| dc.description.abstract | Trypanosoma evansi ,Steele 1885 infection in northern Kenya
camels was diagnosed by an enzyme-linked immunosorbent assay
(ELISA), mouse inoculations. and blood smears. The ELISA results
indicated a current or past trypanosome prevalence rate that ranged
from 73% to 95% in the sampled camel herds. The blood smear test
revealed a maximum of 11.5% and a mean of 3.9% infection rates while
the mouse inoculations revealed a maximim of 19.2% and a mean of
- 11.3% infection rate in the sampled herds. The mouse inoculation test
(MIT) was found to be the most sensitive and suitable means of diagnosis
of camel trypanosomiasis in northern Kenyan camels. Trypanosome
infection rates were elevated during the wet season months as diagnosed
by MIT. The mean trypanosome infection rate was 13.7 + /-5% for the wet
season and 4.55+ I =2% for the dry season.
Absence of Glossina spp. in northen Kenya suggests mechanical
transmission of trypanosomiasis in this region. Mechanical transmission
is the mode of transmission whereby a parasite is transferred from one
host to another without undergoing development within a vector.
Mechanical transmission of camel trypanosomiasis within northern Kenya
was ascertained by regular monitoring of 10 sentinel camels. Three of
these animals became infected 7-9 months after introduction, in the
absence of Glossina spp. Glossina spp. were not identified in the study
area following monitoring by biconical traps.
Biting flies identified in the study area using sweep-nets and
biconcal traps comprised of six tabanids, two hippoboscids and two
muscids. Results of this study showed a seasonal abundance of these
flies during and after the rains, which coincided with outbreaks of camel
trypanosomiasis. This coupled with the fact that the major camel
trypanosome T.evansi , is transmitted only mechanically, and infection of
sentinel camels in the absence of Glossina spp., suppport and confirm
the occurrence of mechanical transmission in nature.
Laboratory experiments showed that a tabanid (Haematopota
brunnescus, Ricardo), Stomoxys calcitrans Linnaeus, and Glossina
morsitans morsitans Westwood, could mechanially transmit T. evansi
from infected to non-infected mice . Dissection and inoculation of fly
mouthparts into mice revealed that these fly mouthparts could contain
viable trypanosomes for several minutes after infective blood meals.
Dissection of mouthparts of field collected H.camelina, H.minuta. and,
T taeniola after infective blood meals on camels revealed mean
trypanosome infection rates of 14.5%, 23.3% and 27.4% respectively.
Inoculation of triturated mouthparts of H.camelina, H.minuta and
Ttaeniola (following blood meals on infected camels) infected 6%, 12%
and 53.3% of mice inoculated respecively. These dissection and
inoculation experiments further support the concept of mechanical
transmission of trypanosomes by haematophagous insects. | en |
