The veterinary and medical importance of sand flies is determined by their ability to transmit viral, bacterial and protozoal diseases. Among sand fly-transmitted diseases, the most relevant is leishmaniosis, affecting animals and humans. Worldwide, leishmaniosis is the third most important vector-borne disease and present as a large variety of disease manifestations differing markedly in their severity and health impact.

The causative agents of canine leishmaniosis are Leishmania infantum in the Mediterranean Basin and the Middle East and L. chagasi in South and Central America. Initially, L. chagasi was considered to be distinct from L. infantum, however, recent molecular studies indicate that they are indistinguishable.

For a more detailed description please see the chapter Sand Fly-Borne Diseases at www.cvbd.org.

Distribution

Canine leishmaniosis has a worldwide distribution and can be found in the Mediterranean region, Asia, Africa and America. First reports on canine leishmaniosis were recently published also from the U.S.. It remains unclear until now whether the disease was imported from abroad, or is already endemic in the country.

Clinic

Leishmaniosis is a chronic disease with an incubation period of months to years. Once a dog got ill, the parasites will never been completely eliminated. If the disease becomes patent, progression is usually rapid and death may occurs within a few weeks to months. There is a wide variety of signs in dogs, including skin lesions (alopecia, scaling and ulceration), weight loss or poor appetite, ocular lesions, nosebleed, lameness, anaemia, renal failure and diarrhoea.

Human health risk

L. infantum in Europe and L. chagasi in South America, for which dogs are the main reservoir, can cause visceral leishmaniosis in humans. This most severe kind of human leishmaniosis has a mortality rate of 100%, if untreated. According to the WHO, 500,000 new human cases are estimated per year worldwide, particularly in children or immunosuppressed adults and mostly in Asia and South America.

For Leishmania infantum, dogs function as a reservoir host. Several studies showed that the prevalence of human leishmaniosis could be significantly decreased with the control of leishmaniosis in dogs.

Sand fly control

A recent field study¹ in Italy proved that sand fly control by repellent and insecticidal parasiticides is an effective way to prevent canine leishmaniosis infection in dogs. The results showed that advantix^®, when applied once or twice a month, yielded in a very high percentage of protection against leishmaniosis infection of more than 88.9% under natural conditions in an endemic area. Thus dogs were protected from sand fly bites.