The concentration of organochlorines (OCs) such as organochlorine pesticides and polychlorinated biphenyls were measured in adipose tissue collected from 14 male hippopotami at Mfuwe in the southern part of the Luangwa National Park, Zambia. The samples contained low levels of OCs, and the concentrations of OCs were comparable to or lower than reported for wild herbivores studied in other parts of the world.

The concentration of organochlorines (OCs) such as organochlorine pesticides and polychlorinated biphenyls were measured in adipose tissue collected from 14 male hippopotami at Mfuwe in the southern part of the Luangwa National Park, Zambia. The samples contained low levels of OCs, and the concentrations of OCs were comparable to or lower than reported for wild herbivores studied in other parts of the world.

Psittacine beak and feather disease (PBFD) is a common viral disease of wild and captive psittacine birds characterized by symmetric feather loss and beak deformities. The causative agent, beak and feather disease virus (BFDV), is a small, circular single-stranded DNA virus that belongs to the genus Circovirus. BFDV can be detected by PCR or the use of haemagglutination (HA) and haemagglutination inhibition (HI) assays that detect antigen and antibodies respectively. Erythrocytes from a limited number of psittacine species of Australian origin can be used in these tests. In South Africa, the high cost of these birds makes them difficult to obtain for experimental purposes. Investigation into the use of erythrocytes from African Grey parrots and Brown-headed parrots yielded positive results showing the haemagglutinating activity of their erythrocytes with purified BFDV obtained from confirmed clinical cases of the disease. The HA activity was further confirmed by the demonstration of HI using BFDV antiserum from three different African Grey parrots previously exposed to the virus and not showing clinical signs of the disease.

Psittacine beak and feather disease (PBFD) is a common viral disease of wild and captive psittacine birds characterized by symmetric feather loss and beak deformities. The causative agent, beak and feather disease virus (BFDV), is a small, circular single-stranded DNA virus that belongs to the genus Circovirus. BFDV can be detected by PCR or the use of haemagglutination (HA) and haemagglutination inhibition (HI) assays that detect antigen and antibodies respectively. Erythrocytes from a limited number of psittacine species of Australian origin can be used in these tests. In South Africa, the high cost of these birds makes them difficult to obtain for experimental purposes. Investigation into the use of erythrocytes from African Grey parrots and Brown-headed parrots yielded positive results showing the haemagglutinating activity of their erythrocytes with purified BFDV obtained from confirmed clinical cases of the disease. The HA activity was further confirmed by the demonstration of HI using BFDV antiserum from three different African Grey parrots previously exposed to the virus and not showing clinical signs of the disease.

Poisoning with cardiac glycoside-containing plants is collectively the most important plant-associated poisoning of livestock in southern Africa. As a diagnosis of this significant poisoning is currently based on circumstantial evidence, a practical chemical procedure indicating the presence of cardiac glycosides in plants and animal specimens would be of considerable benefit. The fluorescence polarization immunoassay (FPIA) method, used to determine digoxin plasma levels in humans and dogs, was adapted to estimate cardiac glycoside levels in known cardiac-glycoside- containing plants as well as in the rumen and organs of dosed sheep. Positive FPIA values were obtained with bufadienolide-containing plants, while negative results were obtained with plants not known to contain cardiac glycosides. The FPIA has aided in the diagnosis of cardiac glycoside poisoning in livestock and game in 30 outbreaks examined at the Division of Toxicology, Onderstepoort Veterinary Institute. Each outbreak is briefly described. As a result of this assay, a better understanding of cardiac glycoside poisoning has been reached.

Poisoning with cardiac glycoside-containing plants is collectively the most important plant-associated poisoning of livestock in southern Africa. As a diagnosis of this significant poisoning is currently based on circumstantial evidence, a practical chemical procedure indicating the presence of cardiac glycosides in plants and animal specimens would be of considerable benefit. The fluorescence polarization immunoassay (FPIA) method, used to determine digoxin plasma levels in humans and dogs, was adapted to estimate cardiac glycoside levels in known cardiac-glycoside- containing plants as well as in the rumen and organs of dosed sheep. Positive FPIA values were obtained with bufadienolide-containing plants, while negative results were obtained with plants not known to contain cardiac glycosides. The FPIA has aided in the diagnosis of cardiac glycoside poisoning in livestock and game in 30 outbreaks examined at the Division of Toxicology, Onderstepoort Veterinary Institute. Each outbreak is briefly described. As a result of this assay, a better understanding of cardiac glycoside poisoning has been reached.

Dairy cattle reared in western Kenya are exposed to medium to high levels of trypanosomosis risk. The social background, farm characteristics and dairy cattle productivity of 90 and 30 randomly selected farmers from medium- and high-risk trypanosomosis areas, respectively, were compared. All the 120 farmers were visited between July and August 2002. Data analysis was performed using descriptive statistics and analysis of variance. The results showed that increased trypanosomosis risk represented by an increase in disease prevalence in cattle of 1% to 20 % decreased the density of dairy cattle by 53 % and increased the calving interval from 14 to 25 months. The increased risk was also associated with a significant increase in cattle mortalities and in a lactation period of 257 to 300 days. It was concluded that removal of the trypanosomosis constraint on dairy production would lead to expansion of dairying since the domestic demand for dairy products is expected to increase.

Dairy cattle reared in western Kenya are exposed to medium to high levels of trypanosomosis risk. The social background, farm characteristics and dairy cattle productivity of 90 and 30 randomly selected farmers from medium- and high-risk trypanosomosis areas, respectively, were compared. All the 120 farmers were visited between July and August 2002. Data analysis was performed using descriptive statistics and analysis of variance. The results showed that increased trypanosomosis risk represented by an increase in disease prevalence in cattle of 1% to 20 % decreased the density of dairy cattle by 53 % and increased the calving interval from 14 to 25 months. The increased risk was also associated with a significant increase in cattle mortalities and in a lactation period of 257 to 300 days. It was concluded that removal of the trypanosomosis constraint on dairy production would lead to expansion of dairying since the domestic demand for dairy products is expected to increase.

A survey to determine the prevalence of bovine tuberculosis caused by Mycobacterium bovis and certain other infectious diseases was conducted on 42 free-ranging African buffaloes, (Syncerus caffer) from May to June 1997 in the Queen Elizabeth National Park, Uganda. Using the gamma interferon test, exposure to M. bovis was detected in 21.6 % of the buffaloes. One dead buffalo and an emaciated warthog (Phacochoerus aethiopicus) that was euthanased, were necropsied; both had miliary granulomas from which M. bovis was isolated. None of the buffaloes sampled in Sector A of the park, which has no cattle interface, tested positive for bovine tuberculosis (BTB) exposure. The prevalence and distribution of BTB does not appear to have changed significantly since the 1960s, but this may be due to fluxes in the buffalo population. Serological testing for foot-and-mouth disease (FMD) demonstrated positive exposure of 57.1% of the buffaloes sampled, with types A, O and SAT 1-3, which is the first known report of FMD antibodies to A and O types in free ranging African buffaloes. Foot-and-mouth disease virus types SAT 1 and SAT 3 were isolated from buffalo probang samples. Two percent of the buffaloes had been exposed to brucellosis. None of the buffaloes tested had antibodies to rinderpest, leptospirosis or Q fever.

A survey to determine the prevalence of bovine tuberculosis caused by Mycobacterium bovis and certain other infectious diseases was conducted on 42 free-ranging African buffaloes, (Syncerus caffer) from May to June 1997 in the Queen Elizabeth National Park, Uganda. Using the gamma interferon test, exposure to M. bovis was detected in 21.6 % of the buffaloes. One dead buffalo and an emaciated warthog (Phacochoerus aethiopicus) that was euthanased, were necropsied; both had miliary granulomas from which M. bovis was isolated. None of the buffaloes sampled in Sector A of the park, which has no cattle interface, tested positive for bovine tuberculosis (BTB) exposure. The prevalence and distribution of BTB does not appear to have changed significantly since the 1960s, but this may be due to fluxes in the buffalo population. Serological testing for foot-and-mouth disease (FMD) demonstrated positive exposure of 57.1% of the buffaloes sampled, with types A, O and SAT 1-3, which is the first known report of FMD antibodies to A and O types in free ranging African buffaloes. Foot-and-mouth disease virus types SAT 1 and SAT 3 were isolated from buffalo probang samples. Two percent of the buffaloes had been exposed to brucellosis. None of the buffaloes tested had antibodies to rinderpest, leptospirosis or Q fever.

A survey conducted in five villages in a resource-poor farming community in Qwa-Qwa, using the rapid rural appraisal technique and a questionnaire survey, showed that a significant proportion of the farmers (84 %) use traditional or alternative methods to control ectoparasites, while 16 % use commercial acaricides (c2 = 7.1; P 0.05). Alternative control methods included the use of used engine oil, household disinfectant and paraffin. Killing of ticks was the main reason for control (40 %), with disease control being second (20 %). Other reasons given for controlling ticks were to prevent damage to teats, to provide animals with a clean appearance and to protect hides. Some 40 % of farmers were aware of the effects of ticks on their animals. There is a need for farmer education that will provide information on integrated tick management and its advantages over absolute reliance on commercial acaricides.

A survey conducted in five villages in a resource-poor farming community in Qwa-Qwa, using the rapid rural appraisal technique and a questionnaire survey, showed that a significant proportion of the farmers (84 %) use traditional or alternative methods to control ectoparasites, while 16 % use commercial acaricides (c2 = 7.1; P < 0.05). Alternative control methods included the use of used engine oil, household disinfectant and paraffin. Killing of ticks was the main reason for control (40 %), with disease control being second (20 %). Other reasons given for controlling ticks were to prevent damage to teats, to provide animals with a clean appearance and to protect hides. Some 40 % of farmers were aware of the effects of ticks on their animals. There is a need for farmer education that will provide information on integrated tick management and its advantages over absolute reliance on commercial acaricides.

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum and two field isolates of NAD-independent H. paragallinarum has previously been tested in unvaccinated chickens. In this study, the disease profiles caused by the NAD-dependent isolates of H. paragallinarum in vaccinated chickens were studied. It was shown that the clinical signs induced in the vaccinated chickens were substantially less severe than were those in unvaccinated chickens, as was expected. However, due to the high virulence of the serovar C-3 isolates, clinical signs in the vaccinated chickens challenged with this isolate were still detected. These were as severe as those occurring in unvaccinated chickens challenged with serovar B-1 isolates. Although the clinical signs induced in unvaccinated birds challenged with serovar A-1 were more severe than those occurring when vaccinated birds were challenged with serovar C-3, the overall disease profiles were similar. Substantial clinical signs were recorded in vaccinated birds challenged with serovar C-3. This could be interpreted as vaccination failure if the disease profile obtained in unvaccinated birds is not considered. It was found that a high level of protection was provided by this vaccine against challenge by serovar C-3. The high virulence of this serovar resulted in the development of clinical signs in vaccinated birds. These findings could possibly explain the large number of so-called vaccination failures that are reported in South Africa.

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum and two field isolates of NAD-independent H. paragallinarum has previously been tested in unvaccinated chickens. In this study, the disease profiles caused by the NAD-dependent isolates of H. paragallinarum in vaccinated chickens were studied. It was shown that the clinical signs induced in the vaccinated chickens were substantially less severe than were those in unvaccinated chickens, as was expected. However, due to the high virulence of the serovar C-3 isolates, clinical signs in the vaccinated chickens challenged with this isolate were still detected. These were as severe as those occurring in unvaccinated chickens challenged with serovar B-1 isolates. Although the clinical signs induced in unvaccinated birds challenged with serovar A-1 were more severe than those occurring when vaccinated birds were challenged with serovar C-3, the overall disease profiles were similar. Substantial clinical signs were recorded in vaccinated birds challenged with serovar C-3. This could be interpreted as vaccination failure if the disease profile obtained in unvaccinated birds is not considered. It was found that a high level of protection was provided by this vaccine against challenge by serovar C-3. The high virulence of this serovar resulted in the development of clinical signs in vaccinated birds. These findings could possibly explain the large number of so-called vaccination failures that are reported in South Africa.

Twelve Tuli weaner steers aged 1 year were randomly subdivided into three groups of four animals and infected with different doses of Calicophoron microbothrium metacercariae. Each animal in Group I received a low dose (LD) of 5 000 metacercariae, Group II a medium dose (MD) of 15 000 metacercariae, Group III a high dose (HD) of 25 000 metacercariae and one additional animal was kept as an uninfected control (C). After infection, one animal from each group was slaughtered on Day 28, 42, 56 and 84 post infection (pi) and samples from the ileum, jejunum, duodenum, abomasum and the rumen were collected for histopathological and cytological examination. On Day 28 pi, the gross pathological lesions observed in the duodenum of the LD and the MD animals were similar and comprised duodenal thickening, corrugation, hyperaemia, petechiation and ulceration. In the HD animal the duodenal lesions were similar but more severe. The abomasal folds were severely oedematous in the MD group and nearly occluded the abomasal lumen. Moderate oedema of the abomasal folds was also present in the LD and HD animals. The gross pathological lesions regressed in all the infected groups with increasing age of infection and had disappeared completely by Day 56 pi. On Day 28 pi the histopathological lesions in the duodenum and jejunum of the LD and MD groups were similar, comprising subtotal villous atrophy, hyperplasia of Brunner's glands and Peyer's patches and moderate infiltration of eosinophils, mast cells and a few globule leukocytes, basophils and lymphocytes in the lamina propria. The HD group had total villous atrophy, severe hyperplasia and cystic dilatation of Brunner's glands, which had expanded to cover the entire submucosa. On Day 42 pi the histopathological lesions were still present in the MD and the HD groups comprising subtotal villous atrophy and hyperplasia of Brunner's glands. Heavy infiltrations of eosinophils, moderate amounts of mast cells and a few basophils, globule leukocytes and lymphocytes were still present in the lamina propria of all three groups. On Day 56 pi, a few glands were still cystic in the MD and the HD groups. Moderate cell infiltrations were still present in the lamina propria of all the three groups and by Day 84 pi complete regeneration had occurred in all animals.

Twelve Tuli weaner steers aged 1 year were randomly subdivided into three groups of four animals and infected with different doses of Calicophoron microbothrium metacercariae. Each animal in Group I received a low dose (LD) of 5 000 metacercariae, Group II a medium dose (MD) of 15 000 metacercariae, Group III a high dose (HD) of 25 000 metacercariae and one additional animal was kept as an uninfected control (C). After infection, one animal from each group was slaughtered on Day 28, 42, 56 and 84 post infection (pi) and samples from the ileum, jejunum, duodenum, abomasum and the rumen were collected for histopathological and cytological examination. On Day 28 pi, the gross pathological lesions observed in the duodenum of the LD and the MD animals were similar and comprised duodenal thickening, corrugation, hyperaemia, petechiation and ulceration. In the HD animal the duodenal lesions were similar but more severe. The abomasal folds were severely oedematous in the MD group and nearly occluded the abomasal lumen. Moderate oedema of the abomasal folds was also present in the LD and HD animals. The gross pathological lesions regressed in all the infected groups with increasing age of infection and had disappeared completely by Day 56 pi. On Day 28 pi the histopathological lesions in the duodenum and jejunum of the LD and MD groups were similar, comprising subtotal villous atrophy, hyperplasia of Brunner's glands and Peyer's patches and moderate infiltration of eosinophils, mast cells and a few globule leukocytes, basophils and lymphocytes in the lamina propria. The HD group had total villous atrophy, severe hyperplasia and cystic dilatation of Brunner's glands, which had expanded to cover the entire submucosa. On Day 42 pi the histopathological lesions were still present in the MD and the HD groups comprising subtotal villous atrophy and hyperplasia of Brunner's glands. Heavy infiltrations of eosinophils, moderate amounts of mast cells and a few basophils, globule leukocytes and lymphocytes were still present in the lamina propria of all three groups. On Day 56 pi, a few glands were still cystic in the MD and the HD groups. Moderate cell infiltrations were still present in the lamina propria of all the three groups and by Day 84 pi complete regeneration had occurred in all animals.

Serum samples from 20 out of 180 (11.1 %) apparently healthy Nigerian indigenous chickens were negative for antibodies against chicken anaemia virus using the enzyme-linked immunosorbent assay (ELISA). Of the 160 positive sera (88.9 %), 12 (7.5 %) had titres ranging from 1 500-3 000, 46 (28.8 %) had titres from 3 000-5 000 while 102 (63.8 %) had titres between 5 000-11 000. The overall mean titre value was 5 845 + 2 402. This appears to be evidence of a natural outbreak of the infection since the chickens had no history of vaccination against any poultry disease.

Serum samples from 20 out of 180 (11.1 %) apparently healthy Nigerian indigenous chickens were negative for antibodies against chicken anaemia virus using the enzyme-linked immunosorbent assay (ELISA). Of the 160 positive sera (88.9 %), 12 (7.5 %) had titres ranging from 1 500-3 000, 46 (28.8 %) had titres from 3 000-5 000 while 102 (63.8 %) had titres between 5 000-11 000. The overall mean titre value was 5 845 + 2 402. This appears to be evidence of a natural outbreak of the infection since the chickens had no history of vaccination against any poultry disease.

In this study we evaluated the validity of well-known human electrocardiographic markers of myocardial pathology in Dorper sheep. These markers include: the duration of the QRS complex of premature ventricular complexes (PVCs), the presence of notching of the QRS complex of PVCs and change of the ST-segment of PVCs. It was shown that these three electrocardiographic phenomena correlate with myocardial pathology in the hearts of Dorper sheep. We also describe a new electrocardiographic indicator of myocardial pathology, namely an increase in the frequency of cardiac memory T waves as a new electrocardiographic surrogate for myocardial pathology in the hearts of Dorper sheep.

In this study we evaluated the validity of well-known human electrocardiographic markers of myocardial pathology in Dorper sheep. These markers include: the duration of the QRS complex of premature ventricular complexes (PVCs), the presence of notching of the QRS complex of PVCs and change of the ST-segment of PVCs. It was shown that these three electrocardiographic phenomena correlate with myocardial pathology in the hearts of Dorper sheep. We also describe a new electrocardiographic indicator of myocardial pathology, namely an increase in the frequency of cardiac memory T waves as a new electrocardiographic surrogate for myocardial pathology in the hearts of Dorper sheep.