The study shows that treated dog collars can reduce transmission of the disease, which causes fever, swollen liver and spleen, and anaemia, by 40 per cent.
Domestic dogs are the main carriers of Leishmania infantum, one of the parasites that causes visceral leishmaniasis. The parasite is transferred to humans by blood-sucking sandflies that live on the dogs.
One way of combating the disease — which is endemic in at least 70 countries in Latin America, Africa, Europe and Asia — is to cull infected dogs. But this strategy often fails, due to delays in diagnosis and because dog owners refuse to comply.
In Brazil the incidence of animal-related visceral leishmaniasis has increased steadily over the past two decades, despite spraying 200,000 houses with insecticide and killing 20,000 dogs a year.
"The protective effect of dog collars against leishmaniasis transmission was as good, or better, than that shown in dog culling trials," says Clive Davies from the London School of Hygiene and Tropical Medicine, who conducted the study together with researchers from the Tabriz University of Medical Sciences in Iran.
But the researchers warn that dog collars may not be as effective in other parts of the world. "In Iran, this strategy is sound because all stray dogs are killed as a generic disease control measure," they said in last week's Lancet.
And even if stray dogs are culled, collaring programmes would not prevent transmission from wild animals, such as jackals and foxes.
However, the significant reduction in transmission found in this study suggests that collaring dogs — in some parts of the world at least — could be a practical and effective way of reducing the burden of leishmaniasis.
© SciDev.Net 2002
Link to research paper in the Lancet (this requires free registration with the Lancet)
Photo credit: CDC