Cryptosporidium parvum genotype IIa and Giardia duodenalis assemblage A in Mytilus galloprovincialis on sale at local food markets

Meta-analysis of the Cetacea gut microbiome: Diversity, co-evolution, and interaction with the anthropogenic pathobiome

Despite their critical roles in marine ecosystems, only few studies have addressed the gut microbiome (GM) of cetaceans in a comprehensive way. Being long-living apex predators with a carnivorous diet but evolved from herbivorous ancestors, cetaceans are an ideal model for studying GM-host evolutionary drivers of symbiosis and represent a valuable proxy of overall marine ecosystem health. Here, we investigated the GM of eight different cetacean species, including both Odontocetes (toothed whales) and Mysticetes (baleen whales), by means of 16S rRNA-targeted amplicon sequencing. We collected faecal samples from free-ranging cetaceans circulating within the Pelagos Sanctuary (North-western Mediterranean Sea) and we also included publicly available cetacean gut microbiome sequences. Overall, we show a clear GM trajectory related to host phylogeny and taxonomy (i.e., phylosymbiosis), with remarkable GM variations which may reflect adaptations to different diets between baleen and toothed whales. While most samples were found to be infected by protozoan parasites of potential anthropic origin, we report that this phenomenon did not lead to severe GM dysbiosis. This study underlines the importance of both host phylogeny and diet in shaping the GM of cetaceans, highlighting the role of neutral processes as well as environmental factors in the establishment of this GM-host symbiosis. Furthermore, the presence of potentially human-derived protozoan parasites in faeces of free-ranging cetaceans emphasizes the importance of these animals as bioindicators of anthropic impact on marine ecosystems.

Prevalence of Blastocystis sp. and other gastrointestinal pathogens among diarrheic COVID-19 patients in Italy

Background

Gastrointestinal pathogens (GPs) contribute significantly to the burden of illness worldwide with diarrhoea being the most common among gastrointestinal symptoms (GSs). In the COVID-19 disease, diarrhoea, could be one of the initial presenting symptoms. However, no data on the potential correlation between diarrhoea-causing pathogens and SARS-CoV-2 infection are available. Therefore, we carried out a 2-years retrospective study aimed to evaluate the prevalence of "classic" GPs among SARS-CoV-2 infected and non-infected patients with diarrhoea in Italy.

Methods

Results of SARS-CoV-2 research from nasopharyngeal and detection of GPs from stool swab samples by Allplex™ SARS-CoV-2 and GI Virus, Bacteria and Parasite Assay were analysed for all patients with diarrhoea referring to Policlinico Ospedaliero Universitario, Foggia, (Italy) from February 2022 to October 2023.

Results

Out of the 833 involved patients, 81 (3.9%) were COVID-19 positive, while 752 (90.3%) were COVID-19 negative. Among COVID-19-positive patients, 37% (n = 30/81) were found positive for one or more GPs with a higher prevalence of protozoan parasites (18.5%) (Blastocystis ST1-ST4 subtypes, Dientamoeba fragilis genotype I), followed by bacteria (7.4%) (Campylobacter sp., Salmonella sp.). Viral pathogens were more frequent among COVID-19 negative patients (Adenovirus, Norovirus). Among GPs, Blastocystis ST3 subtype was the most prevalent registered in the 16% of patients (p = 0.0001).

Conclusions

Based on obtained results, a likely interaction between the classic GPs and SARS-CoV-2 infection can be speculated, driven by protozoan parasites. Moreover, these results also provide baseline data to understand more deeply Blastocystis sp. role in this scenario of dysbiosis, particularly in those cases of SARS-CoV-2 co-infection.

A review on microbial contamination cases in Tunisian coastal marine areas

Microbial pollution in marine environments is one of the critical issues with regard to the sanitary status of recreational activities and seafood harvesting due to a potential contamination by pathogenic microorganisms. This review's objectives were to identify instances of bacterial, viral and protozoan parasite pollution in the Tunisian coastal region and to make recommendations for further research. Fecal indicators such as Escherichia coli and Salmonella spp. were detected in samples of clams and mussels. Vibrionaceae species were also recorded in seawater, sediment, fish and clams in different sites from north to south with the dominance of Vibrio alginolyticus. Bivalve mollusks collected from the Tunisian coast have been revealed to harbor viruses as well as protozoan parasites. Furthermore, the isolation of multidrug-resistant bacterial strains from Tunisian coastlines proves the significant spread and circulation of antibiotic resistance caused by the massive use of antibiotics. In conclusion, we suggest intensive monitoring and cutting-edge wastewater treatment technologies to enhance seawater quality and preserve the biodiversity of aquatic life. Rapid detection techniques for the most important pathogenic microorganisms in seafood and seawater must be also developed to reduce human health risk.

Occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis in the invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (SE Italy)

The occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis was molecularly investigated in the hemolymph, gills, stomach, hepatopancreas and gonads of the eleven invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (Mediterranean Sea). Out of 11 blue crabs, 6 (54.5%) and 4 (36.4%) were found positive to T. gondii and C. cayetanenis, respectively; parasites were found only in the six females analysed, while the remaining five males resulted negative. Moreover, out of 55 tissues samples, 7 (12.7%) and 8 (14.5%) were positive to T. gondii and C. cayetanensis, respectively with hemolymph and gills being the most infected tissues. This is the first report of the presence of protozoan pathogens in wild crab species collected from a Mediterranean lagoon. The present results may provide a baseline reference on microbial infection in the species for invaded Mediterranean waters, and on the potential health risks related with its consumption if eaten raw.

Evaluation of real-time qPCR-based methods to detect the DNA of the three protozoan parasites Cryptosporidium parvum, Giardia duodenalis and Toxoplasma gondii in the tissue and hemolymph of blue mussels (M. edulis)

The protozoan parasites Cryptosporidium spp., Giardia duodenalis and Toxoplasma gondii can be transmitted to humans through shellfish consumption. No standardized methods are available for their detection in these foods, and the performance of the applied methods are rarely described in occurrence studies. Through spiking experiments, we characterized different performance criteria (e.g. sensitivity, estimated limit of detection (eLD95_METH), parasite DNA recovery rates (DNA-RR)) of real-time qPCR based-methods for the detection of the three protozoa in mussel's tissues and hemolymph. Digestion of mussels tissues by trypsin instead of pepsin and the use of large buffer volumes was the most efficient for processing 50g-sample. Trypsin digestion followed by lipids removal and DNA extraction by thermal shocks and a BOOM-based technique performed poorly (e.g. eLD95_METH from 30 to >3000 parasites/g). But trypsin digestion and direct DNA extraction by bead-beating and FastPrep homogenizer achieved higher performance (e.g. eLD95_METH: 4-400 parasites/g, DNA-RR: 19-80%). Direct DNA recovery from concentrated hemolymph, by thermal shocks and cell lysis products removal was not efficient to sensitively detect the protozoa (e.g. eLD95_METH: 10-1000 parasites/ml, DNA-RR ≤ 24%). The bead-beating DNA extraction based method is a rapid and simple approach to sensitively detect the three protozoa in mussels using tissues, that can be standardized to different food matrices. However, quantification in mussels remains an issue.

Prevalence and distribution pattern of Cryptosporidium spp. among pre-weaned diarrheic calves in the Republic of Korea

Cryptosporidium spp. are protozoan parasites that belong to subphylum apicomplexa and cause diarrhea in humans and animals worldwide. Data on the prevalence of Cryptosporidium spp. and its subtypes among calves in the Republic of Korea (KOR) are sparse. Hence, our study aimed to investigate the prevalence and association between the age of calf and the identified Cryptosporidium spp. and to determine the genotypes/subtypes of Cryptosporidium spp. in pre-weaned calves with diarrhea in the KOR. A total of 460 diarrheic fecal samples were collected from calves aged 1−60 days and screened for Cryptosporidium spp. by the 18S rRNA gene. Species identification was determined using the sequencing analysis of the 18S rRNA gene, and C. parvum-positive samples were subtyped via the sequence analysis of the 60-kDa glycoprotein (gp60) gene. Sequence analysis based on the 18S rRNA gene revealed the presence of three Cryptosporidium spp., namely, C. parvum (n = 72), C. ryanae (n = 12), and C. bovis (n = 2). Co-infection by these species was not observed. The infection rate was the highest in calves aged 11−20 days (26.1%, 95% CI 17.1−35.1), whereas the lowest rate was observed in calves aged 21−30 days (7.7%, 95% CI 0.0−16.1). The prevalence of C. parvum was detected exclusively in calves aged ≤20 days, and the highest infection rate of C. ryanae was seen in calves ≥31 days of age. The occurrence of C. parvum (χ² = 25.300, P = 0.000) and C. ryanae (χ² = 18.020, P = 0.001) was significantly associated with the age of the calves. Eleven different subtypes of the IIa family that belonging to C. parvum were recognized via the sequence analyses of the gp60 gene. Except for two (IIaA18G3R1 and IIaA15G2R1) subtypes, nine subtypes were first identified in calves with diarrhea in the KOR. IIaA18G3R1 was the most frequently detected subtype (72.2% of calves), followed by IIaA17G3R1 (5.6%), IIaA15G2R1 (4.2%), IIaA19G4R1 (4.2%), IIaA16G4R1 (2.8%), IIaA17G4R1 (2.8%), IIaA19G3R (2.8%), IIaA14G1R1 (1.4%), IIaA14G3R1 (1.4%), IIaA15G1R1 (1.4%), and IIaA19G1R1 (1.4%) These results suggest that the prevalence of Cryptosporidium spp. is significantly associated with calf age. Furthermore, the findings demonstrate the high genetic diversity of C. parvum and the widespread occurrence of zoonotic C. parvum in pre-weaned calves. Hence, calves are a potential source of zoonotic transmission with considerable public health implications.

Zoonotic giardiasis: an update

Giardia duodenalis is a common intestinal parasite in various hosts, with the disease giardiasis being a zoonosis. The use of molecular typing tools has improved our understanding of the distribution and zoonotic potential of G. duodenalis genotypes in different animals. The present review summarizes recent data on the distribution of G. duodenalis genotypes in humans and animals in different areas. The dominance of G. duodenalis assemblages A and B in humans and common occurrence of host-adapted assemblages in most domesticated animals suggests that zoonotic giardiasis is probably less common than believed and could be attributed mainly to contact with or contamination from just a few species of animals such as nonhuman primates, equines, rabbits, guinea pigs, chinchillas, and beavers. Future studies should be directed to advanced genetic characterization of isolates from well-designed epidemiological investigations, especially comparative analyses of isolates from humans and animals living in the same household or community. This will likely lead to better understanding of zoonotic transmission of G. duodenalis in different environmental and socioeconomic settings.

Does the Consumer Sociodemographic Profile Influence the Perception of Aspects Related and Not Related to Food Safety? A Study in Traditional Spanish Street Markets

Street food markets are important for local economic development, but they must also meet visitors' demands while operating. Since consumers' trust is based on their perception on different aspects of these markets, the aim of this work was to study which factors most affected their purchase decision criteria. A total of 950 surveys were collected in 21 street markets (Canary Islands, Spain), recording data from the consumers' estimation on food safety-related items (i.e., hygiene conditions of market installations, products, and food handlers) as well as other categories (i.e., prices and staff professionalism). The gathered data let us determine whether sociodemographic consumers variables like age, gender, or education level influenced their perceptions. The scores showed a strong correlation, the subsequent principal components analysis explained 81% of variability only with the first two components. The level of tolerance toward all items underlies in the first component, which was significantly higher for those aged 60 and older, but no significant correlation was found for gender or level of education. The youngest participants were more demanding about food safety-related aspects, while the middle-aged group was more critical of prices. This was especially true of females, who demanded better quality:price ratios. Knowing these preferences could facilitate the development of more effective marketing strategies, helping make street markets more competitive.

Potential Risk of Three Zoonotic Protozoa (Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii) Transmission from Fish Consumption

In recent decades, worldwide fish consumption has increased notably worldwide. Despite the health benefits of fish consumption, it also can suppose a risk because of fishborne diseases, including parasitic infections. Global changes are leading to the emergence of parasites in new locations and to the appearance of new sources of transmission. That is the case of the zoonotic protozoa Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii; all of them reach aquatic environments and have been found in shellfish. Similarly, these protozoa can be present in other aquatic animals, such as fish. The present review gives an overview on these three zoonotic protozoa in order to understand their potential presence in fish and to comprehensively revise all the evidences of fish as a new potential source of Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii transmission. All of them have been found in both marine and freshwater fishes. Until now, it has not been possible to demonstrate that fish are natural hosts for these protozoa; otherwise, they would merely act as mechanical transporters. Nevertheless, even if fish only accumulate and transport these protozoa, they could be a "new" source of infection for people.

Molecular detection of genotypes and subtypes of Cryptosporidium infection in diarrheic calves, lambs, and goat kids from Turkey

The studies on Cryptosporidium infections of animals in Turkey mostly rely on microscopic observation. Few data are available regarding the prevalence of Cryptosporidium genotypes and subtypes infection. The aim of this study is to analyse the detection of Cryptosporidium genotypes and subtypes from young ruminants. A total of 415 diarrheic fecal specimens from young ruminants were examined for the Cryptosporidium detection by use of nested PCR of the small subunit ribosomal RNA (SSU rRNA) gene and the highly polymorphic 60 kDa glycoprotein (gp60) gene followed by sequence analyses. The results of this study revealed that 25.6% (106 of 415) of the specimens were positive for Cryptosporidium spp. infection. We identified 27.4% (91/333), 19.4% (13/67), and 13.4% (2/15) of positivity in calves, lambs and goat kids, respectively. Genotyping of the SSU rRNA indicated that almost all positive specimens were of C. parvum, except for one calf which was of C. bovis. Sequence analysis of the gp60 gene revealed the most common zoonotic subtypes (IIa and IId) of C. parvum. We detected 11 subtypes (IIaA11G2R1, IIaA11G3R1, IIaA12G3R1, IIaA13G2R1, IIaA13G4R1, IIaA14G1R1, IIaA14G3R1, IIaA15G2R1, IIdA16G1, IIdA18G1, IIdA22G1); three of them (IIaA12G3R1, IIaA11G3R1 and IIaA13G4R1) was novel subtypes found in calves and lambs. Additionally, three subtypes (IIaA11G2R1, IIaA14G3R1, and IIdA16G1) were detected in young ruminants for the first time in Turkey. These results indicate the high infection of Cryptosporidium in Turkey and propose that young ruminants are likely a major reservoir of C. parvum and a potential source of zoonotic transmission.

Investigations from Northern Greece on mussels cultivated in areas proximal to wastewaters discharges, as a potential source for human infection with Giardia and Cryptosporidium

Marine bivalves are usually cultivated in shallow, estuarine waters where there is a high concentration of nutrients. Many micro-pollutants, including the protozoan parasites Giardia duodenalis and Cryptosporidium spp., which also occur in such environments, may be concentrated in shellfish tissues during their feeding process. Shellfish can thus be considered as vehicles for foodborne infections, as they are usually consumed lightly cooked or raw. Therefore, the main objective of this study was to investigate the presence of both parasites in Mediterranean mussels, Mytilus galloprovincialis that are cultivated in Thermaikos Gulf, North Greece, which is fed by four rivers that are contaminated with both protozoa. Moreover, the occurrence of these protozoa was monitored in treated wastewaters from 3 treatment plants that discharge into the gulf. In order to identify potential sources of contamination and to estimate the risk for human infection, an attempt was made to genotype Giardia and Cryptosporidium in positive samples. Immunofluorescence was used for detection and molecular techniques were used for both detection and genotyping of the parasites. In total, 120 mussel samples, coming from 10 farms, were examined for the presence of both protozoa over the 6-month farming period. None of them were found positive by immunofluorescence microscopy for the presence of parasites. Only in 3 mussel samples, PCR targeting the GP60 gene detected Cryptosporidium spp. DNA, but sequencing was not successful. Thirteen out of 18 monthly samples collected from the 3 wastewater treatment plants, revealed the presence of Giardia duodenalis cysts belonging to sub-assemblage AII, at relatively low counts (up to 11.2 cysts/L). Cryptosporidium oocysts (up to 0.9 oocysts/L) were also detected in 4 out of 8 samples, although sequencing was not successful at any of the target genes. At the studied location and under the sampling conditions described, mussels tested were not found to be harboring Giardia cysts and the presence of Cryptosporidium was found only in few cases (by PCR detection only). Our results suggest that the likelihood that mussels from these locations act as vehicles of human infection for Giardia and Cryptosporidium seems low.

First report of detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão

Abstract The aim of this study was to report on detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão. To conduct this study, 200 farmed oysters were acquired in the municipality of Raposa and 100 in Paço do Lumiar; and a further 100 oysters were taken from the natural stock in the municipality of Primeira Cruz. This total of 400 specimens sampled was divided into 80 pools composed of five animals each. The gills and visceral mass of each oyster were removed for DNA extraction (per pool of oysters), using a commercial kit. The nested PCR technique (with the primer SAG-1) was then used to investigate any presence of protozoa. This molecular technique demonstrated the presence of DNA of T. gondii in 2.5% of the pools of oysters (n = 2/80): these oysters were exclusively from farms. The results from this study allow the conclusion that oysters of the genus Crassostrea that are farmed in the state of Maranhão are capable of filtering oocysts of T. gondii and maintaining them in their tissues. They are therefore potential sources of contamination for humans and other animals.

Efficiency of the Q3 lab-on-chip Real Time-PCR platform for detecting protozoan pathogens in bivalve mollusks

The zoonotic protozoan parasites Toxoplasma gondii, Cryptosporidium parvum and Giardia duodenalis have been recorded worldwide in economically important edible shellfish, and are thus likely to represent a significant public health risk. Therefore, an innovative, user-friendly diagnostic tool is required in order to improve food safety control. The Q3 system is a miniaturized platform whose efficiency and applicability were investigated and compared with results obtained using standard Real-Time PCR. Tanks of saltwater containing acclimated Mytilus galloprovincialis, Ruditapes philippinarum and Ostrea edulis specimens were spiked with purified Cryptosporidium, Giardia and Toxoplasma cysts/oocysts at different concentrations (i.e., 10³, 10⁴ and 10⁵). We then collected 30 specimens for each shellfish species from each group at 24 h and 72 h post-contamination. After DNA extraction, we tested all samples by Real-Time-PCR and Q3, and evaluated the sensitivity, specificity, predictive values, repeatability and concordance between the two systems. Concordance between Real-Time-PCR and Q3 was very good (p < 0.01), especially for Toxoplasma in M. galloprovincialis at both 24 h and 72 h after contamination, and in O. edulis at 72 h. The ability of Q3 to detect all the investigated pathogens was similar to that of Real-Time-PCR, and Q3 was efficient in detecting Toxoplasma in both M. galloprovincialis and O. edulis. This is the first study concerning the use of lab-on-chip technology in a food matrix, and in edible marine mollusks in particular.

Comparison of Cryptosporidium oocyst recovery methods for their applicability for monitoring of consumer-ready fresh shellfish

Growing demand for fresh, unprocessed food favours the emergence of Cryptosporidium infections in humans. Mainly it is food of plant origin or unpasteurized milk which have been involved in food-borne outbreaks of cryptosporidiosis. So far consumption of shellfish contaminated with Cryptosporidium were not associated with human infections although such as possibility exists. In this study an attempt was undertaken to evaluate the analytical performance of three commonly used methods for recovery of Cryptosporidium oocysts from shellfish: i) pepsin digestion of shellfish in conjunction with immunomagnetic separation (IMS) of oocysts (method A), ii) pepsin-HCl treatment of shellfish homogenate without IMS (method B), and iii) a strainer method with direct oocyst extraction and separation from shellfish tissue using IMS (method C). Each method's performance was assessed according to the ISO standard requirements by testing shellfish homogenates seeded with different numbers of C. parvum oocysts. Two groups of parameters were compared, encompassing precision (coefficient of variation (CV)) and accuracy of measurements. These were described by linear regression models allowing calculation of the methods' limits of detection (LOD) and quantification (LOQ). In addition, oocyst recovery efficiencies from shellfish were calculated for each method. All three compared methods allowed for at least 66% recovery of Cryptosporidium oocysts from the tested samples. The best recovery (83.3-100%) in the whole range of tested suspensions was obtained for method C. The accuracy of method B was better (linearity of r² = 0.9996 in the full measurement range) than that of method A (r² = 0.968). Method C showed the best accuracy (r² = 1) and precision (CV 0.2-14.1). Compared to other methods it was also characterised by the best LOD and LOQ, attaining ≅4 and ≅12 oocysts per 3 g of tested shellfish sample respectively. Despite a lack of the ability of method A to give the proportional results in oocysts recovery (non-linearity of the method) compared to the reference values, it achieved the highest LOD and LOQ values among the tested methods. As demonstrated here, the most efficient method for extraction of Cryptosporidium oocysts from shellfish tissues was method C employing sample homogenisation and separation of oocysts from tissue debris using IMS. Used alone this method does not in fact allow for identification of Cryptosporidium species but delivers quantitative results concerning the level of food contamination by parasites.

Protocol standardization for the detection of Giardia cysts and Cryptosporidium oocysts in Mediterranean mussels (Mytilus galloprovincialis)

Marine bivalve shellfish are of public health interest because they can accumulate pollutants in their tissues. As they are usually consumed raw or lightly cooked, they are considered to be a possible source of foodborne infections, including giardiosis and cryptosporidiosis. Although data indicating contamination of shellfish with Giardia cysts and Cryptosporidium oocysts have been published, comparing results from different studies is difficult, as there is no standardized protocol for the detection and quantification of these parasites in mussels, and different researchers have used different analytical approaches. The aim of this study was to identify and characterize the most sensitive protocol for the detection of Giardia cysts and Cryptosporidium oocysts in shellfish. In an effort to test the sensitivity and the detection limits of the protocol, every step of the process was investigated, from initial preparation of the mussel matrix through detection of the parasites. Comparative studies were conducted, including several methods previously applied by other researchers, on commercial mussels Mytilus galloprovincialis spiked with a known number of (oo)cysts of both parasites. As preparation of the mussel matrix plays an important role in the sensitivity of the method, different techniques were tested. These included: (ia) removal of the coarse particles from the matrix with sieving, (ib) extraction of the lipids with diethyl ether, and (ic) artificial digestion of the matrix with pepsin digestion solution, and (ii) the use or not of immunomagnetic separation (IMS) for the concentration of the (oo)cysts. Pre-treatment of the mussel homogenate with pepsin digestion solution, followed by IMS, then detection with a direct immunofluorescence assay, achieved the highest sensitivity: 32.1% (SD: 21.1) of Giardia cysts and 61.4% (SD: 26.2) Cryptosporidium oocysts were recovered, with a detection limit of 10 (oo)cysts per g of mussel homogenate. The outcome of the current study was the standardization of a protocol, with defined detection limits, for the detection of these two protozoan transmission stages in mussels, in order to be used as a reference technique in future studies. Further advantages of this protocol are that it uses the whole mussel as a starting material and does not require difficult handling procedures. The method has potential to be applied in larger surveys and, potentially, to other species of shellfish for the detection of these parasites. However, the composition (lipid to protein ratio) may be of relevance for detection efficiency for some other species of shellfish.

Toxoplasma gondii and Other Zoonotic Protozoans in Mediterranean Mussel ( Mytilus galloprovincialis) and Blue Mussel ( Mytilus edulis): A Food Safety Concern?

Mediterranean mussels ( Mytilus galloprovincialis) and blue mussels ( Mytilus edulis) are among the most consumed fishery products, but they are frequent vehicles of foodborne infection worldwide. In this study, we investigated the occurrence and seasonality of zoonotic protozoans in mussels farmed or sold at retail outlets in Italy. We collected and tested 1,440 M. galloprovincialis and 180 M. edulis. Pooled samples were molecularly tested for Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii and then sequenced. Sixty-two (45.9%; 95% confidence interval, 37.5 to 54.3%) mussel pools tested positive for one or more of the investigated pathogens. Both Mytilus species and samples from all the investigated areas harbored pathogens. Mussels were statistically more contaminated by Cryptosporidium spp., followed by T. gondii and G. duodenalis assemblage A, and M. galloprovincialis was more contaminated than M. edulis ( P < 0.01). Contamination was more likely in mussels at retail outlets ( P < 0.05) than in those from farms and in mussels collected in spring ( P < 0.01) than in other seasons. This is the first report of T. gondii found in M. galloprovincialis in Italy and in M. edulis in Europe. The detection of zoonotic protozoans in a widely consumed food source indicates the need for a more detailed microbiological risk analysis, especially considering that bivalve mollusks are often consumed raw worldwide.

Comparison of freeze-thaw cycles for nucleic acid extraction and molecular detection of Cryptosporidium parvum and Toxoplasma gondii oocysts in environmental matrices

Freeze-thaw DNA extraction methods and PCR primers were compared to optimize detection of Cryptosporidium parvum and Toxoplasma gondii oocysts in different matrices. Increasing FT cycles did not increase parasite DNA detection, and primers targeting the 18S ssrRNA gene yielded the most sensitive detection of C. parvum oocysts.

Giardia: an under-reported foodborne parasite

Foodborne zoonotic pathogens are a serious public health issue and result in significant global economic losses. Despite their importance to public health, epidemiological data on foodborne diseases including giardiasis caused by the enteric parasite, Giardia duodenalis, are lacking. This parasite is estimated to cause ∼28.2 million cases of diarrhoea each year due to contamination of food, but very few foodborne outbreaks have been documented due to the limitations of current detection as well as surveillance methods. The current method for the recovery of Giardia cysts from food matrices using immunomagnetic separation requires further standardisation and cost reduction before it can be widely used. It also should incorporate downstream molecular procedures for genotyping, and traceback and viability analyses. Foodborne giardiasis can be potentially controlled through improvements in national disease surveillance systems and the establishment of Hazard Analysis and Critical Control Point interventions across the food chain. Studies are needed to assess the true prevalence and public health impact of foodborne giardiasis.

Giardia duodenalis in the UK: current knowledge of risk factors and public health implications

Giardia duodenalis is a ubiquitous flagellated protozoan parasite known to cause giardiasis throughout the world. Potential transmission vehicles for this zoonotic parasite are both water and food sources. As such consumption of water contaminated by feces, or food sources washed in contaminated water containing parasite cysts, may result in outbreaks. This creates local public health risks which can potentially cause widespread infection and long-term post-infection sequelae. This paper provides an up-to-date overview of G. duodenalis assemblages, sub-assemblages, hosts and locations identified. It also summarizes knowledge of potential infection/transmission routes covering water, food, person-to-person infection and zoonotic transmission from livestock and companion animals. Public health implications focused within the UK, based on epidemiological data, are discussed and recommendations for essential Giardia developments are highlighted.

First report of Tunisian coastal water contamination by protozoan parasites using mollusk bivalves as biological indicators

In order to establish seawater contamination by emerging protozoan parasites, we used qPCR to molecularly characterize and evaluate the parasitic burden of Giardia duodenalis, Cryptosporidium spp., Toxoplasma gondii, and Cyclospora cayetanensis in 1255 wild bivalve mollusks collected along the Tunisian coasts. T. gondii, G. duodenalis and C. cayetanensis were detected in 6.9% (99% CI=1.6-12.2%) pools of Ruditapes decussatus. None of the samples were found positive to Cryptosporidium spp.; 6.6% pools of R. decussatus were positive for T. gondii Type I, 1.6% for G. duodenalis assemblage A, and 1.6% for the association T. gondii Type I/C. cayetanensis/G. duodenalis assemblage A. R. decussatus harbored up to 77500 oocysts/sample of T. gondii, up to 395 cysts/sample of G. duodenalis, and 526 oocysts/sample of C. cayetanensis. These results provide the first evidence that the Tunisian coasts are contaminated by zoonotic protozoan parasites that can constitute a direct or indirect risk for human health.

Mussels (Perna perna) as bioindicator of environmental contamination by Cryptosporidium species with zoonotic potential

Sources of contamination such as animal feces runoff, organic fertilizer application, and the release of partially treated or untreated sewage can lead to the contamination of aquatic environments by Cryptosporidium spp. The quality of mussels as food is closely related to the sanitary conditions of the marine environment where these bivalves are found. Marine mollusks are filter feeders that are able to retain Cryptosporidium oocysts in their tissue, thus functioning as bioindicators. A total of 72 pooled mussel samples of the species Perna perna were collected at two sites (A and B) in the municipality of Mangaratiba, Rio de Janeiro State, Brazil. Sampling involved removal of 30 mussels, from each collection site every month for one year. The 30 mussels from each sampling were then allocated into three groups of 10. Two Cryptosporidium spp. genes (18S and GP60) were targeted for DNA amplification from the samples obtained. After purification, all of the products obtained were sequenced and phylogenetic analyses were performed. Of the 72 samples analyzed using the nested-PCR for the 18S gene target, 29.2% were positive for the presence of Cryptosporidium spp. Of these samples, 52.4% were collected at site A (ie 11/21) and 47.6% at site B (ie 10/21). The 18S genes of all the samples considered positive for Cryptosporidium spp. were sequenced, and the following three species were identified: Cryptosporidium parvum, C. meleagridis, and C. andersoni. Three distinct C. parvum subtypes (IIaA19G2R2; IIaA20G2R2; IIaA20G3R2) were identified using the GP60 gene. More studies to evaluate the zoonotic potential of this species should be performed as both sampling locations contain human and/or animal fecal contaminants.

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Different species of Cryptosporidium diagnosed in Perna perna mussels.

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C. parvum subtypes of IIa zoonotic subfamily diagnosed in P. perna mussels.

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First report of the zoonotic species C. meleagridis in Brazilian mollusk bivalves.

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Mollusks bivalves used as bioindicator of environmental pollution.

Advances in understanding Giardia: determinants and mechanisms of chronic sequelae

Giardia lamblia is a flagellated protozoan that is the most common cause of intestinal parasitic infection in children living in resource-limited settings. The pathogenicity of Giardia has been debated since the parasite was first identified, and clinical outcomes vary across studies. Among recent perplexing findings are diametrically opposed associations between Giardia and acute versus persistent diarrhea and a poorly understood potential for long-term sequelae, including impaired child growth and cognitive development. The mechanisms driving these protean clinical outcomes remain elusive, but recent advances suggest that variability in Giardia strains, host nutritional status, the composition of microbiota, co-infecting enteropathogens, host genetically determined mucosal immune responses, and immune modulation by Giardia are all relevant factors influencing disease manifestations after Giardia infection.