Leishmania: risk to the blood supply

Abstract

Leishmania infection is most often transmitted to humans via the bite of the phlebotomine sandfly, but transmission of Leishmania by transfusion has also been reported. There has been a huge increase in the incidence of cutaneous and visceral leishmaniasis in Iraq and Afghanistan. The deployment of US troops to these countries and published case reports of transmission to soldiers in endemic areas, by transfusion to infants with immature immune systems, and to individuals immunocompromised by disease or immunosuppressive therapy beckon a reexamination of blood donor deferral procedures. The length of the ongoing military conflict and the nature of exposure indicate that prior decisions regarding blood donor deferral made during the first Gulf War may no longer apply. Operation Iraqi Freedom and Operation Enduring Freedom present a much greater Leishmania threat than did Operation Desert Storm. Because most transmission by transfusion occurs in endemic areas, and visceral infection is asymptomatic in healthy individuals such as blood donors, it is difficult to determine the absolute risk of transmission by transfusion, but review of the literature provides many clues as to the appropriate measures to be taken for blood donor deferral.

Seroprevalence of Leishmania infection among the healthy blood donors in kala-azar endemic areas of Iran

“…It has been shown that Leishmania can circulate in asymptomatic blood donors more than 1 year after exposure (Fichoux et al 1999;Cardo 2006). Therefore there is a risk of transmission of Leishmania to blood recipients due to its subclinical persistence in infected individuals.…”

“…Transmission of Leishmania through transfusion requires parasites to be present in the blood, either within infected white blood cells, or as free amastigotes released from phagocytes (Cardo 2006). Furthermore, the parasite should survive during processing and storage of blood.…”

“…Recent studies carried out on blood donors from different VL-endemic areas of the world have revealed a relatively high rate of Leishmania infection in healthy blood donors (Luz et al 1997;Fichoux et al 1999;Riera et al 2004;Colomba et al 2005;Cardo 2006;Riera et al 2008;Scarlata et al 2008).…”

“…These asymptomatic infected subjects may transmit leishmaniasis to susceptible recipients through transfusion (Cardo 2006).…”

“…Many of frequent recipients of transfusion are patients undergoing treatment for malignancy, recipients of transplants, infants, and patients on steroid. These populations are at risk of acquiring VL through transfusion due to their immunosuppression status (Cardo 2006).…”