Research Communication — Navorsingsberig
Vermeersiekte caused by Geigeria burkei Harv. subsp. burkei var. hirtella
Merxm. in the Northern Province of South Africa
a
b
c
a,d
d
C J Botha , T A Gous , Mary-Louise Penrith , T W Naudé , Leonie Labuschagne and Elizabeth Retief
ABSTRACT
The 1st field outbreak of vermeersiekte induced by Geigeria burkei Harv. subsp. burkei var.
hirtella Merxm. is reported. It is also the first recorded outbreak of this disease in the arid
sweet bushveld of the Northern Province of South Africa. The toxicosis was experimentally
reproduced in a sheep following daily intraruminal administration of 2.5–5.0 g/kg dried,
milled plant material for 18 consecutive days. Neither the sheep in the field outbreak nor
the ewe in the experiment exhibited any signs of regurgitation of rumen contents (vermeersiekte). All developed only the stiff or paretic/paralytic forms of the disease. Serum activities
of CK and GGT were slightly raised in clinically affected sheep (n = 11) during the field
outbreak, and serum activities of AST, GLDH, GGT, LDH and CK increased in the ewe
dosed with the plant material. Analysis of dried, milled Geigeria plant material confirms that
this species is moderately nutritious.
Key words: Geigeria burkei, paralysis, paresis, sheep, stiffness, vermeersiekte.
Botha C J, Gous T A, Penrith M-L, Naudé T W, Labuschagne L, Retief E Vermeersiekte
caused by Geigeria burkei Harv. subsp. burkei var. hirtella Merxm. in the Northern
Province of South Africa. Journal of the South African Veterinary Association (1997) 68(3):
97–101 (En.). Department of Pharmacology and Toxicology, Faculty of Veterinary Science,
University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa.
INTRODUCTION
Vermeersiekte following ingestion of
different Geigeria species is a major intoxication of small stock in South Africa.
Geigeria ornativa is the most important
cause of vermeersiekte in the dry
Griqualand West area of the Northern
Cape11,15. Vahrmeijer13 reported that during
1929–1930 as many as a million sheep died
in Griqualand West. Kellerman et al.11
calculated the economic impact of plant
poisonings and estimated that in 1996
monetary terms the annual loss due
to vermeersiekte mortalities exceeds
6 million Rand. The economic loss could
be considerably higher, as vermeersiekte
is known to be an erosive disease that
causes various production and reproduc-
a
Department of Pharmacology and Toxicology, Faculty of
Veterinary Science, University of Pretoria, Private Bag
X04, Onderstepoort, 0110 South Africa.
b
Veterinary Laboratory, Private Bag X2408, Louis
Trichardt, 0920 South Africa.
c
Pathology Section, Onderstepoort Veterinary Institute,
Private Bag X05, Onderstepoort, 0110 South Africa.
d
Toxicology Section, Onderstepoort Veterinary Institute,
Private Bag X05, Onderstepoort, 0110 South Africa.
e
National Botanical Institute, Private Bag X101, Pretoria,
0001 South Africa.
Received: April 1997. Accepted: July 1997.
0038-2809 Jl S.Afr.vet.Ass. (1997) 68(3): 97–101
tion losses6. G. aspera is associated with
more localised poisoning on the highveld
of Mpumalanga and the northern Free
State10,11. Under experimental conditions
G. burkei subsp. burkei var. zeyheri induced
vermeersiekte, although there is no
confirmed report of any natural field
outbreak10. V a r i ous α,β-unsaturated-8sesquiterpene lactones have been isolated
from different Geigeria species and are
implicated as the toxic principles2,10,11.
The toxicity of the 3 species mentioned
varies. It has been estimated that G. burkei
subsp. burkei var. zeyheri is 3 times and G.
aspera 10 times more toxic than G. ornativa6,10. Sheep in feeding experiments with
G. ornativa hay ingested the plant for
prolonged periods and clinical signs were
noticed only after 3 weeks6. Clinically, 4
forms of the disease are recognised,
namely regurgitation (‘vomition’), stiffness, bloat and paresis/paralysis10. Regurgitation is not a common finding, and
sheep usually exhibit stiffness, particularly of the hindquarters, in the early
stages of the toxicosis10,15. Macroscopical
lesions are usually absent, but a megaoesophagus may be encountered in some
cases and sheep may die from a foreign
body pneumonia if rumen fluid is aspirated10,11. Van der Lugt and Van Heerden14
reported hypertrophy and vacuolation of
e
myo f ibres of the skeletal system,
diaphragm and oesophagus, as well as
foci of myocardial degeneration and
necrosis.
Vermeerbos (the common name for
plants of the genus Geigeria) is reported to
be moderately nutritious15. Grosskopf6
stated that vermeerbos, in limited quantities, appears to be an excellent feed for
sheep, as it retains its protein concentration during winter, whereas that of
grasses rapidly decreases after the
growing season.
FIELD OUTBREAK
During the end of winter (August 1996)
approximately 50 sheep in a flock of 200
Dorpers on the farm Drielingbosch
(23° 17′ S, 29° 41′ E), near Bandolierkop in
the Soutpansberg district of the Northern
Province, exhibited listlessness, stiffness
in the hindquarters, lameness and lagging
behind the rest of the flock. A decline in
their condition was also noticed by
the farmer and some animals became
paretic/paralytic. Some sheep were
unable to rise and remained in sternal or
lateral recumbency. When sheep were
assisted to stand the limbs trembled and a
staggering gait was observed. Two weeks
before the investigation the farmer instituted supplementary feeding consisting
of a salt and flowers-of-sulphur lick, maize
stover and poultry litter. The farmer
incriminated a small, green, herbaceous
bush as the cause of the paretic condition.
On inspection of the camp and observation of the animals it was noticed that the
sheep eagerly ingested the incriminated
herb (Fig. 1), which was the only greenery
available at the time. The plant was recogn i s ed a s a Geigeria species and was
collected and submitted for identification.
The presence of Helichrysum argyrosphaerum in the camp was also noted. The
farmer reported that the flock was moved
8 months previously to another farm,
Potgietersrand (23° 15′ S, 29° 43′ E), where
the veld was trampled and the grazing
sparse, although abundant green Geigeria
was present. The sheep grazed on this
particular farm for 4 months before being
returned to the present property. Blood
97
Fig. 1: Sheep eagerly ingesting Geigeria burkei Harv. subsp. burkei var. hirtella Merxm. on
a farm in the Northern Province.
Laboratory trial
A 1-year-old Dorper ewe, with a cannula
fitted into the rumen, was housed in a
concrete pen at the Laboratory Animal
Facility of the Toxicology Section at the
Onderstepoort Veterinary Institute
(OVI). She had free access to water and
was fed oats hay and a maize meal-based
pelleted concentrate. During a 2 week
adaptation period and throughout the
experimental period, regular clinical
examinations and ECG recordings
(Ectromed) were performed. Before and
during the trial, blood samples were
collected twice a week from the jugular
vein and submitted for determination of
serum activities of glutamate dehydrogenase (GLDH), AST, GGT, CK and LDH.
Dried, milled plant material collected
from the field outbreak was administered
via the rumen cannula on consecutive
days (n = 18) according to the dosing
regimen presented in Table 1. Dosing
ceased once clinical signs were observed.
The ewe was weighed weekly and the
intraruminal dose adjusted accordingly.
A sample of the dried, milled plant
material was also submitted for feed
analysis.
RESULTS
Plant identification
The incriminated plant was identified as
Geigeria burkei Harv. subsp. burkei var.
hirtella Merxm.7,12 (Fig. 2) by the National
Botanical Institute, Pretoria.
Family
Asteraceae
Common name
Most probably also vermeersiektebossie.
Fig. 2: Geigeria burkei Harv. subsp. burkei var. hirtella Merxm.
samples from 21 sheep, ranging from
severely affected (n = 11) to apparently
healthy animals (n = 10), were collected
from the jugular vein. The blood was
allowed to clot, the serum collected and
submitted for determination of aspartate
transaminase (AST), gamma-glutamyl
transferase (GGT), lactate dehydrogenase
(LDH) and creatine kinase (CK) activities.
These serum enzyme activities were
determined by an automated chemical
analyser (Technicon RA-1000 Analyser,
Technicon Instruments Corporation)
using the manufacturer’s methods and
r e a g e n t s , e x cept LD H, where t he
German-recommended method was
used (Boehringer Mannheim). To rule out
98
carboxylic ionophore antibiotic poisoning, samples of the poultry litter (n = 2)
were also submitted for thin layer chromatography (TLC) and calorimetric
analysis5. A necropsy was performed on a
sheep that was euthanased and samples
of brain, lung, liver, spleen, kidney, heart
and skeletal muscle including oesophagus were preserved in 10 % buffered
formalin and submitted for histopathological examination. The tissues were
routinely processed and stained with
haematoxylin-eosin (HE). A provisional
diagnosis of vermeersiekte was made and
plant material was collected, air-dried,
milled and stored in a cold room (–6 °C)
for dosing trials.
Description7,12
A several-stemmed perennial herb with
a woody rootstock, forming a round bush,
semi-woody, 0.2–0.3 m tall. Stems densely
covered with crinkled, whitish, multicellular hairs, branching in upper part with
more than one branch from the apex of
main stem, brownish. Leaves alternate,
sessile, linear, 20–50 × 0.5–1.5 mm, margin
strongly revolute, densely covered with
glands and white, crinkled multicellular
hairs. Flower heads in axils of branches
with leaves involucrate. Involucre globose
to campanulate, 10–20 × 8–10 mm, 4seriate, outer bracts long, leaf-like, append i c u l a t e , i n n e r b r a c t s b r o w n ish,
acuminate-lanceolate, margin in upper
part ciliate. Receptacle setose. Ray florets
female, 8–10 mm long, yellow, deciduous.
Disc florets 5–6 mm long, bisexual,
0038-2809 Tydskr.S.Afr.vet.Ver. (1997) 68(3): 97–101
brownish yellow. Achenes narrowly turbinate, densely silky-strigose, 1.5 mm
long. Pappus usually of 10 broad scales.
Habitat
Grassland.
Distribution
Pietersburg (2329 CD); Haenertsburg
(2329 DD); Potgietersrus and Percy Fyfe
Nature Reserve (2429 AA); Nelspruit (2530
BD); Barberton (2531 CC) (Fig. 3).
Autopsy findings
The carcass was in good condition and
gross lesions included mild anaemia,
muscle pallor, dull, pale areas in the myocardium, moderate hydropericardium,
brain oedema, enlargement and oedema
of the mesenteric lymph nodes, severe
lung oedema with petechial haemorrhages, multifocal petechiae in the thymus,
congestion of the spleen, kidney and liver
and cholestasis. Microscopical examination of the tissue samples submitted
revealed multifocal hyaline degeneration
and some fragmentation of oesophageal
and skeletal muscle. Myocardial lesions
consisted of multifocal hyaline necrosis
and myofibrolysis with mononuclear cell
infiltration accompanied by mild interstitial fibrosis. Lung tissue was characterised
by severe congestion, oedema and
emphysema, with accumulation of alveolar macrophages.
Serum enzyme activities
The serum enzyme activities of the clinically affected and apparently healthy
sheep selected on the farm where the outbreak occurred are presented in Table 2.
Mean serum activities of CK and GGT
were slightly raised in clinically affected
sheep (n = 11). The clinical chemistry
parameters determined for the sheep in
the experiment are presented graphically
(Fig. 4). Notable increases in AST, GGT,
CK and GLDH activities were detected
from Day (D) 10 and LDH activity raised
conspicuously on D 13.
Analysis of poultry litter
The TLC screen for the presence of carboxylic ionophore antibiotics in the poultry litter detected salinomycin. Following
quantification, using the calorimetric
method, the salinomycin concentrations
in the 2 samples of poultry litter were 19
and 21 ppm, respectively.
Experimental case
The ewe dosed with milled G. burkei
subsp. burkei var. hirtella lagged behind
the other sheep and exhibited stiffness in
the hindquarters and recumbency from
0038-2809 Jl S.Afr.vet.Ass. (1997) 68(3): 97–101
Fig. 3: Distribution of Geigeria burkei Harv. subsp. burkei var. hirtella Merxm. in the
Northern and Mpumalanga Provinces of South Africa. ( = known localities.)
n
Table 1: Dosing regimen and body weight of the ewe during the laboratory trial.
Experimental day
0
7
14
20
27
Body weight
Dosing regimen
(kg)
Dose
g/kg × n
38.0
39.0
39.7
36.9
38.1
2.5 × 7
5×7
5×4
—
—
Total dose per day
(g)
95
195
198.5
—
—
Period dosed
Day
0–6
7–13
14–17a
—
—
a
Dosing discontinued after Day 17.
Table 2: Serum enzyme activities of clinically affected and apparently healthy sheep during
the field outbreak.
Enzyme
Clinically affected sheep
(n = 11)
_
x (SD)
Range
CK (U/l 25 °C)
AST (U/l 25 °C)
LDH (U/l 25 °C)
GGT (U/l 25 °C)
101.0 (34.34)
57.82 (11.05)
474.36 (80.04)
37.09 (6.43)
40–166
41–83
343–654
25–53
Apparently healthy sheep
(n = 10)
_
x (SD)
Range
84.9 (27.3)
55.3 (8.04)
452.6 (32.12)
30.6 (4.32)
49–129
41–69
392–499
23–41
Normal valuea
<21
<60
<530
<32
a
Schmidt M, Forstner D 1986 Laboratory testing in veterinary medicine. Diagnosis and clinical monitoring.
Boehringer Mannheim, Mannheim
D 14 which progressed to a severe stiffness, lameness and paresis on D 17 and
D 18. The dosing was discontinued on
D 18 as the clinical signs observed were
considered to be the stiff and paretic
forms of vermeersiekte. From D 19 locomotion improved. Throughout the
experiment, no significant ECG abnormalities were detected and the habitus of
the animal remained unaffected. During
99
Fig. 4: Clinical chemistry parameters of the ewe dosed with dried, milled plant material.
the adaptation period and the initial 2
weeks of dosing the body weight of the
animal increased. However, during the
last week of dosing a 7 % decrease in body
weight occurred (Table 1). The ewe was
considered fully recovered on D 27 based
on the disappearance of clinical signs, the
return of chemical pathology parameters
to baseline activities and an increase in
body weight.
Analysis of dried Geigeria plant
material
The results of the analysis of the dried,
milled plant material dosed are tabulated
(Table 3). A metabolisable energy value of
8.5 % and a crude protein value of 6.77 %
denote a fairly good nutritional quality.
DISCUSSION
The morphological relationship of G.
burkei Harv. subsp. burkei v a r. hirtella
Merxm. with related species and its
distinguishing characteristics are as
follows7,12: G. burkei subsp. burkei v a r
hirtella is characterised by its narrow,
revolute leaves, densely covered not only
with glands but also with white, multicellular hairs. Geigeria c a n b e d i v i d ed
roughly into 2 main groups on basis of leaf
structure. G. burkei, G. aspera Harv., G. filifolia Mattf., G. ornativa O. Hoffm. and G.
acaulis (Sch.Bip.) Benth. & Hook.f. ex Oliv.
& Hiern, for example, have long, linear,
narrow leaves, while species such as G.
pectidea (DC.) Harv. and G. obtusifolia L.
Bolus have much shorter and broader,
elliptical leaves. G. filifolia and G. acaulis
are rosette plants (stemless), G. ornativa
occurs as rosette plants or as erect,
branched herbs with flower heads close
100
Table 3: Analysis (Weende) of dried, milled Geigeria burkei
Harv. subsp. burkei var. hirtella Merxm.
Macro-constituents
% ‘As is’
Moisture
Dry matter (DM)
Ash
Nitrogen
Crude protein
Crude fibre
Crude fat
Calcium
Phosphorus
Metabolisable energy (ME) (MJ/kg) (Rum.)
Nitrogen free extract (NFE)
Total digestible nutrients (TDN)
together. G. burkei subsp. diffusa (Harv.)
Merxm. and G. aspera var. rivularis (J M
Wood & M S Evans) Merxm. are more or
less prostrate, whereas the other taxa are
erect, usually many-stemmed from the
base, as is G. burkei subsp. burkei var.
hirtella. The latter taxon is distinguished
from G. burkei subsp. burkei var. burkei and
var. elata Merxm. in having the leaves
more densely distributed along the stem
and in the lower stature. G. burkei subsp.
fruticulosa Merxm. and G. burkei subsp.
burkei var. zeyheri (Harv.) Merxm. are more
diffusely branched and the flower heads
are smaller than those of G. burkei subsp.
burkei var. hirtella. G. burkei subsp. valida
Merxm. and G. burkei subsp. burkei var
intermedia (S Moore) Merxm. have the
leaves much more densely crowded along
the stem and the flower heads are usually
much larger than those of G. burkei subsp.
burkei var. hirtella. G. burkei subsp. burkei
var. hirtella can be distinguished from
10.60
89.40
10.84
1.08
6.77
29.83
1.01
1.04
0.12
8.50
40.95
56.85
G. aspera by its involucre, which is globose
or campanulate and not narrowly
obovoid; its stems are usually simple
below and branched above, not tending
to branch from ground level.
Although there is experimental evidence for the toxicity of G. burkei subsp.
burkei var. zeyheri10 this is the first confirmed field outbreak of G. burkei subsp.
burkei var. hirtella poisoning in southern
Africa. The prevailing poor grazing conditions at the end of winter and the availability of lush, green Geigeria might
explain why the plant was so eagerly
consumed by the sheep (Fig. 1). This
is also the first recorded outbreak of
vermeersiekte in the arid sweet bushveld
of southern Africa1 and emphasises that
wherever this genus is grazed it should be
regarded as potentially toxic.
Neither the sheep in the field outbreak
nor the ewe in the experiment exhibited
signs of regurgitation of rumen contents,
0038-2809 Tydskr.S.Afr.vet.Ver. (1997) 68(3): 97–101
but developed the characteristic stiff and
paretic/paralytic forms of the disease. It is
generally accepted that not all clinically
affected sheep will develop typical
‘vermeersiekte’ (regurgitation)10,15, a nd
Dorpers are considered to be less
susceptible when compared to breeds
such as Merino and Karakul10.
The sharp rise in serum AST, GLDH,
GGT and LDH activities of the sheep in
the experiment indicate hepatocyte and
biliary damage. Increased AST and GGT
activities have also been observed in
sheep dosed with G. aspera (N Fourie,
Biocon Research Laboratories, pers.
comm., 1997). Van Heerden et al.15 were of
the opinion that GGT and AST may be of
diagnostic value in G. ornativa poisoning.
The Dorper ewe dosed with the plant
material exhibited severe stiffness on
Days 17–18, and the increased AST and
LDH activities observed could reflect
muscle damage, which was confirmed by
the rise in CK activity (Fig. 4). In the field
outbreak, mean CK activity was slightly
higher in the clinically affected group (n =
11) compared to the apparently healthy
sheep (n = 10). A more substantial elevation in CK activity was anticipated, as the
sesquiterpene lactones are primarily myotoxins. However, Joubert9 reported that
serum activities of CK, glutamic oxaloacetate transaminase (GOT = AST) and
GGT did not increase in correlation with
the symptomatology during experimental G. filifolia poisoning in sheep, and Van
Heerden et al.15 reported no increase in
serum CK activity despite the presence of
muscle pathology in sheep with vermeersiekte induced by G. ornativa.
Helichrysum argyrosphaerum (wild everlasting) also occurred on the farm and can
induce paresis/paralysis and amaurosis in
sheep3,10. Since this plant was not eaten
and none of the sheep were blind,
Helichrysum poisoning was ruled out. The
sheep also received a supplementary
ration that included poultry litter. The
carboxylic ionophore antibiotics are often
present in poultry litter and may result in
ionophore poisoning in ruminants,
especially maduramicin4. In sheep,
ionophore poisoning causes skeletal and
cardiac muscle damage with locomotory
0038-2809 Jl S.Afr.vet.Ass. (1997) 68(3): 97–101
disturbances, weakness and recumbency4. However, the poultry litter
contained only an average of 20 ppm
salinomycin, which is within the range of
15–20 ppm recommended for use as a
growth promotant in ruminants8.
Results of the analysis of dried, milled
plant material indicated that the nutritional quality of this particular Geigeria
species is fairly good. This might explain
why the plant was so eagerly consumed
by the sheep (Fig. 1). A crude protein
value of 6.77 %, crude fibre value of
29.93 % and metabolisable energy value
of 8.5 % was determined. Van Heerden et
al.15 reported an average crude protein
value of 11.25 % and crude fibre value of
23.05 % for dried, milled G. ornativa (n =
2). Myburg and co-workers, cited by
Grosskopf6, analysed 84 samples of
G. africana (= G. ornativa) obtained from
Griqualand West and determined a mean
protein percentage of 7.08 % (±1.2) and
mean fibre percentage of 28.82 % (±4.7).
They also analysed 2 specimens of G.
aspera and determined an average protein
percentage of 6.51 % and crude fibre of
27.5 %. Geigeria spp. are therefore nutritious in small quantities10, but become
dangerous when they constitute a major
element in the pasture.
ACKNOWLEDGEMENTS
We thank Prof. T S Kellerman (Toxicology Section, OVI) for valuable advice and
permission to use their facilities, Mrs A R
Schultz (Toxicology Section, OVI) for
performing the ECG recordings, Prof. F
Reyers and staff from the Clinical Pathology Section, Faculty of Veterinary Science,
Onderstepoort, for the determination of
enzyme activities, Dr D B R Wandrag
(Department of Ethology, Faculty of
Veterinary Science, Onderstepoort) for
the feed analysis and Mr D Visser (Veterinary Laboratory, Louis Trichardt) for
technical assistance.
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