Nicodemus M. Useh

Pathogenesis and pathology of blackleg in ruminants: The role of toxins and neuraminidase. A short review

Summary There is no consensus on the pathogenesis of blackleg infection that occurs in ruminants, but toxins and neuraminidase produced by Clostridium chauvoei are believed to play a significant role in the pathogenesis of the disease. This paper provides an update on the role of toxins and neuraminidase in the pathogenesis and pathology of the disease. The use of neuraminidase inhibitors to manage clinical blackleg infections is therefore an alternative therapeutic protocol that should be thoroughly investigated. It is suggested that in vivo clinical trials should be carried out to determine the mechanism of action and clinical efficacy of neuraminidase inhibitors.

The Inhibition of Clostridium chauvoei (Jakari strain) Neuraminidase Activity by Methanolic Extracts of the Stem Barks of Tamarindus indicus and Combretum fragrans

The inhibition of neuraminidase from Clostridium chauvoei (jakari strain) with partially purified methanolic extracts of some plants used in Ethnopharmacological practice was evaluated. Extracts of two medicinal plants, Tamarindus indicus and Combretum fragrans at 100–1000 μg/ml, both significantly reduced the activity of the enzyme in a dose-dependent fashion (P < 0.001). The estimated IC50 values for Tamarindus indicus and Combretum fragrans were 100 and 150 μ/ml respectively. Initial velocity studies conducted, using fetuin as substrate revealed a non-competitive inhibition with the Vmax significantly altered from 500 μmole min−1 mg−1 to 240μmole min−1 mg−1 and 340 μmole min−1 mg−1 in the presence of Tamarindus indicus and Combretum fragrans respectively. The KM remained unchanged at 0.42 mM. The computed Index of physiological efficiency was reduced from 1.19 min−1 to 0.57 min−1 and 0.75 min−1 with Tamarindus indicus and Combretum fragrans as inhibitors respectively.

Changes in the serum profiles of lipids and cholesterol in sheep experimental model of acute African trypanosomosis

6Trypanosoma congolense organisms. Another five uninfected sheep served as control group. Blood samples were collected from all the animals every other day from the day of infection (day 0) up to the termination of the experiment. The samples were used for haematological and parasitological analyses and determination of serum concentrations of total cholesterol, triglycerides, high density lipoprotein-cholesterol (HDL-cholesterol) and low density lipoproteincholesterol (LDL-cholesterol). All animals in the infected group showed parasitaemia by day 11 postinfection (PI) and the infection caused a gradual decline in the values of packed cell volume (PCV) and those of serum total cholesterol, triglycerides, HDL-cholesterol and LDL-cholesterol. Values of all these parameters in the control group remained fairly normal, relative to the pre-infection ones on day 0, throughout the experimental period. The PI mean values of serum total cholesterol, triglycerides, HDLcholesterol and LDL-cholesterol, measured in mmol/l, in the infected group were 3.44 ± 0.71, 1.62 ± 0.40, 0.78 ± 0.20 and 1.92 ± 0.40, respectively, while those in the control group were 4.32 ± 0.18, 2.24 ± 0.11, 1.15 ± 0.10 and 2.26 ± 0.30, respectively. The differences between the PI mean values in the two groups of animals were significant (P<0.05). T. congolense utilization of the molecules could, among other factors, be the cause of the reduced serum levels of these parameters and this could be a contributory factor in the pathophysiology of some of the disorders observed in trypanosome-infected animals.

Blackleg in ruminants

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

Columbin inhibits cholesterol uptake in bloodstream forms of Trypanosoma brucei-A possible trypanocidal mechanism

4.3million. Vaccination has remained the best control strategy against the disease, which is endemic in Africa, USA, Central and Southern America, Asia and Europe.

Haemagglutination Inhibition Antibodies, Rectal Temperature and Total Protein of Chickens Infected with a Local Nigerian Isolate of Velogenic Newcastle Disease Virus

The diterpenoid furanolactone (columbin) from Aristolochia albida inhibited growth of culture forms of Trypanosoma brucei. In vitro analysis of the compound at 5–250 μg/ml showed complete lysis of the parasites within 10–20 minutes post incubation. At 50 μg/ml, columbin killed about 50% of the parasites which initially appeared swollen under phase contrast microscopy. Also the total amount of cholesterol diminished dose-dependently in the presence of 10–100 μg/ml of columbin after a 3-day incubation period. In vivo analysis of the compound in T. brucei-infected mice revealed that 25 mg/kg administered for 3 consecutive days, completely cleared the parasites from the peripheral circulation. However, columbin could not clear parasites in the cerebrospinal fluid.

Aetiology and prevalence of canine anaemia in Zaria: a review of 2139 cases observed at the Veterinary Teaching Hospital of the Ahmadu Bello University, Zaria, Nigeria (1990-2003)

Changes in values of haemagglutination inhibition (HI) antibody titre, rectal temperature (RT) and total protein (TP) were determined for Shaver Brown chickens infected with Newcastle disease virus (NDV) Kudu 113. The infected chickens came down with Newcastle disease by day 3 post infection (PI). The major clinical signs were depression, greenish diarrhoea, paralysis of legs and wings, opisthotonus and torticolis. Mortality and morbidity were 52% and 100%, respectively. There were haemorrhagic lesions in the wall of the intestine, proventricular mucosa and caecal tonsils. There were necrosis and mononuclear cell infiltration of the liver, kidney and spleen. There was a significant increase in daily mean HI antibody titres from days 3 to 9 PI. Similarly, significant rise in daily mean RTs were noticed in the infected chickens from days 1 to 13 PI. On the other hand, there was a decrease in daily mean TP concentrations of infected chickens, beginning from day 3 PI, and the lowest concentration of 2.60±0.15 g/dl was obtained by days 7 and 11 PI. The values of HI, RT and TP for the control chickens were relatively constant during the experiment. The correlation coefficient (r) between HI and RT was positive and highly significant (r = 0.725, p<0.001), while the relationship between HI and TP was negative but highly significant (r = –0.712, p<0.001). It was concluded that NDV Kudu 113 induced increases in values of HI and RT, which occurred concurrently with a decrease in TP concentrations of infected chickens.

Characterization of a sialidase (neuraminidase) isolated from Clostridium chauvoei (Jakari strain)

Summary An investigation was conducted at the Ahmadu Bello University Veterinary Teaching Hospital (ABUVTH) between January, 1990 and September, 2003 to determine the aetiology and prevalence of canine anaemia in Zaria, Nigeria. Out of the 5278 mongrel dogs presented during the period 1990–2003, 2139 (40.5%) were found to be anaemic, with packed cell volume (PCV) values ranging from 7 to 36%. The clinical signs presented by these dogs include: Pale mucous membranes, weakness, depression, anorexia/inapettence and reduced activity. About 50 dogs (about 1%) with helminths and haemoparasitic infestations had high PCV values (37–40%) without clinical presentation of anaemia or disease. Most of the dogs with anaemia (n=2016 or 94.2%) had parasitic infestations. About 1580 (about 74%) of the anaemic cases, attributed to parasitic infestations occurred between May and October. A few dogs (n=55, 2.6%) had anaemia due to poor nutrition, while 68 (3.2%) had anaemia with unknown cause. The public health significance of the parasites reported in this study is discussed.