Salmonella Serovars Isolated from Poultry Breeding Flocks under the Brazilian Official Control Programme Between 2016 and 2018

The control of Salmonella in the poultry production chain combined with biosecurity measures is an important tool to maintain and guarantee the sanitary status of Brazilian flocks. The aim of this work was to compare official laboratory data on molecular typification of Salmonella isolates from poultry breeding flocks in different Brazilian states between 2016 and 2018 and identify the production category with the most positive flocks, in light of current legislation. Surveillance data of positive samples from the official Brazilian Salmonella Control Programme sent to Federal Agricultural Defence Laboratory of São Paulo (LFDA-SP) after molecular characterization were analysed. These data were subject to an exploratory study, undergoing a descriptive statistical analysis followed by the use of frequency and non-parametric hypothesis tests. Overall, 49 serovars were detected in poultry broiler-breeder and layer-breeder flocks. Salmonella ser. Heidelberg, Salmonella ser. Anatum, Salmonella ser. Newport, Salmonella ser. Schwarzengrund and Salmonella ser. Mbandaka were the five most common isolated serovars. The data shows that there is an opportunity to improve biosecurity measures in parent breeder flocks. A total of 16 serovars were identified in turkey-breeders. Salmonella ser. Anatum, Salmonella ser. Newport, Salmonella ser. Brandenburg, Salmonella ser. Litchfield, and Salmonella ser. Livingstone were the most common ones. The four official controlled serovars represented a small part of the isolated strains. These data demonstrate the importance of an official program in Brazil for Salmonella surveillance in breeder flocks combined with biosecurity measures.(AU)

Validation of Alternative Methods of Detection of Salmonella Spp. in Experimentally Contaminated Poultry Environmental Samples

The analysis of Salmonella in the feces and the birds environment is a way of monitoring the colonization in the flocks and verifying the need for the introduction of stricter controls, in such a way that the results of the tests should be known before being sent for slaughter. The polymerase chain reaction (PCR), as well as other rapid methods represent alternatives increasingly used to detect enteric pathogens, but they need proof of effectiveness for their wide use. The aim of this study was to evaluate the equivalence between the results obtained by the methods: real-time PCR (BAX® System), Modified Rappaport-Vassiliadis Semi-solid Medium (MSRV) (ISO 6579) and the traditional method of official reference in Brazil for research of S. Typhimurium and S. Enteritidis in poultry samples. Two hundred and fifty-two samples of disposable shoe covers (DSC) and 252 samples of feces were infected with an average of 2 to 3 log CFU/g of each serovar, and the same samples without fortification were evaluated by the three methods. Five hundred and four diagnoses were obtained with satisfactory results in terms of repeatability (greater than 80%), reproducibility (mean 83,1%), sensitivity (81% to 100%), specificity (95% to 100%), and accuracy (90% to 100%). The compliance test verified that there was not a significant difference between the alternative and the official methods, allowing us to state that the methodologies have had equivalent performances.(AU)

Validation of Alternative Methods of Detection of Salmonella Spp. in Experimentally Contaminated Poultry Environmental Samples

The analysis of Salmonella in the feces and the birds environment is a way of monitoring the colonization in the flocks and verifying the need for the introduction of stricter controls, in such a way that the results of the tests should be known before being sent for slaughter. The polymerase chain reaction (PCR), as well as other rapid methods represent alternatives increasingly used to detect enteric pathogens, but they need proof of effectiveness for their wide use. The aim of this study was to evaluate the equivalence between the results obtained by the methods: real-time PCR (BAX® System), Modified Rappaport-Vassiliadis Semi-solid Medium (MSRV) (ISO 6579) and the traditional method of official reference in Brazil for research of S. Typhimurium and S. Enteritidis in poultry samples. Two hundred and fifty-two samples of disposable shoe covers (DSC) and 252 samples of feces were infected with an average of 2 to 3 log CFU/g of each serovar, and the same samples without fortification were evaluated by the three methods. Five hundred and four diagnoses were obtained with satisfactory results in terms of repeatability (greater than 80%), reproducibility (mean 83,1%), sensitivity (81% to 100%), specificity (95% to 100%), and accuracy (90% to 100%). The compliance test verified that there was not a significant difference between the alternative and the official methods, allowing us to state that the methodologies have had equivalent performances.

A survey for maintenance of virulent newcastle disease virus-free area in poultry production in Brazil

In 2003, Brazil was recognized as a pathogenic Newcastle Disease Virus (NDV) strain-free country for commercial poultry. This research was conducted in Brazil between December 2003 and March 2005 to verify the maintenance of this virulent NDV-free status. Serum samples from 5,455 flocks for commercial poultry farms were collected, comprising 81,825 broiler chickens. The farms were located in nine states of the country, grouped in three geographic regions. Serological evidence of NDV infection was detected in 28.8% of the surveyed farms. However, all fifteen viruses isolated and identified as Newcastle Disease Virus (NDV) were characterized as nonpathogenic strains, based on the Intracerebral Pathogenicity Index. These results showed that Brazil preserves the virulent NDV-free status for commercial flocks.

Prevalence of newcastle disease virus in broiler chickens (Gallus gallus) in Brazil

This study was carried out during 2002/2003, aiming to determine the prevalence of virulent Newcastle disease virus strains (NDV) in Brazilian commercial poultry farms. Clinical samples were obtained from the Southeastern, Southern and Central-Western regions, which comprise the main area of the Brazilian poultry production. Serum samples and tracheal and cloacal swabs of 23,745 broiler chickens from 1,583 flocks, including both vaccinated chickens and those with no vaccination information, were tested for NDV using a diagnostic ELISA kit. The seropositivity was 39.1%, and the isolation percentage by flock varied from 1.0 to 7.6%, and by region from 6.5 to 58.4%. Higher isolation rates (74.3-83.3%) were obtained after three passages in embryonated chicken eggs. All isolates preliminarily identified as NDV were characterized as nonpathogenic strains, as their Intracerebral Pathogenicity Index (ICPI) was below 0.7. Based on results of this study, Brazil can claim a virulent NDV-free status for commercial flocks.

Newcastle disease virus vaccine strains: immunogenicity is not influenced by ICPI

Intracerebral pathogenicity index (ICPI) and mean death time (MDT) were determined using commercial live vaccines against Newcastle disease available in Brazil. The ICPI profiles obtained for B1 vaccine strains were nonvirulent and varied from 0 to 0.19, and their MDT was 104-116 hours. The LaSota strains had an ICPI varying between 0.02 and 0.37 and MDT from 92 to 116 hours. ICPI and MDT for the Clone 30 were 0.11 and 104 hours, respectively. For Ulster vaccines, ICPI and MDT were 0 and >150 hours; for VG-GA was 0.03 and 140 hours; and for C2, 0.04 and >144 hours. Eye drop vaccination and IM challenge, at the 1st week and the 4th week, respectively, resulted in highest protection for B1 (95-100%) and LaSota (90-100%) strains. The variability in vaccine ICPI did not interfere with immune response and all vaccines provided similar protection. All vaccines were considered non virulent and were classified as lentogenic according to the immunobiological product standards.

Newcastle disease virus vaccine strains: immunogenicity is not influenced by ICPI

Intracerebral pathogenicity index (ICPI) and mean death time (MDT) were determined using commercial live vaccines against Newcastle disease available in Brazil. The ICPI profiles obtained for B1 vaccine strains were nonvirulent and varied from 0 to 0.19, and their MDT was 104-116 hours. The LaSota strains had an ICPI varying between 0.02 and 0.37 and MDT from 92 to 116 hours. ICPI and MDT for the Clone 30 were 0.11 and 104 hours, respectively. For Ulster vaccines, ICPI and MDT were 0 and >150 hours; for VG-GA was 0.03 and 140 hours; and for C2, 0.04 and >144 hours. Eye drop vaccination and IM challenge, at the 1st week and the 4th week, respectively, resulted in highest protection for B1 (95-100%) and LaSota (90-100%) strains. The variability in vaccine ICPI did not interfere with immune response and all vaccines provided similar protection. All vaccines were considered non virulent and were classified as lentogenic according to the immunobiological product standards.

Incidence of Salmonella in imported day-old ducklings. Brazil, 1998-2003

The occurrence of Salmonella in a samples of 40 imported day-old duckling flocks was assessed from 1998 to 2003 according to the guidelines of the Brazilian National Poultry Health Program (Programa Nacional de Sanidade Avícola-PNSA). The pathogen was recovered from 26 flocks (65.0%). The most common serovars were S. Saintpaul and S. Kottbus. Up to four serovars were isolated from a single flock. Transportation box swabs (82.6%) and yolk sac pool (47.1%) showed the highest and the lowest frequency of Salmonella isolation, respectively. The high percentage of Salmonella isolation from imported day-old ducklings causes concern because of the zoonotic potential of this agent and its economical importance to commercial poultry breeding.

Incidence of Salmonella in imported day-old ducklings. Brazil, 1998-2003

The occurrence of Salmonella in a samples of 40 imported day-old duckling flocks was assessed from 1998 to 2003 according to the guidelines of the Brazilian National Poultry Health Program (Programa Nacional de Sanidade Avícola-PNSA). The pathogen was recovered from 26 flocks (65.0%). The most common serovars were S. Saintpaul and S. Kottbus. Up to four serovars were isolated from a single flock. Transportation box swabs (82.6%) and yolk sac pool (47.1%) showed the highest and the lowest frequency of Salmonella isolation, respectively. The high percentage of Salmonella isolation from imported day-old ducklings causes concern because of the zoonotic potential of this agent and its economical importance to commercial poultry breeding.

Detecção da infecção pelo vírus da artrite-encefalite caprina: imunodifusão em ágar e reação em cadeia da polimerase com "primers" degenerados

The purpose of this work was to analyse serum and blood cells from caprine origin to detect antibody and proviral DNA of caprine arthritis encephalitis virus (CAEV), respectively. Agar gel immunodiffusion (AGID) and polymerase chain reaction (PCR) with degenerated primers were used. Samples of different geographical regions were analysed: 39 from Mato Grosso do Sul (MS), 19 from São Paulo (SP), 22 from Ceará (CE) including 10 from Canada (imported animals), providing a total of 80 samples. The results obtained by AGID and PCR were discordants, as 25 samples were detected as seropositive, while 16 infected animals were detected by PCR. On the other hand, PCR allowed the identification of infected animals that did not have detectable antibodies by AGID: eight samples from MS and one from CE. Different aspects related to these discordant results are discussed.

O objetivo deste trabalho foi analisar amostras de soro e de células sangüíneas de caprinos para detecção de anticorpos e DNA proviral do vírus da artrite-encefalite caprina (CAEV), respectivamente. Utilizou-se a técnica de imunodifusão em ágar (AGID) e a reação em cadeia da polimerase (PCR) com "primers" degenerados. Foram analisadas amostras de diferentes procedências: 39 de Mato Grosso do Sul (MS), 19 de São Paulo (SP) e 22 do Ceará (CE), dessas últimas, 12 oriundas de animais importados do Canadá. Os resultados de AGID e PCR foram discordantes, pois o primeiro permitiu a detecção de 25 animais soropositivos, enquanto a PCR detectou DNA proviral de CAEV em 16 amostras. Pela PCR foi possível identificar animais infectados cujos testes sorológicos foram negativos pelo AGID: oito amostras do MS e um do CE. São discutidos diferentes aspectos que poderiam estar envolvidos na discordância dos resultados.