Sandflies

Phlebotomine sandflies are small midge-like flies (approx 3 mm in length) which have a hairy appearance and conspicuous black eyes and stilt-like legs. Characteristically their wings are held erect over their body when at rest (in a ‘v’ shape). They have a short hopping flight with many landings.
The sub-family Phlebotominae includes numerous genera of blood-feeding flies including, most importantly, the vectors of leishmaniasis (a protozoan zoonotic disease, caused by more than 20 species of Leishmania parasite).

Leishmaniasis transmission occurs on every continent except Australia and Antarctica. In the Western Hemisphere, leishmaniasis is found in some parts of Mexico, Central America, and South America but it is not found in Chile or Uruguay. In the Eastern Hemisphere, leishmaniasis is found in parts of Asia, the Middle East, Africa, and southern Europe. The disease takes two forms – a lethal systemic disease (visceral leishmaniasis) and localised skin ulcers (cutaneous leishmaniasis).

• 90% of visceral leishmaniasis occurs in India, Bangladesh, Nepal, Sudan, Ethiopia and Brazil
• 90% of cutaneous leishmaniasis occurs in Afghanistan, Algeria, Iran, Saudi Arabia, Syria, Brazil, Colombia, Peru and Bolivia

In the New World it is the sandfly genus Lutzomyia which is responsible for spreading the disease and in the Old World the genus Phlebotomus. Similar to mosquitoes, female sandflies require a blood meal in order to obtain the protein to develop eggs (male sandflies do not bite). Unlike mosquitoes however, the mouthparts of the sandfly are not long and slender stylets, adapted for piercing and sucking but are a short structure designed for sucking up blood from a pool created at the bite site. They are generally crepuscular or nocturnal biters although they may bite during the day under low-light conditions. Sandflies can be both indoor and outdoor biters.

Female sandflies lay their eggs in moist soil, rich in organic matter. The time-period from egg-laying to adult development is about 4 to 6 weeks. Given the very generalised type of breeding site the use of larvicides in sandfly control programmes is generally regarded as impractical. Current sandfly control practices rely on controlling the adults (eg. residual spraying of dwellings and animal shelters, space spray application and insecticide-treated nets).

It is important to note that in some parts of the world the term ‘sandfly’ is used to describe biting midges (Ceratopogonidae) and/or black flies (Simuliidae) – neither of these species is responsible for transmitting leishmaniasis.