Cryptosporidium in foodstuffs—an emerging aetiological route of human foodborne illness

A summary of cryptosporidiosis outbreaks reported in France and overseas departments, 2017–2020

Cryptosporidium is a known foodborne pathogen, ranked fifth out of 24 among foodborne parasites in terms of importance and a cause of many cryptosporidiosis outbreaks worldwide. In France, very few outbreaks were reported before 2017, and data recently obtained by the Expert Laboratory of the Cryptosporidiosis National Reference Center (CNR-LE-Cryptosporidiosis) have shown that outbreaks are in fact common and frequently underreported. In this work, we aim to report the characteristics of outbreaks detected in France during the period 2017–2020 and present a summary of investigations carried out by the CNR-LE-Cryptosporidiosis. During the study period, there were eleven cryptosporidiosis outbreaks, including three with no identified origin. Among the eight identified outbreaks: six were due to water contamination (five tap water and one recreational water), one was due to direct contact with infected calves, and one was due to consumption of contaminated curd cheese. Among these outbreaks, five of them exceeded one hundred cases. Recent results obtained by the CNR-LE-Cryptosporidiosis revealed the multiannual occurrence of Cryptosporidium outbreaks in France. Waterborne outbreaks were more frequently detected, while foodborne outbreaks which are more difficult to detect were likely underreported.

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Massive Cryptosporidium outbreaks were detected in France recently.

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Waterborne origin appeared predominant.

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Foodborne origin is probably strongly neglected.

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Develop adapted monitoring and preventing strategies could reduce cryptosporidiosis

Role, ownership and presence of domestic animals in peri-urban households of Kisumu, Kenya

Low- and middle-income countries are experiencing rapid urban population growth, particularly in peri-urban informal settlements. In these urban areas, animal husbandry remains a valuable source of income and protein-rich foods but may also present a risk of zoonotic disease threat. To date, there have been studies that have assessed the prevalence and nature of animal ownership in these communities. This cross-sectional survey assessed the geographical, sociocultural and economic factors behind the presence, ownership and purpose of domestic animals in three informal peri-urban communities of Kisumu, Kenya. A majority (n = 587) of the study households exhibited domestic animal presence in the living space yet only 32% of households reported animal ownership (n = 252). The purposes of ownership included: for meat/eggs (55%); for income, sale or trade (43%); for milk production (31%); and as companions/pets (31%). Among households that owned animals, 76% reported that at least one animal slept in the house at night. In multivariate logistic regression, the following factors were significantly associated with household animal ownership: ownership of agricultural land (OR = 1.94, 95% CI = 1.12, 3.35), perceiving a strong community bond (OR = 2.28, 95% CI = 1.25, 4.16), and household membership in a community group (OR = 1.64, 95% CI = 1.04, 2.60). This research demonstrates the high prevalence of animal ownership in a low-income and high-density peri-urban neighbourhood of an African city, which may facilitate zoonotic disease transmission. Further research should assess if and to what extent animal ownership in such communities is associated with disease risk.

[Molecular characterization of Cryptosporidium spp. isolated in humans in two different locations in Spain]

Molecular PCR based diagnostic techniques have enabled us to distinguish between the different, morphologically identical, Cryptosporidium species that can infect humans. Of the 23 recognized species in the genus, at least 9 are able to infect humans. As the intensity of the clinical manifestations, pathogenicity, excretion of oocysts, and incidence, are different between this species, molecular studies are crucial for a better understanding of the epidemiology of human cryptosporidiosis. Samples form two independent studies are analyzed in this publication. One included 23 samples from Madrid, and the other, 72 samples from La Coruña. All of them positive for Cryptosporidium spp. by microscopic methods and belonging to isolated cases of human cryptosporidiosis. For the identification of the species responsible for the infection, the 18S rDNA diagnostic region and the COWP gene diagnostic regions were used. Out of the 95 samples tested, in 77 cases we were able to extract and amplify DNA. In those cases the species responsible for the infection were: C. parvum (40 cases, 2 Madrid and 38 La Coruña), C. hominis (30 cases, 10 Madrid and 20 La Coruña) and C. meleagridis (2 cases, 1 Madrid and 1 La Coruña). In 5 samples it was impossible to detect the species responsible for the infection, but their positivity was confirmed by PCR (4 Madrid and 1 La Coruña). The genotypes of the isolates from patients correlated well with animals from the same regions.

Molecular detection of pathogens in water--the pros and cons of molecular techniques

Pollution of water by sewage and run-off from farms produces a serious public health problem in many countries. Viruses, along with bacteria and protozoa in the intestine or in urine are shed and transported through the sewer system. Even in highly industrialized countries, pathogens, including viruses, are prevalent throughout the environment. Molecular methods are used to monitor viral, bacterial, and protozoan pathogens, and to track pathogen- and source-specific markers in the environment. Molecular techniques, specifically polymerase chain reaction-based methods, provide sensitive, rapid, and quantitative analytical tools with which to study such pathogens, including new or emerging strains. These techniques are used to evaluate the microbiological quality of food and water, and to assess the efficiency of virus removal in drinking and wastewater treatment plants. The range of methods available for the application of molecular techniques has increased, and the costs involved have fallen. These developments have allowed the potential standardization and automation of certain techniques. In some cases they facilitate the identification, genotyping, enumeration, viability assessment, and source-tracking of human and animal contamination. Additionally, recent improvements in detection technologies have allowed the simultaneous detection of multiple targets in a single assay. However, the molecular techniques available today and those under development require further refinement in order to be standardized and applicable to a diversity of matrices. Water disinfection treatments may have an effect on the viability of pathogens and the numbers obtained by molecular techniques may overestimate the quantification of infectious microorganisms. The pros and cons of molecular techniques for the detection and quantification of pathogens in water are discussed.

Effectiveness of standard UV depuration at inactivating Cryptosporidium parvum recovered from spiked Pacific oysters (Crassostrea gigas)

When filter-feeding shellfish are consumed raw, because of their ability to concentrate and store waterborne pathogens, they are being increasingly associated with human gastroenteritis and have become recognized as important pathogen vectors. In the shellfish industry, UV depuration procedures are mandatory to reduce pathogen levels prior to human consumption. However, these guidelines are based around more susceptible fecal coliforms and Salmonella spp. and do not consider Cryptosporidium spp., which have significant resistance to environmental stresses. Thus, there is an urgent need to evaluate the efficiency of standard UV depuration against the survival of Cryptosporidium recovered from shellfish. Our study found that in industrial-scale shellfish depuration treatment tanks, standard UV treatment resulted in a 13-fold inactivation of recovered, viable C. parvum oocysts from spiked (1 x 10(6) oocysts liter (-1)) Pacific oysters. Depuration at half power also significantly reduced (P < 0.05; ninefold) the number of viable oocysts recovered from oysters. While UV treatment resulted in significant reductions of recovered viable oocysts, low numbers of viable oocysts were still recovered from oysters after depuration, making their consumption when raw a public health risk. Our study highlights the need for increased periodic monitoring programs for shellfish harvesting sites, improved depuration procedures, and revised microbial quality control parameters, including Cryptosporidium assessment, to minimize the risk of cryptosporidiosis.

Advances in the epidemiology, diagnosis and treatment of cryptosporidiosis

Cryptosporidiosis, the disease caused by protozoa of the genus Cryptosporidium, represents a major public health problem in both developing and developed countries. The infection can be severe and life threatening among immunocompromised individuals, particularly in AIDS patients and in those with primary immunodeficiency diseases. This review examines the essential aspects of the epidemiology of the infection, highlighting the role of animals, water and food. A critical evaluation of the diagnostic tools used in clinical settings is also provided. Lastly, the review examines the chemotherapeutic options available to treat the infection, and underlines the need to design and test new drugs. The review concludes with a five-year outlook on some aspects of interest for future research on this pathogen.

Cryptosporidium

This review discusses characteristics of the genus Cryptosporidium and addresses the pathogenesis, reservoirs, public health significance and current applications for the detection and typing of this important pathogen. By increasing knowledge in key areas of Cryptosporidium research such as aetiology, epidemiology, transmission and host interactions, the numbers of cases of human cryptosporidiosis should be reduced.

Tools for investigating the environmental transmission of Cryptosporidium and Giardia infections in humans

Cryptosporidiosis and giardiasis are major public health concerns. The role of water and food in the epidemiology of these diseases is now well recognized. Molecular techniques are available to determine the species and genotypes of Cryptosporidium and Giardia and to distinguish human from non-human pathogens. Validated methods to determine the species, genotype and subgenotype that are present in heterologous mixtures should be applied to environmental samples to enable the monitoring and characterization of infection sources, disease tracking and the establishment of causative links to both waterborne and foodborne outbreaks. Meaningful interpretation of population structures and occurrence-prevalence baselines can be performed only by analysing a well-planned set of samples from all possible sources taken regularly over time, rather than focusing on outbreak investigations. For food, this includes such analyses in the country of origin.