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Toxocara canis is a zoonotic nematode parasite that can be transmitted to humans by food or water contaminated with T. canis eggs from infected dog feces. High-pressure processing (HPP) is a useful alternative to thermal treatments to eliminate pathogens from foods. Most of the research on HPP has focused on prokaryotes, but little is known about its effects on eukaryotic organisms. We evaluated the ability of HPP to affect embryonation of T. canis eggs to test the hypothesis that HPP treatment can delay development of T. canis eggs. Efficacy of HPP was determined by using an embryonation assay on T. canis eggs from naturally infected puppies. For each treatment, 2500 T. canis eggs in tap water were placed in sealable plastic bags and subjected to 138-400 megapascals (MPa; 1 MPa=10 atm=147 psi) for 60 s in a commercial HPP unit. We found that treatment with 300 or 400 MPa for 60 s killed 100% of eggs using embryonation as the standard. Treatment with 250, 241, and 207 MPa was less effective and killed 80%, 56%, and 8% of eggs, respectively. Results from this study suggest that HPP may be a useful treatment to protect foods from T. canis contamination.

We have previously demonstrated that high pressure processing (HPP) is effective in preventing in vitro replication of murine norovirus strain 1 (MNV-1), a human norovirus surrogate, in a monocyte cell line following extraction from MNV-1-contaminated oysters. In the present study, the efficacy of HPP to prevent in vivo replication within mice fed HPP-treated MNV-1-seeded oyster extracts was evaluated. Oyster homogenate extracts seeded with MNV-1 were given 5-min, 400-MPa (58,016-psi) treatments and orally gavaged into immunodeficient (STAT-1(-/-)) female mice. Mice orally gavaged with HPP-treated MNV-1 showed significant (P ≤ 0.05) weight loss leading to enhanced morbidity, whereas those given 100 and 200 PFU of HPP-treated MNV-1 were comparable to uninfected controls. MNV-1 was detected, via real-time PCR, within the liver, spleen, and brain of all mice fed non-HPP-treated homogenate but was not detected in the tissues of mice fed HPP-treated homogenates or in uninfected control mice. Hepatocellular necrosis and lymphoid depletion in the spleen were observed in non-HPP-treated MNV-1 mice only. These results clearly show that HPP prevents MNV-1 infection in vivo and validates that viral inactivation by HPP in vitro is essentially equivalent to that in vivo. Further, the data suggest that HPP may be an effective food processing intervention for norovirus-contaminated shellfish and thus may decrease risk to both immunocompromised and immunocompetent individuals who consume shellfish., (Copyright ©, International Association for Food Protection)

Four strains of Enterobacter sakazakii were inoculated into tryptic soy broth and reconstituted powdered infant formula and exposed to high-pressure processing. Pressures of 200, 400, and 600 MPa were used for each medium for 1 min. E. sakazakii was reduced by more than 6 log (strains A and B) in both media at 600 MPa. Strain B was significantly (P < or = 0.05) more pressure resistant than the other strains, with just more than a 3-log reduction at 600 MPa in both media. The reconstituted infant formula has a significant (P < or = 0.05) protective effect for certain strains and pressures (strain B at 400 MPa and strain D at 400 and 600 MPa). Differences in log reductions between media (milk and broth) were also observed for certain strains and specific pressures (strain B at 400 MPa and strain D at 400 and 600 MPa; P < or = 0.05). This research showed that E. sakazakii, when present in reconstituted powdered infant formula, can be submitted to high-pressure processing (600 MPa for 1 min) and achieve log reductions ranging from 3 to 6.84, depending on the strain.

Ingestion of Toxoplasma gondii tissue cysts can result in severe disease in immunocompromised individuals and pregnant women. Treatment of meat and meat products to eliminate viable T. gondii tissue cysts would provide a means to protect consumers. In this study, we examined the effects of high-pressure processing (HPP) on ground pork containing viable tissue cysts of the VEG strain of T. gondii. Ground pork containing tissue cysts was exposed to 400, 300, 200, 100, or 0 MPa treatment for 30, 60, or 90 sec in a commercial HPP unit. The HPP-treated ground pork was subjected to acid-pepsin digestion and bioassayed in mice. The results of the mouse bioassay revealed that none of the mice inoculated with tissue cysts exposed to 400 or 300 MPa became infected, whereas all mice inoculated with tissue cysts exposed to 200, 100, or 0 MPa became infected with T. gondii regardless of exposure time. Results indicate that HPP treatment of ground pork with 300 MPa of pressure will render tissue cysts of T. gondii nonviable and make pork safe for human consumption.

There has been significant concern in recent times about the safety of molluscan shellfish for human consumption. Despite extensive efforts to assure a safe supply of molluscan shellfish, the number of cases of disease and death are still great enough to cause concern among the public. The number of cases of illness and death associated with the ingestion of shellfish falls in the lower end of the range of other similar microbial pathogen-related foodborne disease. Disease and deaths due to viruses and naturally occurring bacteria are now of greatest concern because they are the most often cited causative agents. The greatest risk of disease or death due to shellfish consumption is among the population with underlying health conditions who choose to consume raw shellfish. Control strategies to limit shellfish-borne disease should focus upon disease and death caused by viruses and naturally occurring bacteria among at-risk populations.