Systematics of Spanish sandflies, vectors of leishmaniasis, and the role of the Strait of Gibraltar in their evolution
Introduction
Some 12 million people worldwide have the 'tropical' disease leishmaniasis, and in Spain and other Mediterranean countries it is increasingly associated with AIDS. Some sandfly species transmitting leishmaniasis cannot easily be distinguished microscopically, and so DNA sequence markers were used for the first time to show that one species is restricted to north Africa, not having managed to cross the Gibraltar Strait or establish itself in the regions of southern Spain with a north African climate. Each sandfly species is adapted to a different ecological setting and so this information is important for predicting the spread of leishmaniasis following man-made or natural environmental changes, including global warming.
Female sandflies (Phlebotomus) obtain nutrients by sucking blood, when they can transmit Leishmania parasites from domestic dogs, the reservoir hosts, to humans.
Project
Human leishmaniasis is a disease caused by a protozoan (a unicellular organism), which is naturally transmitted from domestic and wild reservoir hosts (often dogs and foxes) to man by sandflies (the vectors). Many sandflies look alike and so, in this project, DNA sequences were used to identify some of the species (subgenus Larroussius) recorded as transmitting human and canine leishmaniasis in Spain and in north Africa. Sandflies were captured in Andalucia (in the provinces of Huelva, Granada and Almeria) and other populations (Catalonia, France, Morocco) were sent to us by colleagues.
Using sticky-paper traps to sample sandflies in Spain
Male sandflies of the subgenus Larroussius were dissected and their heads and claspers (= external genitalia) slide-mounted in order to identify them microscopically as being either Phlebotomus perniciosus or P. longicuspis. DNA was extracted from the remaining body parts and the polymerase chain reaction was used to amplify fragments of DNA, which were compared by sequence analyses (Esseghir et al. 2000. Biological Journal of the Linnean Society 70, 189-219) or by agarose gel separation of Randomly Amplified Polymorphic DNA (RAPD) fragments (Martin-Sanchez et al., 1995. Bol.Dir.Malariol.San.Amb. 35 (Supplement ISOPS II), 205-216). Using these analyses, only P. perniciosus was identified in Spain, thereby confirming recent suspicions that P. longicuspis is restricted to north Africa.
Contacts
UK Project Leader:
Dr Paul D Ready (The Natural History Museum)
Spanish Project Leader: Prof Francisco Morillas Marquez. Spanish Institution: Universidad de Granada
An example of cutaneous leishmaniasis
Last updated 31-Oct-2002