Abstract:
The efficacy of Triladyl®, a commercial cryomedium for bull semen, in the cryopreservation of both human
and animal infective trypanosomes as compared to EDTA Saline Glucose (ESG) 10% glycerol was evaluated
in the current study. Cryopreserved Trypanosoma brucei rhodesiense, T. evansi, T. b. brucei and T.
congolense were first propagated in irradiated mice. At the peak of parasitemia, parasites were harvested by
cardiac puncture and 106,105,104103,102 and 10 dilutions made using whole blood bled from clean mice.
These dilutions were divided into two equal portions of 0.5 ml each and cryopreserved in both ESG 10%
glycerol and neat Triladly®. The procedure was also repeated with T. congolense and T. vivax species of
trypanosomes directly isolated from naturally infected cattle. After 1 month of cryopreservation, 0.4 ml each
portion of this dilution was injected intraperitonially into irradiated Swiss white mice. Results on pre-patent
period (ppp) and progression of parasitemia showed no difference in the recovery of samples cryopreserved
using the 2 media. However, mice injected with T. b. brucei cryopreserved in the 2 media showed highly
significantly (p < 0.01 by t-test) lower ppp when compared to the other species of trypanosomes which had
no significant difference. However, the ppp in mice injected with trypanosomes cryopreserved in ESG 10%
glycerol was significantly lower (p < 0.05 by t-test) when compared to those cryopreserved in Triladyl®.
The interaction between media and species was highly significant indicating therefore that the difference in
cryopreservation between the two media varies from one species of trypanosome to the other. The
interaction between dose and species was also highly significant (p < 0.01 by t-test) implying therefore that
the effect of the inoculum dose varied from one species to the other leading to the conclusion therefore that
although Triladyl® appears as good a cryopreservative medium as ESG 10% glycerol, the choice will be
determined by the species of trypanosome.
