HoBi-like pestivirus infection in an outbreak of bovine respiratory disease

HoBi-like is an emerging pestivirus of the family Flaviviridae detected in cattle herds and biological products of bovine origin in many parts of the world, causing disease similar to that observed in bovine viral diarrhea virus (BVDV) infections. In this study we reported the detection of HoBi-like pestivirus in an outbreak of respiratory disease in calves from Brazil, seropositive for viruses of the bovine respiratory disease complex (BRDC). Thus, serum samples and nasal swabs were collected from calves up to one year old, presenting or not clinical signs of respiratory disease. Serum samples were submitted to virus neutralization test (VNT) for BVDV-1, BVDV-2, bovine herpesvirus-1 (BoHV-1), bovine respiratory syncytial virus (BRSV) and bovine parainfluenza-3 (BPIV-3). These samples were also tested for the presence of pestiviruses (BVDV-1, BVDV-2 and HoBi-like) and BoHV-1 by RT-PCR and PCR, respectively. Nasal swabs were analyzed by RT-PCR for pestiviruses, BRSV and BPIV-3. VNT results showed high serological prevalence and a wide range of antibodies titers, for all viruses studied, in calves of different age groups. The RT-PCR amplified the 5'UTR and E2 regions of pestiviruses of four calves, from both nasal swabs and serum samples, which sequencing identified the HoBi-like pestivirus. This is the first detection of HoBi-like in nasal secretions of calves in an outbreak of respiratory disease in Brazil, along with the serological detection of other respiratory viruses. We concluded that HoBi-like pestivirus should be considered as part of the BRDC, as a differential diagnosis, to take correct measures of control and prophylaxis.

Coxiella burnetii associated with BVDV (Bovine Viral Diarrhea Virus), BoHV (Bovine Herpesvirus), Leptospira spp., Neospora caninum, Toxoplasma gondii and Trypanosoma vivax in reproductive disorders in cattle

This is a cross-sectional study to assess the presence of antibodies in ruminants against selected pathogens associated with reproductive disorders in cattle in four Brazilian states, including the zoonotic agent Coxiella burnetii. The used tests were Virus Neutralization Assay for IBR and BVD, Microscopic Agglutination Test for Leptospira spp., Indirect Fluorescent Antibody Test (IFAT) for C. burnetii and Toxoplasma gondii, and Enzyme-Linked Immunosorbent Assay for Neospora caninum and Trypanosoma vivax. Seropositivity for C. burnetii was 13.7% with titers from 128 to 131,072; 57.8% for BoHV-1, with titers between 2 and 1,024; 47.1% for BVDV-1a, with titers from 10 to 5,120; 89.2% for N. caninum; 50% for T. vivax; and 52.0% for Leptospira spp., with titers between 100 to 800 (the following serovars were found: Tarassovi, Grippotyphosa, Canicola, Copenhageni, Wolffi, Hardjo, Pomona and Icterohaemorrhagiae); 19.6% for T. gondii with titer of 40. This is the first study that has identified C. burnetii in cattle associated with BoHV and BVDV, N. caninum, Leptospira spp., T. gondii and T. vivax. Thus, future studies should be conducted to investigate how widespread this pathogen is in Brazilian cattle herds.

Bovine respiratory syncytial virus seroprevalence and risk factors in non-vaccinated dairy cattle herds in Brazil

BACKGROUND

The cattle industry is one of the most important Brazilian agribusiness sectors and is a strong contributor to the national economy. Annually about 44.6 million calves are bred, which makes the optimal management of these animals extremely important. Several diseases can affect the initial stages of the bovine production chain, being the bovine respiratory syncytial virus (BRSV) one of the most relevant pathogens. This study aimed to characterize the epidemiology of BRSV infection in dairy cattle herds of São Paulo State, Brazil, using serological and risk factors analyses. For that, 1243 blood samples were collected of animals from 26 farms and a questionnaire about possible risk factors for BRSV prevalence was performed. The obtained blood sera were analyzed using virus neutralization test (VNT).

RESULTS

VNT results showed high BRSV prevalence in dairy cattle herds, reaching 79.5% of seropositivity. The BRSV seroprevalence among studied farms ranged from 40 to 100%. The analysis of risk factors indicated that the age group and the occurrence of coinfection with bovine herpesvirus 1 (BoHV-1) and bovine viral diarrhea virus 1 (BVDV-1) should be associated with a higher prevalence of BRSV, while natural suckling was considered a protective factor.

CONCLUSIONS

The study showed that adult animals over 1 year old are an important risk factor for the high seroprevalence of BRSV in herds. The high BRSV prevalence associated with BoHV-1 and BVDV-1 suggests that biosecurity measures should be applied in order to reduce viral dissemination. Additionally, the natural suckling may be an important management to protect calves from high BRSV seroprevalence.

Congenital tremor in piglets: Is bovine viral diarrhea virus an etiological cause?

Congenital tremor in pigs involves several etiologies, including pestivirus, which may cause neurological injuries in different animal species. To evaluate whether bovine viral diarrhea virus (BVDV), an important pestivirus, is one of the etiological agents of congenital tremor in swine, gilts and the fetuses were challenged at 45 days of gestation with BVDV-2. Four pregnant gilts were inoculated oronasally, four gilts underwent fetal intrauterine inoculation, and two gilts constituted the control group. Antibody titers were determined by virus neutralization (VN), and viral RNA was detected by RT-PCR. Blood samples were collected from all gilts and piglets born to obtain whole blood and serum for analysis. One third of the neonates were euthanized at three days old, and samples of the encephalon, brain stem and spinal cord were collected for anatomopathological evaluation and viral RNA detection. The piglets that remained alive were clinically evaluated every day, and blood sampling was performed regularly for 35 days. The piglets from gilts in both inoculation treatment groups showed no clinical neurological signs and were born with no viral RNA in their blood and organs. Piglets born from oronasally inoculated gilts did not present antibodies against BVDV-2 at birth, although they were acquired by passive maternal transfer. In contrast, intrauterine-inoculated piglets were born with high antibody titers (80 to 640) against the agent, which remained high until the end of the experimental period. Microscopically, no noticeable changes were observed. Macroscopically, 29.5% of the total piglets euthanized, from both inoculation groups, were born with a low cerebellar:brain ratio. Nevertheless, some piglets had a high cerebellar:brain ratio, indicating the need for standardizing this value. Thus, it was concluded that BVDV is not an etiological agent for congenital swine tremor.

Description of risk factors associated with the detection of BVDV antibodies in Brazilian pig herds

Bovine viral diarrhea virus (BVDV) infects ruminants as primary hosts. However, other animals like pigs are susceptible. This study was conducted to investigate seroprevalence and risk factors associated with the detection of BVDV antibodies in pig herds. A total of 1.705 serum samples of 33 finisher herds, from seven Brazilian states, were collected in slaughterhouses. The samples were tested by virus neutralization (VN) test. In total, 5.35% (91/1.705) were positive and 64% (21/33) of the herds had positive animals. A significant association with "trucks are not cleaned and disinfected" and "visitors do not respect 72-h interval between visits to farms" (P < 0.05) was found in association with detection of BVDV-2 antibodies. This study suggests that important biosecurity gaps are present in Brazilian pig farms, as the presence of BVDV antibodies in pigs suggests (direct or indirect) contact with population(s) of ruminant species. Closing biosecurity gaps prevents spread of BVDV and other pathogens such as foot-and-mouth disease virus (FMDV) between pig and ruminant farms. This data should be taken in account by CSF surveillance programs, once cross-reaction in serologic tests between classical swine fever virus (CSFV) and BVDV antibodies has been shown to occur.

ERADICATION PROGRAM OF FOOT AND MOUTH DISEASE IN THE STATE OF SÃO PAULO: EVALUATION OF OFFICIAL DATA OBTAINED BETWEEN 1997-2012

Abstract Foot and mouth disease (FMD), a highly contagious disease that affects cloven-hoofed animals, is known by the economic losses it causes in farms and in regions where it is endemic. The State of São Paulo has not recorded FMD outbreaks since 1996. Based on official data from 1997 to 2012, this study organized, analyzed, and confronted the following information with the current literature: a) the FMD vaccination rates from 1997 to 2012 in São Paulo; b) the results of the official monitoring designed to demonstrate the effectiveness of vaccination against FMD; c) the passive surveillance procedures and compliance with reports of suspected vesicular disease in the State of São Paulo; d) the results of the official monitoring designed to demonstrate the absence of viral circulation in the State of São Paulo; e) the relation between the preventive measures adopted by the veterinarian official service with the challenge of FMD outbreaks in other neighboring states. Finally, the description of the free area without vaccination implementation prospects for the State of São Paulo, classification granted by the World Organization for Animal Health (OIE). The data analysis showed that sanitary measures, strategies, and the methodology to assess the efficacy of the FMD eradication program in the State of São Paulo were efficient. Even though the data suggest that the state is able to upgrade to a FMD free area without vaccination, some aspects should be taken into account, such as the structure of the state's Official Veterinary Service, disease control programs in states epidemiologically related with São Paulo and the commitment of the whole supply chain with surveillance and eradication of FMD.

DESCRIÇÃO DAS AÇÕES DE VIGILÂNCIA EM FOCOS DA DOENÇA DE AUJESZKY

<title>Resumo</title><p>A doença de Aujeszky (DA) é conhecida na suinocultura pelo seu grande impacto produtivo e econômico. Este trabalho teve como objetivo a descrição das ações de defesa sanitária animal utilizadas na identificação de focos dessa enfermidade. Foram selecionadas duas situações de foco de DA que ocorreram no Município de Cerqueira César, um caso apresentando somente animais sororreagentes (Foco 1) e outro em que havia animais com sinais clínicos da enfermidade (Foco 2). Estão descritos os métodos de identificação de focos utilizados nas ações de vigilância e o diagnóstico da situação epidemiológica encontrada. As medidas aplicadas na erradicação dos focos nos sistemas de produção de suínos infectados foram as prescritas na legislação de defesa sanitária animal e todos os focos identificados foram eliminados. Ao final, concluiu-se que as ações de defesa sanitária e a legislação em vigor foram eficazes, demonstrando que os sistemas de notificações das suspeitas da enfermidade são facilitadores das ações de vigilância.</p>

Molecular characterization of group A bovine rotavirus in southeastern and central-western Brazil, 2009-2010

Rotavirus is an important cause of neonatal diarrhea in humans and several animal species, including calves. A study was conducted to examine 792 fecal samples collected from calves among 65 dairy and beef herds distributed in two of Brazil's major livestock producing regions, aiming to detect the occurrence of rotavirus and perform a molecular characterization of the rotavirus according to G and P genotypes in these regions. A total of 40 (5.05%) samples tested positive for rotavirus by the polyacrylamide gel electrophoresis (PAGE) technique. The molecular characterization was performed by multiplex semi-nested RT-PCR reactions, which indicated that the associations of genotypes circulating in herds in Brazil's southeastern region were G6P[11], G10P[11], G[-]P[5] + [11], G[-]P[6] in the state of São Paulo and G6P[11], G8P[5], G11P[11], G10P[11] in the state of Minas Gerais. In the central-western region, the genotypes G6P[5] + [11], G6P[5], G8P[-], G6P[11], G [-] P[1], G[-] P[11], and G[-] P[5] were detected in the state of Goiás, while the genotypes G6P[5], G8[P11], G6[P11], G8[P1], G8[P5], G6[P1] were circulating in herds in the state of Mato Grosso do Sul. The genotypic diversity of bovine rotavirus found in each region under study underlines the importance of characterizing the circulating samples in order to devise the most effective prophylactic measures.

[Antibodies to the rabies virus in humans working in a veterinary hospital environment at the Universidade Federal de Mato Grosso. Cuiabá, MT, Brazil]

A characterization of the serological profile of 102 workers in constant activities in a veterinary hospital environment at the Universidade Federal de Mato Grosso was made through epidemiological data and serological tests to the rabies virus from November 1999 to November 2000. Of these, 27 had been vaccinated in a pre-exposure scheme and 75 had not received any kind of antirabies immunization. The results of the study classified the people into four groups (G1, G2, G3 and G4). In G1, 19 (18.6%) people that had been previously vaccinated showed a titration level lower than 0.5UI/mL; in G2, 8 (7.8%) people who had been previously vaccinated showed a titration level higher than 0.5UI/mL; in G3, 67 (65.6%) people who had not been vaccinated against rabies virus showed a titration level lower than 0.5UI/mL; and finally in G4, 8 (7.8%) people who had never received any kind of vaccine scheme showed a titration level higher than 0.5UI/mL. The results showed that epidemiological evaluation and serological profile are necessary people working in a veterinary hospital environment while being pre-exposure vaccinated.

Monitoração da leucose enzoótica bovina no gado leiteiro da região de Pitangueiras (SP)

Anticorpos précipitantes contra o antígeno gp51 do vírus da Leucose Enzoótica Bovina foram pesquisados em amostras de soros de vacas leiteiras da região do município de Pitangueiras, no Estado de São Paulo. As amostras sanguíneas eram de animais provenientes de sete propriedades rurais que foram acompanhadas anualmente de 1992 até 1995. Durante o ano de 1992 foram analisados 140 soros, dos quais 24 (17,1%) eram reagentes positivos, 21 (15,0%) suspeitos e 95 (67,9%)negativos. Em 1993, dos 122 soros testados, 25 (20,5%) foram positivos, 8 (6,6%) suspeitos e 89 (72,9%) negativos. No ano de 1994 foram testadas 135 amostras, das quais 45 (33,3%) eram positivas, 19 (14,1%) suspeitas e 71 (52,6%) negativas. Finalmente, em 1995, foram analisadas as amostras de 119 animais sendo que 60 (50,4%) eram positivas, 11 (9,2%) suspeitas e 48 (40,4%) negativas. Os resultados obtidos evidenciam que no decorrer do experimento houve um nítidoaumento na prevalência da Leucose Enzoótica Bovina com o passar do tempo. Sob o prisma da Defesa Sanitária Animal, a crescente disseminação da doença na população estudada serve como alerta sobre o comportamento epidemiológico e sobre a evolução na difusão da enfermidade em nosso meio.