Parasite identification in the surveillance of imported leishmaniasis cases in Italy

An accurate Leishmania classification was defined since 1980s by the use of isoenzyme analysis. To date, this procedure still represents the reference identification technique, despite the increasing use of molecular approaches. Studies and surveillance methods on leishmaniases are strongly conditioned by the knowledge and mapping of all the parameters characterizing each nosogeographical entity. On this respect, the identification of parasites from all the actors of the natural life cycle plays a key role. With the increasing population movements and climate changes, novel risk factors could be identified associated to Leishmania geographical distribution and spreading: a) the introduction into Italy of new populations of L. infantum from other countries; b) the introduction of new Leishmania species that may find a suitable milieau to support their life cycle in our country. The objective of this report is to present the surveillance activity on imported leishmaniases by the Leishmania Identification Reference Centre, ISS. Two different methodologies were routinely applied: a) isoenzyme electrophoretic analysis, which requires parasite culture, and b) a number of molecular techniques, used for both diagnosis and parasite identification, differently applied according to the geographical origin of the suspected leishmaniasis case. When possible, both types of methodologies were applied. From 1986 to June 2002, 38 imported cases of leishmaniases were identified: 9 visceral (VL) and 29 cutaneous (CL) cases, of which 22 from the Old and 7 from the New World. Pathology, Leishmania species/zymodeme and geographical origin features are reported in the paper. Seven out of 9 VL patients were HIV positive, of whom 5 detected in the period 1993-1995. This high importation rate can be associated to the general increase in Mediterranean Leishmania/HIV coinfections in that period. Following HAART treatment, VL imported cases became occasional; no introduction of new L. infantum populations has been detected. On the other hand, our findings show an increase of CL imported cases from different areas of the Old and New Worlds. This phenomenon, however, is so far limited to new Leishmania species that could hardly be introduced in our country, because of their strict biological requirements (i.e. vectors and/or natural reservoir hosts). Since June 2002, 10 further suspected imported cases were recorded. For these patients--whose Leishmania identification is still in course--the origin/visited geographical areas were only slight different from the previous. However, the characteristics of the patients are changing: there are more immigrants that occasionally visited their place of origin, and Italian military staff.