Effects of acute bovine trypanosomosis (Trypanosoma vivax) on plasma kinetics of intravenously administered lactose.

Four calves infected with Trypanosoma vivax and four uninfected control calves were each injected intravenously with repeated doses of 0.5 g lactose kg-1 body weight, thrice daily at intervals of 4 h. Plasma samples were collected at specified time intervals and analysed for lactose. Pharmacokinetic parameters were calculated from the data. T. vivax infection delayed excretion of lactose from the body, thus leading to significantly (P < 0.001) increased biological half life (t1/2) and a significantly (P < 0.001) reduced elimination rate constant for lactose in the body. The apparent volume of distribution and total clearance of lactose were not affected by the infection. T. vivax infection also appeared to cause accumulation of lactose in the plasma after repeated intravenous administration.

Effect of acute Trypanosoma vivax infection on cattle erythrocyte glutathione and susceptibility to in vitro peroxidation.

During acute Trypanosoma vivax infection of calves, produced by intravenous inoculation, the mean packed cell volume and red blood cell counts of the infected animals decreased significantly (P < 0.05) between Days 6 and 13 post-infection (pi). The moderately severe normocytic anaemia started to develop during the first wave of parasitaemia which occurred from Day 2 pi and peaked between Days 4 and 5 pi. The mean erythrocyte glutathione (GSH) concentration of the infected calves decreased significantly (P < 0.05) from 58.4 +/- 11.4 mg 100ml-1 red blood cells (RBC) on Day 0 pi to 44.5 +/- 12.8 mg 100ml-1 RBC on Day 5 pi. As the GSH values recovered on Day 6 pi and increased thereafter, another slight decrease (P > 0.05) in GSH concentration occurred on Day 12 pi at the second peak of parasitaemia followed by a significant (P < 0.05) increase to 79.1 +/- 14.6 mg 100ml-1 RBC on Day 13 pi. In the uninfected calves, the mean GSH values ranged from 47.7 +/- 7.0 to 60.8 +/- 6.8 mg 100ml-1 RBC. When washed, erythrocytes of the infected and uninfected calves were separately challenged with hydrogen peroxide. They produced comparable amounts of thiobarbituric acid reactive substances as a measure of by-products of lipid peroxidation. This suggested that the ability of the erythrocytes to prevent peroxidative injury was not reduced, because GSH regeneration was probably enhanced and the antioxidant capacity of the erythrocytes was maintained.

Use of the enzyme-linked immunosorbent assay for screening cattle for Brucella antibodies in Nigeria.

The prevalence of Brucella antibodies in settled Fulani cattle herds in Kaduna State, Nigeria, was determined by using the enzyme-linked immunosorbent assay (ELISA) technique. Out of a total of 762 animals drawn randomly from 40 cattle herds in various areas of the state, 50 (6.6%) tested positive. There was no significant difference (P<0.01) in the number of reactors between male and female animals. Brucella antibodies were detected in animals in all areas of the state but prevalence was highest in Kaura area (26.8%) and was lowest in Zonkwa area (1.0%). Out of the 762 animals, 23 (3.0%) tested positive in the agglutination test (SAT) while 16 (2.1%) tested positive in the Rose-bengal plate test (RBTP). This study indicated that cattle in Nigeria have antibodies to Brucella tested by ELISA technique and that seropositive animals are located in distinct foci. The identification of these pockets of infection on a nation-wide basis will be crucial for future brucellosis control programmes.

Increased susceptibility of erythrocytes to in vitro peroxidation in acute Trypanosoma brucei infection of mice.

Trypanosoma brucei, Wamba strain, produced an acute infection in mice, and mortality was observed 2 days after the onset of parasitaemia which occurred 3-5 days postinfection. Anaemia was observed in the tail blood of the survivors. When washed erythrocytes from the heart blood were incubated in physiological saline containing 1.5% hydrogen peroxide, the erythrocytes of the infected mice produced significantly greater amounts of by-products of lipid peroxidation (measured as thiobarbituric acid reactive substances) than the erythrocytes of the control mice. This observation suggested that the infected mice may have a reduced ability in the prevention of free radical mediated lipid peroxidation in the erythrocyte membrane. It is concluded that peroxidative injury to the erythrocytes may contribute to the pathogenesis of anaemia in trypanosomosis.

Biochemical differences (O-acetyl and glycolyl groups) in erythrocyte surface sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle.

Differences in the distribution and concentration of O-acetyl and glycolyl groups in erythrocyte sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle were investigated. Erythrocyte surface sialic acid concentrations were 25.4 +/- 5.5 mg per dl and 5.9 +/- 0.97 mg per dl in N'dama and Zebu animals, respectively. In N'damas, O-acetyl and glycolyl groups were present in concentrations of 16.4 +/- 4.3 mg per dl and 12.8 +/- 2.9 mg per dl, respectively, whereas the corresponding values in Zebus were 2.8 +/- 5.0 mg per dl and 7.6 +/- 1.7 mg per dl, respectively. The differences between N'dama and Zebu cattle in surface sialic acids and in O-acetyl and glycolyl groups were significant (P < 0.01 to < 0.001). N'dama erythrocyte sialic acids had more O-acetyl than glycolyl groups while those of Zebus had less O-acetyl than glycolyl groups. These findings may be relevant to the trypanotolerance of N'dama cattle.

The course of experimental Trypanosoma vivax infection in Uda sheep.

The course of experimental Trypanosoma vivax infection in eight Uda rams was studied. All the infected animals became parasitaemic 2 days post-inoculation and remained so throughout the study period. A three-phase disease pattern was recognized, i.e. acute, subacute and chronic stages lasting 17-85 days. The disease was characterized by fever and a terminal decrease in rectal temperature despite an increase in parasitaemia with time for rams with acute and subacute infections. Mean weight loss was most marked in subacute followed by chronic cases. Gross pathological changes observed in some infected rams with subacute and chronic trypanosomosis were oedema of the face and lower jaw, hydropericardium and atrophy of the pericardial fat. Petechial haemorrhages were observed on the surfaces of the heart and kidney of rams with acute infection. Anaemia was most severe in infected rams with acute disease, followed by those with subacute infections. Also, hypoproteinaemia was observed in all infected rams. Severe clinical findings associated with the death of all the infected rams during this study might indicate that the Uda breed of sheep in very susceptible to trypanosomosis. It is, therefore, recommended that this breed of sheep, which is strictly bred and reared in tsetse-free Sahel savannah, should not be introduced into endemic areas devoid of therapeutic cover and strict tsetse fly control.

Comparative studies of gastrointestinal helminths of poultry in Zaria, Nigeria.

Two-hundred and ten digestive tracts of local chickens reared in and around Zaria, Northern Nigeria, under the extensive native free range system of management and 203 digestive tracts of exotic chickens raised under the intensive system of management were examined for parasites. Two hundred and one (95.7%) of the local chickens were infected and 24 (11.8%) of the exotic chickens also. Among the local chickens, 12 species of nematodes and 7 species of cestodes were recovered. Only one nematode and one cestode species were recovered from the exotic chickens. The prevalence of helminth infections between local and exotic chickens was significantly different at 1%.

Electrophoresis of bovine erythrocyte sialic acids: existence of additional band in trypanotolerant Ndama cattle.

Mild acid-hydrolysis of erythrocyte surface sialic acids of the trypanotolerant Ndama and the trypanosusceptible White/Fulani Zebu breeds of cattle was performed. The cleaved sialic acids from the two breeds of cattle were simultaneously subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE), along with commercial standard N-acetylneuraminic acid (MW 309.28), blank gel and plasma proteins. The cleaved sialic acids migrated in the globulin fractions, as shown by the plasma protein electrophoresis. While the Ndama and the Zebu erythrocytes had one migrating band each of which coincided with the standard N-acetylneuraminic acid, the Ndama had another trailing band of sialic acid, of an estimated molecular weight of 30 kDa, which may account for the higher erythrocyte sialic acid concentrations of the Ndama. This additional band was absent in the Zebu. All these bands were readily reproducible.

Elevation of morphological abnormalities of spermatozoa in the semen of Zebu bulls consequent to Trypanosoma vivax and Trypanosoma congolense infections.

Twenty-four Zebu bulls were used in a 12-wk long study. Eight bulls were infected with T. vivax , eight others with T. congolense and eight bulls served as controls. All the infected bulls developed chronic trypanosomiasis. Mean percentage base-line values prior to infection for acrosomal, sperm-head, detached heads, proximal cytoplasmic droplets, distal cytoplasmic droplets, sperm-tail, midpiece and total sperm morphological abnormalities ranged between 0.1+/-0.1 for acrosomal and 8.7+/-3.4 for total morphological abnormalities in the semen of the bulls. These values were very low and within the range of those for fertile bulls. Following infection, there was a progressive increase in the mean values of all the abnormalities. Peak percentage mean values recorded for total sperm morphological abnormalities in the course of the investigation in the bulls infected with T. vivax and T. congolense and in the controls were 95+/-7.2, 100+/-0 and 7.9+/-5.0, respectively. Mean percentage values throughout the duration of the investigation for control bulls were low and within the normal range for fertile bulls. These values differed (P<0.001) from the elevated values of the infected bulls. The results indicate that trypanosomiasis due to either T. vivax or T. congolense infections can cause a marked increase in morphological abnormalities of spermatozoa which can, in turn reduce the fertility of breeding bulls.

Pathological changes in male genitalia of cattle infected with Trypanosoma vivax and Trypanosoma congolense.

Samples for histological studies were taken from the genitalia of 14 bulls (five infected with Trypanosoma vivax, five with T. congolense and four uninfected control animals), slaughtered 12, 22 or 30 weeks post-infection. Infection with Y58 strain of T. vivax and strain 2295 of T. congolense caused various grades of lesions in the male reproductive organs, especially the testes and epididymides. T. congolense produced more severe degenerative changes than T. vivax. It is concluded that in long-standing cases, the result of trypanosome infection is either serious infertility or even sterility.

Comparative haematological changes following Trypanosoma vivax and T. congolense infections in Zebu bulls.

A comparative study of haematological changes subsequent to Trypanosoma vivax and Trypanosoma congolense infections was carried out using 24 Zebu bulls during a period of 12 weeks. Eight bulls were infected with T. vivax, another eight with T. congolense and eight served as controls. Infected bulls developed chronic trypanosomiasis which was characterized by many clinical manifestations including intermittent pyrexia. Elevated rectal temperatures of up to 105 and 106 degrees F were recorded, respectively, in all bulls infected with T. vivax or T. congolense. Mean parasitaemia was higher and more chronic in T. congolense-infected bulls and ranged between means of 0 and 3.06 in all infected bulls. There was a slight and transient drop in packed cell volume (PCV) of T. vivax-infected bulls as against a marked and more chronic drop in T. congolense-infected bulls. Mean PCV of T. vivax- and T. congolense-infected bulls and controls ranged between 28 and 38, 17 and 38, and 31 and 38%, respectively. Haemoglobin (Hb) concentrations also decreased in infected bulls. The decrease was greater and more chronic in the T. congolense-infected bulls. Values ranged between means of 10.47 and 13.84, 5.44 and 14.16, and 10.24 and 14.12 g dl-1 in T. vivax- and T. congolense-infected and control bulls, respectively. Total plasma proteins also decreased in infected bulls; this was more marked in the T. congolense-infected group. Values for T. vivax-infected, T. congolense-infected and control bulls ranged between means of 7.66 and 8.99, 6.26 and 8.81, and 7.94 and 8.78 g dl-1, respectively.2+ that the indigenous T. vivax strains are more

Erythrocyte surface sialic acid in Ndama and Zebu cattle.

Erythrocyte surface sialic acid concentrations were measured in the trypano-tolerant Ndama and trypano-susceptible Zebu breeds of cattle. All animals were uninfected and had no records of previous exposure to infection by African pathogenic trypanosomes. Ndama adults had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Ndama calves. Ndama adults and calves had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Zebu adults. There were no significant differences between the packed cell volume (PCV), haemoglobin (Hb) concentrations and total leukocyte counts (WBC) of these breeds. The finding of much higher erythrocyte surface sialic acid concentrations (about 7-fold) in the Ndama than in the Zebu is discussed in relation to the induction of anaemia by trypanosome sialidase in both breeds and to how a relative trypano-tolerance may occur in the Ndama.

Depleted serum haptoglobin in acute bovine trypanosomiasis.

Haemoglobin-binding protein (Haptoglobin, Hp) was assayed in the sera of control and zebu calves with acute T. vivax infection. Hp in control Zebu calves ranged between 123.5 and 236.5 mg dl-1 while Hp in the infected calves was too low to measure or absent. It was suggested that absence of Hp in the infected calves may be as a result of gradual intravascular haemolysis and removal of the Hp-Hb complex by the reticuloendothelial system.

Leukocyte response in experimental Trypanosoma vivax infection in cattle.

Eight Zebu cattle were infected with Trypanosoma vivax stock Y58, while 8 served as uninfected controls. The infected animals developed early leukopenia due to concomitant lymphopenia and neutropenia. It is suggested that an increase in trypanosomal antigens and neuraminidase in the infected cattle at this time may have an effect on peripheral leukocytes.

Variation in erythrocyte surface and free serum sialic acid concentrations during experimental Trypanosoma vivax infection in cattle.

Erythrocyte surface and free serum sialic acid concentrations were determined during experimental Trypanosoma vivax infection in cattle. All infected calves developed mild trypanosomiasis, with significant decreases in mean packed cell volume occurring 15, 16, 20, 22 and 24 days after infection. The anaemia was preceded by significant decreases in mean erythrocyte surface sialic acid concentrations on days 7, 13 and 14, with yet another significant decrease on day 31 after infection. These decreases in erythrocyte surface sialic acid concentrations coincided with the parasitaemic waves. Free serum sialic acid concentration, however, showed an increase, though non-significantly, on day 8, which coincided with both a decrease in erythrocyte surface sialic acid and the initial parasitaemic wave. It is postulated that the early anaemia observed in infected animals may be attributable to the activities of the circulating trypanosomes which produce neuraminidase which, in turn, cleaves off surface sialic acid, thus rendering the erythrocyte more prone to phagocytosis by the recticuloendothelial system.

Variations with age in serum iron and iron-binding capacity in zebu cattle.

The variations with age in serum iron concentration and iron-binding capacity in zebu cattle were investigated. Serum iron concentration was lower in calves from birth to four weeks of age than in older cattle. Total iron-binding capacity decreased while percentage saturation increased with advancing age.

Observations on the course and pathology of Trypanosoma vivax in Red Sokoto goats.

The course of trypanosomiasis was observed over a period of 68 days in eight Red Sokoto goats experimentally infected with Trypanosoma vivax strain Y58. The goats developed parasitaemia five days after infection; the intensity of parasitaemia varied within and between individual goats. The course of the disease was acute, subacute or chronic. Anaemia was the principal clinocopathological feature of the disease. The rate of development of anaemia was not related to the degree of parasitaemia. Other clinical signs included emaciation, weakness, rough hair coat, profuse lacrimation and development of corneal opacity. Bone marrow of infected goats showed marked erythroid hyperplasia. Erythrophagocytosis and haemosiderosis in the bone marrow, liver and spleen were the principal histopathogical features in infected goats.