Identification of Leishmania isolates from a Lebanese population

Phlebotomine sand fly-borne pathogens in the Mediterranean Basin: Human leishmaniasis and phlebovirus infections

Pathogens transmitted to humans by phlebotomine sand flies are neglected, as they cause infectious diseases that are not on the priority list of national and international public health systems. However, the infections caused by protozoa of the Leishmania genus and viruses belonging to the Phlebovirus genus (family Phenuiviridae)—the most significant group of viruses transmitted by sand flies—have a relevant role for human pathology. These infections are emerging in the Mediterranean region and will likely spread in forthcoming decades, posing a complex threat to human health. Four species and 2 hybrid strains of Leishmania are pathogenic for humans in the Mediterranean Basin, with an estimated annual incidence of 239,500–393,600 cases of cutaneous leishmaniasis and 1,200–2,000 cases of visceral leishmaniasis. Among the phleboviruses, Toscana virus can cause neuroinvasive infections, while other phleboviruses are responsible for a typical “3-day fever”; the actual incidence of Phlebovirus infections in the Mediterranean area is unknown, although at least 250 million people are exposed. Here, we reviewed the current literature on epidemiology of sand fly–borne infections in the Mediterranean Basin, with a focus on humans. Our analysis indicates the need for increased public health activities directed to determine the disease burden of these infections as well as to improve their surveillance. Among the emerging challenges concerning sand fly–borne pathogens, the relationships between sand fly–borne protozoa and viruses should be considered in future studies, including epidemiological links between Leishmania and phleboviruses as well as the conditional capacity for these pathogens to be involved in interactions that may evolve towards increased virulence.

Identification of Lebanese dermotropic putative Leishmania archibaldi isolates by gp63 PCR-RFLP

Leishmania stocks isolated from cutaneous lesions in Lebanon were characterized by PCR methods. The stocks were typed as putative L. (L.) archibaldi (gp63 PCR-RFLP), belonging to 2 different genotypes (PCR-based schizodeme analysis). This constitutes the first report on the presence of L. (L.) archibaldi in the Middle East.

The epidemiology of leishmaniases in Lebanon

The prevalence of leishmaniasis in Lebanon was studied in 1993-97 for a Lebanese population sample of about 81,000 subjects (60% rural and 40% urban) constituting roughly 3.4% of the total population. The prevalence of cutaneous leishmaniasis was found to be 0.18% in the rural versus 0.41% in the urban areas. Visceral leishmaniasis was practically non-existent in both environments. In addition, skin tests were done and anti-Leishmania antibodies were sought in a sample of the population at risk in the rural area. Skin tests were positive in 2.5% of the tested subjects, and 1% of the normal population had elevated levels of anti-Leishmania antibodies. The difference between the prevalence of clinical disease and positive skin testing and/or antibodies may be due to the existence of past or present subclinical disease. An unexpected finding was that the prevalent dermotropic parasite in Lebanon belongs to the L. donovani complex. Further characterization of the isolates by molecular techniques and definition of the transmission cycle of this parasite may explain our epidemiological findings.

Leishmania donovani invasion of the blood in a child with dermal leishmaniasis

Cutaneous leishmaniasis is highly endemic in eastern Mediterranean countries. The causative organisms are Leishmania tropica or Leishmania major but, further west, variants of Leishmania infantum frequently cause cutaneous leishmaniasis. We report a young girl from Beirut with an acute cutaneous leishmaniasis in whom the causative organism was cultured from both the skin lesion and the blood in the absence of any signs or symptoms typical of systemic involvement. The parasite was found to have a zymodeme typical of organisms belonging to the L. donovani complex. With the negative past history and in the absence of anti-Leishmania antibodies in her serum, post-kala-azar dermal leishmaniasis is an unlikely possibility, especially in view of the rarity of the complication in this part of the world. The infection was probably acquired during a recent visit to Aleppo, where cutaneous leishmaniasis is hyperendemic as similar cases have not been reported in Beirut. This case indicates the need to consider L. infantum strains in addition to L. tropica in cutaneous disease in Aleppo. This case also demonstrates that L. infantum can spread by the haematogenous route, even in a child without evidence of the immunosuppression, which usually predisposes to such spread.