By Mary Hearty
Researchers from the International Centre of Insect Physiology and Ecology (icipe) have developed a much needed non-invasive, rapid, affordable, efficient and easy method to diagnose African animal trypanosomiasis, commonly referred to as sleeping sickness.
In a paper published recently in Frontiers in Microbiology journal, the icipe scientists report that they have identified biomarkers in the urine of cows, which indicate with certainty the presence of trypanosomes infection, even at low levels that would not be detectable through microscopy.
“Using this knowledge, we have developed a process for biomarker-based diagnosis of African animal trypanosomosis. As a result, through a simple urine test, which can be administered even by livestock keepers, it is possible to confirm whether an animal has the disease,” Dr Merid Getahun, icipe scientist and leader of the study explains.
The icipe study investigated the mechanisms of the interactions between trypanosomes and their host animals. In general, a healthy animal produces a range of chemical compounds that may be used for a variety of functions, for example defence against disease causing agents.
Once the trypanosome parasites enter the blood of an animal, a coevolutionary arms race starts between them and their host. The parasites fight to create a conducive environment for their own survival, for example by producing molecules that suppress the immune system of the host.
In turn, the host produces antibodies and defence compounds to ward off the trypanosomes. In the process, the odour profile of the defence compounds in the host animals is changed.
“We identified two classes of compounds in the urine of cows, which are specifically affected by trypanosome infections. The first class of compounds are phenolics, which are ordinarily produced by the animals, but their production is elevated by the infections. The second class of compounds are ionones, whose production is specifically stimulated by the infections. Therefore, these two classes of compounds are predictive biomarkers of African animal trypanosomosis,” Dr Getahun states.
According to the researchers, the icipe biomarker-based diagnosis is highly sensitive and specific. It can detect a wide spectrum of trypanosomes infections, as well as the three most important trypanosome species.
The test can also identify active forms of African animal trypanosomosis, as it returns a negative result for animals after treatment.
Therefore, it can be used to monitor the effectiveness of therapeutic interventions. Moreover, the test is specific to trypanosome infections, as it is negative on animals suffering from other ailments with symptoms similar to African animal trypanosomosis.
“Supported by the right partnerships and pathways, the biomarker-based diagnosis can be translated into a ready-to-use, inclusive innovation. For example, the reagent and activator can be packaged into a dipstick that can be easily applied to a urine sample. This would empower livestock keepers to make evidence-based decision on the health of their animals,” Dr Dan Masiga, Head, icipe Animal Health Theme says.
“This simple, novel diagnostic tool for African animal trypanosomosis is emblematic of icipe’s mission of developing science-led, inclusive innovations that are effective, accessible and affordable to all segments of society, and which have a transformative impact on communities and economies,” Dr Segenet Kelemu, icipe Director General notes.
The technology becomes part of icipe’s arsenal to fight the tsetse fly menace, towards an overall one health goal, through sustainable livestock farming to improve food security, household incomes and nutrition, while addressing the challenges of climate change and protecting the environment.
