A diagnostic protocol to identify water buffaloes (Bubalus bubalis) vaccinated with Brucella abortus strain RB51 vaccine.

The use of live vaccine strain RB51 for vaccination of domestic water buffaloes (Bubalus bubalis) at risk of infection with Brucella abortus is permitted notwithstanding the plans for the eradication and only under strict veterinary control. The antibodies induced by RB51 vaccination are not detectable using conventional diagnostic techniques; therefore, it is necessary to have a specific diagnostic tool able to discriminate vaccinated from unvaccinated animals. The combination of a complement fixation test (CFT) with specific RB51 antigen (RB51-CFT) and a brucellin skin test has been demonstrated to be a reliable diagnostic system to identify single cattle (Bos taurus) vaccinated with RB51. So far, no data are available in the international scientific literature regarding the use of this test association in water buffalo. For this reason the suitability of this test combination has been evaluated in a water buffalo herd. One hundred twenty-seven animals farmed in a herd of Salerno province (Campania, Southern Italy), in the context of a presumptive unauthorized use of RB51 vaccine were chosen for this study. All tested animals resulted negative to Rose Bengal test (RBT) and complement fixation test (CFT) used for the detection of specific antibodies against Brucella field strains. Seventy-one animals (56%) developed RB51 antigen-specific CFT (RB51-CFT) antibodies against RB51 vaccine in a first sampling, while 104 animals (82%) gave positive result to a second serum sampling conducted 11 days after the intradermal inoculation of the RB51 brucellin. One hundred and seven animals (84%) showed a positive reaction to the RB51-CFT in at least 1 sampling, while 111 animals (87%) resulted positive to the RB51 brucellin skin test. Thus, analysing the results of the 3 testing in parallel, 119 animals (94%) were positive to at least 1 of the performed tests. The results suggest that the use in parallel of the RB51 brucellin skin test with RB51-CFT may represent a reliable diagnostic system to identify water buffaloes vaccinated with RB51 vaccine.

Risk factors for the persistence of bovine brucellosis in Sicily from 2008 to 2010.

Bovine brucellosis is a worldwide zoonotic disease, responsible for economic and reproductive losses in farmed animals. Despite the application of control and eradication measures, after several years the brucellosis situation still remains problematic in Sicily, one of the regions with the highest prevalence of infection in Italy. The objective of this paper is to evaluate the possible risk factors influencing the presence of bovine brucellosis in Sicily. Data on existing cattle herds in Sicily and on their structure in 2008, 2009 and 2010 were extracted from the national database (NDb) of holdings and animals. Several possible brucellosis risk factors were considered, in particular herd-related factors and the performances of the control activities carried out by the veterinary services and recorded into national animal health information system (SANAN). Statistical analysis (χ(2) and Mann-Whitney tests) and spatial cluster analysis using a simple spatial Bernoulli model were performed. The multivariable logistic regression was also performed using SPSS for Windows. The spatial distribution of infected herds shows two main clusters of infection, in Messina and in Siracusa provinces. The results of the statistical analysis performed show that the infection is associated to the largest herds (P<0.0001) and to beef and mixed herds (P<0.0001). A significant association can be observed between the infected status in 2010 and presence of positive animals in 2008 or in 2009 (P<0.0001). This article shows the importance of detailed and reliable epidemiological data through information systems, allowing a continuous monitoring of the health status of animal populations and also the evaluation and re-planning of veterinary activities.