Sand Flies (Diptera: Psychodidae) Associated with Visceral Leishmaniasis in El Agamy, Alexandria Governorate, Egypt1

Abstract

Phlebotomies papatasi and P. langeroni colonized from El Agamy, a visceral leishmaniasis focus in Alexandria Governorate, Egypt, were tested for susceptibility to Leishmania donovani (reference strain DD8) and L. major (1 dog strain from El Agamy, reference strain LRC-L137, and 2 isolates from human cutaneous cases). With L. donovani, infection frequencies were 4% (1/24) for P. papatasi and 65% (11/17) for P. langeroni. In P. langeroni, heavy infections (>500 promastigotes) were found throughout the gut of most flies, and 8 parasites were detected in the proboscis of 1 fly on day 5; only 10 promastigotes were found in the midgut of the single infected P. papatasi on day 4. Both P. papatasi and P. langeroni (AGAMY strains) and 2 other Egyptian strains of P. papatasi were susceptible to L. major. In most experiments, infection rates were over 50%, with good parasite development in the gut; promastigotes were observed in the proboscis 5 to 8 days postinfection. Epidemiologically, the El Agamy focus is characterized by human visceral infections with L. donovani, with dogs serving as the reservoir host; L. major also occurs in dogs but there is no evidence for human or rodent infections. Based upon experimental infections and field observations, P. langeroni is the most likely, although not conclusively proven, vector of L. donovani in the El Agamy area.