Susceptibility among breeds of sheep experimentally infected with Leptospira interrogans Pomona serogroup.

Leptospirosis is a disease that negatively affects the productive and reproductive indices of ruminants. Sheep are considered highly resistant to infection, although susceptibility may vary among breeds. Thus, the aim of the present study was to analyze the susceptibility between sheep breeds to the experimental infection by leptospires of the Pomona serogroup. Pomona serogroup, Kennewicki serovar strain (1 × 107 bacteria) was inoculated via the conjunctival route in 12 sheep divided into two groups, one comprising Santa Inês ewes and the other comprising crossbred sheep. In each group, five ewes were challenged with the bacterial strain and one was used as control. All sheep were monitored for 60 days, during which blood samples were collected for serological diagnosis and urine and vaginal fluid samples for molecular and microbiological analyses. Finally, as ewes were submitted to euthanasia and necropsy, some tissues of interest were collected for microbiological, molecular, and histopathological diagnoses. The groups were compared regarding the number of positive reactions according to diagnostic tests. All sheep in each group presented antibodies to Leptospira in all serological analyses, except animals of the control group. However the Santa Inês sheep presented higher concentration and duration of the titers, and their positive reactions were detected earlier than those in crossbred sheep. The antibody titers in group A (median 200, geometric mean 317.48) were significantly different from the group B (median 800, geometric mean 918.96) at D60 post-infection (P = 0,032). The Santa Inês sheep presented a higher number of positive reactions than did the crossbred sheep in the molecular diagnostic tests. According to the molecular diagnosis, the Santa Inês sheep presented more reactions (urine and vaginal fluid) compared to crossbred ewes, but there was no predominance in the detection of leptospiral DNA when comparing urine and vaginal fluid results, nor even between the number of positive kidneys and uterus. The Santa Inês sheep presented a higher number of positive bacteriological cultures. No sheep in either group presented alterations in anatomopathological and histopathological findings. Pure-bred sheep may be more susceptible than crossbred sheep to infection by Leptospira sp. Our findings emphasize the importance of the genital tract as a site of extraurinary infection and indicate the possibility of venereal transmission in the species.

Ehrlichia canis and Rickettsia spp. in dogs from urban areas in Paraiba state, northeastern Brazil

Abstract The aims of our study was to identify Ehrlichia canis and antibodies against Rickettsia spp. belonging to the spotted fever group (SFG) in dogs sampled from Paraiba state, northeastern Brazil. Blood and serum samples collected by convenience from dogs in urban areas of five municipalities were analyzed by real-time PCR for the detection of E. canis DNA and by immunofluorescence assay test (IFAT) for the identification of antibodies against Rickettsia rickettsii, R. felis, R. parkeri, R. amblyommii and R. rhipicephali antigens. E. canis DNA was detected in 8.9% (64/719) of the blood samples, whereas 5.63% (43/763) of the serum samples were positive for at least one of the Rickettsia antigens tested by IFAT. This study showed for the first time the occurrence of E. canis and suggested the circulation of SFG Rickettsia in dogs in the study region of Paraiba state, northeastern Brazil.

Resumo Os objetivos do nosso estudo foram identificar Ehrlichia canis e anticorpos contra Rickettsia spp. pertencentes ao Grupo da Febre Maculosa (GFM) em cães amostrados no estado da Paraíba, nordeste do Brasil. As amostras de sangue e soro, coletados por conveniência, de cães em áreas urbanas de cinco municípios foram analisadas por PCR em tempo real para a detecção de DNA de E. canis e pela Reação de Imunofluorescência Indireta (RIFI) para identificação de anticorpos contra Rickettsia rickettsii, R. felis, R. parkeri, R. amblyommii e R. rhipicephali. O DNA de E. canis foi detectado em 8,9% (64/719) das amostras de sangue, enquanto que 5,63% (43/763) das amostras de soro foram positivas para pelo menos um dos antígenos de Rickettsia testados por RIFI. Este estudo mostrou pela primeira vez a ocorrência de E. canis e sugere a circulação de Rickettsia do GFM em cães na região em estudo do estado da Paraíba, Nordeste do Brasil.

Use of transgenic Aedes aegypti in Brazil: risk perception and assessment.

The OX513A strain of Aedes aegypti, which was developed by the British company Oxitec, expresses a self-limiting transgene that prevents larvae from developing to adulthood. In April 2014, the Brazilian National Technical Commission on Biosafety completed a risk assessment of OX513A and concluded that the strain did not present new biological risks to humans or the environment and could be released in Brazil. At that point, Brazil became the first country to approve the unconstrained release of a genetically modified mosquito. During the assessment, the commission produced a comprehensive list of - and systematically analysed - the perceived hazards. Such hazards included the potential survival to adulthood of immature stages carrying the transgene - should the transgene fail to be expressed or be turned off by exposure to sufficient environmental tetracycline. Other perceived hazards included the potential allergenicity and/or toxicity of the proteins expressed by the gene, the potential for gene flow or increased transmission of human pathogens and the occupation of vacant breeding sites by other vector species. The Zika epidemic both elevated the perceived importance of Ae. aegypti as a vector - among policy-makers and regulators as well as the general public - and increased concerns over the release of males of the OX513A strain. We have therefore reassessed the potential hazards. We found that release of the transgenic mosquitoes would still be both safe and of great potential value in the control of diseases spread by Ae. aegypti, such as chikungunya, dengue and Zika.

La souche OX513A d'Aedes aegypti, qui a été créée par la société britannique Oxitec, exprime un transgène autolimitant qui empêche les larves de se développer et de devenir adultes. En avril 2014, la Commission technique nationale de biosécurité du Brésil a procédé à une évaluation des risques liés à la souche OX513A et conclu qu'elle ne présentait pas de nouveaux risques biologiques pour les êtres humains ou l'environnement et pouvait être lâchée au Brésil. Le Brésil est donc devenu le premier pays à approuver le lâcher non contraint d'un moustique génétiquement modifié. Au cours de l'évaluation, la commission a établi une liste exhaustive des risques perçus, qu'elle a par ailleurs systématiquement analysés. Ces risques incluaient la survie potentielle à l'âge adulte des larves immatures porteuses du transgène ­ si le transgène ne s'exprime pas ou est désactivé par une exposition à la tétracycline suffisante dans l'environnement. Les autres risques perçus incluaient les potentielles propriétés allergisantes et/ou la toxicité des protéines exprimées par le gène, l'éventualité d'un flux de gènes ou d'une transmission accrue d'agents pathogènes pour l'homme et l'occupation de sites de reproduction vacants par d'autres espèces vectrices. L'épidémie d'infections à virus Zika a accentué l'importance accordée par les responsables politiques, les organismes de réglementation ainsi que le grand public à Ae. aegypti en tant que moustique vecteur, et a accru l'inquiétude relative au lâcher de mâles de la souche OX513A. Nous avons donc réévalué les risques potentiels. Nous estimons que le lâcher de moustiques transgéniques serait à la fois sans danger et extrêmement utile pour lutter contre les maladies transmises par Ae. aegypti, telles que le chikungunya, la dengue et le virus Zika.

La cepa OX513A de Aedes aegypti, que desarrolló la empresa británica Oxitec, expresa un transgén autolimitado que impide que las larvas se desarrollen hasta la edad adulta. En abril de 2014, la Comisión Nacional Técnica de Bioseguridad de Brasil realizó una evaluación de riesgos de OX513A y concluyó que la cepa no presentaba nuevos riesgos biológicos para los humanos o el medioambiente y que podría liberarse en Brasil. En ese momento, Brasil se convirtió en el primer país en aprobar la liberación ilimitada de un mosquito modificado genéticamente. A lo largo de la evaluación, la comisión redactó una lista completa, y analizada sistemáticamente, de las posibles contingencias. Entre dichos peligros se encontraba la posible supervivencia hasta la edad adulta de etapas inmaduras que portan el transgén, en caso de que éste no consiga expresarse o se inutilice debido a la exposición a la suficiente tetraciclina medioambiental. Otras posibles contingencias eran la alergia y/o toxicidad de las proteínas expresadas por el gen, la posibilidad de un flujo genético o el aumento de la transmisión de patógenos humanos y la ocupación de lugares de cría desocupados por parte de otras especies vectores. La epidemia por el virus de Zika aumentó la importancia de Ae. aegypti como vector, entre los responsables y reguladores políticos, así como entre el público general, y aumentó las preocupaciones acerca de la liberación de machos de la cepa OX513A. Por lo tanto, se han vuelto a evaluar los posibles riesgos. Se ha descubierto que la liberación de mosquitos transgénicos sería segura y tendría un gran valor potencial en el control de la propagación de enfermedades por Ae. aegypti, como la fiebre chikungunya, el dengue y la enfermedad por el virus de Zika.

Performance of an indigenous ß-mercaptoethanol-modified antigen in comparison with a commercial reference in direct agglutination test for detection of canine visceral leishmaniasis.

We compared the performance of a locally produced ß-mercaptoethanol-modified promastigote antigen (ß-ME-Ag) of an indigenous Leishmania infantum strain against that of a trypsinized Leishmania donovani reference (REF-Ag) in the direct agglutination test (DAT) for detection of canine visceral leishmaniasis (CVL). One hundred and fifty-one serum samples collected from dogs belonging to four groups with different conditions were included. At a DAT titre of 1 : 320, statistically determined as optimal cut-off value for ß-ME-Ag, and 1 : 160 for REF-Ag, a sensitivity and a specificity of 100 % were estimated for ß-ME-Ag in comparison with 96.6 % and 100 %, respectively, for REF-Ag. Overall, levels of agglutination titres recorded for the two antigens were highly concordant (Cohen's κ = 0.879) in both the CVL and non-CVL groups. Based on current results, and ease experienced in processing the antigen and reading the test outcome, we recommend incorporation of ß-ME-Ag in DAT for confirmation or exclusion of suspected CVL in dogs.