Preliminary Study Of The Prevalence Of Helminths And Their Associated Pathological Lesions In Four Fish Species From River Tana

Une étude préliminaire a été menée entre janvier et mai 2006 pour enquêter sur la prévalence des helminthes et leurs lésions pathologiques chez quatre espèces de poisson. Au total, 43 poissons frais de la rivière Tana, vendus au marché de Gikomba, ont été achetés et autopsiés. Ces poissons étaient 15/43 (34,9%) de l'espèce Oreochromis, 11/43 (25,6%) Clarias spp., 10/43 (23,2%) Cyprinus carpio et 7/43 (16,3%) Barbus spp. A l'autopsie, on a trouvé plusieurs vers Contraceacum au troisième stade larvaire dans la cavité abdominale, les muscles et derrière les branchies. Au total, 91% des poissons-chats (Clarias spp.) et 20% des tilapias (Oreochromis spp.) avaient une infestation « modérée à grave » de vers Contraceacum. L'intensité de l'infestation variait entre 1 et 593 helminthes par poisson, ce qui a provoqué une grave péritonite et l'adhérence sur les organes viscéraux. Au microscope, les helminthes causaient une forte infiltration des hétérophiles, des macrophages, des plasmocytes et la fibrose des organes. Il y avait une atrophie de la pression de l'épithélium du canal biliaire chez un tilapia, qui a été causée par un ténia migrateur pleurocercoide, un protozoaire Cryptocotyle incrusté sur l'arc branchial, et des lésions parasitaires granulomateuses sur les parois des intestins. Les autres lésions observées étaient des hémorragies, des ulcères et des blessures sur les nageoires, autour de la bouche et sur la peau. Les résultats de cette étude montrent que les poissons de la Rivière Tana sont infestés par les helminthes qui provoquent de graves lésions pathologiques chez les poissons affectés. Ces poissons peuvent aussi servir de réservoirs de ces parasites pour les poissons d'aquaculture.Bulletin of Animal Health and Production in Africa Vol. 56 (1) 2008: pp. 38-4

Prevalence and intensity of Paracamallanus species infection in farmed and wild catfish

A total of 108 randomly selected farmed and wild Clarias gariepinus (catfish) obtained from the upper Tana river basin were examined for intestinal helminthes between July 2007 and April 2008. Over fifty two per cent (52.8 %) had Paracamallanus species worms in the gastrointestinal tract. Wild cafish had 37 % compared to farmed ones at 15.7 % (p < 0.05); prevalence in adult fish was 34.3 % while young catfish had 18.5 % (p > 0.05). There was no difference in Paracamallanus spp. infection between the male and female catfish (p > 0.05). A mean worm intensity of 3.0 with a range of 1 - 41 worms per fish was recorded. The worm load per fish was 1.7, 4.4, 3.5, 2.2, 2.3 and 3.7 worms in farmed, wildfish, adult, young, female and male catfish, respectively. Worm load differed between farmed and wild catfish (p < 0.05), but not between the sex and age groups (p > 0.05). This study reports the occurrence of the Paracamallanus species in catfish for the first time in Kenya.Key words: Clarias gariepinus, Paracamallanus species, prevalence, intensity and Tana river basin)

IgE and mast cells in host defense against parasites and venoms.

IgE-dependent mast cell activation is a major effector mechanism underlying the pathology associated with allergic disorders. The most dramatic of these IgE-associated disorders is the fatal anaphylaxis which can occur in some people who have developed IgE antibodies to otherwise innocuous antigens, such as those contained in certain foods and medicines. Why would such a highly "maladaptive" immune response develop in evolution and be retained to the present day? Host defense against parasites has long been considered the only beneficial function that might be conferred by IgE and mast cells. However, recent studies have provided evidence that, in addition to participating in host resistance to certain parasites, mast cells and IgE are critical components of innate (mast cells) and adaptive (mast cells and IgE) immune responses that can enhance host defense against the toxicity of certain arthropod and animal venoms, including enhancing the survival of mice injected with such venoms. Yet, in some people, developing IgE antibodies to insect or snake venoms puts them at risk for having a potentially fatal anaphylactic reaction upon subsequent exposure to such venoms. Delineating the mechanisms underlying beneficial versus detrimental innate and adaptive immune responses associated with mast cell activation and IgE is likely to enhance our ability to identify potential therapeutic targets in such settings, not only for reducing the pathology associated with allergic disorders but perhaps also for enhancing immune protection against pathogens and animal venoms