-179- 



nondi v iding, binucleated form and an extremely long mononucleated form 

 were seen in the abdominal midgut (Fig. 4-9 and 4-10). 



The highest degree of infection anterior to the stomodeal valve 

 occurred from day four through eight in Lu. diabol ica and day five 

 through day eight in Lu . shannoni . Once inoculated with leishmanial 

 parasites, sand flies of both species usually maintained the infection 

 for life, but the degree of infection tended to diminish beyond eight 

 days. 



Leishmania mexicana amazonensis (strain untyped). Twenty-four 

 (96%) of 26 Lu. diabol ica became infected when fed on histiocytomas of 

 the foot of a Syrian hamster infected with L. mexicana amazonensis . 

 Six (25%) took second blood meals on uninfected hamsters, five to 

 seven days after the infecting blood meal. For the first three days 

 of the infection, the parasite growth pattern paralleled that of L. 

 mexicana (strain WR-411), with the heaviest infections in the 

 abdominal midgut and anterior migration to the cardia (Table 4-5). 

 Massive infections were not observed, nor was attachment to the 

 stomodeal valve. The infections seemed to be more localized, with the 

 predominant form after three days being a rounded promastigote rather 

 than the long-slender form seen previously in infections of L 

 mexicana (strain WR-411). 



Leishmania brazil iensis guyanensis (strain MH0M/SR/80/CUMC 1). 

 Thirteen (46.4%) of 28 Lu. diabol ica and 3 (42.9%) of 7 Lu. shannoni 

 became infected when fed on a histiocytoma at the base of the tail of 

 a white mouse infected with L _b. guyanensis . Initial development and 

 establishment of the infection was in the hind triangle where short, 

 rounded promastigotes attached in bunches to the hindgut wall 



