COMPARATIVE STUDY OF TRYPANOSOMOSIS EXPERIMENTALLY INDUCED IN SAVANNAH BROWN GOATS USING Trypanosoma brucei, Trypanosoma congolense AND Trypanosoma vivax.
COMPARATIVE STUDY OF TRYPANOSOMOSIS EXPERIMENTALLY INDUCED IN SAVANNAH BROWN GOATS USING Trypanosoma brucei, Trypanosoma congolense AND Trypanosoma vivax.
No Thumbnail Available
Date
1986
Authors
ANTHONY, KOJO BEDU SACKEY
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Trypanosomosis in the Savannah Brown (SB) breed of goat was evaluated in a two phase
investigation. The first phase involved the study oi the prevalence of natural trypanosomosis in
the SB goat in its natural habitat of the Guinea and Sudan Savannah zones of Northern Nigeria.
The study which spanned 28 months involved the random examination of 717 goats of all sexes
and aged between 3 months and 5 years and from a total of 42 flocks through physical and
haematological evaluations. These goats were kept by nomadic Fulani cattle herdsmen;
established private livestock farms; Institutional Livestock farms and household flocks, which were
receiving Veterinary Health Services regularly or on request. Twenty of the goats were positive for
trypanosome parasites, giving an infection rate of 2.79%. Out of 20 goats sampled in the Southern
Guinea Savannah 2 (infection rate of 10.00%) were positive, 11 out of 522 goats (2.1096) in the
Northern Guinea Savannah and 7 out of 175 goats (4.00%) in the Sudan Savannah were also
positive. Major clinical signs observed included orchitis, pyrexia of up to 41.0°C, abortion,
emaciation in those positive for trypanosome parasites and weak kids born to infected does. T.
vivax was the only trypanosome species isolated. The only potential trypanosome vectors identified
were biting flies namely Stomaxys calcitrans, Tabanus sp., Hipobosca sp. and Musca spp. The
study revealed the occurrence of natural trypanosomosis in the Savannah Brown goat in its
presumed tsetse-fly free Savannah zone where this breeed of goat is predominantly found: T.
vivax was the only trypanosome from this zone, a finding which confirm the observation of earlier
workers that T. vivax is easily transmitted by biting flies. The result goes forth to show the need
for vigorous control measures against trypanosomosis in the small ruminants represented by this
breed of goat in an effort to enhance the regular supply of animal protein to the teeming
population as this breed of goat is a major source of meat in Nigeria.
A comparative study of trypanosomosis experimentally induced in the Savannah Brown breed
of goats by using T. brucei, T. congolense and T. vivax was carried out, using four groups of 8
Savannah Brown bucks each, aged between 6-12 months.
An aspect of it involved observing clinical and haematologicai manifestations of
trypanosomosis due to these three pathogenic African animal irypanosomes. One group was
inoculated via the jugular route with T. vivax (stabilate 146), another with T. cungoleme (stabilate
136), the third group with T. brucei (stabilate 135) and the fourth group used as uninfected
control. The goats were later bled at regular intervals and level of parasitaemia, rbc and pcv levels,
total wbc levels, total protein and body- weights evaluated using approved standard procedures at
regular intervals. Prcpatcnt periods observed were 2.3, 4.3 and 4.4 days for the T. vivax, T. brucei
and T. congoleme infected groups respectively. Observed clinical signs included fluctuating
pyrexia which in most cases coincided with parasitaemia. Parasitaemic peaks were pronounced in
the T. brucei group, an indication that this trypanosome species is pathogenic to goats contrary to
previous reports. The lowest mean pcv level of 8.0% occured in the T. congolcnsc group. The
greatest fall in mean rbc level was in the T. vivax group whilst the least fall was in the T. brucei
group. The disease produced three distinct phases namely the acute ( 0 - 1 5 days post infection),
subacute (16 - 33 days) and chronic (34 - 74 days). Anaemia was of the normocytic
normochromic form in the early stages of the disease but became microcytic normochromic at the
latter stage in all the infected groups. The primary leucocyte response in all the infected groups was
lymphocytosis and later neutrophilia in the T. vivax group, concurrent lymphocytosis and
neutrophilia in the T. congolense and T. brucei groups, though there occurred neutropenia in the T.
hrucei group in the chronic phase. Bilateral epiphora was very severe in the T. vivax and T.
congolense infected goats. The occular discharges of some of the infected goats were found to he
positive for trypanosome parasites especially during period of peak parasitaemia. How the parasite
got in to the occular discharges cannot be explained from our study. Central nervous system
complications like trembling, paddling movements, limb paralysis, staggering were observed most
particularly in the T. brucei-infected goats. All the infected groups had progressive fall in mean
body weights especially in the chronic phase of the infection. Most of the observations here agree
with findings reported for trypanosome infected cattle, thus further indicating that the Savannah
Brown goal is highly susceptible to Uypanosomosis in the same vein as it s cattle counterpart. Also
that this breed of goat is highly susceptible to all the three species of trypanosomes contrary to
earlier reports that T. brucei was as pathogenic to small ruminants as T. vivax and T. congolense
arc.
The pathological changes due to experimentally induced trypanomosis due T. brucei, T.
congolense and T. vivax were also investigated. Carcasses of all infected goats were anaemic
especially in the subacute and chronic cases. Lymphoid organs (lymph nodes and spleen) were
enlarged and hyperplastic, livers of infected goats were enlargement with areas of necrosis as well
as fibrous connective tissue proliferation especially in the T. brucei and T. congolense infected
goats. In the T brucei and T. congolense infected goats, kidney lesions included areas of petechial
and echymotic haemorrhages in the cortex and medulla regions as well as areas of focal and
diffuse necrosis in the proximal and distal convoluted tubules. Haemorrhages of tracheal and
bronchial mucosal surfaces as well as mononuclear cellular infilteration of the alveoli were evident
in the T. brucei and T. congolense infected goats. All except one of the goats that developed
cough were negative for bacterial isolates. Testicles were atrophied; they had also undergone
degeneration as shown by the distortated basal layers. Also seminiferous tubules necrosis, fibrous
tissue proliferative and aspermia in the chronic stages in all the infected goats. Pericardial space
fluid ranged from 20 - 45 mis compared to 5 - 10 mis in the control group. The T. brucei and T.
congolense-infected goats manifested areas of necrosis as well as infilteration of mononuclear
cells in the myocardia. Although brain and pituitary gland capillaries were highly congested but
had no significant microscopic lesions were observed in all the infected goats.
Impression smears taken at post mortem from jugular and aortic blood vessels were
positive for trypanosomes though at very low parasitaemia. However smears from organs at post
mortem were negative for trypanosome in all the infected goats. The three trypanosome species
produced severe lesions which were closely related. These lesions so produced could adversely
affect the performance of the goats affected goats.
The effect of trypanosomosis on the serum biochemical components was studied during this
second phase. The experimental goats were bled at specific intervals in the course of the study and
serum samples prepared and assayed using the appropriate methods, for chlorine (C1-) sodium
(Na+), pottasium (K+), bicarbonate (HC03-), glucose, bilirubin, albumin, serum glutamic oxaloacetic
transminase (SGOT) and Total protein (TP) levels. Differences between the control and the
x
infected groups were significant (p<0.05). The mean albumin levels in the T. vwax group was
significantly lower (p<0.05) than those of T. brucei and T. congolense groups. Whilst the mean
glucose level in the T. congolense group was also significantly lower (p<0.05) compared to the
other infected groups. A significant drop in the values of Na+> CI- and HCG3- levels occured in
the T. vivax infected goats. Similarly T. brucei infected group produced drop in the level of
albumin, total protein as well as the greatest rise in K+ and SGOT levels. On the other hand, the
lowest mean glucose level and highest bilirubin and blood urea Nitrogen levels were observed in
the T. congolense group. The study revealed the serious effect of trypanosomosis on the serum
biochemical components and therefore an idea of the consequences of the disease on the metabolic
activities of affected goats.
The role of trypanosome sialidase enzymes in the pathogenesis of anaemia in animal
trypanosomosis using the goal as an animal model was evaluated. Significant differences
(p<0.001) existed between the mean rbc sialic-acid concentration of the control and infected
groups. The greatest fall in rbc sialic-acid concentration or the highest sialidase enzyme cleavage
activity occured in the T. vivax group (5.82 ± 0.19 -1.88 ± 0.28 mg/dl or 67.7% reduction)
followed by T, brucei (5.85 ± 0.43 to 2.28 ± 0.36 mg/dl or 61.33% reduction) and T. congolense
(5.09 ± 0.11 to 3.94 ±0.18 mg'dl or 33.22% reduction). That of the control group was 1.04%
reduction (5.78 ± 0.32 to 5.72 ± 0.25 mg/dl). The study further reinforced the reported findings of
earlier workers that there is a mammalian blood stream form of sialidase enzyme in T. vivax. It also
added weight to the suspicion that though mammalian form of sialidases have not been confirmed
in T. brucei and T. congolense, the rbc sialic-acid cleavage activities of these two trypanosome
xi
species suggest the presence of some forms of sialidase, possibly trans-sialidase which undertake
the cleavaging. The study also revealed that sialidase enzyme plays a major role in the pathogenesis
of trypanosomosis induced anaemia because of the relationship between fall in rbc sialic acids and
consequent tall in rbc and pcv levels in all the infected goats. The results obtained also gave a
favourable disposition to the future use of small ruminants in further investigations into the
relationship between sialidase enzyme and anaemia of animal trypanosomosis
Description
ANTHONY KOJO BEDU SACKEY
B.Sc. HONS - AGRICULTURE, UNIVERSITY OF SCIENCE AND
TECHNOLOGY, KUMASI-GHANA, JUNE, 1974
D.V.M., AHMADU BELLO UNIVERSITY, ZARIA NIGERIA, JUNE, 1980
CERTIFICATE IN VETERINARY ECONOMICS AND EPIDEMIOLOGY
ABU ZARIA, NIGERIA/UNIVERSITY OF READING, GREAT BRITAIN,
1983
M.Sc. VETERINARY MEDICINE, AHMADU BELLO UNIVERSITY,
ZARIA NIGERIA, 1986
A DISSERTATION SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU
BELLO UNIVERSITY, ZARIA, NIGERIA IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF
PHILOSOPHY, DEPARTMENT OF VETERINARY SURGERY AND
MEDICINE
Keywords
COMPARATIVE,, TRYPANOSOMOSIS,, EXPERIMENTALLY,, INDUCED,, SAVANNAH,, GOATS, Trypanosoma,, Trypanosoma,, brucei,,, congolense,, Trypanosoma,, vivax.