Detección molecular de virus de encefalitis de Saint Louis en mosquitos de Buenos Aires, Argentina

Durante el mes de marzo de 2013 una población de palomas torcazas (Zenaida auriculata) se instaló en una zona céntrica de la ciudad de Buenos Aires. Conociendo el rol que poseen estas aves como hospedadores competentes del virus de la encefalitis de Saint Louis (SLEV), fue colocada en el lugar una trampa de luz tipo CDC, a fin de realizar una vigilancia entomológica. Durante ese mes,fueron capturados 5 grupos de mosquitos (n = 48), 3 correspondieron a la especie Culex pipiens (n = 10) y 2 a Culex spp.(n = 38), no pudiéndose determinar en estos últimos con precisión la especie por encontrarse dañados. En un grupo de mosquitos Culex spp. se detectó el SLEV por técnicas moleculares. Posteriormente fue secuenciado y clasificado como perteneciente al genotipo III.

During March 2013 a population of eared doves (Zenaida auriculata) was established in the center of City of Buenos Aires. Considering the role of these birds as host competent for Saint Louis encephalitis virus (SLEV), a CDC light trap was put in place to perform entomologic surveillance. During this month 5 pools of mosquitoes (n = 48) were collected and taxonomically determined. Three of them were classified as Culex pipiens (n = 10) and the other two were Culex spp. (n = 38). In this case, the mosquitoes species could not be determined due to that individuals were damaged. One of the Culex spp. pool was found to be positive for Saint Louis encephalitis virus by molecular techniques. This was then sequenced and classified as genotype III.

Detección molecular de Rickettsia massiliae y Anaplasma platys en garrapatas Rhipicephalus sanguineus y caninos domésticos del municipio de Bahía Blanca (Argentina) / Molecular detection of Rickettsia massiliae and Anaplasma platys infecting Rhipicephalus sanguineus ticks and dogs, Bahía Blanca (Argentina)

Background: Rickettsioses, ehrlichioses and anaplasmoses are caused by Gram negative obligate intracellular bacteria and transmitted mainly by arthropods. Aim: To detect and perform the molecular characterization of these pathogens in ticks and domestic dogs in Bahia Blanca City (Buenos Aires, Argentina). Methods: Fifty six blood samples from dogs and 82 ticks (75 Rhipicephalus sanguineus and 7 Amblyomma tigrinum) were studied. The samples were analyzed by PCR for Rickettsia (intergenic space 23S-5S rRNA), Ehrlichia/Anaplasma (16S rRNA), and Anaplasma platys (16S rRNA). Results: 12% of R. sanguineus resulted positive for Rickettsia, identified by sequencing as Rickettsia massiliae; and 37.5% of the canine blood samples analyzed were positive for A. platys. Molecular characterization was also performed by amplification of the fragment of the citrate synthase gene (gltA) (Rickettsia genus) and the groESL gene (A. platys). Phylogenetic trees were constructed using the neighbor-joining method. These trees revealed that sequences obtained are similar to those from other geographical regions. Conclusion: The results indicate the presence of R. massiliae in R. sanguineus ticks for the second time in an urban area of South America and A. platys infection in dogs, being the southernmost region of Argentina where it has been notified.

Introducción: Las rickettsiosis, ehrlichiosis y anaplasmosis son causadas por bacterias gramnegativas, intracelulares obligadas y transmitidas principalmente por artrópodos. Objetivo: Detectar y caracterizar molecularmente estos patógenos en garrapatas y caninos domésticos del municipio de Bahía Blanca (provincia de Buenos Aires, Argentina). Material y Métodos: Se estudiaron 56 muestras sanguíneas de caninos, 75 garrapatas Rhipicephalus sanguineus y 7 Amblyomma tigrinum. Las muestras fueron analizadas por RPC para Rickettsia (espacio intergénico 23S-5S ARNr), Ehrlichia y Anaplasma (16S ARNr), y Anaplasma platys (16S ARNr). Resultados: Se detectó positividad a Rickettsia en 12% de R. sanguineus, identificándose por secuenciación a Rickettsia massiliae. Las muestras sanguíneas de los caninos resultaron en 37,5% positivas a A. platys. También se caracterizaron molecularmente por la amplificación del fragmento del gen citrato sintasa (gltA) (género Rickettsia) y del gen groESL (A. platys). Se construyeron árboles filogenéticos utilizando el método del vecino más cercano (neighbor-joining) revelando que las secuencias obtenidas son similares a las de otras regiones geográficas. Conclusión: Los resultados indican la presencia de R. massiliae en garrapatas R. sanguineus en una segunda zona urbana de Sudamérica y la infección por A. platys en caninos, siendo la región más austral de Argentina donde ha sido notificada.

Molecular detection of Neorickettsia risticii in Brazilian free-tailed bats (Tadarida brasiliensis) from Buenos Aires, Argentina

Neorickettsia risticii is the causative agent of Potomac Horse Fever, a severe febrile disease affecting horses, transmitted by trematodes species with a complex life cycle. A total of 30 insectivorous bats (Brazilian free-tailed bat Tadarida brasiliensis) were analyzed by PCR for presence of genus Anaplasma, Ehrlichia, Neorickettsia and Rickettsia. Three samples showed positive reactions for genus Anaplasma, Ehrlichia and Neorickettsia, and the sequences were 99.67% identical to Neorickettsia risticii. The role of bats in the life cycle of N. risticii has yet to be elucidated; however bats may be reservoirs for this bacterium. To our knowledge, this is the first evidence of N. risticii in Argentina.