Comparative performance of three TSE rapid tests for surveillance in healthy sheep affected by scrapie.

Rapid tests specific for sheep and goats became part of European Union-wide active scrapie surveillance in 2006. Performance of three approved TSE rapid tests for the detection of sheep infected with scrapie in field cases in the pre-clinical stage of the disease was compared. The medulla oblongata of 969 asymptomatic sheep of various genotype and breed aged over 18 months from 23 Italian flocks affected with scrapie, were tested by the Bio-Rad TeSeE Sheep/Goat (A), the IDEXX HerdChek BSE-Scrapie Antigen Test Kit, EIA (B) and the Prionics(®)-Check Western Small Ruminant (C) rapid tests. Of 136 positive samples of classical scrapie, as confirmed by Western blot assay, 132 were positive with test A (Se 97.06%, CI 95% 92.64-99.19); 135 with test B (Se 99.26%, 95% CI 95.97-99.98) and 128 with test C (Se 94.12%, 95% CI 88.74-97.43). Tests A and B showed the best performance on analytical sensitivity. All three systems demonstrated good reproducibility: being the intrarater and interrater kappa coefficients always over 0.83. The one available atypical scrapie sample was positive with tests A and B, negative with test C. Considering the discrepant results in the detection of low PrP(sc) concentrations and of the atypical case, differences can be expected in the efficacy of an active surveillance system, depending on the test adopted.

Gastroenteritis outbreak at holiday resort, central Italy.

During the summer of 2003, a gastroenteritis outbreak spread throughout a holiday resort in central Italy. Fecally contaminated groundwater and seawater were leaking into the non-drinking-water system, which was found to be connected to the drinking-water system of a large resort. This contamination had a primary role in the onset of the outbreak and spread of the infection.

An outbreak of gastroenteritis in a holiday resort in Italy: epidemiological survey, implementation and application of preventive measures.

A major gastroenteritis outbreak was reported in a vacation resort in Central Italy in 2003. A total of 183 cases were identified. The case-control study identified a statistically significant correlation between the disease and sea bathing, use of sanitary facilities in bungalows and of common showers. Stool samples taken from people affected were found positive for Norovirus (68%, 13 of 19 samples), Rotavirus (38%, 1 of 14 samples) and Campylobacter (7%, 3 of 8 samples). Environmental investigations revealed serious faecal contamination of the groundwater and the presence of Norovirus in the seawater near the resort. The mixing of groundwater and seawater with the non-drinking water system - which was also found to be connected to the drinking water system - had a primary role in the onset and spread of infection within the village. The complete absence of any gastroenteritis epidemics among the site guests since 2006 demonstrates the effectiveness of the environmental corrective measures taken.

Effectiveness of an RT-booster-PCR method for detection of noroviruses in stools collected after an outbreak of gastroenteritis.

Noroviruses exhibit a wide genomic and antigenic diversity, making laboratory diagnosis difficult. The abrupt onset of the illness does often not allow timely sample collection. Three different methods (a commercially available ELISA, a published RT-PCR and an RT-booster-PCR) were compared for detecting noroviruses in stools collected after the end of a gastroenteritis outbreak. Both ELISA and the RT-PCR detected noroviruses in 6 samples out of the 41 samples collected and tested. The RT-booster-PCR, however, was able to detect noroviruses in 23 (56%) of the samples with 20 of the samples confirmed by sequencing. Confirmation of PCR products was also undertaken by Southern hybridisation with controversial results (e.g. lack of confirmation on samples positive by sequencing). The results show that common molecular diagnostic methods may fail sometimes to detect the presence of noroviruses in a relevant proportion of samples. A sensitive detection method, such as the RT-booster-PCR described below may resolve the cases.

Detection of multiple noroviruses associated with an international gastroenteritis outbreak linked to oyster consumption.

An international outbreak linked to oyster consumption involving a group of over 200 people in Italy and 127 total subjects in 13 smaller clusters in France was analyzed using epidemiological and clinical data and shellfish samples. Environmental information from the oyster-producing area, located in a lagoon in southern France, was collected to investigate the possible events leading to the contamination. Virologic analyses were conducted by reverse transcription-PCR (RT-PCR) using the same primer sets for both clinical and environmental samples. After sequencing, the data were analyzed through the database operated by the scientific network FoodBorne Viruses in Europe. The existence of an international collaboration between laboratories was critical to rapidly connect the data and to fully interpret the results, since it was not obvious that one food could be the link because of the diversity of the several norovirus strains involved in the different cases. It was also demonstrated that heavy rain was responsible for the accidental contamination of seafood, leading to a concentration of up to hundreds of genomic copies per oyster as detected by real-time RT-PCR.