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New vaccine trials to prevent visceral leishmaniasis

12 March, 2012, Esther Nakkazi

The first ever vaccine to prevent visceral leishmaniasis (VL)—the second-largest parasitic killer in the world after malaria—is entering dual clinical trials in the US and India.

Sudan is the second-most affected country in the world after India although isolated cases of VL also occur in Ethiopia, Kenya, Uganda, Somalia, and Tunisia. In 2006, approximately 30,000 cases of VL occurred in East Africa.

Leishmaniasis has a 90 percent fatality rate and if left[frax09alpha] untreated for a period of two years it kills instantly—much more quickly than AIDS- and known as the parasitic version of HIV/AIDS as it affects vital organs and bone marrow, destroying white and red blood cells.

It is caused by the Leishmania parasite and transmitted by infected sand flies.

“With this clinical trial, we hope to launch a new era in the fight against Visceral Leishmaniasis,” said Franco Piazza, the Medical Director at Infectious Disease Research Institute (IDRI), a US based non-profit research organization and leader of the vaccine’s clinical development.

Scientists also warn that the geographical range for leishmaniasis is now expanding spurred on by global warming, mass migration and rapid urbanization with cases being reported in previously unaffected areas.

Worldwide, VL causes an average 500,000 cases and 50,000 deaths each year. It now occurs in 88 countries, affecting 12 million people.

“For the first time, an advanced vaccine to prevent this devastating disease is being tested in people,” said Dr. Piazza.

The IDRI vaccine, called LEISH–F3 + GLA-SE, is a highly purified, recombinant vaccine which incorporates two fused Leishmania parasite proteins.

It works by activating the immune system to kill the parasite that causes VL, the first of its kind to be developed. As a synthetic vaccine, it can be manufactured at low cost in resource poor settings.

The Phase 1 clinical trial will enroll 36 adult volunteers in Washington State who will be randomly assigned to receive one of three versions of the vaccine, which differ in the amount of adjuvant included. The trial will evaluate the safety and immunogenicity of each version.

A second Phase 1 trial will take place in India, where IDRI is transferring its vaccine technology to Gennova Biopharmaceuticals. VL is known as kala-azar, a Hindi word that means black fever, named after the fever that ravages affected individuals, whose skin becomes dark gray.

“Our partnership with India will speed the development of an effective vaccine and accelerate control of the disease,” said Steve Reed, IDRI founder and Chief Scientific Officer.

While the disease can be treated, current treatments are too expensive, difficult to administer, or toxic. Drug resistance is also a growing problem in India. Current drug treatments for African VL are primarily toxic antimonials, costing $50-100, although newer drugs are being developed.

“We are very pleased to be working with IDRI on this vaccine, which is important to the many people who suffer from this disease in India as well as to the millions of people who are infected around the world,” said Dr. Shyam Sundar, Professor of Medicine at the University’s Institute of Medical Sciences.

The Phase 1 clinical trials are being funded by the Bill & Melinda Gates Foundation. Subsequent clinical trials will involve larger numbers of people who are at high risk of developing VL during their daily lives, because they are frequently bitten by sand flies.

“Only such large trials, conducted in real-life situations of disease exposure, will determine the full effectiveness of the LEISH–F3 + GLA-SE vaccine.”

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