First detection of Rio Negro virus (Venezuelan equine encephalitis complex subtype VI) in Córdoba, Argentina

Rio Negro virus (RNV) (Venezuelan equine encephalitis subtype VI) circulates only in Argentina; in northern provinces, isolates have been obtained from mosquitoes and rodents since 1980 and have been associated with acute febrile illness in humans. However, no studies of RNV have been performed in the central area of the country. We carried out molecular and serological detection of RNV in Córdoba, a province of the central part of the country, in mosquitoes and humans, respectively. One mosquito pool tested positive for alphavirus RNA by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). Subsequent sequencing determined that this alphavirus grouped with RNV. Serological studies detected antibodies to RNV in one human serum sample, which was obtained during the same period that RNV was detected using the aforementioned molecular methods. This is the first report of RNV circulation in the central area of Argentina, indicating an expansion of its original distribution. These results highlight the importance of strengthening surveillance procedures in endemic areas, as well as in new regions where RNV may emerge.

Virológica 91

In december 1975 a hitherto unknow Flavivirus was isolated from the cerebellum and upper spinal cord of a 39-years-old farmer in the region of Ribeira Valley, Säo Paulo, Brazil. The new virus, isolated and characterized by Lopes et al., was named Rocio (ROC), strain SP H34675. VEE virus is serologically grouped in the genus Alphavirus of family Togaviridae based upon cross-reactivity by hemagglutination inhibition (HI complement fixation (CF) and neutralization (N) tests

Relación entre mosquitos vectores y aves acuáticas en la transmisión potencial de dos arbovirus / The relationship between mosquito vectors and aquatic birds in the potential transmission of 2 arboviruses

The authors studied for two years the role of the chicks of aquatic birds in the arboviral cycles in coastal lagoons in central Panama in order to determine the relation between Culex (Melanoconion) ocossa and Mansonia (Mansonia) dyari mosquitoes in the transmission and dissemination of the viruses of Saint Louis Encephalitis (SLE) and Venezuelan Equine Encephalitis (VEE). Mosquitoes were captured every fifteen days on two consecutive nights to isolate the virus, using light traps (CDC) and baited traps. The attempts to isolate the virus were made using Vero cell cultures and the determination of antibodies was performed. The results of the serologic tests seem to indicate that four bird species: the ex (?) heron (Bubulcus ibis), the American heron (Casmerodius albus), the spoon-billed duck (Cochlearius cochlearius) and the needle crow (Anhinga anhinga) could function as intermediate hosts in the transmission cycle of SLE. Two species, the ibis (Endocimus albus) and the spoon-billed duck (Cochlearius cochlearius) could also be intermediate hosts of VEE in the coastal lagoons of Panama. The presence of antibodies in chicks could indicate an infection acquired recently, after their birth, in this area. The VEE virus was recovered from blood filled mosquitoes which had fed on a spoon-billed duck probably infected and exposed in a Trinidad #10 trap. No SLE virus was isolated. Other unknown viruses were isolated from mosquitoes selected for these studies, such as C. ocossa and M. dyari. The results obtained with these studies indicate the need for more studies utilizing new field techniques in order to establish a link between SLE and VEE, the vector mosquitoes and the aquatic birds in the coastal lagoons of the area under investigation

Rocio and Venezuelan eqüine encephalomyelitis virus activities in Brazil

Existem evidências em humanos e vertebrados silvestres da atividade do vírus rócio no Vale do Ribeira até 1991. Os dados sugerem a circulaçäo do vírus no ciclo selvático envolvendo mosquitos e possivelmente pássaros com infecçöes humanas tangenciais. Parece que o ciclo de transmissäo no meio ambiente modificado pelo homem, como certamente ocorreu na epidemia de 1975-77, näo está atualmente presente. Considerando os interesses econômicos e as mudanças no meio ambiente, aconselha-se um aperfeiçoamento na vigilância das infecçöes por Rócio

Actividad del virus de la encefalitis equina venezolana en el norte de Colombia, abril y mayo de 1983 / Venezuelan equine encephalitis virus activity in northern Colombia during April and May 1983

Venezuelan equine encephaltis (VEE) virus was isolated from sentinel hamsters exposed in the Rio de Oro region of Colombia, in the Lake Maracaibo drainage área near the border with Venezuela, in 1983-13 years after the first strain was isolated from the region near Tibu. Hydroxylapatite elution profiles of three isolates from the Rio de Oro region were typical of enzootic strains. Relative abundance data and past isolations suggest that culex (Melanoconion) pedroi is a probable enxootic vector at this focus. The virus was no isolated from forests near Santa Marta and Magangue in the Rio Magdalena drainage área in 1983-9 and 16 years, respectively, after the last previous isolations in those áreas. However, equine animals 2 to 10 years of age and humans 25 to 67 years of age living near the Magangue field study área were positive for VEE virus-specific neutralizing antibodies

Estudio seroepidemiólogico de encefalitis por virus venezolano en la zona de Barlovento / Seroepidemiologic study of encephalitis due to Venezuelan virus in Barlovento zona

El presente trabajo describe el aislamiento de virus encefalomielítico equino, a partir de mosquitos colectados en el campo y su identificación en el laboratorio. El uso de animales centinelas y su seroconversión, demuestra la actividad viral vigente. El impacto de esta antroponosis en la población humana, está descrito mediante el estudio seroepidemiológico, observándose una positividad de 12% de las muestras tomadas

Demostracion del virus de la encefalitis equina venezolana tipo enzootico en la hemolinfa de mosquitos Psorophora confinnis infectados por via oral / Demonstration of Venezuelan equine encephalitis virus: enzootic type in the haemolymph of the Psorophora confinnis mosquitoes infected by mouth

Se llevo a cabo un experimento con el proposito de determinar si en mosquitos Psorophora confinnis (Arribalzaga, 1.891) infectados por via oral con una cepa exootica de Encefalitis Equina Venezolana era posible detectar el virus en la hemolinfa de estos mosquitos. El virus se pudo demostrar en la hemolinfa a las 24 horas post-infeccion en el 66.6% de los mosquitos, en el 75% de los mosquitos a los 2 y 9 dias post-infeccion y en el 100% de los mosquitos a los 6, 7, 8, 10, 11, 12 y 13 dia post-infeccion. Todos los mosquitos en los cuales se demostro virus en la hemolinfa fueron probados para intento de aislamiento de virus en el mosquito total y hubo una perfecta correlacion entre las dos. Los mosquitos que fueron negativos para virus en la hemolinfa tambien lo fueron cuando se probaron como mosquito total. En algunas hembras tomadas al azar se hizo una comparacion de los titulos del virus en la hemolinfa y en el mosquito total y no se encontro una diferencia significativa