Romário Cerqueira Leite

Reassessment of the potential economic impact of cattle parasites in Brazil

The profitability of livestock activities can be diminished significantly by the effects of parasites. Economic losses caused by cattle parasites in Brazil were estimated on an annual basis, considering the total number of animals at risk and the potential detrimental effects of parasitism on cattle productivity. Estimates in U.S. dollars (USD) were based on reported yield losses among untreated animals and reflected some of the effects of parasitic diseases. Relevant parasites that affect cattle productivity in Brazil, and their economic impact in USD billions include: gastrointestinal nematodes -

Detection of Rickettsia rickettsii in the tick Amblyomma cajennense in a new Brazilian spotted fever-endemic area in the state of Minas Gerais

7.11; cattle tick (Rhipicephalus (Boophilus) microplus) -

Efeito acaricida de óleos essenciais e concentrados emulsionáveis de Eucalyptus spp em Boophilus microplus

3.24; horn fly (Haematobia irritans) -

Coxiella symbiont in the tick Ornithodoros rostratus (Acari: Argasidae)

2.56; cattle grub (Dermatobia hominis) -

Identification of Some Chemical Components of the Essential Oil from Molasses Grass (Melinis minutiflora Beauv.) and their Activity Against Cattle-Tick (Boophilus microplus)

0.38; New World screwworm fly (Cochliomyia hominivorax) -

Human ehrlichioses in Brazil : first suspect cases.

0.34; and stable fly (Stomoxys calcitrans) -

Host Specificity of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) with Comments on the Drop-off Rhythm

0.34. The combined annual economic loss due to internal and external parasites of cattle in Brazil considered here was estimated to be at least USD 13.96 billion. These findings are discussed in the context of methodologies and research that are required in order to improve the accuracy of these economic impact assessments. This information needs to be taken into consideration when developing sustainable policies for mitigating the impact of parasitism on the profitability of Brazilian cattle producers.

Percepção dos produtores de leite do município de Passos, MG, sobre o carrapato Boophilus microplus (Acari: Ixodidae), 2001

The present study evaluated rickettsial infection in Amblyomma spp. ticks collected in a farm in Coronel Pacheco, a Brazilian spotted fever (BSF) endemic area. A total of 78 A. cajennense and 78 A. dubitatum free-living adult ticks were collected and tested by polymerase chain reaction (PCR) targeting a fragment of the rickettsial gene gltA. Only one pool of three A. cajennense ticks showed the expected product by PCR. This pool was further tested by PCR using sets of primers targeting the rickettsial genes gltA, ompA, and ompB. All reactions yielded the expected bands that by sequencing, showed 100% identity to the corresponding sequences of the Rickettsia rickettsii gene fragments gltA (1063-bp), ompA (457-bp), and ompB (720-bp). The minimal infection rate of R. rickettii in the A. cajennense population was 1.28% (at least one infected tick within 78 ticks). The present study showed molecular evidence for the presence of R. rickettsii in A. cajennense from a BSF-endemic area in Coronel Pacheco, state of Minas Gerais. Although R. rickettsii has been previously reported infecting A. cajennense ticks in Brazil and other Latin American countries, the present study performed the first molecular characterization of R. rickettsii from the tick A. cajennense.

Life cycle of the tick Haemaphysalis leporis-palustris (Acari: Ixodidae) under laboratory conditions

Realizou-se um estudo sobre a acao biocida de Eucalyptus citriodora, Eucalyptus globulus e Eucalyptus staigeriana no carrapato Boophilus microplus, buscando-se a producao de acaricidas menos agressivos ao meio ambiente. Os oleos essenciais das tres especies e os concentrados emulsionaveis de E. globulus e E. staigeriana foram testados em cinco concentracoes diferentes contra larvas e femeas ingurgitadas de B. microplus. Os oleos foram submetidos a analise por cromatografia gasosa acoplada a espectrometria de massas (CG/EM), a fim de se investigar sua composicao. O citronelal e o principal componente do oleo de E. citriodora, sendo responsavel por sua acao acaricida. O mesmo ocorre com o 1,8-cineol em E. globulus. Em E. staigeriana existem varias substâncias que agem sinergicamente contra B. microplus. O oleo essencial de E. citriodora matou 100% dos carrapatos a uma concentracao media de 17,5%, o de E. globulus a 15% e o de E. staigeriana a 12,5%. Os concentrados emulsionaveis de E. globulus mataram 100% dos carrapatos a uma concentracao media de 9,9% e o de E. staigeriana a uma concentracao de 3,9%. O desenvolvimento de produtos que possam ser testados a campo e comercializados a precos competitivos serao passos a serem seguidos. Os biocarrapaticidas tem um apelo comercial grande, permitindo controlar B. microplus de um modo menos agressivo ao meio ambiente.

Rickettsioses emergentes e reemergentes numa região endêmica do Estado de Minas Gerais, Brasil

In the present study, the presence of tick-associated bacteria and protozoa in Ornithodoros rostratus ticks (adults, nymphs, and eggs) from the Pantanal region of Brazil were determined by molecular detection. In these ticks, DNA from protozoa in the genera Babesia and Hepatozoon, and bacteria from the genera Rickettsia, Borrelia, Anaplasma, and Ehrlichia were not detected. Conversely, all tested ticks (100%) yielded PCR products for 3 Coxiella genes (16S rRNA, pyrG, cap). PCR and phylogenetic analysis of 3 amplified genes (16S rRNA, pyrG, cap) demonstrated that the agent infecting O. rostratus ticks was a member of the genus Coxiella. This organism grouped with Coxiella symbionts of other soft tick species (Argasidae), having different isolates of C. burnetii as a sister group, and these 2 groups formed a clade that grouped with another clade containing Coxiella symbionts of hard tick species (Ixodidae). Analysis of tick mitochondrial 16S rRNA gene database composed mostly of tick species previously shown to harbor Coxiella symbionts suggests a phylogenetic congruence of ticks and their Coxiella symbionts. Furthermore, these results suggest a very long period of coevolution between ticks and Coxiella symbionts and indicates that the original infection may have occurred in an ancestor common to the 2 main tick families, Argasidae (soft ticks) and Ixodidae (hard ticks). However, this evolutionary relationship must be confirmed by more extensive testing of additional tick species and expanded populations.