Tropical theileriosis, a tick-borne hemoprotozoan disease
caused by Theileria annulataand transmitted by Hyalommaspp.,
is one of the most devastating blood parasites affecting cattle,
buffalo, and sheep. The prevalence, morbidity, and mortality
of tropical theileriosis are considerably high [1,2]. It is estimat-
ed that 250 million cattle in many countries including Iran,
Turkey, India, and China are at a risk of the disease, which causes
serious economic loss through bovine mortality and loses pro-
ductivity [3,4]. In their mammalian hosts, the parasites have a
complex life cycle. Infection is initiated by the transformation
of macroschizont-infected cells in the lymph nodes draining
the site of inoculation of sporozoites by ticks. The cattle infec-
tive form of the parasite is the sporozoite transforming into sch-
izonts in WBC of the mononuclear lineage. The schizont under-
goes further differentiation to merozoites, which are released
upon lysis of the infected cells. Once released from host cells,
the merozoites enter erythrocytes. This is followed by the devel-
opment of piroplasms in erythrocytes and the parasite becomes
infective for the vector [5,6].
Weakness, weight loss, anorexia, high body temperature,
petechia on the conjunctival mucosa, swollen lymph nodes,
anemia, and cough are the most common clinical symptoms
in theileriosis. On later stages of theileriosis, infected animals
cannot stand up, their body temperatures are under normal
values (< 38.5℃), and ichterus, dehydration, and blood in feces
are occasional clinical symptoms [7,8]. Biochemical and hema-
tological parameters and ECG may be changed in this disease
[4,8]. The present study was conducted on 20 affected buffaloes
for the determination of these changes.
MATERIALS AND METHODS
Animals and samples for clinical investigations
This research was carried out during the disease season from
June to October 2007 in Tabriz, Iran. Twenty adults (13 females
and 7 males) of water buffaloes with severe theileriosis and 20
healthy buffaloes were selected. The age of all animals used in
this study ranged 1.5-5 yr. Infected buffaloes were diagnosed
by clinical signs and observation of parasites in the blood (which
Biochemical, Hematological, and Electrocardiographic
Changes in Buffaloes Naturally Infected with
Korean J Parasitol. Vol. 46, No. 4: 223-227, December 2008 DOI: 10.3347/kjp.2008.46.4.223
A. Hasanpour1, G. A. Moghaddam2and Ahmad Nematollahi3,�
1Department of Clinical Science, Faculty of Veterinary Medicine, Islamic Azad University Tabriz Branch, Tabriz, Iran; 2Department of Clinical Science,
Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran; 3Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz,
Abstract: Changes in selected blood and serum components and electrocardiography (ECG) were investigated in 20
adults (13 females and 7 males) of water buffaloes suffering from severe theileriosis. The age of all animals used in this
study ranged 1.5-5 yr. Theileriosis was diagnosed by observation of parasites in the peripheral blood and the presence of
schizonts in lymphocytes that were provided from swollen lymph nodes. Statistically significant decreases were observed
in the means of RBC, WBC, and packed cell volume (PCV) in blood of infected animals. The means levels of sodium, cal-
cium, phosphorus, and potassium of infected animals were lower than healthy animals, but only the decrease of potassi-
um was significant. The mean serum activities of aspartate transferase and alanine aminotransfrase were significantly
higher than in uninfected animals. Three cases had atrial premature beat, 2 cases had sinus tachycardia, 2 had sinus
arrhythmia, and 1 had first degree of atrioventricular block in ECG. The present study showed that T. annulata infection in
cattle is associated with hematological and biochemical, and ECG changes.
Key words: Theileria annulata, biochemical parameter, hematological parameter, buffalo, theileriosis
●Received 8 April 2008, accepted after revision 5 November 2008.
* Corresponding author (email@example.com)
Korean J Parasitol. Vol. 46, No. 4: 223-227, December 2008
are prepared from the auricular vein) and lymph node samples.
The animals showed a high percentage of parasitemia. The par-
asites were evident as schizonts, sometimes in circulating lym-
phocytes, but mainly in biopsy smears of enlarged lymph nodes
stained with Giemsa. Piroplasms were also easily visible in ery-
throcytes. Over 20-30% of RBC are infected. Blood-sucking
ticks were found on many parts of the buffaloes and were iden-
tified as Hyalommaspp. The clinical manifestations were enlarge-
ment of the prescapular lymph nodes, pyrexia, inappetence,
cachexia, mucous membrane discharge, hemorrhages, dyspnea,
cessation of rumination, protrusion of the eyeball, lacrimation,
The smears were air-dried, fixed with methanol, stained with
Giemsa, and carefully examined under the oil immersion objec-
tive of a microscope to estimate the degree of infection. For esti-
mating parasitemia, the percentage of piroplasm-infected ery-
throcytes was calculated among 100 cells. Similarly, smears of
lymph node biopsies were stained with Giemsa and examined
for schizonts. Clinical and parasitological observations were
recorded for all the animals showing the clinical signs of T. annu-
lata infection. Two samples of blood were obtained from the
jugular vein of buffaloes. The sample with anticoagulant was
used to do hematological tests and to measure PCV, RBC, WBC,
and differential count of WBC. The RBC and WBC counts were
determined by a hemocytometer. The other sample was cen-
trifuged to take the sera, and the biochemical parameters such
as total protein, calcium, phosphorus, alanine aminotransferase
(ALT), aspartate aminotransferase (ALT), sodium and potassi-
um levels of sera were measured. The PCV % was measured by
microcentrifuge. The levels of total protein, calcium, phospho-
rus, alkaline phosphatase, and aspartate aminotransferase were
measured with biochemical methods, and those of sodium and
potassium with a flame photometer [9-11].
After 30 min rest, ECG using 3 channel ECG system and base
apex lead was obtained in about 30 sec. The positive electrode
of lead I was attached to the skin of the left thorax at the 5th
intercostal space immediately caudal to the olecranon, and the
negative electrode placed on the jugular furrow in the caudal
third of the right neck. The ground electrode was placed remote
from the heart. The electrodes were placed using alligator clips
and gel. In order to ensure good adherence of electrodes to the
skin, that coat of the skin was shaved and cleaned with alcohol
prior to the application of gel . Types of arrhythmias were
The differences of means of laboratory values between buf-
faloes with theileriosis and normal animals were compared
using the Student’s t-test. The presence of cardiac arrhythmias
was analyzed as percent. Values of P < 0.05 or P < 0.01 were
In hematological analyses, decreases were observed in the
mean RBC count, hematocrit value, hemoglobin amount, and
WBC count in buffaloes with thileriosis. The mean of RBC was
4.4 ± 0.2 × 106and WBC was 7.8 ± 0.2 × 103in these ani-
mals. The mean % of PCV in the sick buffaloes was 21.7 ±1.3%
The serum levels of sodium and potassium in the buffaloes
with theileriosis were 130.9 ±3.3 and 6.2 ±0.3 meq/L, respec-
tively. Calcium and phosphorus mean levels were 9.2 ± 0.1
and 4.8 ± 0.7 mg/dl, respectively, and the mean level of total
protein in the serum was 8.5 ± 0.1 gr/dl. The serum levels of
ALT and AST enzymes were 166.2 ± 6.2 and 136.7 ± 4.5 μ /L,
respectively (Table 2).
4.4 ± 0.2
8.9 ± 1.0
7.8 ± 0.2
9.9 ± 0.7
21.7 ± 1.3
35.1 ± 3.4
Table 1. Mean levels of hematological parameters in the buffaloes
with theilleriosis and normal
130.9 ± 3.3
134.2 ± 34.2
6.2 ± 0.3
4.7 ± 0.3
9.2 ± 0.1
10.0 ± 1.0
4.8 ± 0.7
5.2 ± 0.2
166.2 ± 6.2
45.8 ± 5.3
136.7 ± 4.5
87.5 ± 6.5
Table 2. Mean levels of sodium, potassium, calcium, and phosphorus, and ALT and AST enzymes in sera of the buffaloes with theile-
riosis and normal
In theileriosis buffaloes, 3 cases had atrial premature beat, 2
cases had sinus tachycardia, 2 had sinus arrhythmia, and 1 had
first degree of atrioventricular block, while normal animals had
any ECG changes (Fig. 1).
T. annulata is a tick-borne protozoan parasite of cattle and
buffaloes that infects leukocytes and causes an acute, lympho-
proliferative disease known as tropical theileriosis. Tropical thei-
leriosis has a particularly devastating impact on small-holder
farmers, which represent the majority of livestock owners in
endemic areas. The methods currently used to protect against
tropical theileriosis are expensive and all have serious limita-
tions in efficacy and sustainability. Therefore, there is a need
and demand for improved control methods focused on the
disease prevention [4,12,13].
In the present study, animals showed a high percentage of
parasitemia and exhibiting clinical signs of tropical theileriosis.
T. annulata spreads through the lymphoid system and other
organs rapidly, and induces production of TNF-αand IFN-γ.
These cytokines disrupt the physiological integrity of the host.
Moreover, the presence of parasites in the pituitary and adrenal
glands can cause disturbance of the immune and endocrine sys-
tems [14,15]. Cytokines (TNF-α , IL-1, and IL-6) produced by
infected mononuclear cells are responsible for the diverse clini-
cal symptoms of tropical theileriosis, such as depression, pyrex-
ia, anorexia, cachexia, and disseminated hemorrhages .
RBC counts and hematocrit values were lower in infected
animals compared to normal ranges. These results were in agree-
ment with other reports [2,17]. Erythrophagocytosis due to an
immune-mediated mechanism might be responsible for the
erythrocyte destruction . Removal of the piroplasm-infect-
ed erythrocytes by macrophages in the organs of the reticuloen-
dothelial system has been suggested as a cause of anemia [17,
19]. In addition, pro-inflammatory cytokines, particularly TNF-
α , have been implicated in mediating anemia associated with
tropical theileriosis [14,16]. The decrease in RBC could be due
to increased levels of activated complement products. Additio-
nally, since oxidized erythrocytes may be destroyed easily by
erythropagocytosis, oxygen radicals may also be involved in
the pathogenesis of anemia [20-22].
In this study, leucopenia was seen in infected animals. Some
researchers have demonstrated that the leucocyte count increased
immediately following Theileria infection and then significant-
ly decreased within several days [23,24]. T. annulata-induced
leucopoenia is mainly mediated by TNF-α. This decrease
is related to a destruction of lymphocytes in lymphoid organs
and infiltration of these cells into various organs [2,24].
In our study, the buffaloes with theileriosis had hyponatrem-
ia, hypocalcemia, hypophosphatemia, and hyperkalemia. The
difference between the means of sodium, calcium, and phos-
phorus in the sera of animals with theileriosis and normal ranges
in healthy animals were not significant, but the levels of potas-
sium were significantly (P < 0.05) different. In theileriosis, hy-
pocalcaemia and hyponatremia were probably due to the hypo-
proteinemia, decreased dietary intake, intestinal malfunction,
and kidney damage. The decreased serum phosphorus concen-
tration in cattle with theileriosis is the results of diarrhea and
renal wasting. The AST and ALT values in animals with theile-
riosis were significantly higher than the normal values (P< 0.01).
These finding supports the results of Hilali et al.  and Singh
et al.  obtained in their studies on theileriosis. The occur-
rence of parasites in any tissue causes the parasitic tissue dam-
age. In hepatic injury seen in theileriosis, increased serum activ-
itiesof AST and ALT are closely associated with the hepatic func-
tion. Furthermore, the significant rises in the serum AST and
ALT activities were due to muscle trauma caused by prolonged
recumbency in theileriosis.
Three cases had atrial premature beat, 2 cases had sinus tachy-
cardia, 2 cases had sinus arrhythmia, and 1 had first degree of
atrioventricular block. Variation in the rhythm and rate of the
heart in animals can occur due to strong and varying autonom-
ic influence but can also be a reflection of a primary myocardial
disease. Other factors such as acid-base imbalance can influence
Hasanpour et al.: Biochemical, hematological and ECG changes in Theileria annulata-infected buffaloes 225
Fig. 1. Kinds of cardiac arrhythmias in the buffaloes with theilerio-
sis. A, normal; B, atrial premature beat; C, sinus arrhythmia; D, first
degree of atrioventricular block.
Korean J Parasitol. Vol. 46, No. 4: 223-227, December 2008
the rate and rhythm. These factors must be taken into consider-
ations in the assessment of apparent abnormalities detected on
clinical examination of the cardiovascular system. Sinus tachy-
cardia caused by pain, hyperthermia, anemia, electrolyte imbal-
ance, and fall in the arterial blood pressure . In these buf-
faloes, there were hyperthermia, anemia, and electrolyte imbal-
ance. In sick cattle and buffaloes, atrial fibrillation most com-
monly occurs in association with gastrointestinal, metabolic,
and hemolytic diseases .
In our study buffaloes with theileriosis had anemia, and meta-
bolic and electrolyte imbalances that caused atrial fibrillations.
Sinus arrhythmia is a normal physiological arrhythmia that
occurs at slow resting heart rates and is associated with varia-
tions in the rate of discharge from the sinoatrial node. This arr-
hythmia also can be induced with electrolyte imbalance. The
first degree of atrioventricular block is an ECG diagnosis and
cannot be detected clinically. It occurs when conduction is de-
layed at the atrioventricular node. It can be associated with elec-
trolyte imbalance, overdosing with calcium, digoxin, and car-
diomyopathy. In buffaloes with theileriosis maybe there were
these factors . ECG changes in buffaloes have not established
in other studies, but in cows and horses these had been estab-
lished. A large scale cross-sectional study of 952 healthy dairy
cattle aged 1 or more yr produced the following prevalence of
arrhythmias; 8.5% sinus arrhythmia, 1.6% first-degree atrioven-
tricular block, 0.6% ventricular premature complex, 0.4% atrial
premature complex, 0.2% sinus bradycardia, and 0.1% ventric-
ular escape beats. Atrial fibrillation was not observed in this
study . In a previous study, the efficacy of ketamine and
bupivacaine in enhancing the epidural analgesia induced by
medetomidine was evaluated in 10 buffalo calves. The ECG
changes included tall T wave, QS pattern, RS pattern, ST eleva-
tion, and heart blocks at different intervals, which were more
frequent and pronounced in animals given bupivacaine with
medetomidine . Perinodal myocardial fibrosis and microvas-
cular abnormality have been reported in horse with sinoatrial
and atrioventricular block, and considered as the excitatory
cause, because myocardial fibrosis is common in horses .
According to the kinds of arrhythmias and electrolyte imbal-
ance, it is concluded that arrhythmias in these buffaloes may
be physiologic, and treatment as well as balancing of electrolytes
will remove arrhythmias. Based on these observations, it can
be concluded that severe T. annulata infection is associated with
profound changes in hematological and biochemical profiles
and ECG parameters.
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