Food and Waterborne Parasitology最新文献

Prenatal systematic screening for congenital toxoplasmosis has been performed in Austria and France since 1975 and neonatal screening for congenital toxoplasmosis has been part of the New England Newborn screening program since 1986.

In this narrative review we review the data leading up to the systematic screening programs in Austria and France, highlighting the main finding of the European Union funded research in the 1990s and early 2000s. Different descriptive studies of the effect of pre- or postnatal treatment are discussed. Toxoplasma gondii has different genetic lineages with different pathogenicity in humans. This means that results in areas with a low pathogenic lineage cannot be extrapolated to an area with highly pathogenic lineages. The importance of meat as a source of infection is discussed in the light of an increased prevalence of T.gondii in organic livestock production .

The pathophysiological mechanisms of Cryptosporidium infection are multifactorial and not completely understood. Some advances achieved recently revealed that the infection by Cryptosporidium parvum induces cytoskeleton remodeling and actin reorganization through the implication of several intracellular signals involving, for example, PI3K, Src, Cdc42 and GTPases. It has also been reported that the infection by C. parvum leads to the activation of NF-κβ, known to induce anti-apoptotic mechanisms and to transmit oncogenic signals to epithelial cells. Despite the growing evidence about the hijacking of cellular pathways, potentially being involved in cancer onset, this information has rarely been linked to the tumorigenic potential of the parasite. However, several evidences support an association between Cryptosporidium infection and the development of digestive neoplasia. To explore the dynamics of Cryptosporidium infection, an animal model of cryptosporidiosis using corticoid dexamethasone-treated adult SCID (severe combined immunodeficiency) mice, orally infected with C. parvum or Cryptosporidium muris oocysts was implemented. C. parvum-infected animals developed digestive adenocarcinoma. When mechanisms involved in this neoplastic process were explored, the pivotal role of the Wnt pathway together with the alteration of the cytoskeleton was confirmed. Recently, a microarray assay allowed the detection of cancer-promoting genes and pathways highly up regulated in the group of C. parvum infected animals when compared to non-infected controls. Moreover, different human cases/control studies reported significant higher prevalence of Cryptosporidium infection among patients with recently diagnosed colon cancer before any treatment when compared to the control group (patients without colon neoplasia but with persistent digestive symptoms). These results suggest that Cryptosporidium is a potential oncogenic agent involved in cancer development beyond the usual suspects. If Cryptosporidium is able to hijack signal transduction, then is very likely that this contributes to transformation of its host cell. More research in the field is required in order to identify mechanisms and molecular factors involved in this process and to develop effective treatment interventions.

Cryptosporidium spp. are obligate, intracellular parasites that cause life-threatening diarrhea among children and immunocompromised adults. Transmission occurs by the fecal-oral route following ingestion of thick-walled oocysts that can contaminate, persist, and resist disinfection in water and food. Sodium hypochlorite, peroxides, ozone, formaldehyde, and ammonia are suitable disinfectants against Cryptosporidium oocysts. Effective concentrations of these chemicals can be toxic and not practical for downstream research use of non-viable oocysts. Oocyst inactivation approaches such as UV light, heat, and treatments with ethanol or methanol are generally more accessible for routine lab use, yet their applicability in Cryptosporidium assay development is limited. The aims of this study were to evaluate methods of inactivation of Cryptosporidium oocysts that can be readily applied in the laboratory and test the utility of whole inactive oocysts in quantitative PCR (qPCR). Experiments were performed on C. parvum oocysts subjected to heat (75 °C/10 min) or treated with increasing concentrations of ethanol and methanol over time. Viability assays based on propidium iodide (PI) staining, in vitro excystation, and infection of the Hct-8 cell line were used to evaluate the efficacies of the treatments. Excystation of sporozoites was not impaired with 24 h exposures of oocysts to 50% ethanol or methanol, even though significant PI incorporation was observed. Concentrations of ≥70% of these chemicals were required to completely inhibit excystation and infection of Hct-8 cells in vitro. Inactivated oocysts stored for up to 30 days at 4 °C retained cyst wall integrity and antigenicity as observed by light microscopy and immunofluorescence. Moreover, non-viable oocysts applied directly in qPCR assays of the COWP gene were useful reference reagents for the identification and quantification of Cryptosporidium in spiked water samples. In summary, we have established a practical approach to inactivate C. parvum oocysts in the laboratory that is suitable for the development of detection or diagnostic assays targeting the parasite.

The International Trichinella Reference Centre (ITRC) is the official laboratory of the International Commission on Trichinellosis, of the World Organization for Animal Health and of the European Union Reference Laboratory for Parasites. The ITRC was established in 1988 as a repository of Trichinella strains and a source of reference materials and information for international scientific research. To date, more than 8000 Trichinella isolates collected throughout the world have been identified at the species or genotype level by the ITRC staff and the information has been stored in a freely accessible database providing the largest collection of data available for scientists involved in the systematics and epidemiology of this parasite. This paper presents a summary of the data collected over 33 years of activity and describes the database functionalities. It finally advocates the potential of the database to improve knowledge of the epidemiology and taxonomy of Trichinella, which in turn may help the international surveillance of Trichinella species.

The main reservoir hosts of nematodes of the genus Trichinella are wild carnivores, although most human infections are caused by the consumption of pork. This group of zoonotic parasites completes the entire natural life cycle within the host organism. However, there is an important phase of the cycle that has only been highlighted in recent years and which concerns the permanence of the infecting larvae in the striated muscles of the host carcasses waiting to be ingested by a new host. To survive in this unique biological niche, Trichinella spp. larvae have developed an anaerobic metabolism for their survival in rotting carcasses and, for some species, a resistance to freezing for months or years in cold regions. Climate changes with increasingly temperatures and reduction of environmental humidity lower the survival time of larvae in host carcasses. In addition, environmental changes affect the biology and ecology of the main host species, reducing their number and age composition due to natural habitat fragmentation caused by increasing human settlements, extensive monocultures, increasing number of food animals, and reduction of trophic chains and biodiversity. All of these factors lead to a reduction in biological and environmental complexity that is the key to the natural host-parasite balance. In conclusion, Trichinella nematodes can be considered as an indicator of a health natural ecosystem.

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.

Detection of Toxoplasma gondii in chicken products indicates risk of transmission to consumers. The objective of the current study was to investigate the molecular prevalence of T. gondii in free-ranging and industrial chickens in Guilan province, Northern Iran. A total of 150 chicken heart samples including 75 free-range and 75 industrial chickens were collected from farmers' markets and chicken retailers in Guilan, Northern Iran, between October 2017 and August 2018. Genomic DNA were extracted from samples and examined for evidence of T. gondii using polymerase chain reaction (PCR) targeting the B1 gene. The B1-positive samples were further analyzed by nested-PCR for SAG1 gene. Of the 150 samples, T. gondii DNA fragments were detected in 59 (39.3%), including 30 (40%) free-range and 29 (38.7%) industrial chicken. No significant differences of T. gondii DNA detection was observed between the free-range and industrial chicken samples (p = 0.73). Four selected positive samples were used for amplifying and sequencing of the SAG1 gene. The results revealed that all four sequences of SAG1 had 100% similarity with T. gondii sequences previously isolated from an AIDS/HIV patient in Mazandaran province, Northern Iran. Furthermore, the phylogenetic analysis demonstrated that all four sequences were closely related to Type I of T. gondii. However, our Type I identification is preliminary and needs to be confirmed by further multilocus sequence typing (MLST) analysis. The findings of the present study provide new data about the presence of T. gondii DNA in chicken hearts in the study area. These results confirm that chicken can be used as sentinels for environment contamination; however, further studies are needed to determine the viability of T. gondii in chicken hearts from Iran for risk assessment.

The ciliate Balantioides coli is a human enteric parasite that can cause life-threatening infections. It is a food- and waterborne parasite, with cysts being the infective stage. Despite its importance as a potential pathogen, few reports have investigated its presence in environmental samples, and some issues need attention including i) The accuracy of B. coli identification. In most cases, the protozoa is identified only by its morphological traits, which can be identical to those from other parasitic ciliates of animals. Genetic analysis of cysts recovered from environmental samples is necessary for species confirmation. In addition, genetic methods used with faecal samples need to be adequately validated with environmental matrices. ii) The methodology for searching this parasite in environmental samples. The protocols include an initial phase to isolate the cysts from the matrix followed by a second phase in which concentration procedures are usually applied. The methods may be valid but are not standardised and differences between studies could affect the results obtained. iii) The areas that needs further research. The development of genetic identification methods and standardised analytical protocols in environmental samples are required, as well as the assessment of viability and infectivity of B. coli cysts. The development of axenic culture systems will boost research on this parasite.

Trichinella spiralis larvae have very special characters that make them able to completely transform the function of the affected muscle cells towards a self-serving environment, offering them nourishment and protection via what is known as “nurse cells”. This setting may be affected by drugs that are used for the treatment of co-morbidities and co-infections as calcium channel blockers, which are widely used in clinical practice. In the present study, the effects of verapamil, ivermectin (IVM), and their combined administration on the parasitic burden, immuno-pathology and angiogenesis were investigated during experimental trichinellosis. Estimation of intestinal adult parasitic stages and muscle larvae was done. VEGF gene expression and CD31 immunohistochemical local expression were measured to investigate angiogenesis, in addition to histopathological examination to explore the extent of inflammation. Although verapamil did not have an effect on the adult worm count during the intestinal phase, it induced an anti-inflammatory effect on intestinal pathology. During the muscle phase, it was very effective in reducing the larval count by 93.78%. IVM effectively reduced the worm count by 85.34%, and the muscle larval count by 97.84%, while combined verapamil and IVM administration resulted in a significant reduction in both adult parasites by 69.5% and larval stages by 99%. Both verapamil and IVM and their combination induced a potent decrease in local CD31 protein expression and VEGF gene expression. The important role of calcium and calcium channels during the pathology of trichinellosis, in addition to the pivotal role of calcium on biological processes such as immunity and angiogenesis, make calcium-channel blockers promising candidates for drug repurposing in the management of helminthic infection.