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Prevalence of fecal contamination in sandpits in public parks in Sapporo City, Japan
Veterinary Parasitology 128 (2005) 115–119 www.elsevier.com/locate/vetpar
Prevalence of fecal contamination in sandpits in public parks in Sapporo City, Japan Junji Matsuo*, Satoshi Nakashio Division of Medical Technology, Department of Health Sciences, Hokkaido University School of Medicine, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan Accepted 4 November 2004
Abstract A total of 107 sandpits in public parks in Sapporo City were examined, 9 and 73 were contaminated with helminth eggs and fecal coliforms, respectively. Of the nine in which eggs were detected, eight were contaminated with Toxocara spp. and one with Capillaria spp. eggs. The contamination rate of sandpits of more than 30 m2 ranged from 43 to 50%, while in those 30 m2 or less it was between 73 and 92%. Although helminth eggs were evenly distributed throughout all layers of the sandpits, fecal coliforms were localized on the sandpit surfaces. Recovered Toxocara eggs were identified according to their size and surface structures, and almost all eggs were T. cati. Based on these results, and given the inherent habits of cats, measures to prevent their defecation in sandpits are needed, especially ones of smaller size. # 2004 Elsevier B.V. All rights reserved. Keywords: Toxocara; Egg; Contamination; Sandpit
1. Introduction Toxocara canis and T. cati are the common roundworms of dogs and cats, respectively, and are considered causative agents of human toxocariasis, which occurs by accidental ingestion of embryonated eggs (Despommier, 2003; Fisher, 2003). In a seroepidemiological study, Hummer et al. (1992) ascertained that institutionalized adults with mental retardation are at a high risk from toxocariasis. * Corresponding author. Tel.: +81 11 706 2830; fax: +81 11 706 4916. E-mail address: [email protected] (J. Matsuo).
Children also have a potentially higher risk of infection with Toxocara spp. because of pica habits and regular contact with sandpits contaminated with eggs (Despommier, 2003; Fisher, 2003). Thus, it is suspected that human toxocariasis is closely associated with environmental conditions. Contamination of soil with Toxocara eggs has been reported in public parks, school playgrounds, and gardens, and the prevalence of Toxocara eggs in sandpits varies from 0 to 75%; however, especially public parks in urban or suburban areas have been found to be highly contaminated (Dunsmore et al., 1984; Duwel, 1984; Uga et al., 1989; Shimizu, 1993; Uga, 1993; Abe and Yasukawa, 1997; Loh and Israf,
0304-4017/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2004.11.008
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J. Matsuo, S. Nakashio / Veterinary Parasitology 128 (2005) 115–119
1998; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). The reasons for this are thought to be because almost all the ground is paved, and because pets frequent these areas (Uga et al., 1989; Shimizu, 1993; Alonso et al., 2001; Despommier, 2003). Measures to prevent sandpit contamination have been studied. Uga and Kataoka (1995) and Abe and Yasukawa (1997), for example, evaluated measures required to control fecal contaminations, such as sand replacement or fence construction. Such preventative methods are only being slowly instituted and do not completely prevent Toxocara egg contamination, for which no really effective method has yet been found. As a prophylaxis against toxocariasis, is it therefore important to understand the current status of fecal contamination of sandpits. This study aimed to provide information on the extent of fecal contamination in sandpits in public parks in Sapporo, Japan, and to ascertain the relationship between contamination rates and environmental factors, as well as the distribution of sandpit contamination. Additionally, from the morphological features of the Toxocara eggs recovered from sandpits, an attempt was made to determine the animals mainly responsible for defecating in them.
2. Materials and methods 2.1. Study area The survey was carried out from June to December 2003 in East and West Sapporo, Northern Japan. Sapporo City has a mean annual air temperature of 8.5 8C, a mean annual air humidity of 68%, and on average 496 cm of snowfall a year. Both study areas are residential; however, the Western area contains some mountainous parts.
were examined in more detail. To reveal the horizontal and vertical distributions of helminth eggs or fecal coliforms, soil samples were collected from various sites (horizontally from outer, inner, and central areas and vertically from depths of 3 and 15 cm). 2.3. Detection of helminth eggs Helminth eggs were detected as described previously (Uga and Kataoka, 1995), except that the sucrose solution used had a specific gravity of 1.27. Briefly, soil samples were dried overnight at room temperature then filtered using a 150-mm mesh sieve. Approximately 2 g of the powdery sand was placed in a tube, washed with 0.5% Tween 80 solution, and suspended in sucrose solution. The suspension was mixed well and centrifuged at 500 g for 10 min. Next, tubes containing the suspension were filled to the brim with additional sucrose solution and covered with a cover slip. After a final centrifugation of the tube together with the cover slip at 45 g for 5 min, the cover slip was transferred to a glass slide and examined at 100 magnification. 2.4. Detection of fecal coliforms To detect fecal coliforms, soil samples were examined using the most probable number (MPN) method with EC broth (Nissui, Tokyo, Japan) within 2 h of soil collection. A 10-g soil sample was suspended in 90 ml of sterilized phosphate buffered saline (pH 7.2), agitated thoroughly, and diluted to 10 1. Ten- or one-milliliter aliquots of each suspension were inoculated into sets of five tubes containing EC broth. Culture was conducted at 44.5 8C for 24 h in a water bath. The MPN of fecal coliforms was calculated from the numbers in the positive tubes. 2.5. Data analysis
2.2. Recovery of soil A total of 107 sandpits in public parks were randomly selected and examined. Soil from a depth of approximately 3 cm of the sandpit was collected into polythene bags, and taken to the laboratory for analysis. Helminth eggs and fecal coliforms were adopted as the indicators of fecal contamination. Nine sandpits were contaminated with helminth eggs and so
Data analysis of the relationship between contamination rates and environmental factors was conducted using the Mann–Whitney U-test. The horizontal and vertical distributions of sandpit contamination were analyzed with the Kruskal–Wallis test and Mann– Whitney U-test, respectively. The remaining tests were conducted with the x2-test. Statistical significance was defined as p < 0.05.
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117
3. Results 3.1. Prevalence of fecal contamination Of the 107 soil samples examined, 9 (8%) and 73 (68%) were contaminated with helminth eggs and fecal coliforms, respectively (Table 1). Both helminth eggs and fecal coliforms were recovered from eight sandpits. There was no significant difference between the contamination rates of the East and West study areas (p > 0.05). Of the nine sandpits in which helminth eggs were detected, eight were contaminated with Toxocara spp. eggs and one with Capillaria spp. eggs. Egg counts for positive samples varied from 1 to 3 eggs per soil sample. The relationship between contamination rates and two environmental factors studied, namely the sizes of the parks and sandpits, are shown in Fig. 1. Helminth eggs and fecal coliforms were evenly detected in parks of different sizes; however, smaller sandpits were contaminated with fecal coliforms to a greater extent than the bigger ones (p < 0.05). That is, the contamination rates of sandpits of more than 30 m2 ranged from 43 to 50%, while those of sandpits 30 m2 or less were between 73 and 92%. 3.2. Distribution of fecal contamination Further surveys carried out on the nine sandpit samples initially determined to be contaminated with helminth eggs revealed that seven continued to be contaminated; four with Toxocara eggs, and three with Capillaria eggs. Table 2 shows horizontal and vertical distributions of fecal contamination, respectively. Helminth eggs were detected in six outer, seven inner, and seven central horizontal study sites, and vertically in nine surface and eleven deep layer sites. There were no significant differences between horizontal and vertical distributions (p > 0.05);
Table 1 Contamination rates of sandpits in public parks in Sapporo City Area
East West a
No. of parks examined
No. of sandpits contaminated with (%) Fecal coliforms
Helminth eggs
50 57
32 (64) 41 (72)
5 (10) 4 (7)
a
p > 0.05 with the x2-test.
a
Fig. 1. Contamination rates of different sized parks (A) and sandpits (B). Note that some sandpits (n = 29) were excluded from Fig. 1B because their size was unknown. There was a significant relationship between contamination rates and sandpit size using the Mann– Whitney U-test (p < 0.05).
Table 2 Distribution of fecal contamination in sandpits Position
No. of sandpits contaminated with Fecal coliforms (MPN/g)a
Horizontal Outer Inner Central
Helminth eggsb
<0.2
0.2–10
10<
0 2 2
12 5 9
6 11 7
6 7 7
9 17
17 7
9 11
Vertical (depth (cm)) 3 1 15 3
a p > 0.05 with the Kruskal–Wallis test among horizontal position; p < 0.05 with the Mann–Whitney U-test among vertical position. b p > 0.05 with the x2-test among each position.
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Table 3 Morphological characteristics of Toxocara eggs detected in sandpits Park no.
22 47 50 66 Referencea a
No. of eggs detected
4 3 7 8 T. canis T. cati
Size (mm)
Types of surface structure (%)
Major axes
Minor axes
T. canis
T. cati
Intermediate
68.9–73.8 71.3–78.7 64.0–78.7 66.4–78.7 71.6–91.2 63.7–88.1
59.0–61.5 61.5–64.0 54.1–64.0 54.1–68.9 64.4–79.0 53.3–73.3
1 (25) 0 (0) 0 (0) 0 (0) (89) (5)
1 (25) 2 (67) 4 (57) 4 (50) (1) (67)
2 (50) 1 (33) 3 (43) 4 (50) (11) (22)
Uga et al. (2000).
however, more than 10 MPN/g of fecal coliforms were recovered in surface layers of 17 sites and in deeper layers of 7 sites (p < 0.05). 3.3. Morphological characteristics of the recovered Toxocara eggs A total of 22 Toxocara eggs, all embryonated, were recovered from four sandpits. Of these, 10 (45%) contained motile larvae (data not shown). The morphological characteristics of the recovered Toxocara eggs are shown in Table 3. The major and minor axes of the eggs were 64.0–78.8 mm and 54.1– 68.9 mm, respectively. Eggs were classified based on the surface structures observed by light microscopy (Uga et al., 2000); one (5%) was T. canis, 11 (50%) were T. cati, and the remaining 10 (45%) were of intermediate type.
4. Discussion The present study was carried out to ascertain contamination rates in local sandpits in Sapporo. Over the past two decades, many reports have documented contamination rates of Toxocara eggs in Japan (Uga et al., 1989; Shimizu, 1993; Uga, 1993; Abe and Yasukawa, 1997) and other countries (Dunsmore et al., 1984; Duwel, 1984; Loh and Israf, 1998; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). Although it is not possible to compare this study directly with these other surveys because of the different sampling and detection methods used (Ruiz de Yba´ n˜ ez et al., 2001), the contamination rates observed here are relatively similar to those reported previously. Eggs of Ancylostomidae, Trichuris, Capirallia, and Toxascaris
leonina have been reported as recovered from sandpits in public parks (Uga et al., 1989; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). Here, Toxocara and Capillaria eggs were detected; it is possible that these results show differences in parasitic fauna in different regions. Fecal contamination of sandpits was not related to the size of the park, but was associated with sandpit area. That is, smaller sandpits were more highly contaminated with fecal coliforms. One reason might be that as defecation habits of dogs and cats do not depend on sandpit size and since fecal bacteria concentrations are not diluted in soil, fecal coliforms would thus be detected at higher rates in small sandpits. Uga (1993) reported widespread contamination of sandpits with eggs, but less contamination with Toxocara eggs in deeper layers. In the present study, helminth eggs were evenly distributed throughout all layers of the sandpits as in the past survey. It has been shown that animal defecations are distributed evenly (Uga et al., 1996) possibly as a result of earthworms and small mammals (Despommier, 2003; Fisher, 2003). Fecal coliforms, however, were found localized on sandpit surfaces where they might easily die. To prevent fecal contamination, it is important to identify the main animal responsible for defecating in sandpits. By examining the surface structures of eggs, some attempts have been made to identify Toxocara species. Ratios of T. canis to T. cati have been previously reported as 1:3 or 2:3 using scanning electron microscopy (Uga et al., 1989; Shimizu, 1993). However, using light and scanning electron microscopy, Uga et al. (2000) showed that the surface coat of Toxocara eggs has some diversity. Although PCR technique can identify more accurately
J. Matsuo, S. Nakashio / Veterinary Parasitology 128 (2005) 115–119
(Wu et al., 1997), because of the complexity of the manipulation, in this study Toxocara eggs were comprehensively identified by size and surface structures. Consequently, almost all the Toxocara eggs were identified as T. cati, showing that cats were the main contaminating animals. This result is in accordance with 144 days of camcorder observation (Uga et al., 1996); however, that method is relatively time-consuming. The zoonotic potential of T. cati is underestimated compared with T. canis with regards to human toxocariasis (Fisher, 2003); however, in this study, sandpits were highly contaminated with T. cati eggs. As a prophylaxis against human toxocariasis, preventative measures reflecting the inherent habits of cats need to be implemented. Further, the administration of antihelminthics by veterinarians (Habluetzel et al., 2003) or the better education of pet owners may be effective reducing the occasions of parasitic infection. It is also important for children to be made better aware of the need to wash after playing in sandpits.
Acknowledgement The authors thank Dr. Shoji Uga of Kobe University School of Medicine, Kobe, Japan for kindly supplying the instruments for parasite egg examination.
References Abe, N., Yasukawa, A., 1997. Prevalence of Toxocara spp. eggs in sandpits of parks in Osaka city, Japan, with notes on the prevention of egg contamination by fence construction. J. Vet. Med. Sci. 59, 79–80. Alonso, J.M., Stein, M., Chamorro, M.C., Bojanich, M.V., 2001. Contamination of soils with eggs of Toxocara in a subtropical city in Argentina. J. Helminthol. 75, 165–168.
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Despommier, D., 2003. Toxocariasis: clinical aspects, epidemiology, medical ecology, and molecular aspects. Clin. Microbiol. Rev. 6, 265–272. Dunsmore, J.D., Thompson, R.C., Bates, I.A., 1984. Prevalence and survival of Toxocara canis eggs in the urban environment of Perth, Australia. Vet. Parasitol. 16, 303–311. Duwel, D., 1984. The prevalence of Toxocara eggs in the sand in children’s playgrounds in Frankfurt/M. Ann. Trop. Med. Parasitol. 78, 633–636. Fisher, M., 2003. Toxocara cati: an underestimated zoonotic agent. Trends Parasitol. 19, 167–170. Habluetzel, A., Traldi, G., Ruggieri, S., Attili, A.R., Scuppa, P., Marchetti, R., Menghini, G., Esposito, F., 2003. An estimation of Toxocara canis prevalence in dogs, environmental egg contamination and risk of human infection in the Marche region of Italy. Vet. Parasitol. 113, 243–252. Hummer, D., Symon, K., Groskopf, I., 1992. Seroepidemiologic study of toxocariasis and strongyloidiasis in institutionalized mentally retarded adults. Am. J. Trop. Med. Hyg. 46, 278– 281. Loh, A.G., Israf, D.A., 1998. Tests on the centrifugal flotation technique and its use in estimating the prevalence of Toxocara in soil samples from urban and suburban areas of Malaysia. J. Helminthol. 72, 39–42. Ruiz de Yba´ n˜ ez, M.R., Garijo, M.M., Alonso, F.D., 2001. Prevalence and viability of eggs of Toxocara spp. and Toxascaris leonina in public parks in Eastern Spain. J. Helminthol. 75, 169– 173. Shimizu, T., 1993. Prevalence of Toxocara eggs in sandpits in Tokushima city and its outskirts. J. Vet. Med. Sci. 55, 807–811. Uga, S., Matsumura, T., Aoki, N., Kataoka, N., 1989. Prevalence of Toxocara species eggs in the sandpits of public parks in Hyogo prefecture, Japan. Jpn. J. Parasitol. 38, 280–284. Uga, S., 1993. Prevalence of Toxocara eggs and number of faecal deposits from dogs and cats in sandpits of public parks in Japan. J. Helminthol. 67, 78–82. Uga, S., Kataoka, N., 1995. Measures to control Toxocara egg contamination in sandpits of public parks. Am. J. Trop. Med. Hyg. 52, 21–24. Uga, S., Minami, T., Nagata, K., 1996. Defecation habits of cats and dogs and contamination by Toxocara eggs in public park sandpits. Am. J. Trop. Med. Hyg. 54, 122–126. Uga, S., Matsuo, J., Kimura, D., Rai, S.K., Koshino, Y., Igarashi, K., 2000. Differentiation of Toxocara canis and T. cati eggs by light and scanning electron microscopy. Vet. Parasitol. 92, 287– 294. Wu, Z., Nagano, I., Xu, D., Takahashi, Y., 1997. Primers for polymerase chain reaction to detect genomic DNA of Toxocara canis and T. cati. J. Helminthol. 71, 77–78.
Prevalence of fecal contamination in sandpits in public parks in Sapporo City, Japan Junji Matsuo*, Satoshi Nakashio Division of Medical Technology, Department of Health Sciences, Hokkaido University School of Medicine, North-12, West-5, Kita-ku, Sapporo 060-0812, Japan Accepted 4 November 2004
Abstract A total of 107 sandpits in public parks in Sapporo City were examined, 9 and 73 were contaminated with helminth eggs and fecal coliforms, respectively. Of the nine in which eggs were detected, eight were contaminated with Toxocara spp. and one with Capillaria spp. eggs. The contamination rate of sandpits of more than 30 m2 ranged from 43 to 50%, while in those 30 m2 or less it was between 73 and 92%. Although helminth eggs were evenly distributed throughout all layers of the sandpits, fecal coliforms were localized on the sandpit surfaces. Recovered Toxocara eggs were identified according to their size and surface structures, and almost all eggs were T. cati. Based on these results, and given the inherent habits of cats, measures to prevent their defecation in sandpits are needed, especially ones of smaller size. # 2004 Elsevier B.V. All rights reserved. Keywords: Toxocara; Egg; Contamination; Sandpit
1. Introduction Toxocara canis and T. cati are the common roundworms of dogs and cats, respectively, and are considered causative agents of human toxocariasis, which occurs by accidental ingestion of embryonated eggs (Despommier, 2003; Fisher, 2003). In a seroepidemiological study, Hummer et al. (1992) ascertained that institutionalized adults with mental retardation are at a high risk from toxocariasis. * Corresponding author. Tel.: +81 11 706 2830; fax: +81 11 706 4916. E-mail address: [email protected] (J. Matsuo).
Children also have a potentially higher risk of infection with Toxocara spp. because of pica habits and regular contact with sandpits contaminated with eggs (Despommier, 2003; Fisher, 2003). Thus, it is suspected that human toxocariasis is closely associated with environmental conditions. Contamination of soil with Toxocara eggs has been reported in public parks, school playgrounds, and gardens, and the prevalence of Toxocara eggs in sandpits varies from 0 to 75%; however, especially public parks in urban or suburban areas have been found to be highly contaminated (Dunsmore et al., 1984; Duwel, 1984; Uga et al., 1989; Shimizu, 1993; Uga, 1993; Abe and Yasukawa, 1997; Loh and Israf,
0304-4017/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2004.11.008
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J. Matsuo, S. Nakashio / Veterinary Parasitology 128 (2005) 115–119
1998; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). The reasons for this are thought to be because almost all the ground is paved, and because pets frequent these areas (Uga et al., 1989; Shimizu, 1993; Alonso et al., 2001; Despommier, 2003). Measures to prevent sandpit contamination have been studied. Uga and Kataoka (1995) and Abe and Yasukawa (1997), for example, evaluated measures required to control fecal contaminations, such as sand replacement or fence construction. Such preventative methods are only being slowly instituted and do not completely prevent Toxocara egg contamination, for which no really effective method has yet been found. As a prophylaxis against toxocariasis, is it therefore important to understand the current status of fecal contamination of sandpits. This study aimed to provide information on the extent of fecal contamination in sandpits in public parks in Sapporo, Japan, and to ascertain the relationship between contamination rates and environmental factors, as well as the distribution of sandpit contamination. Additionally, from the morphological features of the Toxocara eggs recovered from sandpits, an attempt was made to determine the animals mainly responsible for defecating in them.
2. Materials and methods 2.1. Study area The survey was carried out from June to December 2003 in East and West Sapporo, Northern Japan. Sapporo City has a mean annual air temperature of 8.5 8C, a mean annual air humidity of 68%, and on average 496 cm of snowfall a year. Both study areas are residential; however, the Western area contains some mountainous parts.
were examined in more detail. To reveal the horizontal and vertical distributions of helminth eggs or fecal coliforms, soil samples were collected from various sites (horizontally from outer, inner, and central areas and vertically from depths of 3 and 15 cm). 2.3. Detection of helminth eggs Helminth eggs were detected as described previously (Uga and Kataoka, 1995), except that the sucrose solution used had a specific gravity of 1.27. Briefly, soil samples were dried overnight at room temperature then filtered using a 150-mm mesh sieve. Approximately 2 g of the powdery sand was placed in a tube, washed with 0.5% Tween 80 solution, and suspended in sucrose solution. The suspension was mixed well and centrifuged at 500 g for 10 min. Next, tubes containing the suspension were filled to the brim with additional sucrose solution and covered with a cover slip. After a final centrifugation of the tube together with the cover slip at 45 g for 5 min, the cover slip was transferred to a glass slide and examined at 100 magnification. 2.4. Detection of fecal coliforms To detect fecal coliforms, soil samples were examined using the most probable number (MPN) method with EC broth (Nissui, Tokyo, Japan) within 2 h of soil collection. A 10-g soil sample was suspended in 90 ml of sterilized phosphate buffered saline (pH 7.2), agitated thoroughly, and diluted to 10 1. Ten- or one-milliliter aliquots of each suspension were inoculated into sets of five tubes containing EC broth. Culture was conducted at 44.5 8C for 24 h in a water bath. The MPN of fecal coliforms was calculated from the numbers in the positive tubes. 2.5. Data analysis
2.2. Recovery of soil A total of 107 sandpits in public parks were randomly selected and examined. Soil from a depth of approximately 3 cm of the sandpit was collected into polythene bags, and taken to the laboratory for analysis. Helminth eggs and fecal coliforms were adopted as the indicators of fecal contamination. Nine sandpits were contaminated with helminth eggs and so
Data analysis of the relationship between contamination rates and environmental factors was conducted using the Mann–Whitney U-test. The horizontal and vertical distributions of sandpit contamination were analyzed with the Kruskal–Wallis test and Mann– Whitney U-test, respectively. The remaining tests were conducted with the x2-test. Statistical significance was defined as p < 0.05.
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117
3. Results 3.1. Prevalence of fecal contamination Of the 107 soil samples examined, 9 (8%) and 73 (68%) were contaminated with helminth eggs and fecal coliforms, respectively (Table 1). Both helminth eggs and fecal coliforms were recovered from eight sandpits. There was no significant difference between the contamination rates of the East and West study areas (p > 0.05). Of the nine sandpits in which helminth eggs were detected, eight were contaminated with Toxocara spp. eggs and one with Capillaria spp. eggs. Egg counts for positive samples varied from 1 to 3 eggs per soil sample. The relationship between contamination rates and two environmental factors studied, namely the sizes of the parks and sandpits, are shown in Fig. 1. Helminth eggs and fecal coliforms were evenly detected in parks of different sizes; however, smaller sandpits were contaminated with fecal coliforms to a greater extent than the bigger ones (p < 0.05). That is, the contamination rates of sandpits of more than 30 m2 ranged from 43 to 50%, while those of sandpits 30 m2 or less were between 73 and 92%. 3.2. Distribution of fecal contamination Further surveys carried out on the nine sandpit samples initially determined to be contaminated with helminth eggs revealed that seven continued to be contaminated; four with Toxocara eggs, and three with Capillaria eggs. Table 2 shows horizontal and vertical distributions of fecal contamination, respectively. Helminth eggs were detected in six outer, seven inner, and seven central horizontal study sites, and vertically in nine surface and eleven deep layer sites. There were no significant differences between horizontal and vertical distributions (p > 0.05);
Table 1 Contamination rates of sandpits in public parks in Sapporo City Area
East West a
No. of parks examined
No. of sandpits contaminated with (%) Fecal coliforms
Helminth eggs
50 57
32 (64) 41 (72)
5 (10) 4 (7)
a
p > 0.05 with the x2-test.
a
Fig. 1. Contamination rates of different sized parks (A) and sandpits (B). Note that some sandpits (n = 29) were excluded from Fig. 1B because their size was unknown. There was a significant relationship between contamination rates and sandpit size using the Mann– Whitney U-test (p < 0.05).
Table 2 Distribution of fecal contamination in sandpits Position
No. of sandpits contaminated with Fecal coliforms (MPN/g)a
Horizontal Outer Inner Central
Helminth eggsb
<0.2
0.2–10
10<
0 2 2
12 5 9
6 11 7
6 7 7
9 17
17 7
9 11
Vertical (depth (cm)) 3 1 15 3
a p > 0.05 with the Kruskal–Wallis test among horizontal position; p < 0.05 with the Mann–Whitney U-test among vertical position. b p > 0.05 with the x2-test among each position.
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Table 3 Morphological characteristics of Toxocara eggs detected in sandpits Park no.
22 47 50 66 Referencea a
No. of eggs detected
4 3 7 8 T. canis T. cati
Size (mm)
Types of surface structure (%)
Major axes
Minor axes
T. canis
T. cati
Intermediate
68.9–73.8 71.3–78.7 64.0–78.7 66.4–78.7 71.6–91.2 63.7–88.1
59.0–61.5 61.5–64.0 54.1–64.0 54.1–68.9 64.4–79.0 53.3–73.3
1 (25) 0 (0) 0 (0) 0 (0) (89) (5)
1 (25) 2 (67) 4 (57) 4 (50) (1) (67)
2 (50) 1 (33) 3 (43) 4 (50) (11) (22)
Uga et al. (2000).
however, more than 10 MPN/g of fecal coliforms were recovered in surface layers of 17 sites and in deeper layers of 7 sites (p < 0.05). 3.3. Morphological characteristics of the recovered Toxocara eggs A total of 22 Toxocara eggs, all embryonated, were recovered from four sandpits. Of these, 10 (45%) contained motile larvae (data not shown). The morphological characteristics of the recovered Toxocara eggs are shown in Table 3. The major and minor axes of the eggs were 64.0–78.8 mm and 54.1– 68.9 mm, respectively. Eggs were classified based on the surface structures observed by light microscopy (Uga et al., 2000); one (5%) was T. canis, 11 (50%) were T. cati, and the remaining 10 (45%) were of intermediate type.
4. Discussion The present study was carried out to ascertain contamination rates in local sandpits in Sapporo. Over the past two decades, many reports have documented contamination rates of Toxocara eggs in Japan (Uga et al., 1989; Shimizu, 1993; Uga, 1993; Abe and Yasukawa, 1997) and other countries (Dunsmore et al., 1984; Duwel, 1984; Loh and Israf, 1998; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). Although it is not possible to compare this study directly with these other surveys because of the different sampling and detection methods used (Ruiz de Yba´ n˜ ez et al., 2001), the contamination rates observed here are relatively similar to those reported previously. Eggs of Ancylostomidae, Trichuris, Capirallia, and Toxascaris
leonina have been reported as recovered from sandpits in public parks (Uga et al., 1989; Alonso et al., 2001; Ruiz de Yba´ n˜ ez et al., 2001). Here, Toxocara and Capillaria eggs were detected; it is possible that these results show differences in parasitic fauna in different regions. Fecal contamination of sandpits was not related to the size of the park, but was associated with sandpit area. That is, smaller sandpits were more highly contaminated with fecal coliforms. One reason might be that as defecation habits of dogs and cats do not depend on sandpit size and since fecal bacteria concentrations are not diluted in soil, fecal coliforms would thus be detected at higher rates in small sandpits. Uga (1993) reported widespread contamination of sandpits with eggs, but less contamination with Toxocara eggs in deeper layers. In the present study, helminth eggs were evenly distributed throughout all layers of the sandpits as in the past survey. It has been shown that animal defecations are distributed evenly (Uga et al., 1996) possibly as a result of earthworms and small mammals (Despommier, 2003; Fisher, 2003). Fecal coliforms, however, were found localized on sandpit surfaces where they might easily die. To prevent fecal contamination, it is important to identify the main animal responsible for defecating in sandpits. By examining the surface structures of eggs, some attempts have been made to identify Toxocara species. Ratios of T. canis to T. cati have been previously reported as 1:3 or 2:3 using scanning electron microscopy (Uga et al., 1989; Shimizu, 1993). However, using light and scanning electron microscopy, Uga et al. (2000) showed that the surface coat of Toxocara eggs has some diversity. Although PCR technique can identify more accurately
J. Matsuo, S. Nakashio / Veterinary Parasitology 128 (2005) 115–119
(Wu et al., 1997), because of the complexity of the manipulation, in this study Toxocara eggs were comprehensively identified by size and surface structures. Consequently, almost all the Toxocara eggs were identified as T. cati, showing that cats were the main contaminating animals. This result is in accordance with 144 days of camcorder observation (Uga et al., 1996); however, that method is relatively time-consuming. The zoonotic potential of T. cati is underestimated compared with T. canis with regards to human toxocariasis (Fisher, 2003); however, in this study, sandpits were highly contaminated with T. cati eggs. As a prophylaxis against human toxocariasis, preventative measures reflecting the inherent habits of cats need to be implemented. Further, the administration of antihelminthics by veterinarians (Habluetzel et al., 2003) or the better education of pet owners may be effective reducing the occasions of parasitic infection. It is also important for children to be made better aware of the need to wash after playing in sandpits.
Acknowledgement The authors thank Dr. Shoji Uga of Kobe University School of Medicine, Kobe, Japan for kindly supplying the instruments for parasite egg examination.
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