MIAMI BEACH — Some American soldiers are returning from Iraq with a dormant pathogen in tow: cutaneous leishmaniasis. Symptoms of the infection can take 4–6 months to appear after a bite from an infected sand fly, and some unknowingly infected military personnel return to their communities before the lesions develop. This puts community dermatologists in the position of having to treat this tropical infection.
There is a seasonal variance to this protozoan parasitic infection that corresponds with the activity of sand flies in the Middle East. During the 2003–2004 season, localized cutaneous leishmaniasis was frequently diagnosed in U.S. military personnel, with most infections caused by Leishmania major, according to a presentation at the annual meeting of the American Society of Tropical Medicine and Hygiene.
There have been more than 500 reported cases since January 2003 among soldiers from Operation Enduring Freedom and Operation Iraqi Freedom, according to U.S. Army medical research data.
Experience with 300 soldiers treated at Walter Reed Army Medical Center in Washington demonstrates that there are multiple presentations for localized cutaneous leishmaniasis. Of the infected patients, 98% were male, 96% were in the U.S. Army, and 91% were enlisted personnel. Almost three-quarters (73%) were white; 16% were African American, 6% were Hispanic, and 5% were from other ethnic groups.
“Patients with lighter skin were overrepresented in our cohort,” said Naomi E. Aronson, M.D., professor of medicine and director of the infectious diseases division, Uniformed Services University of the Health Sciences, Bethesda, Md.
Cutaneous leishmaniasis manifests after the multiplication of the organism in phagocytes in the skin. The mean number of skin lesions per patient was 3, and the range was 1–47. The mean time between appearance of a lesion and initiation of treatment was 13 weeks.
Papules often appear first, followed by ulcerative lesions. Lesions commonly appear in pairs. Nodules are uncommon in leishmaniasis. A rare presentation is a large psoriasiform-type plaque containing several small lesions. “I've seen about 10 cases of this form,” Dr. Aronson said. Facial lesions, including those on the lips or pinna of the ear, tend to be more inflammatory, Dr. Aronson commented.
Leishmaniasis lesions do not typically feature purulent drainage; if the lesion is tender with pus, it is likely a bacterial superinfection, Dr. Aronson explained. Both the lesions and the resultant bacterial infection may require concurrent treatment courses.
Sand flies are attracted to bright colors, so soldiers are sometimes bitten on exposed tattoos, she said. “A common complaint in our clinic is 'the sand fly messed up my tattoo.'” The cutaneous form of the disease is ultimately self-healing, although disfiguring scars can remain. The visceral and mucosal forms of leishmaniasis are often more serious and sometimes fatal. Educate patients that not all treatments are 100% effective, Dr. Aronson suggested. “It is important to give patients realistic expectations that leishmaniasis may not be gone, but it should improve.”
There are no leishmaniasis treatments that have been approved by the Food and Drug Administration. Topical treatments include heat therapy and cryotherapy. Some lesions will respond to treatment with ThermoMed (Thermosurgery Technologies, Inc.) but others only partially respond, Dr. Aronson reported. A clinical trial investigating the technology is underway at Walter Reed Army Medical Center. Cryotherapy with liquid nitrogen is another treatment strategy.
Standard therapy for all forms of the disease is pentavalent antimony of sodium stibogluconate (Pentostam, GlaxoSmithKline) or meglumine antimonate (Glucantime, Aventis). The usual parenteral regimen of sodium stibogluconate, for example, is 20 mg/kg per day for 20 days.
Pentavalent antimonials are available only through an Investigational New Drug (IND) protocol from the Centers for Disease Control and Prevention. Investigational agents require a lot of paperwork—and institutional review board approval—before they are available for use, Kenneth R. Dardick, M.D., said during a separate presentation at the meeting. Pharmacists need to be educated about storage requirements and nurses instructed to handle the agents as they would a chemotherapy drug. Informed consent is required from patients.
It is possible that physicians working in a community hospital will see only one or two cases of this rare disease. Physicians unfamiliar with use of pentavalent antimonials should consult military and/or CDC infectious disease experts, suggested Dr. Dardick, a family physician at Mansfield Family Practice, Windham Hospital, Storrs, Conn.
The IND requirements “can be novel for a community hospital,” Dr. Dardick added. “But cutaneous leishmaniasis can be successfully diagnosed and treated in a community hospital with appropriate index of suspicion.”
Soldiers may get bitten on exposed tattoos, Dr. Naomi E. Aronson said. Courtesy Dr. Naomi E. Aronson