Leishmaniose canine dans le Rif (côte méditerranéenne marocaine) : enquête séro-épidémiologique

Dans le but d'évaluer la situation de la leishmaniose canine dans le foyer situé dans le versant Nord-Est de la chaîne montagneuse du Rif, une enquête séro-épidémiologique a été menée dans différentes localités de la province de Nador (côte méditerranéenne marocaine). Des échantillons de sérum collectés sur 257 chiens ont été analysés par les techniques d'immunofluorescence indirecte (IFI) et d'enzyme-linked immunosorbent assay (ELISA) pour détecter les anticorps anti-Leishmania infantum. Les résultats montrent que 48 (18,7 %) des chiens examinés sont positifs en IFI et 54 (21,0 %) le sont en ELISA ; la concordance des deux méthodes étant de 96,1 %. D'autre part, le taux d'infection est significativemenl plus élevé chez les chiens âgés de plus de quatre ans et ne dépend pas du sexe de l'animal. Les symptômes les plus fréquemment relevés sur les chiens séropositifs sont la polyadénite (57,4 %), l'amyotrophie (51,9 %) et les lésions cutanéo-muqueuses ( 25,9 %). Cependant, 38,9 % de ces mêmes chiens ne présentent pas de symptômes pouvant évoquer la leishmaniose. Des Leishmania isolées sur trois des chiens examinés ont toutes été identifiées comme étant L. infantum MON-1. Ces résultats montrent que le versant Nord-Est des montagnes du Rif est l'un des foyers les plus actifs de leishmaniose viscérale dans le pourtour méditerranéen et confirment le rôle que joue le chien comme principal réservoir de L. infantum

Leishmaniose canine dans le Rif (côte méditerranéenne marocaine) : enquête séro-épidémiologique

Dans le but d'évaluer la situation de la leishmaniose canine dans le foyer situé dans le versant Nord-Est de la chaîne montagneuse du Rif, une enquête séro-épidémiologique a été menée dans différentes localités de la province de Nador (côte méditerranéenne marocaine). Des échantillons de sérum collectés sur 257 chiens ont été analysés par les techniques d'immunofluorescence indirecte (IFI) et d'enzyme-linked immunosorbent assay (ELISA) pour détecter les anticorps anti-Leishmania infantum. Les résultats montrent que 48 (18,7 %) des chiens examinés sont positifs en IFI et 54 (21,0 %) le sont en ELISA ; la concordance des deux méthodes étant de 96,1 %. D'autre part, le taux d'infection est significativemenl plus élevé chez les chiens âgés de plus de quatre ans et ne dépend pas du sexe de l'animal. Les symptômes les plus fréquemment relevés sur les chiens séropositifs sont la polyadénite (57,4 %), l'amyotrophie (51,9 %) et les lésions cutanéo-muqueuses ( 25,9 %). Cependant, 38,9 % de ces mêmes chiens ne présentent pas de symptômes pouvant évoquer la leishmaniose. Des Leishmania isolées sur trois des chiens examinés ont toutes été identifiées comme étant L. infantum MON-1. Ces résultats montrent que le versant Nord-Est des montagnes du Rif est l'un des foyers les plus actifs de leishmaniose viscérale dans le pourtour méditerranéen et confirment le rôle que joue le chien comme principal réservoir de L. infantum

First genomic study on Lake Tanganyika sprat Stolothrissa tanganicae : a lack of population structure calls for integrated management of this important fisheries target species

BackgroundClupeid fisheries in Lake Tanganyika (East Africa) provide food for millions of people in one of the world's poorest regions. Due to climate change and overfishing, the clupeid stocks of Lake Tanganyika are declining. We investigate the population structure of the Lake Tanganyika sprat Stolothrissa tanganicae, using for the first time a genomic approach on this species. This is an important step towards knowing if the species should be managed separately or as a single stock. Population structure is important for fisheries management, yet understudied for many African freshwater species. We hypothesize that distinct stocks of S. tanganicae could be present due to the large size of the lake (isolation by distance), limnological variation (adaptive evolution), or past separation of the lake (historical subdivision). On the other hand, high mobility of the species and lack of obvious migration barriers might have resulted in a homogenous population.ResultsWe performed a population genetic study on wild-caught S. tanganicae through a combination of mitochondrial genotyping (96 individuals) and RAD sequencing (83 individuals). Samples were collected at five locations along a north-south axis of Lake Tanganyika. The mtDNA data had low global FST and, visualised in a haplotype network, did not show phylogeographic structure. RAD sequencing yielded a panel of 3504 SNPs, with low genetic differentiation (F-ST=0.0054; 95% CI: 0.0046-0.0066). PCoA, fineRADstructure and global F-ST suggest a near-panmictic population. Two distinct groups are apparent in these analyses (F-ST=0.1338 95% CI: 0.1239,0.1445), which do not correspond to sampling locations. Autocorrelation analysis showed a slight increase in genetic difference with increasing distance. No outlier loci were detected in the RADseq data.ConclusionOur results show at most very weak geographical structuring of the stock and do not provide evidence for genetic adaptation to historical or environmental differences over a north-south axis. Based on these results, we advise to manage the stock as one population, integrating one management strategy over the four riparian countries. These results are a first comprehensive study on the population structure of these important fisheries target species, and can guide fisheries management.Peer reviewe

Resposta eritropoética de ratos em diferentes graus de parasitemia por Trypanosoma evansi Erithropoietic response in Trypanosoma evansi infected rats with different parasitaemia intensity

O Trypanosoma evansi é um protozoário hemoflagelado que causa, em várias espécies, uma doença caracterizada por altos níveis de parasitemia, com rápido desenvolvimento de anemia. Este trabalho teve como objetivo investigar a relação entre o grau de parasitemia e a alteração na eritropoese de ratos (Rattus norvegicus) da linhagem Wistar infectados experimentalmente com T. evansi. Foram utilizados 42 ratos, dos quais 36 foram inoculados pela via intraperitoneal com 0,2ml de sangue, contendo 2,5 x 104 parasitas. Seis ratos não-inoculados foram utilizados como controles. Após inoculação, a parasitemia foi avaliada a cada 12h. Os grupos para análise foram estipulados de acordo com a média de tripanossomas em 10 campos homogêneos focados aleatoriamente, sendo: A, controle; B, animais que apresentaram um grau de parasitemia entre 1-10 tripanossomas/campo; C, ratos com 11-20 tripanossomas/campo; D, ratos com 21-30 tripanossomas/campo; E, ratos com 31-40 tripanossomas/campo; F, 41-50 tripanossomas/campo; e G, ratos com mais de 51 tripanossomas/campo. Quando os animais apresentaram o número de protozoários equivalente ao grupo, foram coletadas amostras de sangue para realização de hemograma e dosagem de ferro, e foi realizada citologia de medula óssea para avaliação da relação mielóide:eritróide. A análise estatística mostrou redução significativa das hemácias e do hematócrito a partir de 31 tripanossomas/campo (grupos E, F e G; P<0,005) e a redução de hemoglobina ocorreu a partir de 41 tripanossomas/campo (grupos F e G; P<0,005). A relação mielóide:eritróide foi reduzida de 0,7 para 0,6 a partir de 41 tripanossomas/campo (grupos F e G; P<0,005). Não foram detectadas variações na concentração de ferro. Os dados obtidos demonstraram que ratos com parasitemia acima de 31 tripanossomas por campo desenvolvem uma anemia aguda, com um aumento compensatório na atividade hematopoética.<br>Trypanosoma evansi is a flagellate protozoan that causes a disease characterized by high parasitemia and acute anemia in various species. This study was aimed at evaluating and establishing a relationship between different parasitemia levels and eritropoyesis in Wistar rats (Rattus norvegicus) experimentally infected by T. evansi. Forty two animals were used. In 36 animals parasites were inoculated by intraperitoneal blood injection of 0.2ml containing 2.5x104 parasites. Six non-inoculated animals were used as controls. Parasitemia was evaluated every 12 hours and the animals were allocated in groups according to parasitemia levels. Then they were classified according to average number of parasites in 10 random homogeneous fields, Group A: control (not-inoculated); B: rats with 1-10 trypanosomes/field; C: 11-20 trypanosomes/field; D: 21-30 trypanosomes/field; E: 31-40 trypanosomes/field; F: 41-50 trypanosomes/field; G: more then 51. Blood samples were taken when the animals reached the correspondent group number of parasites. Hemogram and iron levels were evaluated and a bone marrow cytology was performed to detect the myeloid:erythroid ratio. Statistical analysis showed a significant reduction on red blood cells count and hematocrit from group E on and also hemoglobin on groups F and G. The myeloid:erythroid ratio reduced from 0.7 to 0.6 on groups F and G (P<0.005). Iron levels alterations were not detected. These data showed that Wistar rats with parasitemia higher then 31 parasites per field have an acute anemia associated to a compensatory hematopoietic activity