Studies on protozoan parasites of small mammals

Mohamed, HA

Abstract

Studies on several different protozoan parasites of small mammals,
moles (Talpa europaea), bank voles (Clethrionomys glareolus), field
voles (Microtus agrestis), field mice (Apodemus sylvaticus), mice,
rats and rabbits are described in this study.
In the mole (Talpa europaea) three parasites were studied:
Elleipsisoma thornsoni, Cyclospora talpae and Trypanosoma talpae.
Elleipsisoma thornsoni was described as a parasite in the red blood
cells of the mole earlier this century and its identity and parasitic
nature was in doubt* Electron microscopic studies conclusively showed
that the parasite was an Apicomplexan and was different from other
blood parasites of haemosporidians and piroplasms by the presence of a
conoid.
Cyclospora talpae, a coccidian in the liver of the mole, was
studied by both the light and electron microscope. In histological
sections, the localisation of macro- and microgametocytes in the
epithelial cells of the bile ducts was investigated. The
ultrastructure of the sexual and asexual stages were studied.
In Trypanosoma (Megatrypanum) talpae, some preliminary aspects of
its reproduction in the mammalian host and the development in
haemogamasid mites was studied. This is the first recorded observation
of the development of mammalian trypanosomes in mites. In these mites
an isosporan-type coccidian (with developmental stages of sporogony
and gametogony) was also found and described. The sporulation of
oocysts was completed inside the mite's body and was typically
isosporan with 2 sporocysts, each with 4 sporozoites.
The second part of this study was concerned with the biology of
the trypansomes of the subgenus Herpetosoma: T. microti. T. evotomys
T. grosi, T. lewisi w/2, T. musculi P/2 and T. nabiasi. Cultivation of
T. microti, T. evotomys and T. grosi in insect tissue culture media
and their ultrastructure is reported and compared with T. lewisi and
T. musculi. T. nabiasi was grown in blood agar medium.
T. microti and T. musculi were grown in Microtus agrestis embryo
fibroblasts to study development in vitro at 37°C of the bloodstream
and reproductive forms. T. microti, T. musculi P/2 and T. lewisi w/2
were also grown for the first time in a new semi-defined, cell-free
medium to study development of the mammalian forms at 37°C.
The successful cultivation of Herpetosoma trypanosomes made it
possible to conduct the biochemical studies, on thin-layer starch-gel
electrophoresis, of six trypanosome species (T. microti, T. evotomys,
T. grosi, T. lewisiw/2, T. musculi P/2 and T. nabiasi) using
13 isoenzymes. Results from 10 isoenzymes of these trypanosomes,
except T. nabiasi which was available only as a weak lysate, were
analysed by two computer programmes which constructed both a
similarity index and a cladistic relationship. The results were in
accord with the previous groupings of these trypanosomes based on
observations of methods of reproduction in mammals and development in
vectors.

Citation

Mohamed, H. Studies on protozoan parasites of small mammals. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Jun 30, 2021
• Additional Information: Funders : European Development Fund (EDF);British Council
• Award Date: Jan 1, 1986