Background Epizootic lymphangitis (EL), caused by Histoplasma capsulatum variety farciminosum (HCF) is a contagious, chronic disease of equines, characterized by development of nodular lesions in the lymph nodes, lymphatic vessels and skin. It is one of the most important diseases of equines in Ethiopia, causing significant economic loss, particularly in the livelihood of carthorse owners. To date there is neither effective diagnostic nor control measure implemented in the country. Furthermore, there is a shortage of data on the epidemiology of the disease in different regions of this country. The aim of this study was to investigate epidemiology of EL in northern Ethiopia, using the conventional methods as well as nested polymerase chain reaction (PCR). Results The presence of HCF genetic material was confirmed in 44% (84/191) of the carthorses. Subclinical infection was observed in 18.2% (22/121) of the apparently healthy carthorses. Considering the nested PCR as a gold standard, sensitivity and specificity of clinical examination were 74% and 92.5%, respectively, while the area under the ROC curve (AUR) was 0.83 (95% confidence interval, 0.77, 0.896). Moreover, a moderate (k = 0.675) agreement observed between the nested PCR and clinical examination. Conclusions This study demonstrated widespread occurrence of EL in northern Ethiopia, and the advantage of the nested PCR in detecting infection of HCF, even before the clinical symptoms became apparent.

From 2010 to 2017, as part of a wider animal welfare program, The Donkey Sanctuary piloted an integrated, community-based model for the control and prevention of epizootic lymphangitis (EZL) in cart mules in Bahir Dar, Ethiopia. Stakeholders included muleteers, service providers, and transport and animal health regulatory authorities. Interventions included muleteer education, wound prevention, harness improvement, animal health professional training, treatment of early EZL cases, euthanasia for advanced cases, and review of transport services and traffic guidelines. The project followed a participatory project management cycle and used participatory learning and action tools to facilitate stakeholder engagement and ownership. Participatory and classical epidemiology tools were employed to raise and align stakeholder understanding about EZL for effective control and prevention and to evaluate the progress impact of the model through annual prevalence surveys. During the intervention, the annual prevalence of EZL reduced from 23.9% (102/430) (95%CI: 19.8%−27.0%) in 2010 to 5.9% (58/981) (95% CI: 4.4%−7.4%) in 2017, and wound prevalence from 44.3% in 2011 to 22.2% in 2017; trends in the reduction of the prevalence maintained in the face of a mule population that increased from 430 in 2010 to ~1,500 in 2017. While non-governmental organization (NGO)-led interventions can facilitate change by trialing new approaches and accessing new skills and resources, sustainable change requires community ownership and strengthening of service provision systems. To this effect, the project raised muleteer competence in mule husbandry and EZL prevention strategies; strengthened veterinary competence; facilitated more mule-friendly traffic, transport, and waste disposal guidelines and practices; supported mule-community bylaws to control EZL; and established a supportive network between stakeholders including trusting relationships between muleteers and veterinary services. To advance the intervention model in other endemic areas, we recommend elucidation of local epidemiological factors with other stakeholders prior to the intervention, early engagement with veterinary and transport service regulatory authorities, early development of bylaws, exploration of compensation or insurance mechanisms to support euthanasia of advanced cases, and additional social, economic, and epidemiological investigations. In line with the OIE Working Equid Welfare Standards, we suggest that integrated community-based interventions are useful approaches to the control and prevention of infectious diseases.

Background: Epizootic lymphangitis (EL), caused by Histoplasma capsulatum variety farciminosum (HCF) is a contagious chronic disease of equines characterized by development of nodular lesions in the lymph nodes, lymphatic vessels and skin. This disease is the most important diseases of equines in Ethiopia causing a significant economic loss, particularly cart pulling equines. Todate there is no sound diagnostic nor control measure implemented in the country. Furthermore, there is a shortage of data on the epidemiology of the disease in different regions of the country including northern Ethiopia. This study was conducted to investigate the epidemiology of EL in northern Ethiopia using the conventional methods and the nested polymerase chain reaction (PCR). Methods: A total of 191 cart-horses were enrolled and used as sources of pus and blood samples. The blood was used for the extraction of the DNA of HCF from buffy coat for nested PCR while the pus samples were cultured on Sabourauds Dextrose Agar for isolation. Statistical Package for Social Sciences (SPSS) version 21 was used for data analysis by applying logistic regression, receiver operating characteristic (ROC) curve and Cohen’s kappa coefficient test. In addition, the level of agreement between the clinical examination and the nested PCR was evaluated. Results: Infection with HCF was confirmed in 44% (84/191) of the horses using nested PCR. Subclinical infection was observed in 18.18% (22/121) of the apparently healthy horses. Considering nested PCR as a gold standard, the sensitivity and specificity of the clinical examination were 74% and 95%, respectively while the area under the ROC curve (AUR) was 0.83 (95% confidence interval, 0.77, 0.896). Moreover, a moderate (k=0.675) agreement was observed between the nested PCR and clinical examination.Conclusions: The findings of the present study showed the wide spread occurrence of EL in northern Ethiopia and the advantage of the nested PCR in detecting of the infection of HCF even before the clinical symptoms are apparent.