Endemic in parts of Africa, epizootic lymphangitis (EZL) is a devastating and poorly understood fungal disease with severe health and welfare consequences in working equids. But newly developed tests could lead to faster, low-cost diagnosis and enable better management.

British and Ethiopian researchers teamed up to trial a molecular diagnostic test that would detect the presence of the fungus Histoplasma capsulatum var. farciminosum (HCF) in blood or pus that oozes from EZL wounds. This new DNA-based test provides more accurate results in much less time than do standard laboratory culture methods and could be adapted for surveillance in endemic regions. It should eventually become far less expensive as well, said Claire Scantlebury, BSc, BVSc, PhD, MRCVS, of the University of Liverpool’s School of Veterinary Science, in the U.K.

“At present, the findings presented in this paper show that it is possible to bypass the culture of equine Histoplasma (a notoriously difficult and time-consuming process that can take up to six weeks to gain diagnostic confirmation) and diagnose the infection directly from clinical samples of pus and, for the first time, equine blood, using nested polymerase chain reaction (PCR) methodology,” she said.

Scantlebury and her fellow researchers evaluated the test’s efficacy on 29 horses with clinical signs of EZL and 20 horses without. The blood test confirmed HCF infection in 25 of the sick horses (meaning the other four might not have had HCF circulating in their blood due to the stage of the disease or the presence of another disease with similar signs), and it even detected HCF in two horses that were not (yet) symptomatic, she said