Leishmaniasis: The Neglected Disease of War, Conflict, and Human Misery

One of the least known consequences of modern conflict in the Middle East and East Africa has been the widespread devastation that results from a tropical infection known as leishmaniasis. The international scientific and diplomatic communities now have an opportunity to work together to prevent the spread of this neglected tropical disease and to develop new treatments or vaccines.

Leishmaniasis is caused by a microscopic protozoan parasite that is transmitted through the bite of small and delicate blood feeding insects known as sandflies. Mostly because of forced human migrations that expose people to sand fly bites as they flee conflicts or while living in refugee settings, together with breakdowns in public health infrastructure, leishmaniasis outbreaks have become the new hallmark of late 20th or 21st century wars and human misery.

There are two major forms of the disease:

Visceral leishmaniasis, also known as kala-azar, affects the liver, spleen, and bone marrow to produce a fatal illness that in some respects resembles leukemia. Indeed, patients who manage to make their way to the United States are often first diagnosed as a new leukemia patient until a bone marrow biopsy reveals the presence of the leishmania parasites. Most of the world's cases occur in East Africa and South Asia. During the war between northern and southern Sudan that began in the 1980s it is estimated that more than 100,000 people died from kala-azar, making this disease one of the most deadly in modern history.

Cutaneous leishmaniasis is a second form associated with disfiguring ulcers on the skin. When ulcers occur on the face they often leave a permanent scar that can be highly stigmatizing, especially for girls and young women. The disease is common in the Middle East and Central Asia and frequently occurred among our troops in Iraq and Afghanistan. It is also found in Latin America, especially in tropical regions of Mesoamerica (even in some parts of Texas) and South America.

Today in Syria, where it is also known as "Aleppo evil", cutaneous leishmaniasis cases are rampant due to breakdowns in public health infrastructure and garbage collection. Sandflies are ubiquitous and it is estimated that more than 100,000 people are affected, including many fleeing to refugee camps across the Syrian border into Turkey and Lebanon. In Central and South America, cutaneous leishmaniasis is a frequent occurrence among people fleeing the drug-related violence in the region.

According to a 2012 study, some of the largest numbers of leishmaniasis cases now occur in complicated conflict and post-conflict nations such as Afghanistan, Algeria, Colombia, Iran, Iraq, Nicaragua, Pakistan, Somalia, Sudan, Syria, and Venezuela.

At the National School of Tropical Medicine at Baylor College of Medicine we have successfully treated leishmaniasis patients who manage to make their way to Houston from abroad. But the regimens required are often long and complicated, and I imagine would be extremely challenging to administer in settings of conflict or post-conflict. This is a disease for which the international scientific community needs to champion the development of safe and effective vaccines. Two non-profit product development partnerships based in the United States, including our Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development, are working to develop new vaccines, as are scientists in Iran and the Middle East. An extraordinary opportunity for what I have termed "vaccine diplomacy" would be joint U.S.-Iran cooperation to develop and test new vaccines.

There is a precedent. Fifty years ago during the Cold War, Dr. Albert Sabin worked with virologists from the USSR to develop and test the first oral polio vaccine, a vaccine now leading to the global eradication of polio. Joint development of a leishmaniasis vaccine would simultaneously provide an important new tool for use in conflict settings, while helping to promote peace between two nations of ideological opposites.

Peter Hotez, M.D., Ph.D. is president of the Sabin Vaccine Institute and the founding dean of the National School of Tropical Medicine at Baylor College of Medicine, where he is also Professor of Pediatrics and Texas Children's Hospital Endowed Chair of Tropical Pediatrics. Prof. Hotez is also the Fellow on Disease and Poverty at the James A. Baker Institute for Public Policy at Rice University. He is the author of Forgotten People, Forgotten Diseases (ASM Press).