High levels of anti-Phlebotomus pemiciosus saliva antibodies in different vertebrate hosts from the re-emerging leishmaniosis focus in Madrid, Spain

摘要

From July 2009 to date, a leishmaniosis outbreak has occurred in the south-west of the Madrid region (Spain) and has already accounted for more than 450 human cases in an area that comprises a population of approximately 500,000. The causative agent is Leishmania infantum and the main vector in the area is Phlebotomus perniciosus. Although canine leishmaniosis prevalence in the focus is not higher than the average in the Madrid region, a wild reservoir the hare has been implicated. In this study, we examined the exposure of Leishmania reservoirs in the area: dogs, hares, and wild rabbits to sand fly bites using the detection of specific IgG antibodies against P. pemiciosus salivary gland homogenate or recombinant salivary proteins. Hares collected in a green park adjacent to the focus (n=59) showed positive exposure to P. pemiciosus bites in comparison to hares from a non-endemic area (Czech Republic, n=18). A significant positive correlation was found between IgG response to yellow protein rSP03B and salivary gland homogenate (r=0.902) and between apyrase rSP01B and salivary gland homogenate (r=0.710). Wild rabbits captured in the study area (n=21) presented higher anti-saliva antibody levels than negative control sera and their IgG response against recombinant salivary proteins were positively correlated with salivary gland homogenate (rSP03B: r=0.710; rSP01B: r=0.666). All sera of dogs from the focus (n=34) showed higher anti-saliva IgG levels than that of non-exposed dogs. Moreover, dogs protected against sand fly bites through the use of topical insecticides and sleeping indoors showed significantly lower antibody levels than the non-protected ones. Antibody response to all three recombinant salivary proteins tested showed positive correlation with salivary gland extract (rSP03B: r=0.858; rSP01: r=0.864; and rSP01B: r=0.861). Data confirmed the exposure of hares, rabbits and dogs to P. pemiciosus bites in the context of an outbreak of human leishmaniosis in Spain, highlighting their involvement in Leishmania transmission by supporting their role as potential reservoirs. This novel methodology represents a promising tool for further epidemiological studies that would help to design better strategies for the control of leishmaniosis in this area and other foci