Leishmania infantum in US-Born Dog

First Report of Autochthonous Canine Leishmaniasis in Hong Kong

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.

Possibility of Leishmania Transmission via Lutzomyia spp. Sand Flies Within the USA and Implications for Human and Canine Autochthonous Infection

Purpose of Review

Leishmaniasis is a leading cause of parasitic death, with incidence rising from decreased resources to administer insecticide and anti-leishmanial treatments due to the COVID-19 pandemic. Leishmaniasis is nonendemic in the United States (U.S.), but enzootic canine populations and potentially competent vectors warrant monitoring of autochthonous disease as a fluctuating climate facilitates vector expansion. Recent studies concerning sand fly distribution and vector capacity were assessed for implications of autochthonous transmission within the U.S.

Recent Findings

Climate change and insecticide resistance provide challenges in sand fly control. While most Leishmania-infected dogs in the U.S. were infected via vertical transmission or were imported, autochthonous vector-borne cases were reported. Autochthonous vector-borne human cases have been reported in four states. Further vaccine research could contribute to infection control.

Summary

Both cutaneous and visceral leishmaniasis cases in the U.S. are increasingly reported. Prevention measures including vector control and responsible animal breeding are critical to halt this zoonotic disease.

Cutaneous Leishmaniasis Caused by an Unknown Leishmania Strain, Arizona, USA

We investigated an autochthonous case of cutaneous leishmaniasis caused by a genetically different Leishmania sp. in a patient in Arizona, USA. This parasite was classified into the subgenus Leishmania on the basis of multilocus DNA sequence and phylogenetic analyses of the rRNA locus and 11 reference genes.

Demographics and travel history of imported and autochthonous cases of leishmaniosis in dogs in the United States and Canada, 2006 to 2019

BACKGROUND

Leishmania infantum infections are reported in foxhounds throughout the United States (US) and Canada, but only rarely in other dog breeds. A seroprevalence report from 2006 documented leishmaniosis in foxhounds (8.9%) tested in the US between 2000 and 2003. All other breeds were seronegative.

OBJECTIVE

To reexamine demographics and travel history of L. infantum-infected dogs in the US and Canada, we hypothesize detection of L. infantum in more foxhounds than nonfoxhounds and that infected nonfoxhounds will have traveled to endemic regions.

ANIMALS

A total of 125 dogs positive for L. infantum by immunofluorescent antibody, PCR, or both.

METHODS

Retrospective, descriptive study of L. infantum-infected dogs between 4 January 2006 and 22 May 2019. Travel history and known lineage to foxhounds was collected from questionnaires.

RESULTS

Leishmania infantum was detected in 125 (6.4%) of 1961 dogs tested between 4 January 2006 and 22 May 2019, of which 10 (8%) were foxhounds and 115 (92%) were nonfoxhound breeds. Travel history available for 69 (55%) dogs showed 60 (86.9%) dogs had traveled outside of the US or Canada. Nine (13%) dogs had not traveled outside of the US or Canada, 5 of which were nonfoxhounds.

CONCLUSIONS AND CLINICAL IMPORTANCE

The majority of L. infantum cases were detected in nonfoxhounds, many of which had traveled to L. infantum-endemic countries, and several nonfoxhound breeds had no travel history. Leishmania surveillance should be considered for dogs that return from L. infantum-endemic regions to monitor emergence of this zoonotic disease in the US and Canada.