Blackleg in ruminants.

Abstract

Abstract Blackleg is a per acute or acute and fatal disease of cattle and sheep caused by Clostridium chauvoei Jakari, Vom and K76 strains in Nigeria, strains NCTC 8070 and 8361 in UK, strain 49 in India and other parts of Asia, strain NC08596 in Germany and other parts of Europe and America, strains ch.16 and ch.22 in Mozambique and Tanzania and strain Awasa in Ethiopia, respectively. The haematological and biochemical changes observed in ruminants with blackleg include haemoconcentration (increased packed cell volume, haemoglobin concentration, red blood cell counts, and total plasma protein concentration), increased erythrocyte sedimentation rate (ESR), decrease in total and differential leucocyte counts (leucopaenia, panleucopaenia i.e. lymphopaenia, neutropaenia, eosinopaenia and monocytopaenia), thrombocytopaenia, increased plasma neuraminidase activity, increased erythrocyte surface and plasma sialic acid concentration, increased levels of serum lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and increased creatine kinase (CK) activity. The leucopaenia and decrease in differential leucocyte counts, increase in plasma sialic acid concentration and decrease in erythrocyte surface sialic acid levels were attributed to the action of neuraminidase, whose activity is increased in the plasma in clinical blackleg. The neuraminidase produced by C. chauvoei is reported to possibly play a significant role in the inflammation and vascular permeability which are observed in blackleg. The pathological changes observed in cattle, sheep and deer with blackleg are essentially similar and are discussed. Some herbal remedies ( Tamarindus indicus and Combretum fragrans ) have been used by the transhumance (nomadic) Fulani pastoralists of rural Nigeria to successfully treat the disease. The economic losses of ruminants to the disease have not been quantified in most countries of the world, but in Nigeria, annual losses of cattle to it have been estimated at US$4.3 million. Vaccination has remained the best control strategy against the disease, which is endemic in Africa, USA, Central and Southern America, Asia and Europe.