Sickness behaviour pushed too far – the basis of the syndrome seen in severe protozoal, bacterial and viral diseases and post-trauma

Certain distinctive components of the severe systemic inflammatory syndrome are now well-recognized to be common to malaria, sepsis, viral infections, and post-trauma illness. While their connection with cytokines has been appreciated for some time, the constellation of changes that comprise the syndrome has simply been accepted as an empirical observation, with no theory to explain why they should coexist. New data on the effects of the main pro-inflammatory cytokines on the genetic control of sickness behaviour can be extended to provide a rationale for why this syndrome contains many of its accustomed components, such as reversible encephalopathy, gene silencing, dyserythropoiesis, seizures, coagulopathy, hypoalbuminaemia and hypertriglyceridaemia. It is thus proposed that the pattern of pathology that comprises much of the systemic inflammatory syndrome occurs when one of the usually advantageous roles of pro-inflammatory cytokines – generating sickness behaviour by moderately repressing genes (Dbp, Tef, Hlf, Per1, Per2 and Per3, and the nuclear receptor Rev-erbα) that control circadian rhythm – becomes excessive. Although reversible encephalopathy and gene silencing are severe events with potentially fatal consequences, they can be viewed as having survival advantages through lowering energy demand. In contrast, dyserythropoiesis, seizures, coagulopathy, hypoalbuminaemia and hypertriglyceridaemia may best be viewed as unfortunate consequences of extreme repression of these same genetic controls when the pro-inflammatory cytokines that cause sickness behaviour are produced excessively. As well as casting a new light on the previously unrationalized coexistence of these aspects of systemic inflammatory diseases, this concept is consistent with the case for a primary role for inflammatory cytokines in their pathogenesis across this range of diseases

Analysis of nematode infection levels among indoor pigs in Thika District, Kenya

The infection levels of various species of nematode infection were studied in 35 indoor pig herds in Thika district, Kenya. Faecal samples were collected from 830 pigs of all ages and examined for nematode eggs per gram (EPG) of faeces using a modified McMaster technique. The infection intensity exhibited a binomial distribution with a majority of animals having only a light infection (EPG range = 0-500). The level of nematode infections was associated with the age of pigs. Thus, the highest mean EPG levels of Oesophagostomum spp. was 218 (SE = ±34), Ascaris suum 215 (SE = ±62), Trichuris suis 155(SE = ±66) and Strongyloides ransomi 24(SE = ±6) were found in adults, weaners, porkers and piglets respectively. The widest individual nematode species range of EPG values was found in T. suis (0 - 10,000) and A. suum (0 - 5300) infections. It is possible that the low EPG levels could be due to aggressive helminth control by local farmers. This could increase costs and possibly lead to the emergence of anthelmintic resistance. To reduce these costs, it is recommended that animals should be treated after faecal examination and laboratory determination of the EPG levels.. Kenya Veterinarian Vol. 31 (2) 2007: pp. 54-5

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)

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