-
ORIGINAL ARTICLE
Seroprevalence of
Toxoplasma
gondii
Infection in Stray and Household
Cats in Guangzhou, China
H. Zhang
1
, D. H.
Zhou
1
, P.
Zhou
1
, Z. R.
Lun
2
, X. G
.
Chen
3
, R. Q.
Lin
1
,
Z. G
.
Yuan
1
and X. Q.
Zhu
1
1
Laboratory
of
Parasitology,
College
of
Veterinary
Medicine,
South
China
Agricultural
University,
483
Wushan
Street,
Tianhe
District,
Guangzhou,
Guangdong
Province
510642,
People’s Republic of
China
2
Center
for Parasitic Organisms, State Key Laboratory of
Biocontrol, School of Life Sciences,
Sun
Yat-Sen
University,
Guangzhou,
Guangdong
Province
510275,
People
’
s
Republic
of
China
3
Department
of
Parasitology,
School
of
Public
Health
and
Tropical
Medicine,
Southern
Medical University, Guangzhou,
Guangdong Province 510515,
People
’
s Republic of China
Running Head:
Toxoplasma gondii
infection
in cats in Guangzhou, China
Correspondence:
X.Q. Zhu.
College of Veterinary Medicine, South China
Agricultural University, 483 Wushan
Street, Tianhe District, Guangzhou,
Guangdong Province 510642,
People’s
Republ
ic of China.
Tel: +86
20 85283730; Fax: +86 20 85283730;
E-mail: xingquanzh@
1
Impacts
?
This article
shows new figures on the present situation of
Toxoplasma gondii
infection
in
stray and household cats in
metropolitan Guangzhou, China.
?
The data
presented provide the most comprehensive picture
of the prevalence of
T.
gondii
in stray and
household cats in Guangzhou, which also indicates
the zoonotic significance
of the
prevalence.
?
The
data
presented
provide
“base
-
line”
information
for
assessing
the
effectiveness
of
future control strategies against
T. gondii
infection in cats
in Guangzhou, China.
2
Summary
The
prevalence
of
anti-
Toxoplasma
gondii
specific
IgG
in
stray
and
household
cats
in
Guangzhou, China
was
determined by ELISA on serum samples
from
206
cats
(117 strays
and 89
households), and the overall infection rate was
25.24%. The infection rate in stray cats
(30.77%)
was
significantly
higher
(p
<
0.05)
than
in
household
cats
(17.98%).
The
rate
of
infection between male
and
female
cats
of both
groups was not
significantly
different
(
p
≥
0.05), 28.13%
versus
32.61% for male and
female in stray cats, respectively, and 18%
versus
17.95% in
household cats. The present investigation
demonstrated that the prevalence of
T.
gondii
infection in cats in
Guangzhou was high, especially in stray cats,
which are probably
the main source of
T. gondii
infection in this
area. Integrated control strategies and measures
should be implemented to prevent and
control
T. gondii
infection
in both stray and household
cats,
which
will
have
significant
implications
for
the
control
of
human
infection
with
T.
gondii.
Keywords:
Cat;
ELISA; Guangzhou;
Seroepidemiology;
Toxoplasma
gondii
; Toxoplasmosis
3
Introduction
Toxoplasma gondii
is
an
obligate
intracellular protozoa parasite that
can
infect
a variety
of
cell types from a wide
range of mammals and birds throughout the world,
including humans
and
nonhuman
primates
(Jacobs
et
al.,
1998).
T.
gondii
infection
does
not
usually
produce
clinical symsptoms.
However, the primary infection during pregnancy in
women and animals
may
cause
abortion,
fetal
abnormalities
or
prenatal
death
(Cook
et
al.,
2000).
More
importantly,
T.
gondii
infection is considered one of
the main reasons of death for the AIDS
patients and other immunocompromised
patients (Montoya and Liesenfeld, 2004).
Felids play a crucial role
in the epidemiology of this parasitic disease,
because they are the
only definitive
host, shedding and excreting millions of infective
oocysts in a short period of
time
(Dubey, 1994) in their faeces. It is generally
suggested that cats probably play a major
role
in
transmitting
T.
gondii
through
environments
contaminated
by
faeces.
It
is
not
convenient
and
may
have
difficulty
in
detecting
T.
gondii
oocysts
in
faecal
examination
of
cats.
Therefore,
serologic
investigation
of
cats
is
important
for
determining
the
epidemiological significance of
T. gondii
infection.
Antibodies to
T. gondii
have been reported in cats worldwide.
There have also been some
surveys of
T. gondii
infections in cats
in some provinces of China in recent years (Lu et
al.
1997; Yu et al., 2006; Yuan et al.
2004; unfortunately, these reports were published
only in
the
Chinese
language).
However,
the
difference
of
T.
gondii
infection
between
stray
and
household
cats
and
the
infection
rates
between
male
ad
female
cats
are
not
quite
clear.
In
order to provide a foundation for the
improved control of
T. gondii
infection
in
cats, the aim
of the present
investigation was to estimate the prevalence of
T. gondii
in stray and
household
cats in metropolitan
Guangzhou, China.
4
Material and methods
Animals
Biometric data for cats including age,
sex and lifestyle were recorded. The information
about
household cats was taken from the
owners and the information about stray cats was
estimated
based on body condition and
by examining dentition.
Blood sampling and serum preparation
Blood
samples
(1.5
ml)
were
collected
from
each
cat
into
sterile
plain
tube
by
jugular
puncture. The samples were left to clot
at room temperature for 3 h and then centrifuged
at
800
g
for 10
min. Each serum sample was transferred into a 0.5
ml sterile tube and preserved
at
–
20
℃
until needed for ELISA.
Determination
of antibodies to
T. gondii
Antibodies to
T.
gondii
were determined using the
CIVTEST
T. gondii
ELISA Kit
(Shenzhen,
China)
according to the manufacturer’s
instructions. Positive
and negative
control sera were
provided
in
the
kit.
The
tests
were
performed
in
the
Veterinary
College
of
South
China
Agricultural
University.
Briefly,
the
T.
gondii
specific
antigen
was
coated
on
a
96-well
ELISA
plate.
After
incubation
of
the
diluted
serum
sample
(1:100)
in
the
test
well
and
subsequent
washing,
a
conjugate
was
added.
The
plate
was
washed
again,
and
then
a
chromogenic
enzyme
substrate
was
added.
The
optical
density
(OD)
at
450
nm
was
read
using a photometer (BIO-RAD).
A relative rate percent (IRPC) value
was obtained using the following formula:
5
IRPC
?
OD450
(sample)
-
meanOD
450
(blank
control)
meanOD450
(negative
control)
-
meanOD450
(blank
control)
The sera
were considered negative to
T.
gondii
if the IRPC < 2.1, and positive
if IRPC
>
2.1.
It
is
to
take
as
0.7
when
the
value
(meanOD
450
negative
control
-
meanOD
450
blank
control) was less than
0.7.
Statistical analysis
Differences
in
the
seroprevalence
of
infected
cats
between
stray
and
household
groups,
between male and female cats were
analyzed using Chi Square Test in SPSS for
Windows,
(Release 11.0 standard
version, SPSS Inc.). The correlation between the
rates of infection in
different age
groups was calculated with Excel
(Microsoft
?
Excel 2003).
Results and discussion
In this investigation, the ELISA method
was utilized due to the ease of its application,
and its
high sensitivity and
specificity when compared with other test methods
(Lappin and Powell,
1991).
In
this
study,
206
cats
(117
households
and
89
strays
were
examined.
Of
these,
82
were
male, 85 were female and 39 unknown sex (Table 1).
As shown in Table 1, the overall
seroprevalence rate was 25.24%.
Seroprevalence for all different groups was 30.77%
in stray
cats and 17.98% in household
cats (Table 1), and ranging from 12.50% to 30.77%
in different
age groups (Table 2).
The seroprevalence of
T.
gondii
in cats has been studied in many
countries. In the present
study, the
overall seroprevalence in cats was 25.24%, which
was lower than that reported in
other
countries
(Miro
et
al.,
2004;
Haddadzadeh
et
al.,
2006),
and
in
Shanghai
and
Hebei
province in China (Lu
et al. 1997; Yuan et al. 2004), but similar to
that reported in Beijing
(Yu et al.,
2006).
6