Relapses versus reinfections in patients coinfected with Leishmania infantum and human immunodeficiency virus type 1

In the Mediterranean basin, Leishmania infantum is a major opportunistic parasite in people with acquired immunodeficiency syndrome (AIDS), and up to 9% of the patients with AIDS suffer from newly acquired or reactivated visceral leishmaniasis. Distinguishing between reinfections and relapses in these patients is important because some apparent treatment failures occur in patients with new rather than reactivated infections. Isoenzyme characterization is limited for use in determining relapsed versus newly acquired leishmaniasis in human immunodeficiency virus (HIV)-infected patients because of the variability of L. infantum and the predominance of the MON-1 zymodeme in people coinfected with HIV. A seminested polymerase chain reaction (PCR) was used to amplify L. infantum minicircle kinetoplast DNA, and, after digestion, the restriction fragment-length polymorphism (RFLP) profiles showed that 3 (7.5%) of 40 patients coinfected with L. infantum and HIV had a new infection, whereas isoenzyme characterization indicated that all 40 patients had infection relapses. These results suggest the utility of this PCR-RFLP analysis in detecting leishmaniasis reinfection in HIV-positive patients.