From 2000 to 2017 the Sabin Vaccine Institute partnered with the Texas Children’s Hospital Center for Vaccine Development at Baylor College of Medicine in Houston, Texas to develop safe, effective and low-cost vaccines for infectious and neglected tropical diseases. Baylor College of Medicine and Texas Children’s Hospital Center for Vaccine Development continue this research as of May 2017.
Leishmaniasis is a debilitating and disfiguring disease affecting poor populations in the tropics, subtropics, and southern Europe.
About the Vaccine
From 2011 to 2017, the Sabin Vaccine Institute Product Development Partnership (Sabin PDP) worked toward the development and global accessibility of a low-cost, safe and effective vaccine for cutaneous leishmaniasis, primarily for children and adults in Latin America and the Middle East and North Africa. As of May 2017, Baylor College of Medicine and the Texas Children’s Hospital’s Center for Vaccine Development continue this research.
The project advances the discovery of leishmaniasis vaccine antigen candidates. Baylor College of Medicine is exploring combination vaccines comprised of not only of Leishmania, but also sand fly salivary gland antigens, which help direct a more effective immune response against the parasite.
Leishmaniasis is a disease caused by the Leishmania parasite, usually transmitted through a bite from a sand fly, which affects the poorest people living in Africa, Asia, Europe and the Americas. Approximately 12 million cases occur globally, with 1.3 million new cases per year. An estimated 20,000 to 30,000 deaths from leishmaniasis occur each year.
There are more than 20 species of the Leishmania parasite known to cause disease in humans. As a result, there are a number of different presentations of the disease. The most common types are cutaneous leishmaniasis, mucosal leishmaniasis, visceral leishmaniasis and post-Kala-azar dermal leishmaniasis. Most deaths from leishmaniasis are the result of visceral leishmaniasis. Cutaneous leishmaniasis is the most common type of leishmaniasis and results in skin sores that may result in infection, scarring and stigmatization.
The most recent estimates from the Global Burden of Disease Study (GBD) 2015 indicate that more than 24,000 annual deaths result from leishmaniasis and 1.4 million disability-adjusted life years (DALYs), ranking leishmaniasis as having one of the highest disease burdens of all the neglected tropical diseases. A more recent update from GBD 2013 indicates that 62,500 people died from the visceral form of leishmaniasis in 2013.
Visceral leishmaniasis (also known as kala-azar) is the third most common parasitic cause of death, after malaria and infantile cryptosporidiosis. Infected individuals present with fever, wasting, anemia, hepatosplenomegaly, and a depressed immune response. Cutaneous leishmaniasis, while not typically a life-threatening infection, is a cause of disfigurement and thus stigma, especially for girls and women. The disease has reached epidemic proportions because of the conflicts and public health breakdowns in Syria (where it sometimes known as “Aleppo evil”), Iraq, Afghanistan and elsewhere in the Middle East and Central Asia, and is widespread in the Americas.
Why We Need a Vaccine
A safe, low-cost preventative vaccine would represent an important tool in the control of leishmaniasis. There are a number of disease reservoirs for the Leishmania parasite, making prevention efforts difficult. Current drug treatments for all three major forms of leishmaniasis are largely effective. However, high cost, toxicity and lengthy, complicated treatment regimens compromise drug therapy’s usefulness as a tool for the elimination of the disease.
Ultimately, the development and delivery of a vaccine could represent one of the most cost-effective means of controlling or eliminating cutaneous or visceral leishmaniasis. It has been estimated that using a vaccine that provides protection for 10 years at 70% efficacy within seven countries of Latin America: Bolivia, Brazil, Colombia, Ecuador, Mexico, Peru and Venezuela could prevent 41,000–144,000 cases of cutaneous leishmaniasis for less than what currently recommended treatments cost. For visceral leishmaniasis, even a vaccine that provides protection for only five years at 50% efficacy would still be cost effective compared to current treatments.
Photo Credit: Anna Grove Photography