From 1997 to 2001, Italy has been affected by two epidemics of high-pathogenicity avian influenza. The first epidemic was caused by a virus of the H5N2 subtype and was limited to eight premises in backyard and semi-intensive flocks. The prompt identification of the disease was followed by the implementation of European Union (EU) directive 92/40/EEC and resulted in the eradication of infection without serious consequences to the poultry industry. The 1999-00 epidemic was caused by a virus of the H7N1 subtype that originated from the mutation of a low pathogenic virus and resulted instead in a devastating epidemic that affected industrially reared poultry, culminating in the infection of 413 flocks. The description of the epidemics and the result of the control policies are reported.
This paper illustrates and discusses the key issues of the geographical information system (GIS) developed by the Unit of Veterinary Epidemiology of the Veneto region (CREV), defined according to user needs, spatial data (availability, accessibility and applicability), development, technical aspects, inter-institutional relationships, constraints and policies. GeoCREV, the support system for decision-making, was designed to integrate geographic information and veterinary laboratory data with the main aim to develop a sub-national, spatial data infrastructure (SDI) for the veterinary services of the Veneto region in north-eastern Italy. Its implementation required (i) collection of data and information; (ii) building a geodatabase; and (iii) development of a WebGIS application. Tools for the management, collection, validation and dissemination of the results (public access and limited access) were developed. The modular concept facilitates the updating and development of the system according to user needs and data availability. The GIS management practices that were followed to develop the system are outlined, followed by a detailed discussion of the key elements of the GIS implementation process (data model, technical aspects, inter-institutional relationship, user dimension and institutional framework). Problems encountered in organising the non-spatial data and the future work directions are also described.
The present paper reports on the development, validation and field application of a control strategy for avian influenza infections in poultry. The "DIVA" (Differentiating Infected from Vaccinated Animals) strategy is based on the use of an inactivated oil emulsion vaccine containing the same haemagglutinin (H) subtype as the challenge virus, but a different neuraminidase (N). The possibility of using the heterologous N subtype, to differentiate between vaccinated and naturally infected birds, was investigated through the development of an "ad hoc" serological test based on the detection of specific anti-N antibodies. This test is based on an indirect fluorescent antibody assay, using as an antigen a baculovirus expressing recombinant N proteins. The vaccination strategy has been tested in the laboratory and shown to be efficacious both against challenge with highly pathogenic AI viruses and with low pathogenicity AI viruses, ensuring clinical protection, reduction of duration and titre of shedding. In addition, vaccination resulted in an increased resistance to infection. The companion diagnostic tests directed to the detection of anti-N1 and anti-N3 antibodies have been validated in the laboratory and using field samples. The serological assay showed an "almost perfect agreement" (Kappa value) with the HI test, with relative sensitivity and specificity values of 98.1 and 95.7, respectively. The results of the present investigation suggest that the "DIVA" control strategy may represent a tool to support the eradication of avian influenza infections in poultry.
Background The serological diagnosis of avian influenza (AI) can be performed using different methods, yet the haemagglutination inhibition (HI) test is considered the 'gold standard' for AI antibody subtyping. Although alternative diagnostic assays have been developed, in most cases, their accuracy has been evaluated in comparison with HI test results, whose performance for poultry has not been properly evaluated. Objective The objective of this study was to estimate the diagnostic sensitivity (Se) and specificity (Sp) of the HI test and six other diagnostic assays for the detection of AI antibodies without assuming a gold standard. Methods We applied a Bayesian version of latent class analysis to compare the results of multiple tests from different study settings reported in the literature. Results The results showed that the HI test has nearly perfect accuracy (i.e. 98·8% sensitivity and 99·5% specificity). It performed well in both chickens and turkeys and yet was less accurate in experimentally infected poultry, compared to naturally infected. Blocking ELISA and the indirect immunofluorescence assay also performed very well. Conclusions Given its very high Se and Sp, the HI test may be effectively considered a gold standard. In the framework of LPAI surveillance, where large numbers of samples have to be processed, the blocking ELISA could be a valid alternative to the HI test, in that it is almost as sensitive and specific as the HI test yet quicker and easier to automate.
Summary Cattle arriving for slaughter at abattoirs in the Veneto region of N. Italy were examined for intestinal carriage of Escherichia coli O157. Rectal swabs were cultured in modified buffered peptone water and E. coli O157 was concentrated by an immunomagnetic separation technique; the magnetic beads were cultured onto cefixime tellurite sorbitol MacConkey agar. Sorbitol non‐fermenting E. coli O157 was isolated from 15 (3.6%) of 419 feedlot cattle but not from 437 veal calves or 65 culled cows. All strains of E. coli O157 hybridized with DNA probes specific for the VT 1 or VT 2 genes, but two strains did not produce toxin detectable by Vero cell assay. Six different plasmid profiles were observed with all strains harbouring the large 93 kb plasmid characteristic of VTEC. Six strains produced urease but otherwise strains were biochemically typical of E. coli O157. One strain was resistant to streptomycin, tetracycline and sulphonamides but the remainder were sensitive to all antimicrobials tested. This is the first description of the isolation of verocytotoxin‐producing E. coli O157 from cattle in Italy. As the contamination of bovine carcasses with E. coli O157 during slaughter and processing has been demonstrated, the risk of transmission of this organism from beef cattle to the human population in the Veneto region, through foods of bovine origin or by other routes, should not be overlooked.
SUMMARY In recent years the control of low pathogenicity avian influenza (LPAI) viruses of the H5 and H7 subtypes has increasingly become a concern. We evaluated the measures (stamping out, controlled marketing, emergency and preventive vaccination, farm density reduction and restocking in homogenous areas) implemented to control the LPAI epidemics that occurred in Italy between 2000 and 2005, using a combination of spatial and space–time analyses and estimates of the basic reproduction ratio ( R 0 ). Clustering of infected farms decreased over the years, indicating the effectiveness of the control strategies implemented. Controlled marketing [relative risk (RR) 0·46, 95% confidence interval (CI) 0·27–0·80], emergency (RR 0·47, 95% CI 0·39–0·57) and preventive vaccination (RR 0·19, 95% CI 0·09–0·41) were the most effective measures, yet R 0 <1 was only for preventive vaccination. Our results are useful for identifying the most effective measures for reducing the risk of the spread of LPAI and optimizing the allocation of resources.
Between 15 August and 7 December 2020, 561highly pathogenic avian influenza (HPAI) virus detections were reported in 15EU/EEA countries and UK in wild birds, poultry andcaptive birds, with Germany (n=370), Denmark (n=65), the Netherlands (n=57) being the most affected countries.The majority of the detections have been reported in wild birds(n=510), primarily in barnacle goose, greylag goose, andEurasian wigeon. Raptors have also been detected infected, particularly common buzzard. The majority of the birds had been found dead or moribund,however, there are also reports ofHPAI virus infection in apparently healthy ducks or geese.A total of 43 HPAI outbreaks were notified in poultry;with signs of avian influenza infection being observed in at least 33 outbreaks;the most likely source of infection was indirect contact with wild birds. Three HPAI virus subtypes, A(H5N8) (n=518), A(H5N5) (n=17) and A(H5N1) (n=6),and four different genotypes were identified, suggesting the occurrence of multiple virus introductions into Europe.The reassortant A(H5N1) virus identified in EU/EEA countries has acquired gene segments from low pathogenic viruses and is not related to A(H5N1) viruses of e.g. clade 2.3.2.1c causing human infections outside of Europe. As the autumn migration of wild waterbirds to their wintering areasin Europe continues, and given the expected local movements of these birds, there is still a high risk of introduction andfurther spread ofHPAI A(H5) viruses within Europe.The risk of virus spread from wild birds to poultry is high and Member States should enforce in 'high risk areas' of their territories the measures provided for in Commission Implementing Decision (EU) 2018/1136.Detection of outbreaks in breeder farms in Denmark, the Netherlands and United Kingdom, highlight also the risk of introduction via contaminated materials (bedding/straw) and equipment.Maintaining high and sustainable surveillance and biosecurityparticularly in high-risk areas is of utmost importance. Two human cases due to zoonoticA(H5N1) and A(H9N2) avian influenza virus infection were reportedduring the reporting period. The risk for the general population as well as travel-related imported human cases are assessed as very low.
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