RESUMO
Glanders, caused by Burkholderia mallei, is a zoonotic disease of equids. Serologic testing for glanders is required by disease-free countries before international movement of equids. The World Organisation for Animal Health Terrestrial Manual recommends the complement fixation test (CFT) for clearance of individual animals for movement, but the CFT is prone to false-positive results. A colorimetric western blot (WB) assay was developed and validated to resolve false-positive CFT results; however, that assay is relatively time-consuming, and the interpretation is subjective. We present here a procedurally similar chemiluminescent WB assay that performs comparably to the validated colorimetric WB assay and offers noticeable benefits of decreased time-to-result and greater ease of interpretation.
Assuntos
Burkholderia mallei , Mormo , Doenças dos Cavalos , Cavalos , Animais , Mormo/diagnóstico , Western Blotting/veterinária , Zoonoses , Testes de Fixação de Complemento/veterináriaRESUMO
Tick-borne pathogens that cause persistent infection are of major concern to the livestock industry because of transmission risk from persistently infected animals and the potential economic losses they pose. The recent reemergence of Theileria equi in the United States prompted a widespread national survey resulting in identification of limited distribution of equine piroplasmosis (EP) in the U.S. horse population. This program identified Babesia caballi-seropositive horses using rhoptry-associated protein 1 (RAP-1)-competitive enzyme-linked immunosorbent assay (cELISA), despite B. caballi being considered nonendemic on the U.S. mainland. The purpose of the present study was to evaluate the suitability of RAP-1-cELISA as a single serological test to determine the infection status of B. caballi in U.S. horses. Immunoblotting indicated that sera from U.S. horses reacted with B. caballi lysate and purified B. caballi RAP-1 protein. Antibody reactivity to B. caballi lysate was exclusively directed against a single â¼50-kDa band corresponding to a native B. caballi RAP-1 protein. In contrast, sera from experimentally and naturally infected horses from regions where B. caballi is endemic bound multiple proteins ranging from 30 to 50 kDa. Dilutions of sera from U.S. horses positive by cELISA revealed low levels of antibodies, while sera from horses experimentally infected with B. caballi and from areas where B. caballi is endemic had comparatively high antibody levels. Finally, blood transfer from seropositive U.S. horses into naive horses demonstrated no evidence of B. caballi transmission, confirming that antibody reactivity in cELISA-positive U.S. horses was not consistent with infection. Therefore, we conclude that a combination of cELISA and immunoblotting is required for the accurate serodiagnosis of B. caballi.
Assuntos
Anticorpos Antiprotozoários/sangue , Babesia/imunologia , Babesiose/veterinária , Doenças dos Cavalos/diagnóstico , Doenças dos Cavalos/imunologia , Proteínas de Protozoários , Animais , Antígenos de Protozoários/imunologia , Babesiose/diagnóstico , Babesiose/imunologia , Ensaio de Imunoadsorção Enzimática , Cavalos , Proteínas de Protozoários/imunologia , Soro/química , Estados UnidosRESUMO
Theileria equi, one of the causative agents of equine piroplasmosis, is endemic in many regions of the world but is considered a 'foreign' animal disease in the USA. In an effort to prevent the importation of T. equi, stringent serological screening of horses is practiced prior to entry to the USA. Current regulatory options available where horses are found to be infected include permanent quarantine with or without chemotherapy, repatriation, or euthanasia. Chemotherapeutics that eliminate infection and subsequently transmission risk are critical in the management of infected horses. In this study, the efficacy of the drug imidocarb dipropionate against experimental T. equi infection was assessed. Of nine horses experimentally inoculated with T. equi isolated from an animal previously imported from Peru, six were treated with imidocarb dipropionate after the resolution of the acute phase of the disease. Elimination of the parasite was demonstrated in 5/6 by nested PCR, blood transfusions to naïve horses, and reversion to seronegative status. The findings support the use of this drug as a potential treatment option in controlling outbreaks of T. equi, and also suggest that 'combination testing' using both serological and PCR detection methods are necessary to demonstrate clearance of infection.
Assuntos
Antiprotozoários/uso terapêutico , Doenças dos Cavalos/tratamento farmacológico , Imidocarbo/análogos & derivados , Theileria/classificação , Theileriose/tratamento farmacológico , Animais , Doenças dos Cavalos/parasitologia , Cavalos , Imidocarbo/uso terapêuticoRESUMO
Arthropod-borne apicomplexan pathogens that cause asymptomatic persistent infections present a significant challenge due to their life-long transmission potential. Although anti-microbials have been used to ameliorate acute disease in animals and humans, chemotherapeutic efficacy for apicomplexan pathogen elimination from a persistently infected host and removal of transmission risk is largely unconfirmed. The recent re-emergence of the apicomplexan Theileria equi in U.S. horses prompted testing whether imidocarb dipropionate was able to eliminate T. equi from naturally infected horses and remove transmission risk. Following imidocarb treatment, levels of T. equi declined from a mean of 10(4.9) organisms/ml of blood to undetectable by nested PCR in 24 of 25 naturally infected horses. Further, blood transfer from treated horses that became nested PCR negative failed to transmit to naïve splenectomized horses. Although these results were consistent with elimination of infection in 24 of 25 horses, T. equi-specific antibodies persisted in the majority of imidocarb treated horses. Imidocarb treatment was unsuccessful in one horse which remained infected as measured by nested PCR and retained the ability to infect a naïve recipient via intravenous blood transfer. However, a second round of treatment eliminated T. equi infection. These results support the utility of imidocarb chemotherapy for assistance in the control and eradication of this tick-borne pathogen. Successful imidocarb dipropionate treatment of persistently infected horses provides a tool to aid the global equine industry by removing transmission risk associated with infection and facilitating international movement of equids between endemic and non-endemic regions.
Assuntos
Doenças dos Cavalos/epidemiologia , Theileria/isolamento & purificação , Theileriose/epidemiologia , Animais , Antiprotozoários/uso terapêutico , Feminino , Doenças dos Cavalos/tratamento farmacológico , Doenças dos Cavalos/parasitologia , Doenças dos Cavalos/transmissão , Cavalos , Imidocarbo/análogos & derivados , Imidocarbo/uso terapêutico , Reação em Cadeia da Polimerase , Fatores de Risco , Theileriose/parasitologia , Theileriose/transmissão , Estados Unidos/epidemiologiaRESUMO
CASE DESCRIPTION: A 7-year-old Quarter Horse gelding was hospitalized in Ocala, Fla, because of lethargy, fever, anorexia, and swelling of distal aspects of the limbs. A tentative diagnosis of equine piroplasmosis (EP) was made on the basis of examination of a blood smear. The case was reported to the Florida State Veterinarian, and infection with Babesia equi was confirmed. The subsequent investigation included quarantine and testing of potentially exposed horses for B equi and Babesia caballi infections, tick surveillance, and owner-agent interviews. CLINICAL FINDINGS: 210 horses on 25 premises were tested for infection with EP pathogens. Twenty B equi-infected horses on 7 premises were identified; no horses tested positive for B caballi. Seven horses, including the index case, had clinical findings consistent with EP Dermacentor variabilis was considered the only potential tick vector for B equi collected, and all D variabilis specimens tested negative for Babesia organisms via PCR assay. Results of the epidemiological investigation suggested that B equi was spread by use of shared needles and possibly blood transfusions. All horses that tested positive were involved in nonsanctioned Quarter Horse racing, and management practices were thought to pose substantial risk of transmission of blood-borne pathogens. TREATMENT AND OUTCOME: Final outcome of B equi-infected horses was euthanasia, death from undetermined causes, or shipment to a US federal research facility. CLINICAL RELEVANCE: This investigation highlights the importance of collaboration between private veterinary practitioners, state veterinary diagnostic laboratories, and regulatory officials in the recognition, containment, and eradication of foreign animal disease.