Sleeping sickness can also be transmitted and spread via the skin

Scientists have made an important new discovery in the study of Human African Trypanosomiasis, more commonly known as African sleeping sickness. The findings could have a major impact on the way the disease is diagnosed, treated and potentially eradicated. The team of researchers, from the University of Glasgow's Wellcome Trust Centre for Molecular Parasitology and the Institut Pasteur in Paris, have discovered that skin plays a significant but overlooked role in harbouring and transmitting the parasite that causes the condition, which is often fatal if left untreated. The disease, which kills thousands in Sub-Saharan African every year, is primarily transmitted to humans via the bite of an infected tsetse fly as it takes a blood meal, with diagnosis then confirmed through the presence of parasites in the blood. The new study, led by Dr Annette MacLeod, definitively shows that substantial quantities of trypanosomes that cause the disease exist within the skin and can be transmitted back to the tsetse fly vector, even in the absence of detectable signs of infection in the animal or detectable parasites in the blood. The researchers were also able to observe the presence of parasites in human skin biopsies from individuals who displayed no symptoms. The study's findings suggest skin-dwelling parasites could be sufficiently abundant in the skin to be ingested, transmitted and so able to spread the disease further.