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One in five Iraq-deployed Service Members may have Leishmania Parasite

microscope photo
 By Zachary Willis

Immune-suppressed at greater risk for disease reactivation later in life

Service members deployed to Iraq could be at risk of lifelong health problems from infected sand flies, including a disease that, untreated, could be fatal, according to a new study in the Sept. 20, 2018 journal, Clinical Infectious Diseases.

close up of a mosquito on skin
Sand flies such as this are responsible for the spread of the
vector-borne parasitic disease Leishmaniasis. Leishmaniasis
is transmitted by the bite of infected female phlebotomine
sand flies. (Photo by James Gathany, Center for Disease
Control and Prevention)
“Nearly one in five persons deployed to endemic parts of Iraq have been infected by a parasite that causes visceral leishmaniasis,” says Dr. Naomi Aronson, director of the Department of Medicine’s Infectious Diseases division at Uniformed Services University of the Health Sciences. “Leishmania parasites persist in the body likely lifelong – potentially putting these infected, yet asymptomatic, U.S. forces personnel at risk with future perturbations of their immune system.”

The study was released in September with researchers, including Aronson, comparing healthy service members, who had been exposed to areas of Iraq where visceral leishmaniasis is prominent, against persons who had not traveled to those regions. Using blood samples and various tests, researchers were able to come to the conclusion that travel around Baghdad and to northwest Iraq correlated with acquiring the infection, and that veterans and service members needed to be aware of their potential to carry the disease which could reactivate later in life.

In Iraq, a bite from an infected sand fly (Phlebotomus alexandri) can transmit Leishmania infantum, the parasite that causes visceral leishmaniasis. No prophylactic medicine or vaccine currently exists and North Americans typically have no protective immunity, leaving them at great risk for future activation of the parasitic infection. Human immunodeficiency virus (HIV), organ transplant, biologic response modifying drugs, poorly controlled diabetes, and alcohol abuse have been found to activate the disease in European and Brazilian adults who have been infected, according to the report.

Also according to the study, activated visceral leishmaniasis manifests itself as a chronic illness, with symptoms such as fever, weight loss, a reduction of mature blood cells, and an enlarged liver and spleen. While it can be successfully treated with liposomal amphotericin, an antifungal, untreated activated visceral leishmaniasis has a mortality rate of more than 90%.

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Dr. Aronson goes on to explain that physicians may not generally consider leishmaniasis during an exam because of unfamiliarity with the way the disease presents itself and because many patients may not exhibit symptoms after exposure. However, it is this asymptomatic trait that makes visceral leishmaniasis particularly harmful, as those who are unaware that they even carry it could transmit the disease through blood donation. Dr. Aronson has made it a goal to get the word out about this neglected tropical disease, and improve its prevention and treatment.

“We plan to engage with the Armed Services Blood Program to discuss a role for decreasing risk in the USA in blood donations from persons deployed to Iraq and Afghanistan, possibly lifelong,” Aronson says.

While there is no blood test to screen for leishmaniasis-infected blood, the disease is mainly white blood cell-associated, making leukodepletion, the process of filtering and removing white blood cells from blood prior to transfusion, an effective method of prevention. Aronson believes that additional study of the natural history of asymptomatic visceral leishmaniasis in deployed military forces and veterans should be done to identify the role of treatment and to determine if any long-term consequences will become associated with future illnesses.

Visceral leishmaniasis is a lifelong health problem, but this new study by Aronson and her team concludes that while the first hurdle may be getting physicians to acknowledge the problem, constant strides toward prevention and treatment can ultimately curb the threat to service members.