CONTROL OF CANINE LEISHMANIASIS IN THE CONTEXT OF "ONE HEALTH"

 

CONTROL OF CANINE LEISHMANIASIS IN THE CONTEXT OF "ONE HEALTH"

Visceral leishmaniasis (VL) is a zoonotic disease caused by a parasite of the genus Leishmania spp, mainly Leishmania infantum and transmitted through the bite of a female sandfly. Although there are several animal reservoirs (including humans), the dog remains a key indirect source in the transmission cycle.

Over the years, millions of dogs have been euthanized as part of government policies to control human VL caused by L. infantum. Public health policies in Central Asian, Caucasus and some Balkan countries continue to recommend the culling of any positive dog. Although in rural areas of China, North African countries and parts of the Middle East culling of dogs remains a common practice, medical therapy in owned dogs is allowed. In Central and South America, dog culling has also been recommended and practiced in several countries.

The Companion Vector-Borne Disease World Forum (CVBD) is a group of scientists working on canine and feline vector-borne diseases. This group contributes to a continuous discussion and update on these diseases and their effects on animals and humans. Since the topic of canine leishmaniasis is of global importance and is frequently discussed, a consensus was reached for greater proactivity towards the control of this disease. At the 13th CVBD World Forum Symposium, held in Windsor, UK in 2018, the control of leishmaniasis caused by L. infantum was discussed reaching the conclusion of the futility of culling infected dogs as a measure to reduce the risk of VL in humans.

The dog culling strategy does not hold for several reasons.

1.      No reliable body of scientific evidence supports the efficacy of culling dogs as a means of reducing the incidence of VL.

2.      Alternative hosts may play a role in maintaining the life cycle of L. infantum and should be considered when formulating an integrated control strategy.

3.      Euthanized dogs are quickly replaced by young dogs that are usually more susceptible to primary infection.

4.      Serological diagnostic tools, often used for screening dogs, have limitations in terms of sensitivity and specificity.

5.      Slaughtering dogs is not a cost-effective and socioeconomically valid alternative (e.g., psychological effect on their owners or euthanasia drugs) for governmental institutions.

6.      Finally, effective control of L. infantum transmission requires approaches that focus not only on the dog, but also on the parasite and, more importantly, on the vector. Thus, the use of dog culling as a strategy to reduce the incidence of VL in humans cannot be justified and should no longer be used.

 

Extensive scientific evidence shows that the regular use of topical repellents is highly effective in preventing sandfly bites and thus the transmission of L. infantum. Consistent use of repellents not only protects dogs from vectors, but also allows a reduction of vectors in the vicinity of humans, potentially resulting in a reduction of human infections. Vaccines are also available in some countries to reduce the risk of clinical signs and disease progression in infected dogs. Chemotherapy and immunotherapy can also reduce the infectivity of treated dogs, leading to a decrease in infected sandflies under experimental conditions.

Danta-Torres; F. et al (2019) “Canine Leishmaniasis Control in the Context of One Health” Emerg. Infec. Dis. 25 (12): 1-4

 

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874277/