Leishmaniasis is a zoonotic disease endemic in 98 countries. Sandflies, several species of which reside in the United States, are the vector. Canine visceral leishmaniasis is common among hounds in the United States. It is spread via vertical transmission; the causative agent is Leishmania infantum.
This study investigated whether L infantum in naturally infected hounds was transmissible via the sandfly species Lutzomyia longipalpis. Female L longipalpis sandflies were allowed to feed on 2 hounds with confirmed naturally acquired L infantum infections. A subset of sandflies were dissected and evaluated for infectivity, and parasite development within the sandflies was confirmed.
Infected sandflies were then allowed to feed on 7 hamsters for 13 days. Hamster blood was screened for the presence of L infantum DNA over the next 5 months. Infection was newly detected in hamsters at 2 months, 3 months, and 4 months. L infantum DNA was found in spleen, bone marrow, and lymph node samples from infected hamsters, with the highest parasite load occurring in the bone marrow.
The authors concluded that naturally occurring leishmaniasis can fully develop within L longipalpis sandflies and be transmitted to susceptible vertebrate hosts. The results suggest companion dogs and humans may be at risk for vector-borne L infantum transmission.
