Anemia infecciosa eqüina: prevalência em eqüídeos de serviço em Minas Gerais

Impact of changes of horse movement regulations on the risks of equine infectious anemia: A risk assessment approach

Equine infectious anemia virus (EIAV) is a transboundary disease affecting a large number of equines worldwide. In this study, we assessed the transmission risk of EIAV in Rio Grande do Sul, Brazil. Serum samples from 1010 animals from 341 farms were initially analyzed using agar gel immunodiffusion to detect viral antibodies, and no antibody-positive animals were found. A risk assessment stochastic model was applied to generate the expected number of potential infections per month and to estimate the time to new infections. Our results estimated 6.5 months as the interval for new infections in the worst-case scenario. Among the variables evaluated, the number of transported animals and the test sensitivity influenced the model the most. These results were then used to revisit the impact of EIAV control regulations, which triggered a change in the diagnostic testing required for animal movement, in which the validity of a negative test for EIAV was extended from 60 to 180 days. Finally, revisiting the annual average of infected farms before and after the new regulation, the number of infected farms increased pre-implementation, and then, the number of culled animals increased, which should impact future EIAV incidence in this region. Our results demonstrated the importance of constant reviews of disease control programs and provided quantitative-based knowledge for decision-makers in official veterinary services.

Identification of large genetic variations in the equine infectious anemia virus tat-gag genomic region

The aetiological agent of equine infectious anaemia (EIA) is the retrovirus equine infectious anemia virus (EIAV) that infects all members of the Equidae family. The EIA is widely disseminated in the Brazilian territory with a high seroprevalence in the Brazilian Pantanal and is mainly diagnosed using agar gel immunodiffusion (AGID). There are few complete EIAV genome sequences available in GenBank, which had an impact on molecular detection studies. In this study, we conducted molecular detection and sequencing of EIAV proviral DNA from Brazilian horses. We analysed the genomic region from exon 1 of tat to gag (tat-gag). Comparative serological tests, comprising AGID and two enzyme-linked immunosorbent assays (ELISAs), were also conducted. Of the 133 samples, 58 were positive in the tat-gag PCR, and 49 nucleotide sequences of 272 bp were obtained. Using this developed tat-gag PCR EIAV proviral DNA was detected in 7% of the AGID-negative samples and 26% of the AGID-negative samples were positive in at least one of the ELISA tests used. Using phylogenetic analysis, the Brazilian Pantanal EIAV sequences grouped in a different clade of EIAV sequences from other countries. Thus, the EIAV sequences can contribute to the knowledge of the tat-gag genomic region in the circulating viruses in the Brazilian Pantanal, in addition to providing new information about the genetic diversity. In addition, the serological results demonstrate the greater sensitivity of the ELISAs used in this study compared to AGID for EIA diagnosis.

Viral Diseases that Affect Donkeys and Mules

Simple Summary

Donkeys have been neglected and threatened by abandonment, indiscriminate slaughter, and a lack of proper sanitary management. They are often treated as “small horses.” However, donkeys and horses have significant genetic, physiological, and behavioral differences. Specific knowledge about viral infectious diseases that affect donkeys and mules is important to mitigate disease outbreaks. Thus, the purpose of this review is to provide a brief update on viral diseases of donkeys and mules and ways to prevent their spread.

Abstract

Donkeys (Equus asinus) and mules represent approximately 50% of the entire domestic equine herd in the world and play an essential role in the lives of thousands of people, primarily in developing countries. Despite their importance, donkeys are currently a neglected and threatened species due to abandonment, indiscriminate slaughter, and a lack of proper sanitary management. Specific knowledge about infectious viral diseases that affect this group of Equidae is still limited. In many cases, donkeys and mules are treated like horses, with the physiological differences between these species usually not taken into account. Most infectious diseases that affect the Equidae family are exclusive to the family, and they have a tremendous economic impact on the equine industry. However, some viruses may cross the species barrier and affect humans, representing an imminent risk to public health. Nevertheless, even with such importance, most studies are conducted on horses (Equus caballus), and there is little comparative information on infection in donkeys and mules. Therefore, the objective of this article is to provide a brief update on viruses that affect donkeys and mules, thereby compromising their performance and well-being. These diseases may put them at risk of extinction in some parts of the world due to neglect and the precarious conditions they live in and may ultimately endanger other species’ health and humans.

Prevalence of Rhodococcus equi from the nasal cavity of 1010 apparently healthy horses

BACKGROUND

Rhodococcus equi is an important cause of foal pneumonia. While its isolation from different sources has been widely evaluated, there is a need to better understand the R. equi epidemiology from samples of the nasal cavity of healthy horses.

OBJECTIVES

To determine the prevalence of R. equi from the nasal cavity of healthy horses, along with its virulence profile, antimicrobial susceptibility and environmental variables associated.

STUDY DESIGN

Cross-sectional study.

METHODS

Swabs from the nasal cavity of 1010 apparently healthy horses from 341 farms were submitted for bacteriological analyses. The identity and virulence profile of the R. equi isolates were assessed by multiplex PCR; antimicrobial susceptibility was determined by the disk-diffusion method. The occurrence of R. equi was calculated at the level of both animal and farm. The association of seven specific environmental factors with R. equi isolation was assessed using logistic regression and by a spatial scan statistical method to determine the presence of local clusters.

RESULTS

Antimicrobial-sensitive R. equi was isolated from 10 (1%) of 1010 horses ranging between 3 and 29 years old. Ten farms (3%) had at least one positive horse. Only one R. equi isolate (10%) was classified as virulent. Red-Yellow Argisol (PVA/PV) soils were significantly associated with R. equi isolation (odds ratio (OR) 8.02; CI_95% , 1.98-32.50, P = 0.01), and areas with well-drained soil were less likely to be test positive (OR 0.85; CI_95% , 0.76-0.96, P = 0.03).

MAIN LIMITATIONS

The use of culture-based method instead of PCR-based assay and the lack of soil sampling.

CONCLUSIONS

Antimicrobial-sensitive R. equi may be considered a minor part of the normal bacterial flora in the nasal cavity of healthy and immunologically functional horses breeding on pasture. Further studies are warranted to determine if soils rich in iron and well-drained are, in fact, associated with the occurrence of R. equi.

Equine infectious anaemia in equids of Southern Pantanal, Brazil: seroprevalence and evaluation of the adoption of a control programme

ABSTRACT: The working equid population in Corumbá, Southern Pantanal, is very large and has a crucial role in the main economic activity of the State of Mato Grosso do Sul, the beef cattle industry. The aim of the present study was to estimate the prevalence of equine infectious anaemia (EIA) in working equids of ranches in the municipality of Corumbá, by the official agar gel immunodiffusion (AGID) test, and evaluate the adoption of the Programme for the Prevention and Control of Equine Infectious Anaemia proposed by Embrapa Pantanal and official entities in the 1990s. From September to November 2009, forty ranches distributed through the area of the municipality were visited, and serum samples were obtained from 721 equines and 232 mules. According to previous publications and the present data, it was concluded that the prevalence of EIA in this population has increased from 18.17% to 38.60%, which represents at this time approximately 13,000 infected animals. There was no significant difference between the apparent prevalence of equines and mules. It was also verified that the control programme was not known by the greater part of the interviewed ranch owners, managers and foremen and, in their perception, EIA is not a primary threat to address. Among the studied variables, the serologic testing practice significantly reduced the risk for the presence of EIA seropositivity, as well as the separation of riding equipment and segregation of seropositives.

Equine infectious anemia on Marajo Island at the mouth of the Amazon river

Abstract: Equine infectious anemia (EIA) is a transmissible and incurable disease caused by a lentivirus, the equine infectious anemia virus (EIAV). There are no reports in the literature of this infection in Equidae on Marajo Island. The objective of this study was to diagnose the disease in the municipalities of Cachoeira do Arari, Salvaterra, Santa Cruz do Arari and Soure, on Marajó Island, state of Pará, Brazil. For serological survey samples were collected from 294 horses, over 5-month-old, males and females of puruca and marajoara breeds and from some half-breeds, which were tested by immunodiffusion in Agar gel (AGID). A prevalence of 46.26% (136/294) positive cases was found. EIA is considered endemic in the municipalities studied, due to the ecology of the region with a high numbered population of bloodsucking insect vectors and the absence of official measures for the control of the disease.

Prevalence of Streptococcus equi subsp. equi in horses and associated risk factors in the State of Rio Grande do Sul, Brazil

The aim of this study was to estimate the prevalence of equine strangles and to identify associated risk factors for this disease through a cross-sectional study of nasal swabs. Nasal swabs (n=1010) from healthy equines (absence of nasal discharge, lymphadenopathy and cough) from 341 farms were plated on 5% blood agar; of these horses, 24 were identified as positive for Streptococcus equi through isolation, PCR and DNA sequencing. The estimated prevalence for individual animals was 2.3%, and for herds, it was 5.86%. Statistical analysis identified the following as associated risk factors: the number of group events that were attended by the equines (PR: 1.06); the sharing of food containers (PR: 3.74); and at least one previous positive diagnosis of strangles on the farm (PR: 3.20). These results constitute an epidemiological contribution to the horse industry and may support measures for the future control of the disease.

Brucellosis in working equines of cattle farms from Minas Gerais State, Brazil

The present survey aimed at estimating the seroprevalence of brucellosis in working equines of cattle farms from Minas Gerais State, Brazil, and investigating risk factors associated with the infection. Serum samples from 6439 animals, including 5292 horses, 1037 mules and 110 donkeys, were collected from 1936 herds, between September 2003 and March 2004, in 848 municipalities from the state of Minas Gerais, Brazil. The prevalence of antibodies against smooth Brucella spp. found in equines from Minas Gerais State was 1.37% (95% CI: 0.97-1.78), resulting in a prevalence of herds with infected animals of 4.28% (95% CI: 4.21-4.36). There were differences between regions but these were not of major epidemiological relevance nor were most of them statistically significant, given the considerable overlap of confidence intervals. Nevertheless, the point estimates suggest that the three northeastern regions have slightly higher prevalence than the rest of the state, both at the herd and animal levels. No association of Brucella spp. seropositivity with sex, age or host was observed. In conclusion, the present study showed a low but widespread prevalence of antibodies against smooth Brucella in equines kept in cattle farms in Minas Gerais, a state where bovine brucellosis is also widespread albeit with low prevalence.

Ocorrência e fatores de risco associados à identificação da anemia infecciosa equina em equídeos de tração

O objetivo do presente trabalho foi determinar a ocorrência e os fatores de risco associados à identificação da anemia infecciosa equina (AIE) em equídeos de tração na Cidade de São Luís - MA. Amostras de sangue de 154 equídeos apreendidos em vias públicas, pelo Setor de Apreensão de Animais de Tração da Secretaria Municipal de Urbanismo e Habitação, foram coletadas no período de abril a agosto de 2011. Foram analisadas as fichas de atendimento individual para a determinação dos fatores de risco associados a esta enfermidade. Dos animais analisados, 5,20% (8/154) foram positivos. Dentre os fatores de risco avaliados, presença de insetos, permanência dos equídeos em aglomerações por mais de oito horas diárias, condição corporal, estado nutricional, uso repetido de uma mesma agulha entre diferentes equídeos, ocorrência de episódios febris, mucosas amareladas e ausência de conhecimento sobre AIE apresentaram significância estatística (P<0,05) associada à AIE. Os resultados do estudo indicaram que a ocorrência da AIE para equídeos de tração apreendidos na Cidade de São Luís - MA foi baixa. Mesmo assim há a necessidade da realização de diagnóstico sistemático e monitoramento dos animais, além da implantação de medidas de controle, realização de exames sorológicos e implementação da legislação vigente.

Ocorrência de equídeos soropositivos para os vírus das encefalomielites e anemia infecciosa no Estado de Mato Grosso

O presente trabalho determinou a ocorrência de equídeos com sorologia positiva para os vírus das encefalomielites virais dos tipos Leste (EEL), Oeste (EEO) e Venezuelana (EEV) e Anemia Infecciosa (AIE) nos biomas Amazônico, Pantaneiro e Cerrado do Estado de Mato Grosso. A detecção de anticorpos para AIE foi realizada em 886 soros pela prova de Imunodifusão em Gel de Ágar (IDGA), enquanto que para EEL, EEO e EEV foi realizada em 473 soros pela Microtécnica de Soroneutra-lização viral em culturas de células VERO. Para AIE, 46 (5,1%) equídeos foram positivos, não sendo observados animais positivos da região amazônica e a maior frequência ocorrendo no ambiente do pantanal com 36,6% de animais positivos (P < 0,05). Para as encefalites virais, foram detectados 168 (35,5%) equídeos positivos para EEL e 31 (6,5%) para EEV. Não houve soros positivos para EEO. As maiores frequências de animais positivos para EEL foram observadas nos ambientes pantaneiro e amazônico com 45,8% e 62,0%, respectivamente (P < 0,05). Os três biomas estudados apresentaram ocorrência similar (P > 0.05) de animais positivos para EEV, com 4,1%, 6,4% e 10,3% para o pantanal, cerrado e amazônia, respectivamente. Embora não apresentando equídeos reagente ao vírus da AIE na região amazônica, a presença de positivos em Mato Grosso encontra-se dentro do relatado no Brasil. O comportamento diferenciado do vírus da EEL e EEV nos três ecossistemas estudados reforça a presença de animais reservatórios, condições ambientais e climáticas que favorecem a proliferação de vetores que propiciam a infecção pelos vírus no Estado de Mato Grosso.