Seasonal variation of Leishmania major infection rates in sandflies from rodent burrows in Isfahan province, Iran

In preparation for field trials of killed Leishmania major vaccine, natural infections with Leishmania promastigotes were monitored in Phlebotomine sandfly vectors from villages of Borkhar rural district, northeast of Isfahan in central Iran, where L.major zymodeme MON-26 ( = LON-1) has been identified as causing zoonotic cutaneous leishmaniasis (ZCL). Sandflies were collected and dissected weekly, from burrows of rodent colonies, during the "sandfly season', June-October 1991. Leptomonad infection rates were 12% of 26 Phlebotomus ansarii, 8% of 280 P.caucasicus, 11% of 1042 P.papatasi and none of 126 Sergentomyia sintoni, being greatest during late August through September, coinciding with peak activity of the sandflies, 2-3 months before the highest incidence of ZCL human cases in November-December.