Diminazene aceturate is one of a limited number of drugs currently being used in animals to treat the tsetse fly-transmitted protozoal disease, African trypanosomiasis. Efficacy of the drug at the recommended single IM administered doses of 3.5 and 7.0 mg/kg of body weight is widely acknowledged. However, resistance to the drug at these dosages has been reported. Although the mechanisms of resistance to diminazene are poorly understood, field and experimental data indicate that it may develop naturally through administration of subcurative doses, or as a result of cross-resistance. Evidence from other experimental studies indicates that there are additional mechanisms by which trypanosomes may develop resistance to diminazene aceturate. For instance, some populations ot Trypanosoma brucei and T. vivax are refractory to treatment because of their ability to invade the CNS, a site that is believed to be poorly accessible to diminazene. Furthermore, in recent studies carried out in goats, it has been documented that the ability of T. Congolense IL 3274 to survive treatment with diminazene depends on the stage of infection when treatment is administered; populations of the parasite reappeared in animals that were treated on day 19 after tsetse fly challenge, whereas all goats were cured when treated on day 1 of infection. Because trypanosomes are confined to the skin on day 1 after infection, but thereafter invade the blood circulation, it is possible that the efficacy of the treatment on day 1 is attributable to exposure of the small number of parasites, relative to later stages of infection, to higher concentrations of drug than those attained in blood. The objective of the study reported here was to determine whether diminazene's pharmacokinetics differ between plasma and lymph draining the skin of goats and therefore account for the variation in therapeutic activity of the drug at different stages of a tsetse fly-transmitted infection. Peripheral lymph was used for this work because it appears to be identical in composition to tissue interstitial fluid, into which trypanosomes are inoculated by infected tsetse flies when feeding.

Domestic poultry are important natural hosts of Mycobacterium avium (MAC), especially in the traditional poultry management system in the tropics. Qualitative and quantitative studies on a total of 95 chickens from three agro-climatic areas in Ethiopia were examined for avian mycobacteriosis through postmortem examinations and tissue staining (haematoxylin & eosin and acid-fast staining). The mycobacteria species were isolated and identified by using mycobacteriologic culture and experimental infection for virulence assessment. Five of the 95 examined chickens (5.3%) had gross tuberculous lesions in different visceral organs. On histopathologic examination, the lesions showed granuloma with typical Langhan’s giant cells in which acid-fast bacilli were shown by acid-fast stain. The culture on pyruvate-enriched Lowenstein-Jensen slants revealed growth of colonies on samples from 6 (6.3%) of the 95 chickens. Experimental infection with the strains from culture resulted in death of 10 (83.3%) of 12 inoculated chickens 56 to 110 days after inoculation, indicating that the isolates may be virulent strains of MAC. On postmortem examination, the experimentally infected chickens showed similar tuberculous lesions to natural infection that was confined at the site of injection, on the liver, spleen and (in two subjects) small intestine. The inoculated organisms were recovered from the respective organs. Therefore, this study showed that a virulent strain of MAC infects domestic chicken in Ethiopia.

A cross-sectional study to determine individual animal prevalence of bovine tuberculosis (BTB) was conducted on 1171 dairy cattle in 12 randomly selected dairy farms in Ethiopia between January 1999 and May 2001 using comparative intradermal tuberculin (CIT) test and bacteriologic study through milk culturing. An overall individual animal prevalence of 46.8% (548 of 1171 animals) and a herd prevalence of 91.7% (11 of 12 farms) were recorded in 12 dairy farms by the CIT test. There were significant (P <0.0001) differences in individual prevalence between farms and breeds (pure Holstein and their crosses with Zebu). There was positive correlation (r = 0.41) between herd size and prevalence of bovine tuberculosis. Furthermore, a negative linear association (R2 = 0.24) was found between mean score of management of the farm and prevalence, indicating that the prevalence of bovine tuberculosis could be improved by sanitary measures. Breed and management affected the prevalence of BTB (R2 = 0.30) as confounding variables. Mycobacterium bovis was isolated from the milk of 13.3% (4 of 30) reactor cows. The widespread occurrence of BTB in the study farms and isolation of M. bovis from the milk of reactor cows signify its economic importance and potential risk to public health. Generalization and improved use of milk pasteurization within all dairy subsectors is recommended, and this would affect the competitiveness of the dairy sector in Ethiopia.

This study sought to determine if sheep suffer neurological symptoms when fed Acacia angustissima leaves, and whether an equivalent amount of 70% acetone extract would have the same effect. In addition, the study tried to determine if treatment of leaves with 70% acetone would destroy the activity of A. angustissima toxins, and whether extraction with 70% aqueous acetone extract would separate two components of a toxic system. Twenty-five Menz lambs were randomly assigned to one of five treatments (1) A angustissima leaves as half the diet, 2) dried extract (70% aqueous acetone) of the same quantity of leaves, 3) a corresponding amount of residues, 4) a recombination of the dried extract and dried residue, or (5) a control diet containing no A angustissima leaves or extract fractions. All animals fed the leaves and the recombined fractions died or were euthanized when they were observed to be dying of severe neurological derangement. None of the other animals showed any neurological signs of impairement. The results of this study indicate that healthy, well-fed sheep can be poisoned by A angustissima, that the toxins are not destroyed by acetone or oven drying, and that severe neurological intoxication requires two components, which can be separated by acetone extraction.

Hematological parameters were studied in 163 apparently healthy goats comprised of 3 indigenous breeds at Adami-Tulu Agricultural Research Centre (ATARC) and Sheno, Agricultural Research Centre (SARC), Ethiopia. Data were analyzed for the effect of breed, sex, age, and season. Hemoglobin (Hb) was significantly higher (P < 0.0001) for Arsi-Bale (AB) than Longeared Somali (LES) and Central Highland (CH) goats. Packed cell volume (PCV) was significantly lower (P < 0.0001) for LES than the other two breeds. White blood cells (WBC) (P < 0.05), neutrophils (P < 0.0001) and basophils (P < 0.0001) were higher in CH than in the other two breeds. Conversely, lymphocytes were lowest (P < 0.0001) in CH goats compared to other breeds. Female goats had significantly (at least P < 0.05) higher red blood cells (RBC), PCV, WBC, lymphocytes and eosinophils than male goats. In contrast, males had higher (P < 0.05) mean corpuscular hemoglobin (MCH) and neutrophils than females. There was no significant age difference for the erythrocytic series but the age difference was highly significant (P < 0.0001) for the leukocytic series. WBC and lymphocytes decreased as age increased while the reverse was true for neutrophils and eosinophils. Seasonal variation was also considerable for both erythrocytic and leukocytic series. RBC, Hb, lymphocytes, and neutrophils of the indigenous goat breeds were remarkably different compared to most other exotic goat breeds.

A cross-sectional study was conducted between December 2001 and April 2002 on 94 households and 763 (188 indigenous and 575 crossbred) cattle to determine the prevalence of bovine tuberculosis (BTB) and assess its public health implications in smallholder farms in Wuchale-Jida District, Central Ethiopia. Cluster sampling, single intradermal tuberculin (SIDT) and comparative intradermal tuberculin (CIDT) tests, a questionnaire, and mycobacteriology were used. Based on the CIDT test, herd and individual animal prevalences of BTB were 42.6% and 7.9%, respectively. The individual animal prevalence was significantly affected by herd size (P<0.01), age (P<0.0001) and body condition (P<0.05). Among the interviewed households, 24.5% (23 of 94) had experienced at least one human tuberculosis case in the family. Of these families, 43.5% (10 of 23) had reactor cattle. Nevertheless, no statistically significant association (P>0.05) was observed between reactor cattle and human tuberculosis cases in households. The habit of milk and meat consumption was affected by occupation (P<0.0001) and location of household residence (P<0.001). Although the level of education influenced the habit of milk consumption (P<0.05), it did not impact the habit of meat consumption (P>0.05). Less than half (38.3%; 36 of 94) of the respondents knew about BTB, and only 30.8% (29/94) of the respondents were conscious of its transmission from cattle to humans. Secondary data analysis from Muka-Turri clinic indicated that 85.6% of the human tuberculosis cases were from rural parts of the district. Although the BTB prevalence seems low, its potential risk to public health was important based on food consumption, poor sanitary measures, and the lack of understanding about its zoonosis.