| dc.description.abstract | Heartwater is a disease of ruminants transmitted by ticks. It is
mainly found in the African continent and the surrounding islands but
lately isolated cases have been reported elsewhere.
The disease occurs in different forms ranging from peracute to
inapparent forms. It is associated with a febrile reaction, acute
gastroenteritis, hydropericardium and nervous symptoms.
Heartwater is a killer disease and thus effective treatment and
control of the disease are of utmost importance. Tetracylines used early
have been found to be effective but for this, accurate diagnosis of the
disease is important. The only definitive way of diagnosing the disease is
at portmortem when the brain smears stained with giemsa reveal the
rickettsial organisms. Lately, researchers have been doing a lot of
serology work on the disease with the aim of coming up with diagnostic
tests in the live animal. Clinical pathology tests can also help as
diagnostic aids of the disease.
This work was designed with this in mind, to observe the
behaviour of particular blood components of sheep infected with
Cowdria ruminantium and to correlate this with the pathogenesis of the
cell fraction associated with the organisms in blood.
Twenty sheep were used in this work. These were adults,
non-pregnant and of Dopper breed (or Dopper cross). They were
housed in the animal compound, Kabete, and fed on hay, bran and
water. The sheep were mainly purchased from the Faculty Farm,
Kabete.
Fifteen sheep were infected while five were used as
controls. Initially, blood was collected from all four sheep:-
EDTA blood for hematology and clotted blood for biochemistry.
This was done for 3 consecutive days before infection to get the
baseline values. After this 3 experimental sheep were infected
with' Cowdria ruminantium intravenously. A blood stabilate
obtained from Veterinary Laboratories, Kabete was used as the
infective agent.
Body temperatures were monitored twice daily and after
the onset of the febrile reaction, blood samples were taken for
hematological and biochemical analysis. Blood samples were
collected daily in the first 3 days and after that every other day
upto death or recovery. In those sheep that died postmoretm was
carried out.
Some more work was done to try and identify the cell
fraction in blood associated with Cowdria ruminatium.
The animals manifested anorexia, depression, increased respiratory
rate, increased pulse rate, harsh lung sounds with moist rales and
muffled heart sounds. Nervous signs observed in some animals
included circling, high stepping gait, chewing movements, ataxia and
incoordination and then lateral recumbency and paddling movements.
All animals which manifested nervous signs died of the disease.
The major findings on postmortem were froth in the trachea,
congested and oedematous lungs, hydropericardium, ascites, hyrdothorax
and congested and oedematous brain.
From the hematology results, sheep infected with Cowdria
ruminantium showed anaemia, leukopenia during incubation period
followed by a leukocytosis after fever onset. There was a neutrophilia,
lymphopaenia and oesinophils disappeared completely from circulation.
Statistical analysis using analysis of variance showed these findings were
statistically significant.
From the clinical biochemistry results there was an increase in
glucose concentration especially terminally which was statistically
significant.
Of the enzymes analysed, lactate dehydrogenase, creatinine
phosphokinase and aspartate aminotransferase showed the most
signifcant change in that their activities increased. Alkaline phosphatase
and alanine aminotransferase did not show significant changes.
Blood urea nitrogen increased significantly after the febrile
reaction.
The study of the cell fraction associated wi th the organism
revealed the neutrophil as the cell most likely to be associated with
Cowdria ruminantium but this is, of course, subject to exhaustive
research work. | en |
