Effect of Domestic Freezing on the Viability of Toxoplasma gondii in Raw and Dry-Cured Ham from Experimentally Infected Pigs.

ABSTRACT: Toxoplasma gondii is the causative agent of the parasitic disease toxoplasmosis, which is an important foodborne zoonosis. Eating undercooked meat of infected animals has been considered the major transmission route of T. gondii to humans. The present study was conducted to evaluate the efficacy of domestic freezing for inactivation of T. gondii bradyzoites in ham. Raw and dry-cured ham from a pig experimentally inoculated orally with 4,000 oocysts of T. gondii VEG strain was subjected to domestic freezing at -20°C for up to 14 days. The effect was evaluated by bioassay in mice and a quantitative PCR assay. In raw and dry-cured ham, -20°C for 7 and 14 days, respectively, did not inactivate T. gondii. More studies are needed to find the correct temperature and time needed to render the bradyzoites noninfectious for humans. Meanwhile, the recommendations for freezing to inactivate T. gondii in raw or dry-cured meats must be revisited because domestic freezing conditions do not reduce the risk of infection.

Fipronil/(S)-methoprene spot-on to control fleas on cats in a field trial in Spain

The study was conducted in order to evaluate the effect of a fipronil/(S)-methoprene formulation against fleas on naturally infested cats. The study involved a population of 89 cats distributed among 24 veterinary practices in 9 regions of Spain. The product was applied according to label instructions on days 0, 30 and 60. Animals underwent parasitological and clinical assessments on day 0 and thereafter in monthly intervals (every 30 days) until day 90. Ctenocephalides felis was the most abundant species (98.9% of all fleas collected), and flea abundance on Day 0 was associated with the hair type, the location of the household, and the time elapsed from the last anti-flea treatment. Fipronil/(S)-methoprene demonstrated high efficacy and induced the reduction of clinical signs related to the presence of fleas. Clinical signs and flea abundance decreased significantly throughout time (P=0.001) with an efficacy rate of 72.6% at Day 30, 88.4% at Day 60 and 93.9% at Day 90. A high level of flea control and a remission of the clinical signs related to presence of fleas were observed on cats following 3 monthly applications a fipronil/(S)-methoprene formulation.(AU)

Toxoplasma gondii in commercially available pork meat and cured ham: a contribution to risk assessment for consumers.

Toxoplasmosis is an infection caused by Toxoplasma gondii, whose transmission has usually been attributed to ingestion of undercooked or raw meat. Dry-cured ham is a high-quality meat product of increasing economic relevance, and epidemiological studies point to cured meat products as a risk factor for acquiring toxoplasmosis. With the aim of contributing to the risk assessment process, 50 samples of fresh pork meat and commercial cured ham were collected in the city of Zaragoza (northeastern Spain), and the presence of viable forms of T. gondii was analyzed. A mouse concentration bioassay technique was used, and the presence of the parasite in mice was determined by indirect immunofluorescence assay. T. gondii was detected in two samples of rib, reflecting a frequency of 8% positive fresh pork meat (4% positivity of total samples analyzed). Brains of seropositive mice were analyzed by histology and PCR, although the parasite was not isolated in the seroconverted mice. No viable forms were detected either in other types of fresh meat or in the samples of cured ham.

Prevalence and sequence comparison of Phyllodistomum folium from zebra mussel and from freshwater fish in the Ebro River.

We utilised DNA analysis to detect the presence of the digenean Phyllodistomum folium in three cyprinid species, Scardinius erythrophthalmus, Cyprinus carpio and Rutilus rutilus. DNA sequencing of the region containing the genes ITS1-5.8S-ITS2 revealed 100% sequence identity between DNA from the sporocysts found in zebra mussels and DNA from adults located in the urinary system of 29 cyprinid fish. A second genetically different (variation=1.6%) sequence was observed in two samples from R. rutilus. In our opinion, the existence of a complex of species reported as P. folium is supported by recent genetic studies, including our own results. The overall prevalence of P. folium in mussels from the Ebro River was 4.67% in 2006, although during the summer months the rates frequently exceeded 10%.

Determination of the viability of Toxoplasma gondii in cured ham using bioassay: influence of technological processing and food safety implications.

Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii and distributed worldwide. Ingestion of viable cysts from infected raw or undercooked meat is an important route of horizontal transmission of the parasite to humans. Little information is available concerning the effect of commercial curing on cysts of T. gondii. This study is the first in which the influence of processing of cured ham on the viability of T. gondii has been evaluated, using bioassay to assess the risk of infection from eating this meat product. Naturally infected pigs were selected for the study, and a mouse concentration bioassay technique was used to demonstrate viable bradyzoites of T. gondii in porcine tissues and hams. No viable parasites were found in the final product (14 months of curing) based on results of the indirect immunofluorescence assay and histological and PCR analyses. Our results indicate that the consumption of hams cured as described here poses an insignificant risk of acquiring toxoplasmosis. However, additional studies are required to evaluate the safety of ham products cured under different conditions of curing time, salt, and nitrite concentration.

Phyllodistomum folium (Trematoda: Gorgoderidae) infecting zebra mussels (Dreissena polymorpha) in the Ebro River, Spain.

Zebra mussels (Dreissena polymorpha) were first found in the Ebro River (Spain) in Ribaroja reservoir, in the summer of 2001. This paper reports a study to detect parasites in this bivalve species. From September 2003 to August 2004, a total of 1380 zebra mussels were collected and dissected or sectioned in paraffin and haematoxylin and eosin staining. We observed the presence of Phyllodistomum folium (Olfers, 1816) in two hosts (prevalence 0.14%). Sporocysts containing metacercariae were located within the gill lamellae. One of the mussels was collected in January and the other one in July. In both cases the shell length was >2 cm. P. folium had not been previously reported in Spain and D. polymorpha is its only known intermediate host. It represents a new invasive species in this river basin, presumably introduced together with the zebra mussels.