Presence of Trypanosoma lewisi in Rattus norvegicus in Sri Lanka

Abstract

Natural infection of the haemoflagellate, Trypanosoma lewisi, in a laboratory colony of mixed bred rats, Rattus norvegicus, is reported for the first time in Sri Lanka. Some aspects of parasitology and immunology on this host-parasite association were studied. The length rneasurements of the parasite, tlre cyclic development of T. lewisi in R. norvegicus and, in the rat flea, Xenopsylla cheopi,s, confirmed the identification of this haemoflagellate. Fluctuations of parasitaemia of T'. lewisi in these infections ranged between 0 065% - 12,4%. Nine and eight parasite proteins rvere detected bv SDS-PAGE analysis of high and 1ow parasitaemic infections, respectivell,. Sir of these proteins (60, 63,72,75,7g and 79 kD) were shared while three (12.46 and 106 kD) and trvo (56 and 112 kD) proteins were specific t9 n1e! and low parasitaernic infections, respecti.u.elv. Of these specific proteins, the 42 and the 56 kD antigens were detected on immunobiots indicating the iecognition of these proteins b1'spccific host antibodies. This mal'indicate that antibodies againsithe 42 kD protein ma1, be responsible fbr the decline of the high parasitaemic status of f- lewisi infeition in rats while anti- 56 kD antibodies may lsn6 to the complete elimination of T'. lewisi infection in rats. A significant increase in neutrophils and monoc\1es in high parasitaemic rats may indicate a possible role of cellular response.