Correspondence

Visceral Leishmaniasis in Desert Storm Veterans

N Engl J Med 1993; 329:1503-1504November 11, 1993

Article

To the Editor:

In their report (May 13 issue) on visceral infection caused by Leishmania tropica in veterans of Operation Desert Storm,1 Magill et al. provide good laboratory evidence of infection. But were the infections actually acquired as a result of service in Saudi Arabia and the Desert Storm campaign? A brief reminder of the epidemiologic, entomologic, and geographic determinants of leishmania transmission might have been helpful in determining the possible source of the infections.

The authors note that kala-azar is rare in Saudi Arabia but do not state whether similar cases have been seen in the local population or whether there are potential canine or rodent reservoirs or sandfly vectors. Given the limited information, it is difficult to agree that the organism is actually “endemic” in the area. The authors acknowledge a potential 10-year incubation period. Others have noted that the time elapsing between an infecting sandfly bite and the development of skin lesions from Old World cutaneous leishmaniasis ranges from a few weeks to as long as three years2. Magill et al. mention that three of the soldiers were from the same airborne unit and had spent time in Iraq. One of the older names for cutaneous leishmaniasis is Baghdad boil3. The deployment of airborne units usually includes field exercises in which the opportunities for exposure to sandflies may be increased. What was the travel history of the other patients? Could they have been exposed elsewhere?

With the rapid movement of peoples, evaluation of the geographic source of infectious diseases has become increasingly complicated. The confusing epidemiologic and taxonomic picture of leishmaniasis adds another dimension to these cases. The essential first question in the diagnosis of “geographic disease” is, “Where have you been?” Can the authors provide more information about exposure patterns in the area and the answer to the second question, “Where else have you been”?

Markley H. Boyer, M.D., D.Phil., M.P.H.
Tufts University School of Medicine, Boston, MA 02111

3 References

1. 1

   Magill AJ, Grogl M, Gasser RA Jr, Sun W, Oster CN. Visceral infection caused by Leishmania tropica in veterans of Operation Desert Storm. N Engl J Med 1993;328:1383-1387
   Full Text | Web of Science | Medline

2. 2

   Maegraith B, ed. Adams & Maegraith: clinical tropical diseases. 7th ed. Oxford, England: Blackwell Scientific, 1980.
   

3. 3

   Wilcocks C, Manson-Bahr PEC. Manson's tropical diseases. 17th ed. Baltimore: Williams & Wilkins, 1972.
   

Author/Editor Response

The authors reply:

To the Editor: L. tropica, a parasite of the Old World, is found in the Mediterranean, the Middle East, Southwest Asia, and East Africa1. Our patients with viscerotropic leishmaniasis caused by L. tropica had the following histories of exposure: Patients 1, 5, and 6 had attended a three-week jungle training school in Panama in 1990, seven months before their arrival in Saudi Arabia. During Operation Desert Storm, the unit spent August through February in the eastern province of Saudi Arabia, followed by a month in southern Iraq. Patient 5 was stationed in northern Italy from 1986 to 1990, with no travel to southern Italy. Although visceral leishmaniasis has been reported in northern Italy, the causative agent is probably L. infantum rather than L. tropica1. Patient 2 had been stationed in Thailand from 1972 to 1974. Patients 3, 4, and 7 had never been outside the continental United States before their participation in Operation Desert Storm. We believe that five patients (Patients 1 through 4 and Patient 7) acquired their L. tropica infection in Saudi Arabia, since they never left the eastern province during Operation Desert Storm. Patients 5 and 6 could have acquired their infection in neighboring Iraq. Patient 8, who had previously traveled throughout the Middle East, the Mediterranean, East Africa, and Central America, could have acquired his infection before Operation Desert Storm.

L. tropica and L. major are both agents of cutaneous leishmaniasis in eastern Saudi Arabia2. The sandfly vector, Phlebotomus papatasii, and the mammalian reservoir, Psammomys obesus, have been described for L. major, but vectors and reservoirs for L. tropica have not2. Phleb. sergenti is a vector for L. tropica in southwestern Saudi Arabia3. L. tropica was isolated from a rat in Iraq and a dog in India, although a notable mammalian reservoir other than humans has not been reported4.

The “species” L. tropica, as characterized by isoenzyme electrophoresis, is actually a heterogeneous population of parasites4. Strains associated with cutaneous disease may be different from those causing visceral infections5. In addition, the possibility of hybridization between dermotropic strains of L. tropica and imported visceral strains present in some of the thousands of expatriate workers should be investigated.

Newly urbanized Saudi Arabia is an environment in which the customs of the people, their housing, mammalian reservoirs, and sandfly vectors may be changing rapidly. What was true even 10 years ago may not be the case today.

Alan J. Magill, M.D.
Max Grogl, Ph.D.
Walter Reed Army Institute of Research, Washington, DC 20307

Robert A. Gasser, Jr., M.D.
Keesler Air Force Base, Biloxi, MS 39534

Charles N. Oster, M.D.
Walter Reed Army Medical Center, Washington, DC 20307

5 References

1. 1

   Ashford RW, Bettini S. Ecology and epidemiology. In: Peters W, Killick-Kendrick R, eds. The Leishmaniases in biology and medicine. Vol. 1. London: Academic Press, 1987:365-424.
   

2. 2

   Peters W, Al-Zahrani MA. The Leishmaniases -- a public health problem in Saudi Arabia. Saudi Med J 1987;8:333-343
   Web of Science

3. 3

   al-Zahrani MA, Peters W, Evans DA, Chin C, Smith V, Lane RP. Phlebotomus sergenti, a vector of Leishmania tropica in Saudi Arabia. Trans R Soc Trop Med Hyg 1988;82:416-416
   CrossRef | Web of Science | Medline

4. 4

   Le Blancq SM, Peters W. Leishmania in the Old World: 2. Heterogeneity among L. tropica zymodemes. Trans R Soc Trop Med Hyg 1986;80:113-119
   CrossRef | Web of Science | Medline

5. 5

   Oren R, Schnur LF, Ben Yehuda D, Mayner V, Okon E, Rachmilewitz EA. Visceral leishmaniasis: a difficult diagnosis and unusual causative agent. J Infect Dis 1991;164:746-749
   CrossRef | Web of Science | Medline