versão On-line ISSN 1984-2961
Rev. Bras. Parasitol. Vet. (Online) vol.17 no.2 Jaboticabal abr./jun. 2008
Tripanosomatídeos similares a Trypanosoma theileri no carrapato dos bovinos Boophilus microplus
João Ricardo MartinsI; Romário C. LeiteII; Rovaina L. DoyleI
IInstituto de Pesquisas Veterinárias Desidério Finamor/Fundação Estadual de Pesquisa Agropecuária, Estrada do Conde, 6000, Caixa Postal 47, Eldorado do Sul, RS 92990-000, Brasil. E-mail:email@example.com
IIDepartamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6.627, Caixa postal 567, Campus Pampulha, Belo Horizonte, MG 31270-901
Findings of epimastigotes forms of a tripanosomatide is reported in the hemolymph of the cattle tick Boophilus microplus in the state of Rio Grande do Sul, southern Brazil. Morphological evidences suggest they are similar to Trypanosoma theileri, a species described as non pathogenic to cattle, and usually transmitted by tabanids.
Keywords: Trypanosoma, hemolymph, Boophilus microplus.
Descreve-se a ocorrência de formas epimastigotas de um tripanosomatideo na hemolinfa do carrapato do bovino Boophilus microplus no Estado do Rio Grande do Sul. Evidências morfológicas sugerem tratar-se de Trypanosoma theileri , espécie descrita como não patogênica aos bovinos e que usualmente é transmitida por tabanídeos.
Palavras-chave: Trypanosoma , hemolinfa, Boophilus microplus
Flagelate forms of a Trypanosoma sp. showing kinetoplast close or in front of the nucleus, a short ondulant membrane and free flagellum were found in a strain of the cattle tick Boophilus microplus, collected in Guaiba (30 01' 53" S, 51 13' 19" W), state of Rio Grande do Sul, southern Brazil (Figure 1). Examinations were carried out on hemolymph smears of Boophilus females 10 days after dropping, collected by separation of the metatarsal-tarsal joint, fixed with methanol, stained by Giemsa and visualized under oil immersion (1000x). Trypanosomes were not seen in squashed eggs from this infected strain of Boophilus. Forms of T. theileri in Brazil were detected in blood smears of naturally infected cattle in the states of São Paulo, Mato Grosso do Sul, Rio de Janeiro, Pará and Rio Grande do Sul. This hemoflagellate usually shows a very low parasitaemia which make its visualization difficult. Identification of this tick strain infected with this hemoflagelate (which usually lives in the bovine blood stream without showing pathogenicity), caused some concern, since very few reports of ticks as vectors of trypanosomes have been reported in South America (RIBEIRO et al., 1988). Suggestion of the hemolymph of ticks acting as a culture medium for T. theileri was presented by Hoare (1972). Usually hematophagous insects (like tabanids) are incriminated as vector of trypanosomiasis. Morzaria et al. (1986) showed some evidence of the transmission of T. theileri to cattle by Hyalomma anatolicum anatolicum. It was assumed that the source of contamination of this Boophilus strain was the cattle, although there were no reports of contaminated herds suffering from acute trypanosomiasis or other hemoparasitic diseases. Babesiosis and anaplasmosis are considered enzootic in this region. These trypanosomes are currently classified within the group Lewisi, together with T. lewisi and T. melophagium, and are not considered pathogenic for mammals. In Argentina, Gaido et al. (1989) reported a trypanosomatides like T. theileri in B. microplus ticks, not detecting any harmful effect on bovine herd production caused by this protozoan. On the other hand, it may be speculated that the presence of T. theileri in the same vector for bovine babesiosis (i.e. Babesia bovis and B. bigemina) could rise misinterpretations in some diagnostic tests. The finding of B. microplus bearing epimastigote forms of this trypanosome indicates the diversity of invertebrate hosts which can be used by them in order to survive. Nevertheless, the precise role for the tick B. microplus as vector of this protozoan needs further investigation, since no evidence of transovarian transmission was detected despite the observation of trypanosomes in the tick hemolymph.
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Received on September 11, 2007.
Accepted for publication on June 30, 2008.