Warmer Weather Linked to Tick Attack and Emergence of Severe Rickettsioses

The impact of climate on the vector behaviour of the worldwide dog tick Rhipicephalus sanguineus is a cause of concern. This tick is a vector for life-threatening organisms including Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, R. conorii, the agent of Mediterranean spotted fever, and the ubiquitous emerging pathogen R. massiliae. A focus of spotted fever was investigated in France in May 2007. Blood and tissue samples from two patients were tested. An entomological survey was organised with the study of climatic conditions. An experimental model was designed to test the affinity of Rh. sanguineus for biting humans in variable temperature conditions. Serological and/or molecular tools confirmed that one patient was infected by R. conorii, whereas the other was infected by R. massiliae. Dense populations of Rh. sanguineus were found. They were infected with new genotypes of clonal populations of either R. conorii (24/133; 18%) or R. massiliae (13/133; 10%). April 2007 was the warmest since 1950, with summer-like temperatures. We show herein that the human affinity of Rh. sanguineus was increased in warmer temperatures. In addition to the originality of theses cases (ophthalmic involvements, the second reported case of R. massiliae infection), we provide evidence that this cluster of cases was related to a warming-mediated increase in the aggressiveness of Rh. sanguineus, leading to increased human attacks. From a global perspective, we predict that as a result of globalisation and warming, more pathogens transmitted by the brown dog tick may emerge in the future

Detección molecular y análisis filogenético de Hepatozoon canis (Eucoccidiorida: Haemogregarinidae) en perros clínicamente sanos de Bahía Blanca (Buenos Aires)

Las enfermedades caninas causadas por protozoarios y transmitidas por garrapatas representan un importante problema en medicina veterinaria. El objetivo del estudio fue detectar molecularmente Hepatozoon spp., Babesia spp. y Theileria spp. en perros clínicamente sanos de distintas regiones de Argentina y analizar la diversidad genética de los hallazgos obtenidos. Se analizaron 163 muestras de ADN de sangre de perros (40 de Ciudad Autónoma de Buenos Aires; 33 de Bahía Blanca, Buenos Aires; 15 de Castelli, Chaco; 27 de Salsipuedes, Córdoba; 40 de Merlo, San Luis; y 8 de San Miguel, Corrientes). Mediante una PCR que amplifica un fragmento variable (460-540 pb) del gen ARNr 18S incluyendo la región V4 de los géneros Hepatozoon, Babesia y Theileria, el 12,1 % (4/33) de los perros de Bahía Blanca (Buenos Aires) resultaron positivos. Las secuencias obtenidas se identificaron como Hepatozoon canis y resultaron filogenéticamente similares a hallazgos en Sudamérica y en el resto del mundo. El estudio de H. canis en Argentina mediante técnicas moleculares de diagnóstico junto con el análisis filogenético resulta de suma importancia para conocer la situación de este patógeno en el país. SUMMARY. Molecular detection and phylogenetic analysis of Hepatozoon canis (Eucoccidiorida: Haemogregarinidae) infecting healthy dogs from Bahia Blanca (Buenos Aires). Tick-borne protozoan canine diseases represent a major problem in veterinary medicine. The aim of the study was to detect molecularly Hepatozoon spp., Babesia spp. and Theileria spp. in clinically healthy dogs from different regions of Argentina and to analyze the genetic diversity of the findings. DNAs extracted from 163 blood samples from dogs (40 from Buenos Aires city; 33 from Bahia Blanca, Buenos Aires; 15 from Castelli, Chaco; 27 from Salsipuedes, Córdoba; 40 from Merlo, San Luis; and 8 of San Miguel, Corrientes) were studied by PCR amplifying a variable fragment (460-540 bp) of the 18S rRNA gene including the V4 region of the genera Hepatozoon, Babesia and Theileria. Four dogs from Bahia Blanca (12.1%) were positive and the sequences obtained were identified as Hepatozoon canis and were phylogenetically similar to findings in South America and the rest of the world. The study of H. canis in Argentina with molecular methods together with phylogenetic analysis is important in order to know the situation of this pathogen in this country

Ehrlichia canis (Rickettsiales: Anaplasmataceae) en garrapatas Rhipicephalus sanguineus sensu lato del linaje templado (Acari. Ixodidae), provincia de Buenos Aires, Argentina

El objetivo del presente estudio es notificar el hallazgo de Ehrlichia canis en garrapatas Rhipicephalus sanguineus sensu lato (s. l.) del linaje templado (LTe) colectadas sobre un canino con ehrlichiosis monocítica canina de José C. Paz (zona noroeste del Área Metropolitana de Buenos Aires –AMBA-). Se colectaron 32 garrapatas, siendo determinadas taxonómicamente como R. sanguineus s. l. (30 larvas y 2 ninfas). Mediante una PCR inicial para la familia Anaplasmataceae para un fragmento del gen ARNr 16S, resultaron positivas un grupo de 10 larvas y una ninfa. Dichas muestras positivas también fueron amplificadas mediante una PCR para un fragmento del gen dsb del género Ehrlichia, y posteriormente secuenciadas, resultando en un 100% de identidad con E. canis. Los especímenes de R. sanguineus s.l. positivos para E. canis fueron estudiados mediante una PCR para del gen mitocondrial 16S de garrapatas del grupo Metastriata, demostrándose su pertenencia al linaje templado de R. sanguineus s. l. Los estudios experimentales y los antecedentes epidemiológicos relacionan E. canis con R. sanguineus s. l. del linaje tropical, pero considerando que el único linaje de R. sanguineus detectado en AMBA ha sido el LTe, es necesario continuar investigando para dilucidar el mecanismo de transmisión y la dinámica vectorial en esta área. SUMMARY. Ehrlichia canis (Rickettsiales: Anaplasmataceae) in Rhipicephalus sanguineus sensu lato ticks of the temperate lineage (Acari Ixodidae), Buenos Aires Province, Argentina. The aim of the present study was to report the presence of Ehrlichia canis in Rhipicephalus sanguineus sensu lato (s. l.) ticks of the temperate lineage (LTe) collected on a dog with canine monocytic ehrlichiosis from José C. Paz (northwest area of the Buenos Aires Metropolitan Area - BAMA-). Thirty-two ticks were collected (30 larvae and 2 nymphs). A group of 10 larvae and one nymph were positive to Ehrlichia in the initial PCR targeting a fragment of the Anaplasmataceae family 16S rRNA gene. These positive samples were also amplified by PCR for a fragment of the dsb gene of the genus Ehrlichia, and then sequenced, resulting in a 100% identity with E. canis. Specimens of R. sanguineus s.l. positive for E. canis were determined as belonging to the temperate lineage of R. sanguineus s. l. through the analysis of sequences from the tick mitochondrial 16S rRNA gene. Experimental studies and epidemiological background have related E. canis infection with R. sanguineus s. l. ticks of the tropical lineage, but the results of this study put in evidence the needed of new epidemiological studies on the vectorial competence of the different lineages of R. sanguineus s.l. to transmit E. canis