Evaluation of the optimal inoculation of leishmania major culture-derived stationary phase promastigotes required to assess protective immune status in the vervet monkey model

"Vervet monkeys have been shown to be resistant to a homologous challenge of Leishmania major after an active infection followed by self cure responses. Confirmation of the protective immune status of such animals was demonstrated by exposing a group of 4 monkeys to multiple infected sandfly challenge. Two animals revealed small transient nodule formation while in the remaining two; no signs or symptoms were obvserved. In order to ascertain the level of promastigote challenge which was equivalent to such a ""natural"" fly challenge; 3 additional groups of immune vervet monkeys were challenged with 1x103; 1x104 and 105 stationary phase culture promastigotes in the presence of salivary gl and lysates. In all groups; there was no lesion development whatsoever. A second challenge of 1x106; 1x107 and 4x107 in these same animal groups; revealed self healing nodules in the group inoculated with 1x106 promastigotes whilst in the remaining 2 groups challeged at the higher levels; there was nodule formation which progressed to ulceration. A challenge dose of 1x105 culture promastigotes was thus considered to be optimal since this level of challenge in naive animals was demonstrated to result in ulcer formation when inoculated with salivary gland lysates."

Identification of Phlebotomine Sandfly Bloodmeals from Baringo District; Kenya; by Direct Enzyme-Linked Immunosorbent Assay (ELISA)

Direct enzyme-linked immunosorbent assay (ELISA) was used to identify the sources of 356 phlebotomine sandfly bloodmeals from Baringo District; Rift Valley Province; Kenya. Some bloodmeals had been stored for over 4 years before being analysed. Of the 356 sandflies; 62.9 were phlebotomus martini; 14.8 Sergentomyia antennatus; 10.0 S. schwetzi; 6.0 S. clydei; 1.9 S. adleri; 1.6 P. duboscqi; 1.4 S. africanus; and 0.8 S. bedfordi. Out of 224 P. martini bloodmeals; host source was identified for 69. The order of host prefernce for P. martini was: goat 28.5; rabbit 22.7 human 8.9 and other 8.9. Evidence of mixed feeding was shown by 16 sandflies comprising 4 species; 12 of these were P. martini. The most effective methods for trapping bloodfed P. martini; were sticky paper traps in termite hills; followed by light-traps. Of the 224 P. martini trapped; 58.9 were collected with paper traps in termite hills; and 22.7 with light traps. The role played by the 3 most popular hosts for P. martini should be investigated to ascertain whether they act as reservoirs in the transmission of visceral leishmaniasis in Kenya