Leishmania infantum life cycle in Spain: vector and reservoirs
Regarding the life cycle of Leishmania infantum in Spain, which statement is correct?
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A. It is transmitted by Culex mosquitoes, which inoculate amastigotes when they bite
Culex transmits Dirofilaria, not Leishmania. The vector is the sand fly, and the stage it inoculates is the metacyclic promastigote, not the amastigote.
B. The female Phlebotomus perniciosus inoculates metacyclic promastigotes; the dog is the main reservoir, but there are wild reservoirs such as the hare
Correct. The sand fly ingests amastigotes within skin macrophages; they become promastigotes in its gut and are inoculated when it bites. In the Fuenlabrada outbreak (Madrid, from 2009) the main reservoirs were hares and rabbits, not dogs.
C. Dogs are mainly infected by ingesting sand flies or licking other dogs' lesions
The oral route has no epidemiological importance. Almost all infections are due to the sand fly bite; non-vectorial routes (vertical, transfusion, venereal) are minor.
D. Every infected dog develops disease within a few weeks, so seroprevalence matches clinical prevalence
Most infected dogs in endemic areas never become ill: the outcome depends on the immune response (protective Th1 versus Th2). The incubation period ranges from months to years.
lightbulb Key takeaway
In Spain the vectors are P. perniciosus and P. ariasi, active mainly at dusk and from May to October. Infection is not disease: far more dogs are infected than ill. Leishmaniosis is a zoonosis and the dog is its main domestic reservoir.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.