Description
In dogs,Leishmania infantum?causes canine leishmaniosis, a chronic, progressive, often fatal zoonotic disease transmitted by sand flies, with dogs serving as the primary reservoir for human visceral leishmaniasis, posing significant public health risks especially in endemic areas like the Mediterranean, Middle East, and parts of Latin America. Clinical signs are highly variable and often insidious, including cachexia/weight loss, exfoliative/ulcerative dermatitis (especially on ears, muzzle, paws), onychogryphosis (claw overgrowth), generalized lymphadenopathy, splenomegaly, epistaxis, polyuria/polydipsia from glomerulonephritis/proteinuria, ocular lesions (uveitis, keratoconjunctivitis), lameness/polyarthritis, and less commonly fever, vomiting, diarrhoea, or neurologic deficits; many infections remain subclinical for years before progression.
Cats are occasionally infected (especially in endemic regions) but rarely develop severe disease, showing milder signs like cutaneous nodules, lymphadenopathy, or ocular inflammation.
Diagnosis combines clinical signs, serology, and molecular tests, with samples selected by presentation; serum is primary for quantitative serology (IFAT, ELISA) where high titres (>1:100–1:400) support active disease, though cross-reactivity with other Trypanosomastidae occurs. Cytology/histopathology of lymph node, spleen, skin, or bone marrow aspirates may reveal characteristic amastigotes, while blood (EDTA), conjunctival swabs, urine, or tissue biopsies are submitted for PCR to detect parasite DNA.
Quantitative PCR (qPCR) excels by detecting and quantifying L. infantumDNA (e.g., kDNA minicircles) in these samples with high sensitivity (even low parasitaemia), speciating the parasite, monitoring treatment response, and assessing infectivity risk—critical for zoonotic control, as qPCR-positive dogs with skin lesions are highly infectious to sand flies.
