First Report of Autochthonous Canine Leishmaniasis in Hong Kong

Abstract

Canine leishmaniasis is a zoonotic disease caused by Leishmania infantum; transmitted by the bite of phlebotomine sand flies. Leishmania infantum amastigotes were identified by cytology from a locally born Hong Kong dog exhibiting nasal, cutaneous, and systemic disease who was part of a kennel of eight dogs. All eight kennel dogs were subsequently tested serologically by enzyme-linked immunosorbent assay (ELISA) and by polymerase chain reaction (PCR) followed by DNA sequencing for L. infantum infection. The local dog was seropositive and blood and splenic tissue were PCR positive for L. infantum whilst the other kennel dogs were negative on serology and PCR. Autochthonous transmission was suspected for the local dog as Hong Kong lacks known vectors of L. infantum. Either vertical transmission from the deceased dam who had previously died with disease suspicious for leishmaniasis or horizontal transmission from a second non-locally born kennel dog who had been diagnosed previously with leishmaniasis was possible. This is the first recorded autochthonous case of canine leishmaniasis in Hong Kong. Leishmaniasis should be considered as a differential for cutaneous or systemic illness in local untraveled dogs in Hong Kong. In addition, as dogs serve as L. infantum reservoirs for human infection attention should be paid to the possibility of leishmaniasis emerging in Hong Kong.

Keywords: Hong Kong; Leishmania infantum; canine; phlebotomine.

Figure 1

Leishmaniasis disease status and relationships of dogs within the Hong Kong kennel. USA: United States of America. Black rectangles: Male dogs. Blue rounded rectangles: Female dogs.

Figure 2

Nail bed skin histopathology from dog 1 collected in 2015: (a) Granulomatous dermatitis. Haematoxylin and eosin staining; bar = 100 um. (b) Granulomatous dermatitis with macrophages admixed with neutrophils and fewer plasma cells and lymphocytes. Haematoxylin and eosin staining; bar = 10 um. (c) Multiple Leishmania amastigotes within the cytoplasm of a macrophage. Arrow points to a kinetoplast at right angles to the amastigote nucleus. Haematoxylin and eosin staining; bar = 10 um.

Figure 2

Nail bed skin histopathology from dog 1 collected in 2015: (a) Granulomatous dermatitis. Haematoxylin and eosin staining; bar = 100 um. (b) Granulomatous dermatitis with macrophages admixed with neutrophils and fewer plasma cells and lymphocytes. Haematoxylin and eosin staining; bar = 10 um. (c) Multiple Leishmania amastigotes within the cytoplasm of a macrophage. Arrow points to a kinetoplast at right angles to the amastigote nucleus. Haematoxylin and eosin staining; bar = 10 um.

Figure 3

Nasal mucosa histology and splenic aspirates from dog 2: (a) Histopathology of nasal mucosa with granulomatous inflammation. Haematoxylin and eosin staining; bar = 100 um. (b) Nasal sub-mucosa with macrophages admixed with fewer neutrophils, plasma cells, and small lymphocytes. Haematoxylin and eosin staining; bar = 10 um. (c) Splenic aspirate. Wright’s Giemsa stain. Leishmania amastigotes within the cytoplasm of macrophages. Bar = 10 um.