Ethiopia

A retrospective study was conducted to investigate the cause of rectal prolapse in working donkeys in Ethiopia. Analysis of data on rectal prolapse cases obtained from the Donkey Health and Welfare Project clinic at the School of Veterinary Medicine, Addis Ababa University, from 1995 to 2004 revealed that 83.6% (n=177) of the cases were associated with Gasterophilus nasalis. The rest 10.7% and 5.7% were associated with work-related (overloading) cause and diarrhoea, respectively. The mean and median numbers of G. nasalis recovered from the rectum of infected donkeys were 66 and 64, respectively, with a range of 2–195. Over 100 G. nasalis larvae were recovered from the rectum of 22% of the donkeys. Circular demarcated ulcer-like and deep circumferential pits or ring-like mucosal lesions were found at the larval attachment sites. G. nasalis infection and the associated rectal prolapse were observed year round. However, the intensity of rectal larval infection and incidence of rectal prolapse were significantly higher during the rainy season (P<0.01). Age and sex of the donkeys had no significant effect on the intensity of rectal larval infection and incidence of rectal prolapse (P>0.05).

A cross-sectional coprological survey in the regions of Ada, Akaki, Bereh and Boset, and a retrospective postmortem investigation were conducted to study the epidemiology of Parascaris equorum in donkeys and horses in Ethiopia. Faecal samples from 803 working donkeys and 402 horses were collected, and the numbers of worms recovered from 112 donkeys examined postmortem between 1995 and 2004 were analysed. There was a high prevalence of infection and faecal egg output of Parascaris equorum in both donkeys and horses, and the severity of the infection in donkeys was increased irrespective of their age. The prevalence of the infection in the donkeys was 51·1 per cent and in the horses 16·2 per cent, and the prevalence in the donkeys examined postmortem was 55 per cent. There was no significant difference between different age groups of donkeys in either the prevalence or the intensity of the infection. The prevalence of the infection was significantly higher in the Ada and Akaki regions than in the Bereh and Boset regions.

Parascaris equorum is an important parasite of young horses, particularly sucklings and weanlings (Russell 1948, Soulsby 1982, Austin and others 1990, Southwood and others 1998). The parasite has a worldwide distribution, and is usually present wherever horses are raised (Clayton 1986, Southwood and others 1998). It can reduce the growth rate of foals and cause occasional deaths due to intestinal obstruction or rupture (Dipietro and others 1983, Clayton 1986, Ryu and others 2004).

Parascaris equorum has also been reported in donkeys from various regions of the world (Tolliver and others 1985, Vercruysse and others 1986, Pandey and Eysker 1990, Ricci and Sabatini 1992, Burgu and others 1995, Daoud and Al-Alousi 1995, Feseha 1998, Lewa and others 1998, Getachew 1999, Kotwal and others 2000, Matthee and others 2002). However, most of these reports concern only small numbers of animals, and the information is rather fragmentary. There have been no specific studies of the epidemiology, pathogenicity and immunology of parascarid infections in horses and donkeys under the tropical weather conditions of Ethiopia. The aim of the present study was to investigate the epidemiology of this parasite in working donkeys and horses in Ethiopia by means of a cross-sectional coprological survey and retrospective postmortem examination findings.

A 12/13 kDa antigen, tapeworm ELISA test, developed for use in horses, was used to detect parasite-specific serum antibody, IgG(T), in the serum of donkeys. In a pilot study the 12/13 kDa antigen was tested and proved to detect the antibody, IgG(T), in donkey sera. Blood samples from 797 donkeys, naturally exposed to cestode infection, from four geographical localities were collected and sera were prepared and analysed. There was substantial serological evidence that donkeys were potentially infected with A. perfoliata. A range of ELISA OD values were obtained from the serological assay. Over 26% and 7.5% of the donkeys were moderately and highly infected, respectively, showing at least a 34% sero-prevalence. The rest, 66.1%, were either with low infection intensity or negative for A. perfoliata infection. The risk of infections, both in sero-prevalence and intensity, as determined by ELISA optical density (OD), were highest in the highland areas of Ethiopia where pastures are low-lying and wet, and permanent pasture management is regularly practised. Sex, age and body condition of the donkeys had no significant effect either on prevalence of the infection or on the serum antibody level. These results indicate a risk of intestinal disorders, particularly, colic, associated with A. perfoliata infection in donkeys.

A cross-sectional coprological survey in the tropical regions of Ada, Akaki, Bereh and Boset, and a retrospective post-mortem investigation were conducted to study the epidemiology of fasciolosis in working donkeys in Ethiopia. Faecal samples from 803 donkeys were collected, and the number of liver flukes recovered from 112 donkeys at post-mortem between 1995 and 2004 were analysed. There was a high prevalence of fasciolosis irrespective of the age of the donkeys. The overall prevalence of the infection was 44.4% in coprologically examined donkeys, and the prevalence in the donkeys examined post-mortem was 41.9%. The infection prevalence was significantly higher in Bereh and Ada regions than in Akaki and Boset regions. Bereh with 72.6% and Boset with 21.5% showed a significantly higher and lower infection prevalence, respectively, than the rest of the regions (P<0.001). There was no significant difference between different age groups of donkeys in the infection prevalence (P>0.05) but infection intensity was significantly higher in donkeys 8 years old and above (P<0.0001). Both Fasciola hepatica and Fasciola gigantica were identified.

This study was undertaken with the aim of determining reference hematological and serobiochemical values for working Ethiopian donkeys in four districts of Oromia regional state. The study was conducted by taking blood and serum samples from a total of 130 apparently healthy donkeys which were analyzed by using automated hematology analyzer and photometer 5010, respectively. There were significant difference in RBC (p<0.001), PCV (p<0.04), MCV (p<0.001) and MCHC (p<0.001) among the different age groups. The differences in mean values for PCV, Hb, MCV, MCHC, MCH, Hb, total WBC, eosinophils, monocytes and Platelets between sexes were not statistically significant (p>0.05). In the serobiochemical studies significant difference was seen only in the mean creatinine (p<0.003) values among the different age groups. Therefore, the variations in hematological and serum biochemical values ascribed to the effects of age and sex should be taken into consideration in interpreting physiological hematological and serum biochemical parameters in working donkeys.

Cyathostomins are the most important gastrointestinal nematode infecting equids. Their effective control is currently under threat due to widespread resistance to the broad spectrum anthelmintics licenced for use in equids. In response to similar resistance issues in other helminths, there has been increasing interest in alternative control strategies, such as bioactive plant compounds derived from traditional ethnoveterinary treatments. This study used an evidence-based approach to evaluate the potential use of plant extracts from the UK and Ethiopia to treat cyathostomins. Plants were shortlisted based on findings from a literature review and additionally, in Ethiopia, the results of a participatory rural appraisal (PRA) in the Oromia region of the country. Systematic selection criteria were applied to both groups to identify five Ethiopian and four UK plants for in vitro screening. These included Acacia nilotica (L.) Delile, Cucumis prophetarum L., Rumex abyssinicus Jacq., Vernonia amygdalina Delile. and Withania somnifera (L.) Dunal from Ethiopia and Allium sativum L. (garlic), Artemisia absinthium L., Chenopodium album L. and Zingiber officinale Roscoe. (ginger) from the UK. Plant material was collected, dried and milled prior to hydro-alcoholic extraction. Crude extracts were dissolved in distilled water (dH2O) and dimethyl sulfoxide (DMSO), serially diluted and screened for anthelmintic activity in the larval migration inhibition test (LMIT) and the egg hatch test (EHT). Repeated measures ANOVA was used to identify extracts that had a significant effect on larval migration and/or egg hatch, compared to non-treated controls. The median effective concentration (EC-50) for each extract was calculated using PROBIT analysis. Of the Ethiopian extracts A. nilotica, R. abyssinicus and C. prophetarum showed significant anthelmintic activity. Their lowest EC-50 values were 0.18 (Confidence interval (CI): 0.1-0.3), 1.1 (CI: 0.2-2.2) and 1.1 (CI: 0.9-1.4) mg/ml, respectively. All four UK extracts, A. sativum, C. album, Z. officinale and A. absinthium, showed significant anthelmintic activity. Their lowest EC-50 values were 1.1 (CI: 0.9-1.3), 2.3 (CI: 1.9-2.7) and 0.3 (CI: 0.2-0.4) mg/ml, respectively. Extract of A. absinthium had a relatively low efficacy and the data did not accurately fit a PROBIT model for the dose response relationship, thus an EC-50 value was not calculated. Differences in efficacy for each extract were noted, dependent on the assay and solvent used, highlighting the need for a systematic approach to the evaluation of bioactive plant compounds. This study has identified bioactive plant extracts from the UK and Ethiopia which have potential as anthelmintic forages or feed supplements in equids.

A study was conducted to isolate bacteria from septicemic cases in equine species and conduct antimicrobial susceptibility from December 2005 to June 2006 in Debre Zeit and Nazareth areas, Ethiopia. Bacteria were isolated in 20% of the suspected septicemic cases. Seventy percent of the isolates were gram-negative and the rest gram-positive. All bacteria were isolated in pure culture. Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae were isolated with isolation rates of 45%, 30%, and 25%, respectively. In this study, it was found that most bacteria are susceptible to limited antimicrobials. The most effective drugs were polymyxin B (90.0%) followed by gentamicin (85.0%), chloramphenicol (80.0%), and kanamycin (80.0%). Neither of the isolates was susceptible to tetracycline. Statistically significant association was not observed between host risk factors (age, sex, species, and body temperature) with frequency of each bacterial isolate (P > 0.05). The present study is limited in duration and sample size, therefore, further investigation should be carried out to elucidate septicemia in equines adequately in the country. In addition, rational use of antimicrobial therapy should be encouraged to minimize the risk of antimicrobial resistance.

A study was conducted for two consecutive years (1998-1999) to determine the seasonal patterns of strongyle infection in working donkeys of Ethiopia. For the purpose 2385 donkeys from midland and lowland areas were examined for the presence of parasitic ova. A hundred percent prevalence of strongyle infection with similar seasonal pattern of strongyle faecal worm egg output was obtained in all study areas. However, seasonal variations in the number of strongyle faecal worm egg output were observed in all areas. The highest mean faecal worm egg outputs were recorded during the main rainy season (June to October) in both years in all areas. Although an increase in the mean strongyle faecal egg output was obtained in the short rainy season (March-April) followed by a drop in the short dry season (May), there was no statistically significant difference between the short rainy season and long dry season (Nov-Feb) (P > 0.05). A statistically significant difference however, was obtained between the main rainy season and short rainy season, and between the main rainy season and dry season (P < 0.05). Based on the results obtained it is suggested that the most economical and effective control of strongyles can be achieved by strategic deworming programme during the hot dry pre-main rainy season (May), when the herbage coverage is scarce and helminthologically 'sterile', and the arrested development of the parasites is suppose to be terminating. This could insure the greatest proportion of the existing worm population to be exposed to anthelmintic and also reduces pasture contamination and further infection in the subsequent wet season.

Although fasciolosis is an important livestock disease worldwide, the public health importance of human fasciolosis has increased in recent years and it is recognised as an important re-emerging zoonotic disease, its epidemiology and pathogenicity in donkeys, and the epidemiological role they may play have not been determined.

Objectives

To investigate the epidemiology and pathogenicity of fasciolosis in donkeys.

Study design

Cross-sectional coprological and retrospective post-mortem study.

Methods

Faecal samples collected from 803 randomly selected working donkeys from the central region of Ethiopia were analysed by a sedimentation-centrifugation-flotation technique. Further data on liver-flukes and associated pathologies were obtained by routine post mortem examinations of 112 donkeys, subjected to euthanasia on welfare grounds or died. Data were analysed using a generalised linear model and multivariate binary logistic regression in R statistical package with significance level of statistical tests set at P<0.05.

Results

Infection prevalences of 44.4% and 41.9% were obtained in coprologically and post mortem examined donkeys, respectively, irrespective of their age. Both Fasciola hepatica and Fasciola gigantica were identified with the mean infection intensity of 30 flukes. Older donkeys (≥8 years) were found harbouring a significantly higher worm burden (P<0.0001). Gross and histopathologies of hyperplasia and thickening of the bile ducts, fibrosis of large portal areas and irregular bile duct proliferation and hypertrophy were noted.

Conclusions

The high infection prevalence of fasciolosis and the associated hepatic pathologies in working donkeys shows not only the susceptibility of donkeys and the impact it has on their health, but also indicates the important role they can play in the epidemiology of both livestock and human fasciolosis. These further demonstrate the need for these animals to be considered in the overall epidemiological studies and for sound control strategies and prevention of fasciolosis.