Molecular epidemiology of foot-and-mouth disease virus type A in South America.

A databank of 78 VP(1) complete sequences of type A foot-and-mouth disease virus (FMDV) from South American isolates was constructed. Forty-nine samples corresponded to FMDV that circulated between the years 1999-2008, mainly in Venezuela, where most type A outbreaks have occurred lately and twenty-nine to strains historically relevant for the continent. The phylogenetic analysis showed that all South American FMDV belonged to the Euro-SA topotype. Sixteen subgenotypes could be identified, based on a 15% nucleotide divergence cut-off criterion: eight are extinguished, three were active until the year 2002 and the remaining five circulated in Venezuela during the years 2001-2007, illustrating the potential for FMDV diversification under appropriate selective pressure. The last emergencies reported in already-free areas of Colombia in 2004 and 2008 were closely related to isolates acting in Venzuela. Evidence of positive selection over codon 170, within the immunogenic site 4 of VP1 protein, was recorded. A codon deletion in amino acid position 142, within the G-H loop, was found in some isolates within subgenotypes 14, 15 and 16. Conversely amino acid deletion 197 was restricted to all isolates within a particular genetic cluster. The present work is the first comprehensive phylogenetic analysis of FMDV type A in South America, filling a gap of knowledge with respect to both, historical and acting viruses. The results provided evidence that supports the ecosystem dynamics in the region, and also served as an input to establish genetic links of emergencies in already-declared free areas, highlighting the need for strengthening control activities.

Phylogenetic analysis of Foot-and-Mouth Disease Virus type O circulating in the Andean region of South America during 2002-2008.

At present, Foot-and-Mouth Disease (FMD) has been successfully controlled in most territories of South America, where only Ecuador and Venezuela remain as endemic countries. In this context, the precise characterization of circulating viruses is of utmost importance. This work describes the first molecular epidemiology study performed with the complete VP(1)-coding region of 114 field isolates of FMD virus (FMDV) type O, collected in the Andean countries mainly during 2002-2008. Sequences were aligned and compared to isolates responsible for emergencies in the Southern Cone of the continent between the years 2000 and 2006, and to other representative type O viruses worldwide. The results showed that FMD type O viruses isolated in South America and analyzed up to date are placed in 11 different lineages within the Euro SA topotype. Five of these lineages included viruses circulating in Ecuador and Venezuela during 2002-2008. The last emergencies reported in already-free areas in the Andean region, showed close relationships with viruses circulating in these endemic countries. Andean lineages showed a clear separation from the unique lineage containing viruses responsible for the emergencies in the Southern Cone, reflecting the different livestock circuits and providing evidence that support the ecosystem dynamics in the region. A wide geographical dissemination of the same strain in short time intervals has been observed, pointing to animal movements as the most significant risk parameter. This fact, together with an important generation of viral variants in areas under weak control strategies, reinforce the need of stronger official controls, as well as for establishing multinational cooperative measures in the border areas.

Identificación molecular de una cepa de herpesvirus bovino tipo 2 en Venezuela / Molecular identification of a bovine herpes virus type 2 strain in Venezuela

El herpesvirus bovino tipo 2 (HVB-2) es el agente responsable de la mamilitis bovina, enfermedad que puede ser confundida con la fiebre aftosa por las lesiones que ocasiona en la ubre y pezones de las vacas infectadas. Para investigar su presencia en el país, se procesaron con fines de diagnóstico virológico muestras de tejidos epiteliales de ubre, recolectadas de ocho vacas con sospecha clínica de fiebre aftosa. Todas las muestras resultaron negativas a fiebre aftosa y estomatitis vesicular, pero de una de ellas se aisló una cepa viral en cultivo primario de riñón fetal bovino, la cual ocasionó un efecto citopático característico al observado por la acción del virus HVB-2. Mediante la prueba de PCR se amplificó una banda de 422 pb, la cual se correspondió al producto esperado de acuerdo al protocolo empleado para el diagnóstico molecular de herpesvirus bovino tipo 2. El análisis por BLAST y la alineación de las secuencias del amplicon obtenido permitió confirmar la presencia de este virus en el país.

Bovine mamilitis is a viral disease which is caused by Bovine Herpes Virus type 2 (BHV - 2). This disease is difficult to differentiate of Food and Mouth Disease (FMD) because infected cows show vesicles and ulcerating lesions on teats and udder. In order to investigate if BHV-2 is present in Venezuelan cattle udder samples of eight cows undergoing clinical symptoms similar to FMD were taken and tested for viral diagnostic. All samples were negative to FMD and vesicular stomatitis, but a viral strain with cytopathic effect typical to BHV-2 was isolated from one of them when a primary cells culture of bovine kidney fetus was inoculated. The presence of BHV-2 was confirmed in Venezuela according with the cytopathic effect, the PCR product of 422 bp obtained by specific test and the significant alignments by BLAST.

Dinámica de la infección por ascaris suum en un granja porcina del Municipio Carlos Arvelo, Parroquia Güigüe del estado Carabobo Venezuela / Dynamic of ascaris suum on a swine farm in the Carlos Arvelo Municipality in Carabobo state Venezuela

Un estudio sobre dinámica de infección por Ascaris suum se realizó en una granja porcina del municipio Carlos Arvelo del estado Carabobo, con antecedentes de decomisos de hígados por lesiones características del parásito. Se muestrearon 525 animales para análisis coprológico, mediante la técnica McMaster y 40 tractos intestinales en matadero, para determinar cantidad de vermes y análisis coprológico (Técnicas McMaster y Wisconsin). La prevalencia observada fue 22,66 por ciento por coprología y 68,29 por ciento por recuperación de vermes. La disposición espacial de huevos en heces y vermes en tractos intestinales fue en agregados. Los casos de infección se observaron en las etapas; desarrollo (31,43 por ciento), hembras de reemplazo (75,3 por ciento) y engorde (73,3 por ciento), evdenciándose recuentos más altos de huevos por gramo de heces (HPG) en engorde. La intensidad de infección en las etapas desarrollo y engorde fue, en la mayoría de los casos, leve y en poco moderada e independiente del sexo. Se observó una correlación positiva y significativa (P menor o igual 0,05) entre: el grado de infección establecido por HPG y la cantidad de vermes recuperados, demostrándose que la coprología continúa siendo una alternativa diagnóstica válida para evaluar y clasificar esta infección. Igualmente, se demostró asociación significativa (P menor o igual 0,05) entre: carga en vermes hembras y vermes machos; la carga en vermes hembras y el HPG, así como también entre carga vermes machos y HPG. Se demostró presencia de animales falsos positivos atribuidos a la condición de coprofagia. La variación mensual de hígados decomisados por A. suum fue calculada a través del I.V.M durante el período 1996-1999. Sus valores indicaron decomisos durante todo el año, sugieriendo la existencia de condiciones climáticas favorables para el establecimiento de esta infección