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Category Archives: Toxoplasma gondii
Norway – Research – Risk ranking and source attribution of food- and waterborne pathogens for surveillance purposes – Toxoplasma the top risk!
Providing risk managers with the information that they need for decision making is an important element in food-safety management. The present risk assessment was undertaken to establish a scientific basis that could be used to assist the Norwegian Food Safety Authority (NFSA) in implementing risk-based surveillance, monitoring, and control programmes for pathogens in food and water. The assessment approach used here consisted of two steps:(1) risk ranking of 20 selected pathogens based on the incidence and severity of their associated diseases following infection with the pathogens via food or water, and(2) a source attribution process aimed at identifying the main pathogen-food combinations that may pose a risk to human health for each of the ranked pathogens. We used an expert knowledge elicitation (EKE) procedure with a panel of nine experts, including all eight members of the Panel on Biological Hazards of the Norwegian Scientific Committee for Food and Environment (NSCFE) and one invited expert on food/water-borne viral infections.
The 20 pathogens selected for risk ranking were defined in the terms of reference (ToR) received from NFSA. We performed a multicriteria-based ranking of the pathogens in terms of their public health impact from food/water-borne transmission in Norway. The risk ranking utilized six criteria that estimated the incidence of food- and waterborne illness attributable to each pathogen, the severity of acute and chronic illness, the fraction of chronic illness, fatality rate, and the probability for future increased disease burden. For each pathogen, all criteria were scored by the expert panel members, and individual criterion scores were combined into an overall score for every pathogen. To achieve this, each criterion was weighted in terms of its relative importance, as judged by the expert panel. The overall scores so calculated were the basis for the ranking.
For each of the ranked pathogens, the subsequent source-attribution process aimed to identify the main food vehicles, reservoirs, and sources of infection for outbreak-related and sporadic cases of illness, the relative importance of food sources, and preventable risk factors in Norway. To achieve this, both microbiological and epidemiological data were scrutinized. These encompassed results from national surveillance and monitoring programmes, prevalence surveys, outbreak investigations, and research, including analytic epidemiological studies. When Norwegian data were sparse or absent, international reports and research were used.
The six highest-ranked pathogens were, in descending order: Toxoplasma gondii, Campylobacter spp., Echinococcus multilocularis, enterohaemorrhagic E. coli (EHEC), Listeria monocytogenes, and non-typhoid Salmonella. It should be emphasized, however, that confidence intervals revealed considerable overlaps between the scores. The food vehicles associated with the pathogens varied widely. It is notable, however, that fresh produce was identified as being among the main food vehicles for 12 of the 20 pathogens, drinking water was associated with 8, and 5 were linked to raw milk or products thereof
Research- Prevalence of Toxoplasma gondii, Hepatitis E Virus and Salmonella antibodies in meat juice samples from pigs at slaughter in Switzerland
Toxoplasma gondii , hepatitis E virus (HEV) and Salmonella are zoonotic foodborne pathogens that may be transmitted to humans through the consumption of raw or undercooked pork. The aim of this study was to determine the seroprevalence of anti- Toxoplasma gondii , anti-HEV and anti- Salmonella antibodies from healthy pigs at slaughter in Switzerland. In the period of August to September 2020 diaphragm muscle of Swiss fattening pigs was collected in three Swiss abattoirs from a total of 188 farms. Two randomly chosen pig carcasses per farm were selected. On the basis of the slaughter data, the production system and the canton of origin were noted, comparing indoor (n=120) and free-range farming (n=68), and regional allocation. The meat juice of these samples was analyzed for pathogen-specific antibodies using commercial enzyme-linked immunosorbent assay (ELISA) kits. The seroprevalences were 1.3% for T. gondii , 71.8% for the HEV and 5.3% for Salmonella , respectively. Comparing the origins, the results of many cantons weren’t meaningful due to the low number of samples. No regional accumulations were found for T. gondii and the HEV. The results showed that 2.1% of the farms had least one T. gondii seropositive animal, 80.3% had at least one HEV seropositive animal, and 8.5% had at least one Salmonella seropositive animal, respectively. The seropositivity of T. gondi i was higher in free-range pigs than in indoor pigs, whereas anti- Salmonella antibodies were more common in pigs from indoor farming than in outdoor pigs. The seroprevalence of anti HEV-Abs was similar in free-range and indoor farming pigs. Compared to studies from 2012 the seroprevalence of T. gondii has decreased whereas the seroprevalence of the HEV has increased and is highly prevalent among fattening pigs in Switzerland. The low seroprevalence of Salmonella has remained stable in recent years.
FW20017: Food Safety During Pregnancy
Most foods and drinks are safe to consume during pregnancy. But there are some products pregnant women should be careful with or avoid. Public Health and Food Safety authorities in most OECD countries provide risk communication material related to food safety during pregnancy. Such a resource is available on the New Zealand Food Safety (NZFS) website.
However, this advice was published in 2007 and was based on information available then. Since that time a range of new foods has been introduced and become popular in the diet of New Zealanders, while there is improved understanding over which foods might be a risk.
NZFS wants to ensure the food safety advice for pregnancy remains current with the latest science and dietary practices for New Zealand.It is important that food safety advice for pregnant women captures all of the foods that could be a risk, however it needs to balance this with ensuring pregnant women can maintain a varied diet and have access to the widest source of nutrition without being overly restrictive.
To achieve this a research project was commissioned to the Institute of Environmental Science and Research Limited (ESR) to provide a scientifically robust background for updating food safety advice for pregnant women. Food safety considerations are focused on Listeria monocytogenes, Toxoplasma gondii, mercury and caffeine, as these four hazards have known specific impacts on the foetus.
Other microbiological and chemical hazards were not targeted as the risks are not pregnancy specific and food safety advice for the general public is also applicable for pregnant women. This report is restricted to food safety issues and does not cover advice on healthy nutrition during pregnancy.Maternal exposure to the microbiological hazards Listeria monocytogenes and Toxoplasma gondii is strongly linked to adverse effects on the foetus. For two other microbiological hazards, Salmonella spp. and Campylobacter spp., associated with adverse outcomes specific to the pregnancy period, the supporting epidemiological evidence is weaker.
The report has examined up-to-date information on these two other hazards and provided safety advice where relevant.The research examined data on complex changes in the maternal immune system that include both down regulation and up regulation of aspects of the immune system. Evidently pregnant women may be more susceptible to some infections than non-pregnant women, but no more susceptible to most types of infections. However, the complications of common infections in pregnant women can be more severe.
The main outcome of the research is an evaluation of evidence for food safety advice during pregnancy. The report included an evaluation of all food groups listed in the current New Zealand Food Safety’s guide to food safety in pregnancy. Consideration was also given to a small number of foods that were not previously evaluated in relation to pregnancy. Additional advice was proposed for these foods. NZFS agrees with the suggestion that advice should
New Zealand Food Safety Food Safety During Pregnancy be included in the guide for sprouts, recommending that these foods are not eaten unless cooked; for dried herbs recommending thorough cooking and a recommendation to not drink unpasteurised fruit juice and cider (non-alcoholic). The report confirmed that in most cases, New Zealand Food Safety’s advice on foods to eat or not eat during pregnancy are consistent with the available scientific evidence.
In a small number of instances, suggestions were made to better align the advice with the current available evidence. NZFS agrees with these suggestions and intends to expand the advice accordingly. Based on the evidence provided NZFS agrees that the current advice related to low acid soft pasteurised cheeses (e.g. Brie, Camembert, blue, ricotta, mozzarella, feta) should be strengthened to recommend that pregnant women do not eat these cheeses unless cooked.The report supports NZFS’s intention to make its advice on a range of commercial pasteurised dairy products with relatively short shelf-life less restrictive. Currently the advice is to dispose products like pasteurised milk or yoghurt after two days of opening.
The reviewed scientific evidence identified that, if that the products are refrigerated in original packaging and care is taken not to contaminate lids when using, it is safe to follow manufacturer’s advice on the package. Suggested modifications will allow pregnant women better planning of their daily diets and will also reduce unnecessary food wastage.
The report has suggested the current advice related to soft serve ice cream be reconsidered. However, NZFS’s opinion is that, given the likelihood of Listeria sloughing into the product through its processing, current advice to avoid this product during pregnancy is adequate. For some foods the scientific evidence is not currently strong enough to support specific food safety advice on these foods, although the available evidence suggests they may represent potentially emerging risk foods for pregnant women. A brief summary of such foods is provided at the end of the report. NZFS will follow up on any new scientific research related to these products.
Research – 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. View Full-Text
Research – Updated food safety guidance gives pregnant women more certainty and choice on a wider range of foods
New research from New Zealand Food Safety provides pregnant women with more options and certainty about what they can safely eat with updated tips to avoid foodborne illness.
“We’ve looked at new foods that were not previously considered because we want pregnant women to have the most up-to-date food safety information so they can enjoy a diverse diet and stay healthy,” says Dr Claire McDonald, Manager Operational Research at New Zealand Food Safety.
“The guidance reflects the increased diversity in the New Zealand diet. The update not only provides more options, but also ensures all risky foods are captured and provides simple ways to reduce the chance of illness from food,” she said.
“It’s important pregnant women know what’s safe to they can avoid dangerous infections, such as listeriosis and toxoplasmosis, which can affect them more severely than non-pregnant women.”
Dr McDonald said the key information for women include:
- thoroughly cooking seed sprouts (such as alfalfa or mung bean) before eating.
- thoroughly cooking dried herbs before eating.
- avoiding unpasteurised fruit juices and non-alcoholic cider.
- avoiding low-acid, soft, pasteurised cheeses like Brie, Camembert, blue cheeses, ricotta, mozzarella, and feta unless they’re cooked.
- updating guidance on some pasteurised dairy products (i.e. following manufacturer’s labelling advice and “best before” dates, etc.).
- freshly cooked fish, mussels, oysters, crayfish, scallops, etc., should be cooked thoroughly until piping hot and eaten while hot.
- whole melons should be washed and dried before cutting.
- frozen berries should be cooked thoroughly before eating.
- no restrictions on number of servings per week for gemfish, oreo dories, orange roughy, ling and smooth oreo fish species (previous advice limited the number of servings per week to minimise mercury intake).
“We know more about food safety now than we did just a few a years ago and it’s important people educate themselves and take simple steps such as washing produce and cooking certain foods properly,” Dr McDonald said.
Novel foods such as edible insects and food products based on insects could play an important role in both human and animal nutrition in the future. The identification of dangers associated with insect consumption is fundamental to guarantee consumer safety and adequate regulatory guidelines for operators of the food sector. While former studies have focused on the microbiological contamination of fresh or processed edible insects, so far little information is available about the occurrence of foodborne parasites such as Toxoplasma gondii, whose life cycle makes it a candidate for potential insects’ breeding substrate contamination. Hence, we investigated the presence of contaminating T. gondii in farmed edible insects to rule out this further hazard for consumers. Four species of insects most commonly used as food for human consumption were analyzed: Mealworm, African migratory locust, House cricket and Silkworms. Samples included live specimens but also minimally (dehydrated) and highly processed edible insects. Traces of T. gondii DNA were detected in samples of dehydrated mealworm. These results highlight the need for implementing good farming and processing practices with particular care paid to safe storage and handling of feed and substrates used for edible insects to reduce the chance of T. gondii entering the human food chain.
Toxoplasma gondii is a globally important zoonotic parasite ranked as one of the most significant causes of disease burden among the major foodborne pathogens. Consumption of undercooked meat is a well-known risk factor for infection so the aim of this study was to investigate the presence of T. gondii in meat samples from retail outlets in Scotland. In Sampling Period 1, 300 meat samples (39 beef, 21 chicken, 87 lamb, 71 pork and 82 venison) were purchased from butchers’, farmers’ markets, farm shops and supermarkets, and in Sampling Period 2, 67 pure venison samples only were purchased from farmers’ markets, farm shops and supermarkets. DNA was extracted and screened for T. gondii using a quantitative PCR targeting the 529 bp repeat element, and any positive samples were genotyped using PCR-RFLP targeting 10 markers. Meat juice was screened for T. gondii antibodies using a commercial ELISA or modified agglutination assay. Toxoplasma gondii DNA was detected in 0/39 (0%) beef samples, 1/21 (4.8%) chicken samples, 6/87 (6.9%) lamb samples, 3/71 (4.2%) pork samples and 29/82 (35.4%; Sampling Period 1) and 19/67 (28.4%; Sampling Period 2) venison samples. Partial PCR-RFLP genotyping revealed both clonal and non-clonal genotypes. Antibodies to T. gondii were detected in the meat juice of 2/38 (5.3%) beef samples, 3/21 (14.3%) chicken samples, 14/85 (16.5%) lamb samples, 2/68 (2.9%) pork samples and 11/78 (14.1%; Sampling Period 1) and 8/50 (16%; Sampling Period 2) venison samples. This is the first study to report the presence of T. gondii in retail meat products in Scotland and has highlighted venison as a potentially high risk meat. Further work is required to determine viability of parasites in this particular meat product.
Research -Effect of Silver Nanoparticles on the Morphology of Toxoplasma gondii and Salmonella braenderup
The study of silver nanoparticles (AgNPs) has recently increased due to the different antimicrobial properties that have been evaluated. Studies have shown that AgNPs decrease the cell viability of some parasitic species and inhibit bacterial growth and biofilm formation. Toxoplasma gondii is a parasite with different stages of development including the oocyst, and it can survive in the environment for a long time generating contamination of vegetables and water. This parasite has the ability to generate congenital toxoplasmosis and chorioretinitis in humans. Another human pathogen present in water is Salmonella braenderup, this bacterium, when consumed, causes gastroenteritis and typhoid fever. We evaluate the affectation that causes the AgNPs in oocysts of T. gondii and S. braenderup using fluorescence microscopy and scanning electron microscopy techniques. The results showed that at different ratios of AgNPs and microorganisms, as well as at different exposure time during the treatments, morphological alteration of the cell structure of oocysts of T. gondii and S. braenderup was evidenced, suggesting a potential treatment method for the inhibition of the viability of these microorganisms.
Australian researchers have revealed for the first time that males infected with the Toxoplasma parasite can impact their offspring’s brain health and behaviour.
Studying mice infected with the common parasite Toxoplasma, the team discovered that sperm of infected fathers carried an altered ‘epigenetic’ signature which impacted the brains of resulting offspring. Molecules in the sperm called ‘small RNA’ appeared to influence the offspring’s brain development and behaviour.
‘Intergenerational inheritance’ of similar epigenetic changes from men exposed to extreme trauma has been well documented. This latest research, published in Cell Reports, has raised the question of whether Toxoplasma infections — or even possibly other infections — in men before conception could impact the health of subsequent generations.
The research was led by Walter and Eliza Hall Institute researchers Dr Shiraz Tyebji and Associate Professor Chris Tonkin, in collaboration with Professor Anthony Hannan at the Florey Institute of Neuroscience and Mental Health
Think about traffic flow in a city – there are stop signs, one-way streets, and traffic lights to organise movement across a widespread network. Now, imagine what would happen if you removed some of the traffic signals.
Among your brain’s 86 billion neurons are the brain’s own version of stop signals: inhibitory neurons that emit chemicals to help regulate the flow of ions travelling down one cell’s axon to the next neuron. Just as a city without traffic signals would experience a spike in vehicle accidents, when the brain’s inhibitory signals are weakened, activity can become unchecked, leading to a variety of disorders.
In a new study published in GLIA on March 11, Virginia Tech neuroscientists at the Fralin Biomedical Research Institute at VTC describe how the common Toxoplasma gondii parasite prompts the loss of inhibitory signalling in the brain by altering the behaviour of nearby cells called microglia.