-218- 



favorable positions where they may undergo their proper cyclical 

 development. Kil 1 ick-Kendrick et aj_. (1974) suggested that the food 

 ingested by infected flies may have an affect on the anterior spread 

 of promastigotes by enhancing or interfering with attachment and 

 subsequent colonization of the anterior part of the fly. 



More extensive investigations of the ul trastructure of Leishmania 

 in Lu. diabol ica are needed to characterize all morphological forms at 

 various times throughout their development in the alimentary tract of 

 the insect. Special emphasis should be directed to describing the 

 short-slender, highly active forms, which may represent a 

 morphologically-distinct infective stage. 



Transmission of Leishmaniasis 



The results of these experiments clearly demonstrate that Lu . 

 diabol ica and Lu_. shannoni are both competent for transmission of L 

 mexicana between hamsters by individual bites, six to seven days after 

 the infecting blood meal. The mean intervals between the infecting 

 and transmitting blood meals (5.8 and 6.9 days for Lu. diabol ica and 

 Lu . shannoni , respectively) were considerably longer than the three to 

 five days observed by Ward et _al_ . (1977) for L m. amazonensis in Lu . 

 f laviscutel lata , or the just-under four days reported by Strangways- 

 Dixon and Lainson (1966) for L mexicana in Lu. pessoana (Barretto). 

 The longer time may reflect differences in parasite strain, sand fly 

 species, or holding conditions for infected flies. 



Tables 4-7 and 9, indicate that the second blood meal need not be 

 a large one in order for the host to become infected. This agrees 

 with the report of Strangways-Dixon and Lainson (1962) that in the 



