La tique dure Amblyomma variegatum (Acari, Ixodidae) à Madagascar : détermination de seuils de température pour la métamorphose de la nymphe gorgée en adulte

Depuis les 30 dernières années, la tique tropicale Amblyomma variegatum (Acari, Ixodidae) a étendu sa répartition sur les Hauts plateaux de Madagascar. Le contrôle des populations d'Amblyomma variegatum et des maladies associées (cowdriose et dermatophilose) serait plus facile si nous étions capables de prédire la répartition de la tique dans différents environnements. Un modèle de dynamique de population du stade nymphal au stade adulte a été élaboré pour étudier les effets de la température sur le développement de la tique. Des nymphes gorgées ont été placées dans des cages à 6 altitudes différentes et la température a été mesurée toutes les 15 minutes sur chaque site. Les taux de métamorphose de la tique ont été modélisés selon des temps d'attentes température-dépendants, en utilisant les données obtenues sur les Hauts Plateaux de Madagascar. Par une approche bayésienne et un algorithme de simulation Monte Carlo de chaînes de Markov (MCMC), nous avons déterminé les paramètres seuils de température définissant la métamorphose nymphale d'Amblyomma variegatum. Les résultats ont montré que les conditions actuelles de température à Madagascar sont convenables pour la tique, même aux altitudes les plus élevées auxquelles l'élevage bovin est pratiqué (jusqu'à environ 2000 m), bien qu'elles puissent diminuer le taux de métamorphose et probablement augmenter le taux de mortalité. Toutes les zones d'élevage sont donc maintenant exposées au risque d'infestation par Amblyomma variegatum, hormis les régions les plus arides du sud-ouest malgache. Concernant les paramètres contrôlant la métamorphose nymphale d'Amblyomma variegatum, la température de l'air permettant la métamorphose a été estimée à 1,0°C (IC 95% = [0,5 ; 1,5]) ; d'autre part, pour que la métamorphose puisse se produire, le cumul minimal au-dessus de ce seuil a été estimé à 442° Celsius * jours (IC 95% = [428 ; 456]). Des recherches supplémentaires sur les relations entre la température et la métamorphose des nymphes sont attendues pour que le modèle de prédiction puisse évaluer le risque potentiel d'expansion de la tique

Dynamics of African swine fever virus shedding and excretion in domestic pigs infected by intramuscular inoculation and contact transmission

African swine fever virus (ASFV) is a highly virulent swine pathogen that has spread across Eastern Europe since 2007 and for which there is no effective vaccine or treatment available. The dynamics of shedding and excretion is not well known for this currently circulating ASFV strain. Therefore, susceptible pigs were exposed to pigs intramuscularly infected with the Georgia 2007/1 ASFV strain to measure those dynamics through within- and between-pen transmission scenarios. Blood, oral, nasal and rectal fluid samples were tested for the presence of ASFV by virus titration (VT) and quantitative real-time polymerase chain reaction (qPCR). Serum was tested for the presence of ASFV-specific antibodies. Both intramuscular inoculation and contact transmission resulted in development of acute disease in all pigs although the experiments indicated that the pathogenesis of the disease might be different, depending on the route of infection. Infectious ASFV was first isolated in blood among the inoculated pigs by day 3, and then chronologically among the direct and indirect contact pigs, by day 10 and 13, respectively. Close to the onset of clinical signs, higher ASFV titres were found in blood compared with nasal and rectal fluid samples among all pigs. No infectious ASFV was isolated in oral fluid samples although ASFV genome copies were detected. Only one animal developed antibodies starting after 12 days post-inoculation. The results provide quantitative data on shedding and excretion of the Georgia 2007/1 ASFV strain among domestic pigs and suggest a limited potential of this isolate to cause persistent infection

Experimental pig-to-pig transmission dynamics for African swine fever virus, Georgia 2007/1 strain

African swine fever virus (ASFV) continues to cause outbreaks in domestic pigs and wild boar in Eastern European countries. To gain insights into its transmission dynamics, we estimated the pig-to-pig basic reproduction number (R 0) for the Georgia 2007/1 ASFV strain using a stochastic susceptible-exposed-infectious-recovered (SEIR) model with parameters estimated from transmission experiments. Models showed that R 0 is 2·8 [95% confidence interval (CI) 1·3–4·8] within a pen and 1·4 (95% CI 0·6–2·4) between pens. The results furthermore suggest that ASFV genome detection in oronasal samples is an effective diagnostic tool for early detection of infection. This study provides quantitative information on transmission parameters for ASFV in domestic pigs, which are required to more effectively assess the potential impact of strategies for the control of between-farm epidemic spread in European countries.ISSN:0950-2688ISSN:1469-440

Ictiofauna De Riachos Das Cabeceiras Da Bacia Hidrográfica Do Alto Paranapanema

The Paraná River basin has about 600 fish species. In the Upper Paraná, 310 fish species were recorded, with 52 species were registered in the streams and headwaters of the Paranapanema River. The aim of this study was to characterize the stream fish communities in the Upper Paranapanema River basin. Samplings were conducted with electrofishing during the dry season in the year of 2014. The collection effort consisted of 30 streams stretches. As a result, 41 species of stream fish were recorded in the Upper Paranapanema River basin, distributed in 26 genera, 11 families and 7 orders. Thirty-nine percent of the species can be considered rare, 41% intermediate and 20% common. We captured approximately eight species by stream stretch and the estimated richness (Schao2) was 40 ± 6 species. Around 40% of the individuals had less than 50 mm in length. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.16