Protection in the absence of exclusion between two Brazilian isolates of Anaplasma marginale in experimentally infected calves

The seroprevalence of Anaplasma marginale, Babesia bigemina, Babesia bovis and Trypanosoma vivax and the risk factors for these infections were investigated in 509 cows on 37 farms in the semiarid region of Paraíba, northeastern Brazil. Cow serum samples were tested by means of immunofluorescence assay (IFA) against each specific antigen. The mean seroprevalence values per farm were 15.0% (range: 0-75%) for A. marginale, 9.5% (range: 0-40%) for B. bigemina and 26.9% (range: 0-73.7%) for B. bovis. All cows tested negative for T. vivax. Higher prevalence for A. marginale was significantly associated with less frequent acaricide spraying per year and with higher use of injectable antihelminthics. Presence of cows positive for B. bigemina was significantly associated with acaricide use and with presence of horse flies on the farm. Both occurrence and higher prevalence of B. bovis were significantly associated with recent observations of ticks on cattle. Overall, the present results indicate that the region investigated is an enzootically unstable area for A. marginale, B. bigemina and B. bovis, since most animals were seronegative to at least one agent.Keywords: Anaplasma marginale, Babesia bigemina, Babesia bovis, cattle, risk factors, Brazil. ResumoA soroprevalência de Anaplasma marginale, Babesia bigemina, Babesia bovis e Trypanosoma vivax, assim como os fatores de risco para estas infecções, foram investigadas em 37 fazendas (total de 509 vacas) da região semiárida da Paraíba, nordeste do Brasil. A presença de anticorpos nos soros dos animais foi detectada pela técnica de imunofluorescência indireta, utilizando antígenos específicos. Os valores médios de soroprevalência por fazenda foram 15,0% (0-75%) para A. marginale, 9,5% (0-40%) para B. bigemina, e 26,9% (0-73,7%) para B. bovis. Todas as vacas foram soronegativas para T. vivax. As maiores prevalências de A. marginale foram significativamente associadas com menor uso de carrapaticidas por ano e com uso mais frequente de antihelmínticos injetáveis. A soroprevalência de B. bigemina foi significativamente associada com o uso de carrapaticidas, e com a presença de mutucas na fazenda. Tanto a ocorrência como a maior soroprevalência para B. bovis nas fazendas foram significativamente associadas com a presença recente de carrapatos nos bovinos. No geral, os resultados indicam que as fazendas amostradas estão situadas em área de instabilidade enzoótica para A. marginale, B. bigemina, e B. bovis, uma vez que a maioria dos animais foi soronegativa para pelo menos um dos agentes.Palavras-chave: Anaplasma marginale, Babesia bigemina, Babesia bovis, bovino, fatores de risco, Brasil.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Seroprevalence and risk factors for cattle anaplasmosis, babesiosis, and trypanosomiasis in a Brazilian semiarid region

Costa

Ribeiro

Duarte

et al. 2013

“…The UFMG2 isolate has been demonstrated to present high virulence, causing clinical disease in young and adult animals with an incubation period of 21 days (BASTOS et al, 2010). However, challenge with a single dose of a high concentration of erythrocytes from a virulent isolate does not mimic natural infections in which animals are continuously exposed to low concentrations for long periods of time (PACHECO et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Evaluating the effectiveness of an inactivated vaccine from Anaplasma marginale derived from tick cell culture

Lasmar

Carvalho

Filho

et al. 2012

The protective efficacy of an inactivated vaccine from Anaplasma marginale that was cultured in tick cells (IDE8) for use against bovine anaplasmosis was evaluated. Five calves (Group 1) were inoculated subcutaneously, at 21-day intervals, with three doses of vaccine containing 3 × 10(9) A. marginale initial bodies. Five control calves received saline solution alone (Group 2). Thirty-two days after the final inoculation, all the calves were challenged with approximately 3 × 10(5) erythrocytes infected with A. marginale high-virulence isolate (UFMG2). The Group 1 calves seroconverted 14 days after the second dose of vaccine. After the challenge, all the animals showed patent rickettsemia. There was no significant difference (p > 0.05) between the Group 1 and 2 calves during the incubation period, patency period or convalescence period. All the animals required treatment to prevent death. The results suggest that the inactivated vaccine from A. marginale produced in IDE8 induced seroconversion in calves, but was not effective for preventing anaplasmosis induced by the UFMG2 isolate under the conditions of this experiment.

“…All animals were inoculated intravenously with 3.6 × 10 7 erythrocytes parasitized with UFMG2 isolate, a highly virulent sample of A. marginale (Genbank nº EU676175) causing high morbidity and mortality rates in susceptible cattle (BASTOS et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

Effectiveness of enrofloxacin for the treatment of experimentally-induced bovine anaplasmosis

Facury-Filho

Carvalho

Ferreira

et al. 2012

Four groups of six Holstein calves were inoculated with 3.6 × 10 7 erythrocytes parasitized with Anaplasma marginale. The criteria for treatment of calves were increasing A. marginale rickettsemia and 30% reduction of baseline packed cell volume (PCV) of each animal. Group 1 (G1) received 7.5 mg.kg -1 of enrofloxacin in a single dose; Group 2 (G2) 7.5 mg.kg -1 of enrofloxacin twice every three days; Group 3 (G3) 20 mg.kg -1 of long-acting oxytetracycline in a single dose; and Group 4 (G4) a single dose of PBS. Physical examinations, blood smears and PCV were performed daily. On day treatment, G1, G2 and G3 animals had a mean rickettsemia of 17, 23 and 12%, respectively. At 2 days after treatment (DAT) G1 and G2 animals showed a significant reduction of rickettsemia (p < 0.05) compared to G3. G3 animals had high rates of rickettsemia in the first 2 DAT and a slow decrease until stabilization on 9 DAT. The mean PCV in G1 and G2 increased and stabilized after 7 and 8 DAT, respectively. PCV stabilization was achieved in G3 at 13 DAT. Both enrofloxacin and oxytetracycline were effective for the treatment of anaplasmosis, but enrofloxacin was faster reduction of rickettsemia and PCV recuperation (p < 0.05) compared to oxytetracycline Keywords: Anaplasma marginale, enrofloxacin, treatment. ResumoQuatro grupos de seis bezerros da raça Holandesa foram inoculados com 3,6 × 10 7 eritrócitos parasitados com Anaplasma marginale. Os critérios para o tratamento dos bezerros foram aumento da rickettsemia do A. marginale e redução de 30% do valor basal de volume globular (VG) de cada animal. O Grupo 1 (G1) recebeu 7,5 mg.kg -1 de enrofloxacina em dose única; o Grupo 2 (G2), 7,5 mg.kg -1 de enrofloxacina duas vezes a cada três dias; o Grupo 3 (G3), 20 mg.kg -1 de oxitetraciclina de longa ação em dose única; e o Grupo 4 (G4) uma única dose de PBS. Exames físicos, esfregaço sanguíneo e VG foram realizadas diariamente. No dia do tratamento, os animais G1, G2 e G3 apresentaram rickettsemia média de 17, 23 e 12%, respectivamente. Nos primeiros 2 dias após o tratamento (DAT) os animais do G1 e G2 mostraram uma redução significativa de rickettsemia (p < 0,05) em relação ao G3. Animais do G3 tiveram altas taxas de rickettsemia nos 2 DAT e uma diminuição lenta até à estabilização em 9 de DAT. O VG médio no G1 e G2 aumentou e estabilizou após 7 e 8 DAT, respectivamente. A estabilização do VG do G3 foi aos 13 DAT. A enrofloxacina e a oxitetraciclina foram efetivas no tratamento da anaplasmose, mas a enrofloxacina apresentou redução da rickettsemia e recuperação do VG (p < 0,05) mais rápida em comparação com oxitetraciclina.Palavras-chave: Anaplasma marginale, enrofloxacina, tratamento.