Avaliação de testes sorológicos de triagem para diagnóstico da brucelose bubalina / Evaluation of screening serological tests for brucellosis diagnosis in buffaloes

The study compared the performance of three screening serological tests: buffered plate antigen (BPA), Rose-Bengal produced with 1119-3 Brucella abortus strain (RB1119-3), and Rose-Bengal produced with 99 Brucella abortus strain (RB99). Sera from 696 adult female animals were submitted to BPA, RB1119-3, RB99, 2-mercaptoethanol test (ME), and complement fixation test (FC). The gold standard was the combination of CF and ME. The Kappa values for BPA, RB99, and RB1119-3 were 0.82, 0.74, and 0.70, respectively. The relative sensitivity and specificity for the same tests were 0.98 and 0.96, 0.92 and 0.94, and 0.95 and 0.92, respectively. These results indicate that BPA is a better screening test than RB for buffalo, regardless of the B. abortus strain in RB.

Evaluation of the Leishmania recombinant K39 antigen as a diagnostic marker for canine leishmaniasis and validation of a standardized enzyme-linked immunosorbent assay.

Canine infections with Leishmania infantum are important as a cause of serious disease in the dog and as a reservoir for human visceral leishmaniasis (VL). Accurate diagnosis of canine infections is essential to the veterinary community and for VL surveillance programs. A standardized ELISA using a purified recombinant antigen (rK39) specific to VL was compared to the immunofluorescent antibody test (IFAT) as the standard. The ELISA was developed, optimized and evaluated using sera from 6368 dogs. The standardized ELISA and IFAT results were highly concordant. The timing and pattern of ELISA and IFAT seroconversion in dogs followed prospectively after natural infections were very similar. Antibodies reacting with rK39 were more common in asymptomatic canine infections than reported for subclinical human VL. The rK39 ELISA is a relatively simple and rapid assay for assessing the infection status of dogs, and is an alternative to IFAT, especially when screening large numbers of samples.

Reliability of results of the Rose Bengal test performed for export control in northern Somalia.

Sera from sheep and goats in northern Somalia which are exported to countries of the Persian Gulf are systematically checked for brucellosis by local veterinary teams. The standard test used is rapid seroagglutination using the Rose Bengal test (RBT) and seropositive animals are not exported. In order to assess the reliability of the serological results, three randomised batches of samples (653 sera), corresponding to an equivalent number of shipments (October and December 1994 and March 1995) were counterchecked. Control RBTs were carried out by expatriate veterinarians working on behalf of international non-governmental organisations and by the Istituto Zooprofilattico Sperimentale of Padua, Italy, which also performed the complement fixation test (CFT). A fourth batch (n = 100), including a group of sera found positive by the local veterinary teams, was also checked. Agreement ranged from 96.3% to 98.5%.

Serological survey for antibodies against selected infectious agents among fallow deer (Dama dama) in central Italy.

Sera were collected from 224 fallow deer (Dama dama) in reserves in central Italy. Samples were tested for antibodies against Chlamydia spp., Brucella spp. and Coxiella spp. with the complement fixation (CF) test. Indirect immunofluorescence was used to test for antibodies against Borrelia spp. and agglutination tests were conducted for Leptospira interrogans antibodies. Enzyme-linked immunosorbent assay (ELISA) tests were used to detect antibodies against bovine herpesvirus-1 (BHV-1) and bovine viral diarrhoea virus (BVDV). All samples were negative for antibodies against Brucella spp., L. interrogans, Coxiella spp. and BHV-1. Four samples (1.8%) had antibodies against Chlamydia spp., nine (4%) against Borrelia spp. and 10 (4.5%) against BVDV. These results indicate that fallow deer in central Italy have a low rate of exposure to pathogens typical of domestic livestock.

Leptospira interrogans serovar icterohaemorrhagiae seropositivity and the reproductive performance of sows.

The reproductive performance of 28 sows seropositive to Leptospira interrogans serovar icterohaemorrhagiae was compared with that of 87 Leptospira sp. seronegative dams belonging to the same herd. Sows were sampled during 1988 to 1993. During this period the herd was not submitted to any kind of intervention (antibiotic therapy, immunoprophylaxis or rodent control). Relative risks (RR) of return to heat, mummified fetuses, stillbirth, and weak newborn piglets for infected sows were assessed and the differences in means of total piglets born per litter, piglets born alive, piglets effectively housed, weaned piglets, stillbirths, mummified fetuses, weak newborn piglets, weight at birth of the piglets effectively housed, weight at 21 days of life and weight at weaning were evaluated. Seropositive dams had a greater risk of having weak newborn piglets (RR = 1.67, 1.02 < or = CI 95% < or = 2.72) and also of having more weak newborn piglets per litter (P = 0.01). Other variables examined were not different (P > 0.05).

The validity of some haematological and ELISA methods for the diagnosis of canine heartworm disease.

Examinations for heartworm (Dirofilaria immitis) were performed on 175 impounded dogs from a hyperendemic area of the Po Valley (Italy). Each blood sample was used with five haematological diagnostic methods (filtration, direct smear, modified Knott, clotted blood and capillary tube) and three commercial ELISA kits (PetChek, Diasystems, Uni-Tec). The results were compared with the true infection status obtained from post-mortem examination of the heart, pulmonary arteries, thoracic venae cavae and lungs. The prevalence of the infection by adult worms at necropsy was 63%. The sensitivity of the tests ranged from 60% (capillary tube) to 81% (Diasystems) and the specificity from 88% (filtration) to 98% (PetChek). The results of all the tests differed significantly (p < 0.01) from those obtained at necropsy. The sensitivity of the tests was also assessed with respect to the differing numbers of worms in the hosts. A positive correlation between the worm burden and the sensitivity was observed in all the tests. It is apparent that the ELISA methods were better able to detect cases with a low number of worms than the haematological tests.

Preparation and use of a monoclonal antibody to detect Chlamydia psittaci antigen in paraffin-embedded tissue sections.

A murine monoclonal antibody prepared against an ovine abortion isolate of Chlamydia psittaci (A22/Teramo) revealed specific binding to a 57 kDa chlamydial antigen in immunoblotting studies. The monoclonal antibody was able to detect intracytoplasmic chlamydial inclusions and scattered elementary bodies in infected McCoy cell culture, and on formalin-fixed paraffin-embedded tissue sections both from experimentally infected mice and from fetal membranes of cases of ovine enzootic abortion.

Serological investigations for some bacterial and viral pathogens in fallow deer (Cervus dama) and wild boar (Sus scrofa) of the San Rossore Preserve, Tuscany, Italy.

Sera of 43 fallow deer (Cervus dama) of the San Rossore Preserve (Tuscany, Italy) were examined for antibodies against eight pathogens; one proved positive for Brucella sp., 21 for Listeria monocytogenes, 34 for Chlamydia psittaci, three for Coxiella burnetii, one for infectious bovine rhinotracheitis virus, 11 for parainfluenza-3 virus, 25 for bovine viral diarrhea virus and six for bovine respiratory syncytial virus. No age and sex difference in the positivity rates and titers was evidenced, while a sex difference was found both in rates of infection and in titers against parainfluenza-3 virus. Parainfluenza-3 infection was more prevalent in 1984 than in 1983 sampling. Sera of 20 wild boars (Sus scrofa) of the same preserve were examined for antibodies against five pathogens: four sera were positive for Brucella sp., while all were negative for Listeria monocytogenes, Chlamydia psittaci, Coxiella burnetii and Aujeszky's disease virus. Public and animal health involvement with these diseases are discussed for these respective host species.

Spontaneous toxoplasmosis in canaries (Serinus canaria) and other small passerine cage birds.

An outbreak of spontaneous Toxoplasma gondii infection on an Italian bird-farm is described. Small passerine birds (Serinus canaria, Carduelis chloris, Carduelis carduelis, Carduelis spinus, Carduelis cannabina, Pyrrhula pyrrhula) showed clinical signs consisting of anorexia, prostration, weight loss, diarrhoea and dyspnoea accompanied by a high mortality rate. Clinical, pathological, biological and serological investigations were performed. Characteristic lesions and Toxoplasma gondii specimens were identified in several tissues by histopathological examinations. The detection of antibodies against Toxoplasma gondii was constant in dead and sacrificed animals with macroscopic lesions. A therapy based on the administration of sulphadimethoxine and diaveridine was successful in limiting the mortality rate. Four months later some surviving birds developed ocular atrophy. Toxoplasma gondii cysts were observed in the brain and cerebral and ocular lesions described. Sera obtained from these animals were positive (>1:64) for antibodies against Toxoplasma gondii. The authors conclude with some observations on the spread of toxoplasmosis among cage birds.