First detection of Leishmania killicki (Kinetoplastida, Trypanosomatidae) in Ctenodactylus gundi (Rodentia, Ctenodactylidae), a possible reservoir of human cutaneous leishmaniasis in Tunisia
© Jaouadi et al; licensee BioMed Central Ltd. 2011
Received: 28 June 2011
Accepted: 11 August 2011
Published: 11 August 2011
Leishmania killicki was originally described in 1980 in southeast Tunisia. It was also recently reported in Lybia and Algeria. Nevertheless, neither vector nor reservoirs of this parasite are known. The identification of the vector and the animal reservoir host of L. killicki is critical for the establishment of an efficient control strategy.
blood, popliteal lymph node, spleen, bone marrow, liver and skin were collected from 50 rodents in 2009 in south western Tunisia. Samples were smeared onto glass slides, cultured on NNN medium and tested by polymerase chain reaction for Leishmania detection. Parasites were detected by PCR from 10 Psammomys obesus and from two Ctenodactylus gundi. Parasite identification was performed simultaneously by internal transcribed spacer 1 PCR-RFLP and by PCR sequencing. Both Leishmania major and Leishmania killicki were identified from infected Psammomys and Ctenodactylus gundi respectively.
This is the first report of Leishmania killicki identified from Ctenodactylus gundi in Tunisia. This result supports the assumption that C. gundi is a potential reservoir for Leishmania killicki.
In Tunisia, Leishmania infantum, L. major and L. killicki are responsible for cutaneous leishmaniasis (CL). This last taxon has been described in 1980 in Southeast Tunisia, based on the identification of 29 human strains . It is responsible for CL with a chronic evolution of the lesion and a low endemicity (about 10 cases per year). Since 2004, new foci of CL caused by L. killcki have emerged in different parts of the country. Leishmania killicki was also recently reported in Lybia and in Algeria, two neighbouring countries of Tunisia [2–4]. Nevertheless, until recently, little information was available on the epidemiology of L. killicki CL and neither the vector nor reservoir hosts were known.
The collection of wild animals for detection of a possible parasitic infection seems to be the most effective method for reservoir host identification. Therefore, an epidemiological study was carried out in Metlaoui province in Southwestern Tunisia, a new emerging focus of this taxon, with the objective of detecting and characterizing Leishmania killicki infection in wild rodents.
If the detection of L. major in Ps. obesus was an expected result, since this rodent was already described as the reservoir of this Leishmania taxon , our study is the first report of L. killicki infecting a rodent. The detection of this Leishmania species in the bone marrow of asymptomatic animals indicates that it can visceralize in C. gundi. Consequently, this rodent species could be a natural host of L. killicki, and an efficient reservoir host as two out of six specimens were found infected.
Ctenodactylus gundi is a gregarious rock-dwelling rodent found in northern Africa. In Tunisia it exists in the mountainous area of Tataouine (the original focus of L. killicki)  as well as in all emerging Tunisian foci of CL caused by L. killicki. C. gundi populations inhabit crevices within boulder mounds in the vicinity of villages. The rock crevices and caves present suitable breeding sites for sand flies. This rodent species was suspected to be the L. killicki reservoir since the end of the last century [7, 9, 10]; however no evidence has been given before. The detection of L. killicki in C. gundi by both direct examination and PCR method is the first proof of the potential role of this wild rodent as a natural host of this parasite.
Cutaneous leishmaniasis due to L. killicki seems to be a zoonotic disease involving C. gundi in its life cycle. However, the isolation of the parasite from this rodent is crucial for the confirmation of this first result. Further investigation, such collecting wild rodents in other L. killicki foci, is required to discern the potential epidemiologic role of Ctenodactylus gundi in spreading infection.
This study was supported by a grant from WHO/TDR-EMRO (Operational Research in Tropical and Communicable Disease) Ref. SGSS 09/118 and by DGRS/CNRS Project, Ref. 09/R 09-01.
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