Presentation
Case Findings: A 21-year-old male Marine sniper returns from his fourth tour in Afghanistan with complaints of fatigue. He waited a month to seek medical attention because he believed he was simply tired from his last tour, but he has had trouble sleeping since he arrived home. Rather than dismissing his complaints as symptoms of PTSD, an alert clinician orders some blood work. The following is seen on a peripheral blood smear.
What is the diagnosis?
15% PTSD
204% Leishmaniasis
160% Malaria
108% Histoplasmosis
67% Chagas
Correct Answer:
B. Leishmaniasis. Thousands of cases of Leishmaniasis have been diagnosed in United States soldiers returning from Iraq or Afghanistan. The infection is caused by protozoan parasites in the genus Leishmania through the bite of an infected sandfly. The incubation period can vary, but usually lasts for weeks to months. The diagnosis of leishmaniasis can be made by detecting the parasite amastigotes within cells of the reticuloendothelial system. Amastigotes measure up to 5 µm in length and contain a large nucleus and a rod-shaped kinetoplast.
By contrast, PTSD is a possible explanation for the patient’s fatigue. However, medical reasons should be eliminated before pursuing psychological explanations, and PTSD would not explain the findings on the peripheral smear. Malaria would not be present in cells of the reticuloendothelial system, but rather in the red blood cells. The morphology also is inconsistent with the ring forms of the malarial parasite. Histoplasmosis can be difficult to differentiate from Leishmania; the kinetoplast present in this case does help differentiate them when present on the peripheral smear. In Chagas disease, the amastigotes of Trypanosoma cruzi would be seen within an infected cardiac myocyte. The characteristic C-shaped trypomastigotes would be seen on a peripheral blood smear.