Original ArticleNepal Med Coll J 2010; 12(2): 63-65
Soil contamination with Toxocara spp. eggs in the public parks from
three areas of Khorram Abad, Iran
M Zibaei,1 F Abdollahpour,1 M Birjandi1 and F Firoozeh2
1Department of Parasitology, School of Medicine, Lorestan University of Medical Sciences, Khorram Abad, Iran,
2Department of Microbiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran
Corresponding author: Mohammad Zibaei, Ph.D, Assistant Professor of Parasitology, Department of Parasitology and Mycology,
School of Medicine, Lorestan University of Medical Sciences, Khorram Abad, Iran; e-mail: email@example.com
Toxocariasis is a parasitic zoonose caused by the infection of larval nematode Toxocara species. A total of 285
soil samples from January to March 2009 in 18 public parks were collected to test for soil contamination with
Toxocara eggs. Soil samples were investigated for the present of Toxocara eggs using sucrose flotation method.
Distribution of Toxocara spp. eggs in samples collected from public parks was 63.3%. The highest number of
eggs recovered from 200 g of soil was 128. A total 304 eggs were recovered and 42.1% fully developed to
embryonated egg stages. The contamination rate in second region in the studied areas was higher than the other
regions. A similar tendency was observed in parks size, so that parks higher than 10,000 m2 were more highly
contaminated. The present investigation clearly shows that public parks have been contaminated with Toxocara
eggs in Khorram Abad, suggesting that care should be taken when using public parks.
Keywords: Toxocara spp., soil samples, public parks, Khorram Abad, Iran.
Toxocariasis is a zoonotic disease caused by the larvae
stage of Toxocara canis (T. canis) and Toxocara cati (T.
cati). Humans are infected by ingestion of embryonated
eggs in the soil or though contaminated hands and
fomites or eating the meat of paratenic hosts containing
encapsulated larvae.1-3 The larval hatches in the intestine
and migrates into different organs, mainly the liver and
the lungs and then occasionally into the kidney,
myocardium and central nervous system, giving origin
to the VLM syndrome. It can also cause serious ocular
damage by migration into the retina (OLM).4-7
Although cats and dogs are the usual Toxocara hosts,
direct contact with these animals is not considers as a
potential risk by some parasitologistes because the eggs
eliminated with the definitive hosts feces required a
period of 4-6 weeks to become infective, therefore,
contact with soil in public parks is a potential source of
contamination.5-8 The epidemiological studies have noted
the presence of Toxocara spp. infection in stray cats and
dogs in various parts of Iran.9-11 In Urima (Iran) 7.8% of
the public parks studied showed Toxocara spp. 12
Previous reports have noted the present of Toxocara eggs
in soil samples of public parks and children’s playground
in Londrina (100%), Kansas (20.6%), Hanover (30.8%),
Basrah (15.5%) and Kobe (67.7%).13-17
The aim of this study was to provide information on the
Toxocara spp. eggs contamination in soil samples in
public parks in Khorram Abad and to determine the
relationship with several factors.
MATERIALS AND METHODS
Khorram Abad (48° 21', 30° 43') is the largest city in
Lorestan Province in western Iran with 540,000
inhabitants. This area is humid with mean rainfall of
525 mm/year and the maximum mean yearly
temperature of 17.2 C°.
The study was conducted between January and March
2009. Eighteen public parks in the residential areas were
randomly selected and soil samples were collected.
Selection of collecting areas was confined to three
divisions. These are the divisions used by the Khorram
Recovery of soil samples
A soil sample of 200 gm was collected at a depth of 3
cm (one sample of approximately 10 gm every 50 steps).
The soil samples from same park were thoroughly mixed
and stored in sealed and labeled polyethylene bags and
taken to the laboratory. At the time of sample collection,
we examined other factors that are though to have a
relation with Toxocara eggs contamination such as
presence of feces of animals and parks size.
Detection of eggs
For egg detection, soil samples were dried overnight at
room temperature and sifted through a 150 µm mesh
sieve. About 2 gm of powdery soil (produced from about
200 gm of unsifted soil), was placed in a test tube and
suspended in about 8 ml of 0.05% Tween- 20 solution.
After centrifugation of the test tube at 1500 rpm for 10
minutes, the supernatant was removed and sucrose
solution with specific gravity of 1.200 was added up to
a level of 1 cm from the top of the tube. The contents of
the tube were mixed well and centrifuged at 1500 rpm
for 10 minutes. The tube was then filled to the top with
the sucrose solution so that a small convex bubble
formed and a coverslip could be placed on the tube. After
a final centrifugation of the tube at 500 rpm for 5 minutes,
the coverslip from the tube was put on a microscopic
slide and examined at a magnification of 40 and 100 for
Toxocara eggs. Toxocara spp. eggs found in this study
were counted and classified according to their
developmental stage i.e. monocell, 2 to pre-embryonated
Data analysis of the relationship between contamination
rates and changes in environmental factors were
evaluated by the chi- square test. Statistical significance
was defined as p< 0.05.
Table-2: Number of Toxocara spp. eggs recovered from three areas and their
stage of development
Of the 285 samples collected from 18 public parks, 4
(22.2%) public parks were positive for Toxocara spp.
eggs. The highest contamination rate was in public parks
in 2nd area (37.5%) in the studied areas. The egg count
for the position soil samples varied from one to 57 with
mean of 4.8 eggs/200 g of soil (Table-
1). Animal feces (dogs and cats) were
found in 132 of 285 (46.3%) parks
samples. A significant differences was
found in the proportion of the presence
of feces in the soil and contamination
rate (p<0.05). Table 2 shows the total
number of eggs recovered in the
three areas and their stage of
development. A total of 304
Toxocara eggs were recovered and
128 (42.1%) of them were fully
embryonated (Table-2). There were
no significantly difference (p>0.05)
in embryonation rate among the
different areas examined. The
highest rate of contamination (79.0%) was found in
bigger public parks (Table-3). The difference between
extant of public parks and contamination rate was
statistically significant (p<0.05).
The survey revealed that the contamination of public
parks with Toxocara eggs was 22.2% in Khorram Abad,
Iran. Toxocara cati eggs contamination of public places
in Iran was first report by Motazedian et al.8 They
reported that the contamination rate of public places in
Shiraz was 6.3%. Tavassoli et al in Urmia notified a
similar situation. The contamination of Toxocara spp.
eggs in public parks reported 7.8% in Urmia, northwest
Iran.12 The prevalence of Toxocara eggs in our survey
was higher than previous studies in Iran. This fact might
be the consequence of a relatively higher stray cats and
dogs in this region. On other hand, public parks were
not surrounded by fence; therefore the animals can freely
live in them. Toxocara eggs have been found in sand or
soil samples in Turkey (63.0%),
Brazil (53.0%), Italy (64.0%), Spain
(67.0%), Japan (92.0%) and
Thailand (6.0%).5,18-22 The high
prevalence of Toxocara eggs in soil
samples from public parks in 2nd
region of studied areas of Khorram
Abad is evidence that stray cats or
dogs were infected and defecated in
We examined some factors that
might be related to the soil contamination.
Contamination of the soil by Toxocara eggs affected to
a considerable degree by extant of park. In the bigger
parks (higher than 10,000 m2), there are many green areas
in the parks; therefore there are suitable places for
defecation for dogs and cats. The obtained data
Table-3: Relation between contamination of soil sample with Toxocara eggs
and park size
Condition positive parks (%) statistical analysis(x2)*
More than 10000 m2
Less than 10000 m2
* Chi square
No. eggs developed
2 to pre-
Table-1: Prevalence of Toxocara species eggs in soil samples of public parks
No. positive parks (%) No. eggs recovered/200g
Areas No. parks
Nepal Medical College Journal
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illustrating the presence of animal feces would be as an
indicator for prevalence of Toxocara eggs in public
parks. Dubna et al reported that 51.0% of fecal
contamination public places in the Czech Republic were
positive for Toxocara eggs.5 It is important to note that
contamination of parks with feces increase the risk not
only of Toxocara but also of other helminths. The results
of the present study showed that 55.9% of eggs recovered
from soils developed to embryonated stage. Zibaei and
Uga reported that the percent recovery of embryonated
Toxocara eggs from the sandpits of public parks in Kobe
was 9.0%.17 This discrepancy is probably due to the
seasonal change. Because of the climate condition in
Khorram Abad city in winter is mild temperature with
In conclusions, the results of present study showed that
the some public parks of Khorram Abad were
contaminated with feces of animals and Toxocara eggs,
indicating that control measure as well as education of
people is needed for protection from zoonotic infection.
We are grateful to the office of the vice chancellor for research
of Lorestan University of Medical Sciences for financial
support. Furthermore, the authors would like to thank Prof.
Uga for instrument and his guidance.
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