A human challenge study to lay the groundwork for developing a vaccine against neglected tropical diseases

The University of York is leading a study to develop a model of controlled human infection to pave the way for testing new vaccines against leishmaniasis, a neglected disease.

The Leishmania parasite is transmitted by the bite of sandflies. Credit: Jovana Sadlova, Charles University, Prague

Building on important achievements by the University of York and its partners, a study developing a new model of controlled human infection for leishmaniasis is currently recruiting volunteers.

Disease burden

Leishmaniasis, caused by a microscopic parasite called Leishmania, is transmitted by the bite of sandflies and affects more than one million people worldwide each year. The diseases caused by these parasites range from skin lesions that can cause disfigurement to potentially fatal organ damage.

Researchers hope to recruit up to 18 people to participate in this vital research study. The study uses a species of parasite that causes one of the milder forms of leishmaniasis, limited to a skin lesion localized at the site of a sandfly bite. This lesion can be excised at an early stage and several known complementary treatments exist.

Principal investigator, Professor Paul Kaye from Hull York Medical School, said, “We have developed a vaccine against leishmaniasis that is being tested for the treatment of patients with some form of the disease, but to have maximum impact on global health, it is essential to find out if this vaccine can also protect people from infection. One of the ways to achieve this is to develop a model of controlled human infection ”.

Controlled Human Infection Studies

Models of controlled human infection have been used to support vaccine development against cholera, malaria, influenza, dengue, and, more recently, COVID-19. After establishing how the immune system of healthy volunteers responds to the controlled infection, researchers can then design clinical trials to determine if a new vaccine can prevent infection. By closely monitoring the immune system’s response to infection in these controlled environments, researchers can also learn how to improve vaccines.

No vaccine is currently approved to prevent leishmaniasis, but with new vaccine candidates now available, including one developed at the University of York, a challenge model to test them is increasingly urgent.

The researchers hope that the project will lead to the development of a Leishmania human challenge model that will prove invaluable in testing new vaccines and understanding how immunity to infection occurs.

Dr Vivak Parkash, who is the physician leading the clinical study, said: “Over the past two years, we have put together all the pieces needed to develop a safe and effective controlled human challenge model. Our volunteers will play a major role in finalizing the development of this model so that it can be used to improve the health of millions of people around the world.

The research is a collaboration between Hull York Medical School, York University, Department of Parasitology at Charles University in Prague, Department of Microbiology and Immunology at McGill University in Montreal, Center of Medicine Geographic and Tropical Diseases from Sheba Medical. Ctr. & Tel Aviv University and Hebrew University-Hadassah School of Medicine in Jerusalem.

The project is funded by the UK Medical Research Council and the Department of International Development.

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