The relationship between the feeding of Amblyomma variegatum ticks and the skin disease dermatophilosis
dc.contributor.author
Lloyd, Carolyn Marie
en
dc.date.accessioned
2018-05-22T12:44:01Z
dc.date.available
2018-05-22T12:44:01Z
dc.date.issued
1993
dc.description.abstract
en
dc.description.abstract
The relationship between the feeding of Amblyomma variegatum ticks and
Dermatophilus congolensis infections has been studied under laboratory conditions.
en
dc.description.abstract
The local effects of hypersensitive or inflammatory reactions to larval and
nymphal A.variegatum on subsequent D.congolensis infections were investigated
using rabbits and sheep respectively. Multiple or single infestations of ticks were used
to produce hypersensitivity or inflammatory reactions respectively. These reactions
were confirmed by histological assessment of the tick attachment sites. Identical
titrated doses of D. congolensis were applied to the tick attachment sites after the
ticks had detached, a control titration was set up on skin with no previous exposure to
ticks. The progression of the resulting lesions was assessed using a non-parametric
ranking system. There was no significant difference (P > 0.05) between the severity or
duration of the three groups of dermatophilosis lesions, either on the sheep or the
rabbits. Therefore it was concluded that the local effects of the feeding of immature
instars of this tick do not affect the pathogenesis of subsequent D.congolensis
infections.
en
dc.description.abstract
The local effect of hypersensitive or inflammatory reactions to
A.variegatum nymphs on simultaneous D.congolensis infections on rabbits was also
studied. There was an increase in the initial severity of the dermatophilosis lesions and
a positive correlation between inflammatory tick attachment sites and dermatophilosis
foci. However, the local effects of the feeding of nymphal A.variegatum did not result
in the development of chronic dermatophilosis lesions.
en
dc.description.abstract
The systemic effect of adult and nymphal A.variegatum on simultaneous
dermatophilosis lesions was compared, using sheep as the experimental hosts.
Dermatophilus congolensis infections on sheep infested with adult A.variegatum
developed into chronic lesions which persisted for several months. Serological and
skin tests revealed significantly (P < 0.01) reduced humoral and cellular immune
responses in sheep infested with adult A.variegatum compared with sheep infested
with nymphs or control sheep not exposed to ticks.
en
dc.description.abstract
Comparative studies of whole salivary glands from all three instars of
A.variegatum revealed significantly greater (P < 0.01) proportions of type-2 acini
filled with cl secretory granules in the salivary glands from the adult ticks compared
with the salivary glands from the immature ticks. There were also significantly (P <
0.05) greater proportions of individual type-3 acini filled with e secretory granules in
the salivary glands from the adult ticks compared with the salivary glands from the
larval ticks. Gel electrophoresis revealed an 11% dissimilarity between salivary glands
from adult A.variegatum compared with both of the immature instars. Similar analysis
of artificially induced saliva revealed a 48% dissimilarity between the adult and
immature ticks.
en
dc.identifier.uri
http://hdl.handle.net/1842/30394
dc.publisher
The University of Edinburgh
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dc.relation.ispartof
Annexe Thesis Digitisation Project 2018 Block 19
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dc.relation.isreferencedby
Already catalogued
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dc.title
The relationship between the feeding of Amblyomma variegatum ticks and the skin disease dermatophilosis
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dc.type
Thesis or Dissertation
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dc.type.qualificationlevel
Doctoral
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dc.type.qualificationname
PhD Doctor of Philosophy
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