England and Wales in 2014. Practices for investigation and management of cases and outbreaks were compared.

Results

Practice varied among the 24 (86%) respondents in terms of who undertook actions (HPT or Local Authority) to investigate and manage cryptosporidiosis. HPTs without exceedance monitoring detected fewer outbreaks (1/5, 20%) than those with it (13/19, 68%) (P = 0.12), and those that always administered a risk-factor questionnaire detected more outbreaks (12/19, 63%) than those who did this only sometimes (2/5, 40%) (P = 0.62). Significantly more HPTs with a system to detect common exposures reported at least one outbreak (14/19, 74%) compared to HPTs with no system (0/5) (P = 0.01).

Conclusions

Applying exceedance monitoring, using a standardized questionnaire taking into account the incubation period for Cryptosporidium, and having a structured system to detect common exposures increased outbreak detection. Information about all cases should be shared between local public health authorities, and current guidance used for the prevention of spread.

Massive Cryptosporidium infections and chronic diarrhea in HIV-negative patients

Protozoa of the genus Cryptosporidium are common parasites of domestic and wild animals—mammals, birds, reptiles, and fishes. The invasive forms are thick-walled oocysts, which can be present in water supplies, on fruits, vegetables, or in the soil contaminated with feces. In this work, we describe three cases of middle-aged persons with massive Cryptosporidium hominis infection and chronic diarrhea with no immunological abnormalities and no history of previous travels to tropical countries. The lesions discovered during colonoscopy within the large intestine–cryptitis and the histopathological changes were related to massive cryptosporidiosis. All these statements indicate necessity of parasitological stool examination in cases with chronic diarrhea in which no etiological agents are detected, but not only in HIV positive individuals. Parasite’s eradication leads to symptom disappearance as well as improvement of histopathological mucosa alterations.

Accounting for long-term manifestations of Cryptosporidium spp infection in burden of disease and cost-of-illness estimations, the Netherlands (2013-2017)

Background

Burden of disease (BoD) estimations are increasingly used to prioritize public health interventions. Previous Cryptosporidium BoD models accounted only for acute episodes, while there is increasing evidence of long-term manifestations. Our objective was to update Cryptosporidium BoD and cost-of-illness (COI) models and to estimate BoD and COI for the Netherlands in years 2013–2017.

Methods

We performed a scoping literature review and drew an outcome tree including long-term manifestations for which sufficient evidence was found, such as recurrent diarrhea and joint pain. We chose the Disability-Adjusted Life Year (DALY) metric to synthesize years of life lost due mortality (YLLs) and years lived with disability due to non-fatal outcomes (YLDs). For the costs, we adopted a societal perspective accounting for direct healthcare costs, patient costs and productivity losses. Uncertainty was managed using Latin Hypercube sampling (30,000 iterations).

Results

In the Netherlands in 2017, we estimated 50,000 Cryptosporidium cases (95% uncertainty interval (UI): 15,000–102,000), 7,000 GP visits, 300 hospitalizations and 3 deaths, resulting in 137 DALYs (95%UI: 54–255) and €19.2 million COI (95%UI: €7.2 million– €36.2 million). Estimates were highest for 2016 (218 DALYs and €31.1 million in COI), and lowest in 2013 (100 DALYs and €13.8 million in COI). Most of the BoD was attributable to YLD (≈80% of DALYs). The most important cost was productivity losses (≈90% of total COI). Long-term manifestations, including recurring diarrhea and joint pain, accounted for 9% of the total DALYs and 7% of the total COI.

Conclusion

Current evidence supports the inclusion of long-term manifestations in Cryptosporidium models, which contribute close to 10% of the total DALYs and costs. This may be an underestimation, as we were conservative in our assumptions. Cryptosporidium should be considered a priority organism with respect to public health surveillance, even in industrialized countries with high hygiene standards.

Anthroponotic transmission of Cryptosporidium parvum predominates in countries with poorer sanitation: a systematic review and meta-analysis

Background

Globally cryptosporidiosis is one of the commonest causes of mortality in children under 24 months old and may be associated with important longterm health effects. Whilst most strains of Cryptosporidium parvum are zoonotic, C. parvum IIc is almost certainly anthroponotic. The global distribution of this potentially important emerging infection is not clear.

Methods

We conducted a systematic review of papers identifying the subtype distribution of C. parvum infections globally. We searched PubMed and Scopus using the following key terms Cryptospor* AND parvum AND (genotyp* OR subtyp* OR gp60). Studies were eligible for inclusion if they had found C. parvum within their human study population and had subtyped some or all of these samples using standard gp60 subtyping. Pooled analyses of the proportion of strains being of the IIc subtype were determined using StatsDirect. Meta-regression analyses were run to determine any association between the relative prevalence of IIc and Gross Domestic Product, proportion of the population with access to improved drinking water and improved sanitation.

Results

From an initial 843 studies, 85 were included in further analysis. Cryptosporidium parvum IIc was found in 43 of these 85 studies. Across all studies the pooled estimate of relative prevalence of IIc was 19.0% (95% CI: 12.9–25.9%), but there was substantial heterogeneity. In a meta-regression analysis, the relative proportion of all C. parvum infections being IIc decreased as the percentage of the population with access to improved sanitation increased and was some 3.4 times higher in those studies focussing on HIV-positive indivduals.

Conclusions

The anthroponotic C. parvum IIc predominates primarily in lower-income countries with poor sanitation and in HIV-positive individuals. Given the apparent enhanced post-infectious virulence of the other main anthroponotic species of Cryptosporidium (C. hominis), it is important to learn about the impact of this subtype on human health.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3263-0) contains supplementary material, which is available to authorized users.

First Cryptosporidium outbreak in Hungary, linked to a treated recreational water venue in 2015

In June 2015, an outbreak of cryptosporidiosis with 35 cases (23 probable and 12 laboratory-confirmed) occurred among 191 attendees of a residential rehabilitation holiday for paediatric organ transplant patients (n = 49) and their families at a hotel in Somogy county, Hungary. The overall attack rate was 18%. Most of the cases were transplanted children who experienced severe acute disease and required adjustment to their tacrolimus immunosuppression. A retrospective case-control study suggested an association between recreational water exposures and illness: cases were seven times more likely than controls to have swum in the children's pool (odds ratio 7.17; 95% confidence interval 2.9–17.2; P < 0.0001) and five times more likely to have used the jetted whirlpool (odds ratio 5.25; 95% confidence interval 2.1–13.1; P < 0.0001). This was the first outbreak of cryptosporidiosis in Hungary and it is especially unfortunate that it affected vulnerable children who experienced severe symptoms. Cryptosporidium presents specific infection control difficulties in treated recreational water venues; the link to a whirlpool is unusual and highlights the importance of the age-appropriate use of these facilities and reminding users not to immerse their heads or swallow the water. Cryptosporidiosis is more commonly linked to children’ pools where improved bather hygiene and promoting exclusion of diarrhoea cases could help to avoid similar outbreaks.

Widespread occurrence of Cryptosporidium infections in patients with HIV/AIDS: Epidemiology, clinical feature, diagnosis, and therapy

Cryptosporidium infection is a serious threat for HIV/AIDS patients, causing severe diarrhea and even death. The overall prevalence of Cryptosporidium in HIV/AIDS patients was calculated as approximately 8.69% (7,799/89,724), with higher prevalence observed in individuals with diarrhea, individuals with low CD4⁺ T-lymphocyte counts, and antiretroviral therapy-naïve individuals. Cryptosporidium infection was not significantly associated with patient age or gender, national development levels, or continent of residence. Over the period from 2007 to 2017, Cryptosporidium prevalence was 10.09% (3,282/32,517); this figure was higher than that observed in each of the previous observation periods (1985-1995 and 1996-2006), suggesting that the prevalence of cryptosporidiosis has been increasing over time in HIV/AIDS patients. Ten Cryptosporidium species and genotypes have been identified from 1,252 isolates, with C. hominis, C. parvum, and C. meleagridis accounting for 93.53% of infections. Five subtypes each of C. hominis (Ia, Ib, Id, Ie, and If), C. parvum (IIa to IIe), and C. meleagridis (IIIa to IIIe) have been described by sequence analyses of the 60-kDa glycoprotein (gp60) gene. Variation in the clinical manifestations observed in HIV/AIDS patients might be attributed to infection by different Cryptosporidium species, genotypes and subtypes, as well as different sites of infection. New molecular and immunological diagnostic techniques are in development or already commercially available. High-throughput screening methods for development of new or repurposed therapeutics as well as novel parasite genetic manipulation strategies offer hope for improving human cryptosporidiosis therapies. Painstaking efforts by researchers as well as support from governments and funding agencies will be required to make lasting achievements in this field.

Sick leave due to diarrhea caused by contamination of drinking water supply with Cryptosporidium hominis in Sweden: a retrospective study

We investigated sick leave from work, studies, preschool, and kindergarten occurring between 1 November 2010 and 31 January 2011 and associated with a waterborne outbreak of diarrhea caused by Cryptosporidium hominis in late November 2010 in Östersund, Sweden with 45.2% of 60,000 residents being symptomatic. A questionnaire defining acute watery diarrhoea and/or ≥3 diarrhea episodes/day as cryptosporidiosis was sent to 1,508 residents in late January 2011 (response rate 69.2%). Among adults aged 18-60 years, 24.0% took sick leave for a mean of 4.6 (SD ± 4.0) days due to cryptosporidiosis, and an additional 10.6% were absent from work a mean of 4.0 (±2.2) days to care for symptomatic children. Among children (aged ≤17 years), 35.0% stayed home sick from kindergarten/preschool or school/university for a mean of 5.2 (±3.8) days resulting in 5.1 (±4.4) days of absence from work per sick child shared between parents/guardians. The estimated total number of sick leave days was 50,000 for adults and 20,700 for children, with an estimated direct cost of €7 million for employers. The potential impact on society of sick leave caused by waterborne diseases must be considered in decisions regarding the quality of drinking water.

Persisting post-infection symptoms 2 years after a large waterborne outbreak of Cryptosporidium hominis in northern Sweden

OBJECTIVES

In 2010-2011, a large waterborne outbreak of Cryptosporidium hominis affected the city of Östersund in Sweden. Previous findings had suggested that gastrointestinal symptoms can persist for up to 11 months after the initial infection. Here we investigated whether the parasite could cause sequelae in infected individuals up to 28 months after the outbreak. We compared cases linked to the outbreak and the previous follow-up study with non-cases regarding symptoms present up to 28 months after the initial infection. We investigated whether cases were more likely to report a list of symptoms at follow-up compared to non-cases, calculating odds ratio and 95% confidence interval obtained through logistic regression.

RESULTS

A total of 559 individuals (215 cases) were included in the study. Forty-eight percent of the outbreak cases reported symptoms at follow-up. Compared to non-cases, cases were more likely to report watery diarrhea, diarrhea, abdominal pain, fatigue, nausea, headache, or joint stiffness/pain/discomfort at follow-up after adjusting for age and sex. Our findings suggest that gastrointestinal symptoms and joint pain can persist several years after the initial Cryptosporidium infection and should be regarded as a potential cause of unexplained gastrointestinal symptoms or joint pain in people who have had this infection.

Long-term sequelae of sporadic cryptosporidiosis: a follow-up study

To determine the frequency of occurrence of sequelae following cryptosporidiosis. A follow-up study was performed during a case-control study for sporadic cryptosporidiosis in the Netherlands (2013–2016). Cryptosporidiosis cases were invited to complete a follow-up questionnaire 4 months after diagnosis. Using a case-crossover study design, we compared the frequencies of reported symptoms 4 months after the acute phase to those reported 4 months before the onset of illness and during illness. Frequencies of symptoms in the pre- to post-infection phases were also compared with those of a population control group. Cryptosporidium species-specific effects were also studied. Logistic regression was used to calculate adjusted odds ratios (aOR) for symptoms occurrence. Of the 731 available cases, 443 (60%) responded and 308 (42%) could be included in the follow-up study. The median age was 26 years (range 1–80); 58% were female; 30% were infected with C. hominis and 70% with C. parvum. Compared to before illness, cases were significantly more likely to report dizziness (OR = 2.25), headache (OR = 2.15), fatigue (OR = 2.04), weight loss (OR = 1.82), diarrhoea (OR = 1.50), abdominal pain (OR = 1.38) or joint pain (OR = 1.84). However, symptoms of joint pain and headache occurred among cases after illness at a rate that was not significantly different from that observed in the general population. There were no significant differences in post-infection symptom occurrence between C. hominis and C. parvum. The disease burden of cryptosporidiosis extends beyond the acute phase of the infection, with cases reporting both intestinal and extra-intestinal symptoms up to 4 months following infection.

Protozoan parasites in irritable bowel syndrome: A case-control study

AIM

To investigate the putative role of protozoan parasites in the development of irritable bowel syndrome (IBS).

METHODS

The study included 109 IBS consecutive adult patients fulfilling the Rome III criteria and 100 healthy control subjects. All study subjects filled a structured questionnaire, which covered demographic information and clinical data. Fresh stool samples were collected from patients and control subjects and processed within less than 2 h of collection. Iodine wet mounts and Trichrome stained smears prepared from fresh stool and sediment concentrate were microscopically examined for parasites. Blastocystis DNA was detected by polymerase chain reaction, and Cryptosporidium antigens were detected by ELISA.

RESULTS

A total of 109 IBS patients (31 males, 78 females) with a mean age ± SD of 27.25 ± 11.58 years (range: 16 -60 years) were enrolled in the study. The main IBS subtype based on the symptoms of these patients was constipation-predominant (88.7% of patients). A hundred healthy subjects (30 males, 70 females) with a mean ± SD age of 25.0 ± 9.13 years (range 18-66 years) were recruited as controls. In the IBS patients, Blastocystis DNA was detected in 25.7%, Cryptosporidium oocysts were observed in 9.2%, and Giardia cysts were observed in 11%. In the control subjects, Blastocystis, Cryptosporidium and Giardia were detected in 9%, 0%, and 1%, respectively. The difference in the presence of Blastocystis (P = 0.0034), Cryptosporidium (P = 0.0003), and Giardia (P = 0.0029) between IBS patients and controls was statistically significant by all methods used in this study.

CONCLUSION

Prevalence of Blastocystis, Cryptosporidium and Giardia is higher in IBS patients than in controls. These parasites are likely to have a role in the pathogenesis of IBS.

Long-term health effects after resolution of acute Cryptosporidium parvum infection: a 1-year follow-up of outbreak-associated cases

We describe a longitudinal study carried out in an adult outbreak-associated cohort to investigate health effects, including post-infectious irritable bowel syndrome, occurring after resolution of acute Cryptosporidium parvum infection. New symptoms self-reported up to 12 months included: weight loss (31 %), abdominal pain (38 %), diarrhoea (33 %), eye pain (9 %), joint pain (33 %), fatigue (22 %) and symptoms consistent with irritable bowel syndrome (IBS) (28 %). Two people were medically diagnosed with IBS. This study describes for the first time sequelae reported by patients up to 12 months after infection with C. parvum, which appear to be similar to those described with C. hominis.

Symptoms and risk factors of Cryptosporidium hominis infection in children: data from a large waterborne outbreak in Sweden

Cryptosporidium is a major cause of diarrheal disease worldwide. In developing countries, this infection is endemic and in children, associated with growth faltering and cognitive function deficits, with the most severe impact on those aged <2 years. Little has been reported about symptoms and risk factors for children in industrialized countries, although the disease incidence is increasing in such regions. In November 2010, a large waterborne outbreak of C. hominis occurred in the city of Östersund in Sweden. Approximately 27,000 of the 60,000 inhabitants were symptomatic. We aimed to describe duration of symptoms and the risk factors for infection with C. hominis in children aged <15 years in a Western setting. Within 2 months after a boil water advisory, a questionnaire was sent to randomly selected inhabitants of all ages, including 753 children aged <15 years. Those with ≥3 loose stools/day were defined as cases of diarrhoea. The response rate was 70.3%, and 211 children (39.9%) fulfilled the case definition. Mean duration of diarrhoea was 7.5 days (median 6, range 1-80 days). Recurrence, defined as a new episode of diarrhoea after ≥2 days of normal stools, occurred in 52.5% of the cases. Significant risk factors for infection, besides living within the distribution area of the contaminated water plant, included a high level of water consumption, male sex, and a previous history of loose stools. The outbreak was characterized by high attack and recurrence rates, emphasizing the necessity of water surveillance to prevent future outbreaks.

Cryptosporidium spp. Infection in Solid Organ Transplantation: The Nationwide "TRANSCRYPTO" Study

BACKGROUND

Diarrhea is a frequent complication of solid organ transplantation. Cryptosporidiosis is classically reported in patients with acquired immunodeficiency syndrome and emerged as a cause of persistent diarrhea in solid organ transplant patients.

METHODS

Through the ANOFEL Cryptosporidium National Network and the French Transplantation Society, we collected all cryptosporidiosis cases identified in solid organ transplanted patients between 2006 and 2010 in France.

RESULTS

We reported 47 solid organ transplant recipients (41 kidneys) with cryptosporidiosis, mostly men (68%), with a median age of 52 (6-70) years old. Five patients had additional immunodepression favoring cryptosporidiosis (CD40 ligand deficiency [n = 1], human immunodeficiency virus infection [n = 4]). Cryptosporidiosis occurred at a median time of 3.4 (0-19.8) years posttransplant. Exposure to environmental risk factors was found before infection onset in 18 patients. Time between first symptoms and diagnosis was 10 (2-110) days. Four patients had associated extraintestinal location (biliary tract [n = 3] and lung [n = 1]). Thirty-five patients received specific therapy against cryptosporidiosis ie nitozoxanide, 25 in monotherapy, and 10 in association with azithromycin, 13 in association with immunosuppression (IS) reduction. Four patients were cured with IS treatment tapering only. The others patients had neither IS reduction nor specific therapy against cryptosporidiosis. Cryptosporidiosis was complicated by renal failure in 15 patients. Symptoms resolved after a median of 10 days of treatment. Six patients relapsed and 3 died, 1 with evolutive infection.

CONCLUSIONS

Cryptosporidiosis is a late posttransplant infection that disseminated to biliar duct or lung in 9% of patients. When limited to digestive tract, infection may resolve without IS reduction.

Pathogenic Mechanisms of Cryptosporidium and Giardia

Intestinal protozoa are important etiological agents of diarrhea, particularly in children, yet the public health risk they pose is often neglected. Results from the Global Enteric Multicenter Study (GEMS) showed that Cryptosporidium is among the leading causes of moderate to severe diarrhea in children under 2 years. Likewise, Giardia infects approximately 200 million individuals worldwide, and causes acute diarrhea in children under 5 years. Despite this recognized role as pathogens, the question is why and how these parasites cause disease in some individuals but not in others. This review focuses on known pathogenic mechanisms of Cryptosporidium and Giardia, and infection progress towards disease.

Human cryptosporidiosis in Europe

Cryptosporidium has emerged as a significant cause of diarrhoeal disease worldwide, with severe health consequences for very young, malnourished children living in endemic areas and for individuals with highly impaired T-cell functions. In Europe, as elsewhere, the burden of disease has been difficult to measure as a result of the lack of appropriate, standardized surveillance and monitoring systems. The recent occurrence of large water- and foodborne outbreaks in several EU countries, as well as the results of many surveys of human and animal cryptosporidiosis, indicate that this parasite is widespread. Specific subtypes of the zoonotic Cryptosporidium parvum and the anthroponotic C. hominis are responsible for the majority of human cases in Europe. No treatment is currently available to clear the infection, but recent progress in genetic engineering of the parasite, coupled with advances in genomics, have opened important avenues for future research. Here we explore the possible reasons for underascertainment of cryptosporidiosis and the importance of accurate diagnosis in clinical management, the epidemiology of human cryptosporidiosis and key messages from recent outbreaks to highlight important interventions and emerging public health issues.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

Genotyping of Cryptosporidium Species and Their Clinical Manifestations in Patients with Renal Transplantation and Human Immunodeficiency Virus Infection

In the present study we aimed to determine (i) frequency of Cryptosporidium species among patients with renal transplantation (RT) and human immunodeficiency virus (HIV) infection and (ii) relationship of the nature, severity, and duration of symptoms with different species and load of Cryptosporidium. Stool samples from 70 (42 RT and 28 HIV) and 140 immunocompromised patients with and without cryptosporidiosis by modified Kinyoun's staining were subjected to qPCR-melting curve analysis for identification of parasite species. qPCR detected one microscopically negative sample to be positive for cryptosporidiosis. C. hominis, C. parvum, and mixed infection were detected in 50/71 (70.4%), 19/71 (26.8%), and 2/71 (2.8%) patients, respectively. Patients with cryptosporidiosis had higher stool frequency (median, IQR: 4, 3–6/d versus 3, 2–4/d; P = 0.017) and watery stool (52/71 [73%] versus 64/139 [46%]; P = 0.003). Parasite load (median, IQR: Log₁₀ 6.37 (5.65–7.12), Log₁₀ 5.81 (4.26–6.65); P = 0.046) and nausea/vomiting (29/50 [58%] versus 5/19 [26%]; P = 0.032) were more frequent with C. hominis than with C. parvum infection. Thus, Cryptosporidium spp. (mainly C. hominis) is a common cause of diarrhoea in RT and HIV patients.

Parasitic diarrheal disease: drug development and targets

Diarrhea is the manifestation of gastrointestinal infection and is one of the major causes of mortality and morbidity specifically among the children of less than 5 years age worldwide. Moreover, in recent years there has been a rise in the number of reports of intestinal infections continuously in the industrialized world. These are largely related to waterborne and food borne outbreaks. These occur by the pathogenesis of both prokaryotic and eukaryotic organisms like bacteria and parasites. The parasitic intestinal infection has remained mostly unexplored and under assessed in terms of therapeutic development. The lack of new drugs and the risk of resistance have led us to carry out this review on drug development for parasitic diarrheal diseases. The major focus has been depicted on commercially available drugs, currently synthesized active heterocyclic compounds and unique drug targets, that are vital for the existence and growth of the parasites and can be further exploited for the search of therapeutically active anti-parasitic agents.

Post-infection symptoms following two large waterborne outbreaks of Cryptosporidium hominis in Northern Sweden, 2010-2011

Background

In 2010–2011, two large waterborne outbreaks caused by Cryptosporidium hominis affected two cities in Sweden, Östersund and Skellefteå. We investigated potential post-infection health consequences in people who had reported symptoms compatible with cryptosporidiosis during the outbreaks using questionnaires.

Methods

We compared cases linked to these outbreaks with non-cases in terms of symptoms present up to eleven months after the initial infection. We examined if cases were more likely to report a list of symptoms at follow-up than non-cases, calculating odds ratios (OR) and 95 % confidence intervals (CI) obtained through logistic regression.

Results

A total of 872 (310 cases) and 743 (149 cases) individuals responded to the follow-up questionnaires in Östersund and Skellefteå respectively. Outbreak cases were more likely to report diarrhea (Östersund OR: 3.3, CI: 2.0-5.3. Skellefteå OR: 3.6, CI: 2.0-6.6), watery diarrhea (Östersund OR: 3.4, CI: 1.9-6.3. Skellefteå OR: 2.8, CI: 1.5-5.1) abdominal pain (Östersund OR: 2.1, CI: 1.4-3.3, Skellefteå OR: 2.7, CI: 1.5-4.6) and joint pain (Östersund OR: 2.0, CI: 1.2-3.3, Skellefteå OR: 2.0, CI: 1.1-3.6) at follow-up compared to non-cases.

Conclusions

Our findings suggest that gastrointestinal- and joint symptoms can persist several months after the initial infection with Cryptosporidium and should be regarded as a potential cause of unexplained symptoms in people who have suffered from the infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1871-6) contains supplementary material, which is available to authorized users.

An audit of the laboratory diagnosis of cryptosporidiosis in England and Wales

To assess the level of practice consistent with UK national standards for Cryptosporidium testing, an audit was performed of 156 publicly funded clinical microbiology laboratories in England and Wales between August 2013 and April 2014. Responses were received from 85 (54 %) laboratories. First line diagnostic methods used were mainly microscopy with modified Ziehl-Neelsen (mZN) or auramine phenol (AP) staining (68/85, 80 %), enzyme immunoassays (EIAs) (16/85, 19 %) or in-house PCR (1/85, 1 %). The use of EIAs was more widespread than reported previously. Various methods were used for confirmation of positive EIA reactions and laboratories frequently resorted to sending samples to the national reference laboratory for this purpose, indicating that guidance is required for performance monitoring and confirmation of positive reactions. Laboratory positivity rates were related to the diagnostic test used, with highest median rates reported by those using PCR, EIAs or AP microscopy, and the lowest by those using mZN microscopy. One-third of responding laboratories (28/85, 33 %) routinely tested all stools for Cryptosporidium. However, 16 (19 %) laboratories used stool consistency to decide whether to test for this parasite. Other selection criteria included patient age (n = 18; 21 % laboratories), history or clinical details (n = 40; 47 %), duration of hospitalization (n = 18; 21 %) or clinician requests (n = 25; 29 %). To encourage laboratories to test all stools submitted for the investigation of diarrhoeal illness for Cryptosporidium, revision of the guidance in the national standards is under way. This will enable improved assessment of the burden of illness and ability to monitor outbreaks, and measure changes in reported cases.

Aetiology and epidemiology of human cryptosporidiosis cases in Galicia (NW Spain), 2000–2008

Cryptosporidiuminfects millions of people worldwide causing acute gastroenteritis, but despite its remarkable epidemiological and economic impact, information on the epidemiological trends of human cryptosporidiosis is still scarce in most countries. Here we investigate a panel of 486 cases collected in Galicia (NW Iberian Peninsula) between 2000 and 2008, which sheds new light on the epidemiology in this region of the South Atlantic European façade. Incidence rates in Galicia are one order of magnitude higher than those reported in other regions of Spain, suggesting that this parasite remains largely underdiagnosed in this country, and are also larger than those typical of other European countries with available data. Two species dominate our dataset,Cryptosporidium hominis(65%) andC. parvum(34%). The sex ratio of patients infected by either species was 0·5, butC. hominiswas significantly more common in younger males.C. parvuminfections were more acute and required more specialized medical attention, which suggests a differential adaptation of each species to human hosts. The parasites display strong seasonal and geographical variation.C. parvumincidence peaked during summer and was mainly detected in rural areas whileC. hominisinfections were more frequent in autumn and exhibited a more even geographical distribution. Such differences probably reflect their distinct sources of infection – C. parvumis mainly zoonotic andC. hominisanthroponotic – and the effects of climatic variables, like temperature and rainfall.

Large outbreak of Cryptosporidium hominis infection transmitted through the public water supply, Sweden

In November 2010, ≈27,000 (≈45%) inhabitants of Östersund, Sweden, were affected by a waterborne outbreak of cryptosporidiosis. The outbreak was characterized by a rapid onset and high attack rate, especially among young and middle-aged persons. Young age, number of infected family members, amount of water consumed daily, and gluten intolerance were identified as risk factors for acquiring cryptosporidiosis. Also, chronic intestinal disease and young age were significantly associated with prolonged diarrhea. Identification of Cryptosporidium hominis subtype IbA10G2 in human and environmental samples and consistently low numbers of oocysts in drinking water confirmed insufficient reduction of parasites by the municipal water treatment plant. The current outbreak shows that use of inadequate microbial barriers at water treatment plants can have serious consequences for public health. This risk can be minimized by optimizing control of raw water quality and employing multiple barriers that remove or inactivate all groups of pathogens.