The cattle disease nagana, also called African animal trypanosomiasis, caused by the parasites Trypanosoma vivax and Trypanosoma congolense, affects huge swathes of sub-Saharan Africa, and the T. vivax disease has also spread to South America. With around 60 million cattle at risk from the disease, which causes muscle wasting and death, the socio-economic impacts of T. vivax infections in livestock are profound.
Nagana is difficult to diagnose in the field because early symptoms can be easily confused with a myriad of other endemic diseases. There is an urgent need for new, inexpensive and simple, diagnostics that can be used by vets and farmers to test animals prior to deploying expensive medicines. With this in mind, the Global Alliance for Livestock Veterinary Medicines (GALVmed), a not-for-profit livestock health product development and access partnership headquartered in Edinburgh, asked Mike Ferguson and colleagues to discover new diagnostic antigens for T. vivax infections in cattle.
Taking a quantitative proteomics approach, Jennifer Fleming, Lalitha Sastry and Lauren Sullivan identified parasite proteins specifically recognized by antibodies in the sera of infected cattle and made recombinant versions for further testing. One of these was developed into a prototype lateral flow test (see picture) in collaboration with Steven Wall at BBI Solutions plc in the Dundee Technology Park. The device, less than 3 inches long and similar in format to a pregnancy test, can identify within 30 minutes whether or not an animal is infected from a single drop of blood. The simple device does not require electricity or any additional equipment, factors that are essential for deployment in resource-limited settings.
The prototype diagnostic device was evaluated with over a hundred serum samples from uninfected and T. vivax infected cattle. The promising results, just published in the journal PLOS Neglected Tropical Diseases, have inspired GALVmed to further investigate this innovative diagnostic test for use in Africa.
Dr Jeremy Salt, Senior Director of Research and Development at GALVmed, said, “We are delighted with the progress on an effective and simple diagnostic test for T. vivax infection through our partnership with The University of Dundee and BBI Solutions OEM Limited. Such a test could allow millions of smallholder farmers an efficient way to test their cattle for this debilitating disease and give peace of mind that any subsequent treatment for T. vivax infection will be done with the certainty that the animal is infected, which saves the farmer money. This will give more control to the smallholder farmers whose quality of life has been affected by this disease that covers over 10 million square kilometres of Africa.To ensure that the final test is widely used throughout the regions where it's endemic, GALVmed will be working with scientists, manufacturers and distributors in the 40 countries where AAT is rife to create a sustainable supply chain for the final product.”
Mike said: “I am very proud of the talented scientists who did this work, and of the synergistic relationship between the University of Dundee and BBI Solutions plc. Hopefully, with further development by GALVmed, the device will prove sufficiently useful to be adopted for the detection of T. vivax nagana in cattle in the developing world.”