General information
Leishmaniosis is an infectious disease transmitted by insects. The carriers of leishmania are sand flies (phlebotomines). The leishmania are ingested during the sucking act. The promastigote stages multiply in the sandfly and are infectious 6 – 12 days after the sucking act. The pathogen in Europe is Leishmania infantum. From the Bosporus southwards and especially in North Africa, Leishmania tropica is also present. Further species of Leishmania have been described worldwide. The main areas of infection in Europe are Spain, Portugal, Italy and Greece. Foxes and possibly also small rodents are considered to be pathogen reservoirs.
In Germany, natural naturally occurring sand flies (mainly Phlebotomus mascittii; no transmission of Leishmania is known so far) have been found along the Rhine rift in Baden-Württemberg and in Rhineland-Palatinate in the Kaiserslautern region and in Saarbrücken in Saarland.
Infected animals can be asymptomatic for up to 7 years. The onset of the disease is usually characterised by lymphadenopathy, anaemia, and in the cutaneous form of leishmaniasis, skin changes appear on the ear margins, on the nose leather and spectacle formation on the eyes.
In chronic infections, the animals show reduced resilience, weight loss, lymphadenopathy, scaly non-itchy skin change and eye changes.
Resistance of Leishmania to allopurinol
A reduced reduced copy number of the METK gene has been described in cases of in-vitro allopurinol resistance (Yasur-Landau et al. 2018). In vivo, too, individual cases of suspected allopurinol resistance in dogs have been analysed, which correlate with a low copy number (Yasur-Landau et al. 2018, Sigel et al. 2025).
A positive Leishmania PCR with an adequate amount of pathogens is a prerequisite for testing allopurinol resistance. It is recommended to determine the METK copy number if leishmaniosis has recently been diagnosed in order to select the appropriate treatment, or in dogs with leishmaniosis that are being treated with allopurinol and have experienced treatment failure with recurrence of clinical signs and/or changes in laboratory findings.