Detection of Leishmania DNA in wild foxes and associated ticks in Patagonia, Argentina, 2000 km south of its known distribution area

Abstract

Background: Zoonotic Visceral Leishmaniasis (ZVL) is a vector-borne disease affecting humans and other mammals and caused by the protozoan parasite Leishmania (Leishmania) infantum (syn. L. chagasi), belonging to the L. donovani complex. The regions in Northern Argentina (above 32 °S) are its southern distribution limit in South America.

Results: We detected Leishmania sp. DNA (most likely belonging to the L. donovani complex) in 37.5% of 32 grey foxes (Pseudalopex griseus) captured in Argentinean Patagonia (48°S and 50°S). Eleven monosexual pools of Amblyomma tigrinum ticks from eight different foxes (six grey foxes and two culpeo foxes P. culpaeus) were also positive. The southernmost known distribution limit for L. infantum, and the southernmost reported capture of a phlebotominae, had previously been 2000 and 750 km north of our study area, respectively.

Conclusions: This finding is significant because it markedly extends the distribution area of leishmaniasis; supports the existence of a sylvatic cycle in the absence of dogs; and has implications in transmission, indicating that either sand fly distribution is broader than currently thought or non-sand fly Leishmania maintenance is possible. Additional molecular, parasitological, epidemiological and entomological studies are still needed.

Keywords: Kinetoplastida; Leishmania infantum; Lycalopex culpaeus; Lycalopex griseus; Sylvatic cycle; Wildlife.

Fig. 1

Map of South America, showing the accepted distribution area of Leishmania infantum (grey area) [3], the southernmost record of a Phlebotominae (black circle) [19], the southernmost record of a competent vector (black triangle) [31], the Bosques Petrificados National Monument (black star), and the Monte León National Park (white star)

Fig. 2

Leishmania infantum specific PCR amplifying a 145 bp fragment of kDNA. Lane 1: 100 bp low ladder (Sigma-Aldrich); Lane 2: PCR positive control; Lane 3: PCR negative control; Lanes 4–12: Grey foxes (7 positive and 2 negative)