Résumé
St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) present ecological and antigenic similarities and are responsible for serious human diseases. In addition, WNV is a significant pathogen in terms of equine health. The purpose of our study was to analyse the seroprevalence of SLEV and WNV in equine sera collected in Santa Fe Province, Argentina. The seroprevalence determined using the plaque reduction neutralisation test was 12.2% for SLEV, 16.2% for WNV and 48.6% for a combination of both viruses. These results provide evidence of the co-circulation of SLEV and WNV in equines in Santa Fe.
Sujets)
Animaux , Virus de l'encéphalite de Saint Louis/isolement et purification , Encéphalite de Saint-Louis/médecine vétérinaire , Maladies des chevaux/virologie , Equus caballus/virologie , Fièvre à virus West Nile/médecine vétérinaire , Virus du Nil occidental/isolement et purification , Argentine/épidémiologie , Virus de l'encéphalite de Saint Louis/immunologie , Encéphalite de Saint-Louis/diagnostic , Encéphalite de Saint-Louis/épidémiologie , Encéphalite de Saint-Louis/virologie , Maladies des chevaux/diagnostic , Maladies des chevaux/épidémiologie , Études séroépidémiologiques , Fièvre à virus West Nile/diagnostic , Fièvre à virus West Nile/épidémiologie , Fièvre à virus West Nile/virologie , Virus du Nil occidental/immunologieRésumé
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.
Sujets)
Adolescent , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Animaux , Enfant , Enfant d'âge préscolaire , Humains , Nourrisson , Nouveau-né , Adulte d'âge moyen , Jeune adulte , Culicidae/virologie , Virus de l'encéphalite équine du Venezuela/génétique , Encéphalomyélite équine du Vénézuéla/virologie , Vecteurs insectes/virologie , Anticorps antiviraux/sang , Argentine/épidémiologie , Virus de l'encéphalite équine du Venezuela/immunologie , Virus de l'encéphalite équine du Venezuela/isolement et purification , Encéphalomyélite équine du Vénézuéla/diagnostic , Encéphalomyélite équine du Vénézuéla/épidémiologie , Réaction de polymérisation en chaîne , RT-PCR , ARN viral/analyseRésumé
Una virus (UNAV), Togaviridae family, is widely distributed in South America, where infections have been detected in mosquitoes and vertebrate hosts (humans, birds and horses). We analyzed human sera from Córdoba inhabitants aged 44 to 89 years and using a neutralization test, we found a prevalence of UNAV antibodies of 3.8 percent (3/79). The low titers detected suggest past infections probably acquired in rural areas of the Province of Córdoba (central Argentina). None sera were found positive for MAYV neutralizing antibodies. This is the first report of human infections by UNAV in Argentina