Partial selective treatment of Rhipicephalus microplus and breed resistance variation in beef cows in Rio Grande do Sul, Brazil.

Rhipicephalus microplus infestation causes heavy losses in cattle. The majority of farmers control the cattle tick by using long-acting drugs throughout the year, which evidently increases selection pressure for drug resistance. Partial selective treatment (PST) may be used to directly reduce selection pressure by treating only the portion of the herd that is most infested. The objective of this work was to determine the effect of PST in two herds of beef cows and the effect of breed tolerance. The Santiago (n=306 animals) and the São Francisco de Assis (n=204 animals) herds were composed of up to eight pure breeds of Bos taurus and Bos indicus and their crosses and were evaluated during the first and second (8 months) tick generations. Ticks larger than 4.5mm were counted on one side of the animal, and the animals were treated when numbers exceeded 20 ticks per host. On both farms, the tick-tolerant breeds with a high proportion of B. indicus (Braford, Brangus, and Nellore) consistently carried fewer ticks than Charolais. The economical evaluation showed an average profit margin in the use of PST of 674.25% and 1394.5% on the Santiago and São Francisco de Assis farms, respectively, in comparison to all-herd treatment. These results indicate that PST is a reliable tool for health management and may be used as a standard protocol for tick control with significant economic benefits on farms. In addition, the maintenance of the highest possible tolerant/resilient breeds is also an essential factor that should be considered in today's more sustainable animal production systems.

Challenges of nematode control in ruminants: focus on Latin America.

Gastrointestinal nematodes (GIN) of ruminants (cattle, sheep and goats) are ubiquitous and can cause severe injuries to infected animals and significant losses in farming revenues. GIN are able to survive severe environmental and host conditions, but mankind has developed a number of ingenious methods for parasite control. The commerce and use of modern anthelmintic drugs with a broad spectrum of activity has been a solid tool for nearly 40 years, however the continuous use of these drugs, has led to the selection of populations of drug-resistant worms worldwide. At present, the ever-growing agricultural systems in Latin America are facing many challenges and cannot rely on the far-reaching objective of parasitic elimination from the host or the environment. The lack of extensive programs for monitoring drug resistance exacerbates the negative consequences of reduced efficacy, which is evident in some areas with the increase in mortality rate even after treatment. Experts agree that new schemes of parasitic control are needed and should be based on the strategy of targeted selective treatment where affected hosts are identified and treated accordingly. In this article, we will focus our discussion on the challenges for the control of GIN in Latin America by 2020 imposed by reduced drug efficacy. We will evaluate phenotypic and molecular markers, methods for single-animal evaluation, and the implementation of schemes for anthelmintic treatment that address parasites in refugia.

Brazilian spotted fever in dogs / Febre maculosa brasileira em cães

Brazilian spotted fever (BSF) is caused by bacteria Rickettsia rickettsii, highly pathogenic for humans and dogs, and has the Amblyomma cajennense tick as its main vector. Dogs maybe have a significantly participation on the BSF epidemiology, particularly in urban areas, due to the close contact with human beings. Several serologic studies in dogs from different Brazilian regions have indicated a previous contact of these animals with the R. rickettsii, and they are even considered as sentinels for the bacteria distribution. Although dogs are susceptible to R. rickettsii infection, the clinical disease in dogs has been very recently described in Brazil. Common signs of infection may include fever, depression, anorexia, ocular lesions, hemorrhagic petechiaes, anemia and thrombocytopenia, which also may appear in other diseases, such as the canine monocytic ehrlichiosis, considered the most common disease in dogs transmitted by ticks in Brazil. Thus, BSF clinical diagnosis in dogs may be confused by other diseases, causing its sub-notification. The aim of the present review article on BSF in dogs was to describe epidemiologic, clinical and diagnosis aspects, including also the main alternatives for its treatment and control.

A febre maculosa brasileira (FMB) é causada pela bactéria Rickettsia rickettsii, cuja patogenicidade é conhecida para seres humanos e cães, e o carrapato Amblyomma cajennense é tido como seu principal vetor. Os cães podem ter um papel significativo na epidemiologia da FMB devido ao próximo contato com seres humanos. Vários estudos sorológicos em cães em diferentes estados brasileiros indicaram um contato prévio destes animais com a R. rickettsii, sendo inclusive considerados sentinelas para a circulação da bactéria. Apesar de serem susceptíveis à infecção por R. rickettsii, a doença clínica em cães foi relatada apenas recentemente no Brasil, onde observaram-se sinais comuns da infecção, como febre, anorexia, letargia, anemia e trombocitopenia, os quais também podem ser encontrados em outras enfermidades, como a erliquiose monocítica canina, considerada a mais comum das doenças transmitidas por carrapatos em cães no país. Deste modo, o diagnóstico clínico de FMB em cães pode ser confundido com o de outras enfermidades, causando sua subnotificação. Além disso, a observação de sinais oculares em um cão infectado experimentalmente com cepa brasileira de R. rickettsii e sinais neurológicos em outro diagnosticado com FMB sugere que a doença seja semelhante à que ocorre nos Estados Unidos, onde tem sido predominantemente relatada. O objetivo do presente artigo de revisão sobre FMB em

Brazilian spotted fever in dogs / Febre maculosa brasileira em cães

Brazilian spotted fever (BSF) is caused by bacteria Rickettsia rickettsii, highly pathogenic for humans and dogs, and has the Amblyomma cajennense tick as its main vector. Dogs maybe have a significantly participation on the BSF epidemiology, particularly in urban areas, due to the close contact with human beings. Several serologic studies in dogs from different Brazilian regions have indicated a previous contact of these animals with the R. rickettsii, and they are even considered as sentinels for the bacteria distribution. Although dogs are susceptible to R. rickettsii infection, the clinical disease in dogs has been very recently described in Brazil. Common signs of infection may include fever, depression, anorexia, ocular lesions, hemorrhagic petechiaes, anemia and thrombocytopenia, which also may appear in other diseases, such as the canine monocytic ehrlichiosis, considered the most common disease in dogs transmitted by ticks in Brazil. Thus, BSF clinical diagnosis in dogs may be confused by other diseases, causing its sub-notification. The aim of the present review article on BSF in dogs was to describe epidemiologic, clinical and diagnosis aspects, including also the main alternatives for its treatment and control.

A febre maculosa brasileira (FMB) é causada pela bactéria Rickettsia rickettsii, cuja patogenicidade é conhecida para seres humanos e cães, e o carrapato Amblyomma cajennense é tido como seu principal vetor. Os cães podem ter um papel significativo na epidemiologia da FMB devido ao próximo contato com seres humanos. Vários estudos sorológicos em cães em diferentes estados brasileiros indicaram um contato prévio destes animais com a R. rickettsii, sendo inclusive considerados sentinelas para a circulação da bactéria. Apesar de serem susceptíveis à infecção por R. rickettsii, a doença clínica em cães foi relatada apenas recentemente no Brasil, onde observaram-se sinais comuns da infecção, como febre, anorexia, letargia, anemia e trombocitopenia, os quais também podem ser encontrados em outras enfermidades, como a erliquiose monocítica canina, considerada a mais comum das doenças transmitidas por carrapatos em cães no país. Deste modo, o diagnóstico clínico de FMB em cães pode ser confundido com o de outras enfermidades, causando sua subnotificação. Além disso, a observação de sinais oculares em um cão infectado experimentalmente com cepa brasileira de R. rickettsii e sinais neurológicos em outro diagnosticado com FMB sugere que a doença seja semelhante à que ocorre nos Estados Unidos, onde tem sido predominantemente relatada. O objetivo do

Serological survey of Rickettsia sp. in horses and dogs in a non-endemic area in Brazil.

Brazilian Spotted Fever (BSF) is a lethal rickettsiosis in humans caused by the bacteria Rickettsia rickettsii, and is endemic in some areas of Brazil. Horses and dogs are part of the disease's life cycle and they may also serve as sentinel animals in epidemiological studies. The first human BSF case in the State of Paraná was reported in 2005. The present study was conducted in the municipality of Almirante Tamandaré, where no previous case of BSF was reported. Serum samples were collected from 71 horses and 20 dogs from nine properties in the area. Ticks were also collected from these animals. All farmers completed a questionnaire about their knowledge of BSF and animal health management. Serum samples were analyzed by indirect immunofluorescent-antibody assay (IFA) using R. rickettsii and R. parkeri as antigens. Ticks were analyzed by PCR for Rickettsia sp., and all of them were PCR-negative. Six horses (8.45%) and 4 dogs (20%) were identified as seropositive. Farmers were not aware of the correlation between the presence of ticks and risk of BSF. Although a non-endemic area, Almirante Tamandaré is a vulnerable environment for BSF and effective tick control measures are required.

Seroprevalence of Rickettsia bellii and Rickettsia felis in dogs, São José dos Pinhais, State of Paraná, Brazil.

Brazilian spotted fever (BSF) is a vector-borne zoonosis caused by Rickettsia rickettsii bacteria. Dogs can be host sentinels for this bacterium. The aim of the study was to determine the presence of antibodies against Rickettsia spp. in dogs from the city of São José dos Pinhais, State of Paraná, Southern Brazil, where a human case of BSF was first reported in the state. Between February 2006 and July 2007, serum samples from 364 dogs were collected and tested at 1:64 dilutions by indirect immunofluorescence assay (IFA) against R. rickettsii and R. parkeri. All sera that reacted at least to one of Rickettsia species were tested against the six main Rickettsia species identified in Brazil: R. rickettsii, R. parkeri, R. bellii, R. rhipicephali, R. amblyommii and R. felis. Sixteen samples (4.4%) reacted to at least one Rickettsia species. Among positive animals, two dogs (15.5%) showed suggestive titers for R. bellii exposure. One sample had a homologous reaction to R. felis, a confirmed human pathogen. Although Rickettsia spp. circulation in dogs in the area studied may be considered at low prevalence, suggesting low risk of human infection, the present data demonstrate for the first time the exposure of dogs to R. bellii and R. felis in Southern Brazil.

Serological survey of Rickettsia sp. in horses and dogs in an non-endemic area in Brazil / Identificação sorológica de Rickettsia sp. em equinos e cães de área não endêmica no Brasil

Brazilian Spotted Fever (BSF) is a lethal rickettsiosis in humans caused by the bacteria Rickettsia rickettsii, and is endemic in some areas of Brazil. Horses and dogs are part of the disease's life cycle and they may also serve as sentinel animals in epidemiological studies. The first human BSF case in the State of Paraná was reported in 2005. The present study was conducted in the municipality of Almirante Tamandaré, where no previous case of BSF was reported. Serum samples were collected from 71 horses and 20 dogs from nine properties in the area. Ticks were also collected from these animals. All farmers completed a questionnaire about their knowledge of BSF and animal health management. Serum samples were analyzed by indirect immunofluorescent-antibody assay (IFA) using R. rickettsii and R. parkeri as antigens. Ticks were analyzed by PCR for Rickettsia sp., and all of them were PCR-negative. Six horses (8.45 percent) and 4 dogs (20 percent) were identified as seropositive. Farmers were not aware of the correlation between the presence of ticks and risk of BSF. Although a non-endemic area, Almirante Tamandaré is a vulnerable environment for BSF and effective tick control measures are required.

A Febre Maculosa Brasileira (FMB) é uma riquetsiose letal para humanos, causada pela bactéria Rickettsia rickettsii, e é endêmica em algumas regiões brasileiras. Equinos e cães podem participar do ciclo da doença e podem também servir como sentinelas em estudos epidemiológicos. O primeiro caso humano relatado no Estado do Paraná ocorreu em 2005. O presente estudo foi realizado no município de Almirante Tamandaré, região onde não há relatos de casos de FMB. Foram coletadas amostras de sangue de 71 cavalos e 20 cães em nove propriedades rurais na região. Carrapatos também foram colhidos dos animais. Todos os proprietários responderam a um questionário sobre o manejo sanitário dos animais e o conhecimento a respeito da FMB. As amostras de soro foram processadas pela técnica de Reação de Imunofluorescência Indireta (RIFI), utilizando-se os antígenos de R. rickettsii e R. parkeri. Os carrapatos foram analisados por PCR para Rickettsia sp. e todos foram negativos. Seis cavalos (8,45 por cento) e 4 cães (20 por cento) foram identificados como soropositivos. Todos os proprietários desconheciam a relação de carrapatos com a FMB. Embora considerada uma área não endêmica, Almirante Tamandaré é um ambiente vulnerável à FMB e um controle eficiente de carrapatos deve ser implementado.

Seroprevalence of Rickettsia bellii and Rickettsia felis in dogs, São José dos Pinhais, State of Paraná, Brazil / Soroprevalência de Rickettsia bellii e Rickettsia felis em cães, São José dos Pinhais, Paraná, Brasil

Brazilian spotted fever (BSF) is a vector-borne zoonosis caused by Rickettsia rickettsii bacteria. Dogs can be host sentinels for this bacterium. The aim of the study was to determine the presence of antibodies against Rickettsia spp. in dogs from the city of São José dos Pinhais, State of Paraná, Southern Brazil, where a human case of BSF was first reported in the state. Between February 2006 and July 2007, serum samples from 364 dogs were collected and tested at 1:64 dilutions by indirect immunofluorescence assay (IFA) against R. rickettsii and R. parkeri. All sera that reacted at least to one of Rickettsia species were tested against the six main Rickettsia species identified in Brazil: R. rickettsii, R. parkeri, R. bellii, R. rhipicephali, R. amblyommii and R. felis. Sixteen samples (4.4 percent) reacted to at least one Rickettsia species. Among positive animals, two dogs (15.5 percent) showed suggestive titers for R. bellii exposure. One sample had a homologous reaction to R. felis, a confirmed human pathogen. Although Rickettsia spp. circulation in dogs in the area studied may be considered at low prevalence, suggesting low risk of human infection, the present data demonstrate for the first time the exposure of dogs to R. bellii and R. felis in Southern Brazil.

A febre maculosa brasileira (FMB) é uma zoonose veiculada por carrapatos e causada pela bactéria Rickettsia rickettsii, podendo os cães ser hospedeiros sentinelas para essa bactéria. O objetivo do estudo foi determinar a presença de anticorpos contra Rickettsia spp. em cães de São José dos Pinhais, estado do Paraná, Sul do Brasil. Entre fevereiro de 2006 e julho de 2007, amostras séricas de 364 cães foram coletadas e testadas na diluição de 1:64 por Reação de Imunofluorescência Indireta (RIFI) contra R. rickettsii e R. parkeri. Todos os soros reagentes para pelo menos uma espécie de Rickettsia foram testados contra as seis principais espécies de Rickettsia identificadas no Brasil: R. rickettsii, R. parkeri, R. bellii, R. rhipicephali, R. amblyommii e R. felis. Dezesseis amostras (4,4 por cento) reagiram para pelo menos uma espécie de Rickettsia. Dos animais positivos, dois cães (15,5 por cento) apresentaram títulos sugestivos de exposição a R. bellii. Uma amostra apresentou reação homóloga frente à R. felis, um agente patogênico confirmado para seres humanos. Muito embora os resultados demonstrem uma baixa prevalência de Rickettsia spp. em cães, sugerindo um baixo risco de infecção humana, este estudo relatou pela primeira vez a evidência de exposição a R. bellii e R. felis em cães no Sul do Brasil.