Prevalence of Toxocara canis ova in public playgrounds in the Dublin area of Ireland

Toxocara Infection in Dogs and Cats in Isfahan Province of Iran in 2021

Background

Toxocariasis is an acute or chronic disease caused by parasites of the Ascaridae family, especially Toxocara of dogs and cats. Eggs are excreted out by feces of these animals on soil. Infective eggs develop on soil which can be infective to human. In this study, infection rate of Toxocara spp. in dogs and cats of urban and rural areas of Isfahan province of Iran has been investigated.

Materials and Methods

Three hundred and seventy-five stray dog feces and 230 stray cat feces were collected from the public environment (slaughterhouses, parks, children's playgrounds, student dormitories, university environment, streets and squares) in Isfahan province of Iran. At first, dogs' and cats' feces were examined for the presence of Toxocara spp. eggs using formalin ether method. In the second stage, by using molecular methods, Toxocara eggs spp. (Toxocara canis or Toxocara cati) were identified.

Results

From 375 dog fecal samples, 39 (10.40%) and from 230 cat fecal samples, 38 (16.52%) were positive for presence of the Toxocara eggs.

Conclusion

Dogs and cats in Isfahan province of Iran were infected with Toxocara parasite. These infections can be potential risk for human toxocariasis.

WormWatch: Park soil surveillance reveals extensive Toxocara contamination across the UK and Ireland

BACKGROUND

Toxocarosis is a globally distributed zoonotic disease, but sources of infection are not well documented over large geographical scales. To determine levels of environmental contamination, soil from 142 parks and recreational areas across the UK and Ireland was assessed for the presence of Toxocara.

METHODS

Toxocara ova (eggs) were isolated from soil samples by sieving and flotation and then enumerated. Individual eggs were isolated and imaged, and a subset was characterised by species-specific PCR and Sanger sequencing.

RESULTS

Characteristic Toxocara-type eggs were found in 86.6% of parks, with an average of 2.1 eggs per 50 g of topsoil. Representative eggs were confirmed as Toxocara canis by Sanger sequencing, with many eggs containing developed larvae, hence being viable and potentially infective. Positive samples were more common, and egg density was higher, in parks with greater perceived levels of dog fouling.

LIMITATIONS

Samples were collected at a single timepoint and with limited spatial mapping within parks. Further study is needed to discern spatiotemporal differences within parks and recreational areas.

CONCLUSION

Toxocara is widespread in soil in public parks, indicating a need for further efforts to reduce egg shedding from pet dogs. Standardised methods and large-scale surveys are required to evaluate risk factors for egg presence and the impact of interventions.

Potentials and challenges in the isolation and detection of ascarid eggs in complex environmental matrices

Ascarid infections constitute a major concern for both human and animal health risk assessment. Although being effectively transmitted by soil, water and contaminated food, reliable detection of ascarid eggs in environmental media often remains challenging. However, contamination of the environment with ascarid ova has gained more attention as a decisive part of proper risk assessment in recent years. Due to various factors, such as sample matrices, dissociation detergents and flotation solutions, defined and standardised protocols for the isolation of eggs from complex environmental matrices are difficult to establish and therefore limited. Thus, this study reviews common techniques used for the recovery of ascarid eggs from environmental media with special emphasis on sampling strategies, purification procedures and microscopic as well as molecular detection of egg contamination. Despite various advancements, mainly in the field of molecular methods leading to more reliable and sensitive detection, it can be concluded that there is still a need for unified guidelines for sampling and recovery of ascarid eggs derived from complex environmental matrices.

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Standardised methods to assess environmental ascarid egg contamination are needed.

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The environmental sampling strategy has to be adapted to the study hypothesis.

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Egg detection mostly relies on matrix homogenisation, filtration, sedimentation and flotation.

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Microscopic detection is still frequently applied.

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Molecular methods enable more reliable and sensitive detection.

Insights into geohelminth contamination in Bangladesh: feasibility of a modified diagnostic method and prevalence study

INTRODUCTION

The objectives of this study were to evaluate a modified method for isolating geohelminth eggs and to assess the geohelminth contamination in Bangladesh.

METHODS

The efficacy of the modified method was evaluated using naturally contaminated and experimentally seeded soil samples. In total, 240 samples were assessed from four different sites in three geographic contexts. A questionnaire survey with 50 professionals was conducted.

RESULTS

The modified method showed considerable efficacy in isolating parasitic eggs from naturally contaminated soil (54.0%) and experimentally seeded soils (63.0% for Toxocara eggs and 52.0% for Ascaris eggs). The modified method was described as convenient by the majority of participants. Overall prevalence was 52.5%, with several species of helminth observed, including Toxocara sp., Ascaridia galli/Heterakis gallinarum, Ascaris sp., hookworms/strongyles, Capillaria sp., Trichuris sp., and taeniids). The contamination rate was found to be higher around livestock farms (76.7%), followed by latrines (63.3%), households (41.6%), and schools (28.3%).

CONCLUSIONS

The modified method was shown to be feasible in terms of field applicability and egg recovery rate, and could be adopted in low-resource settings. A substantial prevalence of geohelminths was observed, with some of the species associated with zoonoses. These findings highlight the urgent need for widespread mapping of geohelminths to avoid spillovers to animals and humans.

Screening of Zoonotic Parasites in Playground Sandboxes of Public Parks from Subtropical Mexico

The pathological agents Toxoplasma gondii, Ancylostoma caninum, and Toxocara canis are widely distributed zoonotic parasites with high prevalence in tropical and subtropical regions of the world. The aim of the present study was to determine the presence of DNA from these parasites in sand samples from the sand playgrounds in the southeastern region of Mexico. Samples of sand were collected from 68 playgrounds in public parks in the city of Merida, Yucatan, which is the main urban area in the southeast of Mexico. The samples were examined using nested PCR to detect the SAG1 gene from Toxoplasma gondii, and endpoint PCR for the amplification of ITS-2 and rRNA-ITS2 genes from Toxocara canis and Ancylostoma caninum, respectively. The presence of T. gondii DNA was detected in 11.8% (8/68) samples, DNA from A. caninum and T. canis was not detected. Results indicate that playgrounds from the studied sandboxes are contaminated with T. gondii oocysts and may represent a risk of infection for people in contact with the sand, especially for preschoolers.

Substrate type and age are risk factors for gastrointestinal parasitism in greyhound kennels

The control of parasitic infections is particularly challenging in environments that are conducive to the maintenance of parasite lifecycles, such as the greyhound kennel, where the long-term breeding and rearing of dogs is common. The prevalence of gastrointestinal (GI) parasites within the Australian greyhound population has never previously been assessed, which seriously constrains the implementation of effective control measures. The aims of this study were to determine the prevalence and risk factors for GI parasites in Australian greyhounds, identify parasites which may be detrimental to the health and performance of dogs, and evaluate the likelihood of zoonotic transmission to kennel staff. Faecal samples were collected from 721 individual greyhounds situated in kennels across five states of Australia; Western Australia, Queensland, New South Wales, Victoria and Tasmania. Animal husbandry and current parasite control protocols were obtained from each kennel and analysed in conjunction with the detected level of parasitism. Overall parasite prevalence was approximately 60%, ranging from 50 to 70% between states. Eleven parasite genera were identified, with Sarcocystis, hookworm, Giardia and Toxocara detected most frequently. Generalised linear mixed model analyses found the major risk factors associated with parasitism were: a) the type of substrate which dogs were housed; b) age of dogs; and c) geographic region. Parasitism was associated most frequently with young dogs housed on grass/sand substrates, which allowed parasite lifecycles to continue, with constant reinfection the likely outcome. Routine treatment with broad-spectrum anthelmintics did not provide effective control in these environments and the adoption of alternate parasite control strategies is recommended. A substantial risk from zoonotic parasites was also identified, with six of the eleven parasite genera detected considered to be zoonotic and a poor understanding of zoonotic transmission among kennel managers.

Knowledge gaps in the epidemiology of Toxocara: the enigma remains

Toxocara species infect a wide range of companion, domestic and wild animals as definitive and paratenic hosts, via multiple routes of transmission, producing long-lived tissue-inhabiting larvae and resistant eggs that can survive in the external environment. Therefore Toxocara and the disease it causes in humans, toxocariasis, represents an ideal aetiological agent for the development of the one health approach. However, despite increasing awareness of the public health significance of toxocariasis, gaps in our understanding of certain key aspects of the parasite's biology and epidemiology remain. These gaps hinder our ability to integrate research effort within the veterinary, medical and environmental disciplines. This review will highlight key deficits in our understanding of nine dimensions of Toxocara epidemiology and discuss a potential scenario to develop a more integrated, one health approach to improve our understanding of the prevention and control of this complex and cryptic zoonosis.

Methods for Quantification of Soil-Transmitted Helminths in Environmental Media: Current Techniques and Recent Advances

Limiting the environmental transmission of soil-transmitted helminths (STHs), which infect 1.5 billion people worldwide, will require sensitive, reliable, and cost-effective methods to detect and quantify STHs in the environment. We review the state-of-the-art of STH quantification in soil, biosolids, water, produce, and vegetation with regard to four major methodological issues: environmental sampling; recovery of STHs from environmental matrices; quantification of recovered STHs; and viability assessment of STH ova. We conclude that methods for sampling and recovering STHs require substantial advances to provide reliable measurements for STH control. Recent innovations in the use of automated image identification and developments in molecular genetic assays offer considerable promise for improving quantification and viability assessment.

Environmental contamination by canine geohelminths

Intestinal nematodes affecting dogs, i.e. roundworms, hookworms and whipworms, have a relevant health-risk impact for animals and, for most of them, for human beings. Both dogs and humans are typically infected by ingesting infective stages, (i.e. larvated eggs or larvae) present in the environment. The existence of a high rate of soil and grass contamination with infective parasitic elements has been demonstrated worldwide in leisure, recreational, public and urban areas, i.e. parks, green areas, bicycle paths, city squares, playgrounds, sandpits, beaches. This review discusses the epidemiological and sanitary importance of faecal pollution with canine intestinal parasites in urban environments and the integrated approaches useful to minimize the risk of infection in different settings.

Detection of Toxocara eggs in contaminated soil from various public places of Chennai city and detailed correlation with literature

Toxocarosis is one of the most prevalent human helminthosis caused by larvae of Toxocara canis and Toxocara cati, the most widely distributed nematode parasites of dogs and cats respectively. Soil is considered as the principal source of transmission of Toxocara infection to human beings. With increasing population of dogs and cats, soil contamination with ova or eggs of Toxocara can be detected in public and private locations of city backyards, playgrounds, streets, sand pits and so on, regardless of the season of the year. In this context the present study was carried out to estimate the extent of soil contamination with Toxocara eggs in public parks, playgrounds and few kennels situated in different parts of Chennai city. A total of 105 soil samples from 40 public places and 5 kennels were screened for the presence of parasitic eggs. Toxocara eggs were recovered from 5 soil samples indicating an overall prevalence rate of 4.75 %. Out of 80 samples collected from public places, three samples, one each from Mogappair, My lady park (Periamet) and Madras Veterinary College showed the presence of Toxocara spp. eggs indicating an overall prevalence of 3.75 per cent. Out of the 25 samples from 5 kennels, two samples one each from Tambaram and Thorappakkam kennels were positive for Toxocara eggs with prevalence of 8 per cent. Low prevalence of Toxocara eggs in soil samples of these areas can be attributed to the less population of pups, the carriers of adult worms and the active source of soil contamination. The progress made in ABC (animal birth control) programme carried out by both governmental and non-governmental organizations has contributed to reduction of birth rate in dogs and thereby reduced the chances of soil contamination with Toxocara eggs to a certain extent in Chennai city.

Comparative evaluation of flotation techniques for the detection of soil borne parasites

Efficacy of the three conventional flotation techniques in recovering the parasitic forms from soil samples was compared after screening both naturally contaminated and experimentally seeded soil samples. Out of 200 soil samples screened from different locations of Rayalaseema region of Andhra Pradesh, parasitic stages were isolated in 62 (31.0 %), 32 (16.0 %) and 16 (8.0 %) samples by O'Lorcain (J Helminthol, 68:237-241,1994), Kazakos (Am J Vet Res 44:896-900, 1983) and Santarém et al. (Rev Inst Med trop Sao Paulo 51(3):163-167, 2009) methods, respectively. One hundred and forty-four soil samples were seeded with two different concentrations (100/200) of the eggs of Toxocara spp., Ascaris spp. and Ancylostoma spp. and oocysts of Eimeria spp. and were processed by these techniques. Irrespective of parasitic species or concentration, the mean recovery rate of parasitic stages obtained was above 50 ± 4.32, above 33.67 ± 5.084 and below 22.33 ± 2.37 percent by O'Lorcain (1994), Kazakos (1983) and Santarém et al. (2009) methods, respectively. O'Lorcain (1994) method was found better than the other methods for the isolation of soil borne parasitic stages but none of these methods were found to be cent per cent sensitive.

Antagonistic activity of the fungusPochonia chlamydosporiaon mature and immatureToxocara caniseggs

In vitrotests were performed to evaluate the ability of 6 isolates of the nematophagous fungusPochonia chlamydosporiato infect immature and matureToxocara caniseggs on cellulose dialysis membrane. There was a direct relationship between the number of eggs colonized and the increase in the days of interaction, as well as between the number of eggs colonized and the increase in the concentration of chlamydospores (P<0·05). Immature eggs were more susceptible to infection than mature eggs. The isolate Pc-04 was the most efficient egg parasite until the 7th day, and showed no difference in capacity to infect mature and immature eggs in comparison to Pc-07 at 14 and 21 days of interaction, respectively. Isolate Pc-04 was the most infective on the two evolutionary phases of the eggs at most concentrations, but its ability to infect immature eggs did not differ from that presented by the isolates Pc-07 and Pc-10 at the inoculum level of 5000 chlamydospores. Colonization of infective larvae inside or outside the egg was observed in treatments with the isolates Pc-03, Pc-04, Pc-07 and Pc-10. The isolate Pc-04 ofP. chlamydosporiahas great biological capacity to destroy immature and matureT. caniseggs in laboratory conditions.

A comparison of Toxocara canis embryonation under controlled conditions in soil and hair

Toxocara spp. eggs require a period of time under appropriate environmental conditions to become infective to definitive and paratenic hosts. Temperature and humidity are important factors known to affect the levels of development in soil. We aimed to investigate whether the eggs of T. canis could embryonate in dog hair under controlled conditions of temperature and humidity and, if so, to what degree. No previous work had been carried out on embryonation in hair under controlled conditions. Soil samples exposed to the same conditions as the hair samples were considered a suitable comparison in order to investigate differing levels of development. Development at two temperatures (10°C and 20°C) and the addition of water to samples was investigated over a period of 8 weeks. Importantly, we demonstrated that unembryonated T. canis eggs are capable of development in hair under controlled conditions. The rate of development is lower than that observed in soil, but remains biologically significant in terms of the overall numbers of potentially infective embryonated eggs present. Temperature is responsible for the rate of embryonation while moisture is essential for encouraging development and maintaining egg viability in general. In light of these findings the transmission of Toxocara spp. as a result of direct contact with well-cared-for owned dogs seems unlikely, but should not be ignored.

Role of dog behaviour and environmental fecal contamination in transmission ofEchinococcus multilocularisin Tibetan communities

On the Eastern Tibetan Plateau region (Sichuan province, China) dogs are regarded as important definitive hosts ofEchinococcus multilocularis. We studied dog spatial behaviour in 4 Tibetan villages in order to determine the role of dogs in environmental contamination and their potential interactions with small mammal intermediate hosts. We identified definitive host species andEchinococcusspp. infection status of feces collected in the field by PCR methods and analysed the spatial distribution of canid feces. Nocturnal space utilization of GPS collared dogs in and around villages was also undertaken.E. multilocularisDNA was amplified in 23% of dog feces (n=142) and in 15% of fox feces (n=13) but this difference was not significant. However, dog feces were more frequently observed (78% of collected feces) than fox feces and are therefore assumed to largely contribute to human environment contamination. Feces were mainly distributed around houses of dog owners (0–200 m) where collared dogs spent the majority of their time. Inside villages, the contamination was aggregated in some micro-foci where groups of dogs defecated preferentially. Finally, small mammal densities increased from the dog core areas to grasslands at the periphery of villages occasionally used by dogs; male dogs moving significantly farther than females. This study constitutes a first attempt to quantify in a spatially explicit way the role of dogs inE. multilocularisperi-domestic cycles and to identify behavioural parameters required to modelE. multilocularistransmission in this region.

Developmental age, physical fitness andToxocaraseroprevalence amongst lower-secondary students living in rural areas contaminated withToxocaraeggs

Scarce and inconclusive information on general biological impact ofToxocarainvasion on paratenic hosts, and people in particular, has led us to undertake a comprehensive study of the problem. The study has been conducted in a rural environment, which is considered a toxocarosis risk factor. In total 200 soil samples have been screened forToxocaraeggs by flotation, of which 14·5% were positive. Backyards close to households were most heavily contaminated with infectious eggs – 21·7% of positive samples. ELISA serological tests performed on 242 lower-secondary students found 14·5% of the studied population to be definitely positive – 16·5% of boys and 12·8% of girls, respectively. The odds of being infected withToxocarawere 2 times (CI: 1·15–3·85) more likely for individuals who owned a cat than those who did not own a cat. Strong significant correlation between seropositivity and the presence of a dog in a household was found with boys. The level of developmental age was significantly higher in seropositive than in seronegative students. No significant correlation has been observed between the motor abilities and seropositivity of students. Seropositive boys had significantly lower end-of-year grades than their seronegative counterparts.

Contamination of dog hair with eggs of Toxocara canis

Toxocara canis, the common intestinal nematode of dogs and foxes, is the parasite responsible for human toxocarosis. It has recently been shown that dogs may harbour eggs of the parasite in their fur. To further investigate this claim a population of 100 stray dogs was examined to establish the prevalence and intensity of adult toxocaral worm infection in the intestines and eggs harboured in the hair. A novel method of washing the eggs from the hair was used. Sixty-seven percent of dogs were found to have T. canis eggs on their hair with a mean egg retrieval of nearly 584 eggs per gram from positive dogs. The age of the dog was found to be the only significant factor to influence the prevalence and intensity of eggs, with 95% of all the eggs recovered found on puppies. Thirty-nine percent of dogs were found to have adult T. canis worms in their intestine, although a significantly higher percentage of puppies (80%) were infected with worms than adults (22.5%). Puppies also had more worms per infection than adults and have a strong positive correlation between egg and worms numbers whereas adults did not. These studies show that stray dogs, particularly puppies, potentially harbour considerable numbers of eggs on their hair, at densities far higher than those reported in the soil or the general environment.

Prevalence of Toxocara spp., Toxascaris leonina and ancylostomidae in public parks and beaches in different climate zones of Costa Rica

This epidemiological study was conducted in different regions of Costa Rica to determine the prevalence of the developmental stages of potential zoonotic intestinal helminths of dogs and cats in public places. Samples were collected within three main climate zones including rural and urban areas during both the rainy and the dry season. Faecal and environmental samples were taken from 69 parks and beaches. Of the faecal samples 3% contained Toxascaris spp. eggs, 7% Toxocara spp. eggs and 55% contained ancylostomidae eggs. Of the soil samples, 2% contained ancylostomidae eggs and 0.8% contained ascarid eggs. Significant differences in the presence of parasites were found in faecal samples of dry, moist and wet climate zones and between the dry and rainy seasons. Significant differences in the presence of eggs and larvae were also found in the grass samples in the dry, the moist and the wet climate zones and between the different seasons. No significant differences were found between rural and urban areas.

Effects of temperature and humidity on the development of eggs of Toxocara canis under laboratory conditions

The influence of temperature and humidity on the survival and development of Toxocara canis eggs in an in vitro model system was investigated. Two soil samples were inoculated with T. canis eggs and maintained at 3% and 50% humidity and temperatures of 19-24 degrees C. Nine soil samples were inoculated with T. canis eggs of which three samples were kept at 4 degrees C with humidities at 3%, 15%, and 30%; three were maintained at 21 degrees C and three more were incubated at 34 degrees C, and at the same three humidity levels. Samples were monitored every 7 days for a total of 2 months, for the presence and development of eggs. With increasing temperature, the number of eggs undergoing development increased (P<0.01); the number of deformed eggs decreased, the number of infective eggs increased (P<0.01), and egg maturation was accelerated. A decrease in the survival of infective eggs occurred at 34 degrees C. An increase in humidity produced a rise in the number of developed eggs at all three temperatures (P<0.01). This study suggests that elevated temperatures accelerated the development as well as the degradation of eggs of T. canis, whereas the range in humidity was directly correlated with egg development.

Human behaviour and the epidemiology of parasitic zoonoses

The behaviour of Homo sapiens has a pivotal role to play in the macro and microepidemiology of emerging or re-emerging parasitic zoonoses. Changing demographics and the concomitant alterations to the environment, climate, technology, land use and changes in human behavior, converge to favour the emergence and spread of parasitic zoonoses. The recent unprecedented movements of people, their animals and their parasites around the world, introduce and mix genes, cultural preferences, customs, and behavioral patterns. The increasing proclivity for eating meat, fish, crabs, shrimp, molluscs raw, undercooked, smoked, pickled or dried facilitates a number of protozoan (Toxoplasma), trematode (Fasciola sp., Paragonimus spp., Clonorchis sp., Opisthorchis spp., Heterophyes sp., Metagonimus sp., Echinostoma spp., Nanophyetus sp.) cestode (Taenia spp, Diphyllobothrum sp.) and nematode (Trichinella spp., Capillaria spp., Gnathostoma spp., Anisakis sp., Parastrongylus spp.) caused zoonoses. The increasing world population and the inability to keep pace with the provision of adequate sanitation and clean, safe drinking water, has led to an increased importance of waterborne zoonoses, such as those caused by Giardia, Cryptosporidium and Toxoplasma. Our close relationship with and the numerous uses to which we put companion animals and their ubiquitous distribution has resulted in dogs and cats unwitting participation in sharing over 60 parasite species including: Giardia, Cryptosporidium, Toxoplasma, most foodborne trematode species, Diphyllobothrum, Echinococcus spp., Ancylostoma and Toxocara. Changing human behaviour through education, to encourage the proper cooking of food, which may have cultural and social significance, will remain as challenging as controlling stray and feral pet populations, improving hygiene levels and the provision of safe drinking water and the proper use of sanctuary facilities. Long pre-patent periods and the normally insidious sub-clinical nature of most zoonoses makes advice requiring behavioural change for their control a difficult task. Our clearer understanding of the heterogeneity of susceptibility to infection, the complex genetic variations of people and parasite species and the development of molecular epidemiological tools is shedding more light on transmission routes and the spectrum of disease that is observed. Improved and new serological, molecular and imaging diagnostic tests and the development of broad spectrum chemotherapeutic agents has led to the attenuation of morbidity and mortality due to parasitic zoonoses in economically advantaged regions. Such advancements, in partnership with supportive behavioural change, has the potential for a sustainable global reduction in the burden of ill health due to parasitic zoonoses. Whether this will materialise is a challenge for us all.

Ocular Toxocariasis in Schoolchildren

Ocular toxocariasis in humans is typically a unilateral disease caused by second-stage larvae of the Toxocara species. Serological evidence of widespread infection in humans provides little information on clinical disease. There is only a single previous estimate of the prevalence of ocular toxocariasis (from Alabama). The present survey examined the extent of consultant-diagnosed toxocaral eye disease among a population of schoolchildren. More than 120,000 participants were surveyed by questionnaire and follow-up. Two sets of control subjects from the same school and from the same county were compared with persons who had ocular toxocariasis. The prevalence of consultant-diagnosed toxocaral eye disease was 6.6 cases per 100,000 persons when only cases regarded as definite by the consultant ophthalmologist were included. This increased to 9.7 cases per 100,000 persons when both definite and strongly suspected cases were included. Geophagia and a history of convulsion were associated with toxocaral eye disease in both of the case-control studies.

Human toxocariasis and direct contact with dogs

Toxocariasis in man is traditionally thought to be contracted through the ingestion of eggs from contaminated soil. The disease may manifest itself in different syndromes such as ocular larval migrans, visceral larval migrans and covert toxocariasis. This paper assesses the evidence for the soil contamination hypothesis and proposes that direct contact with dogs may provide a better explanation of the epidemiology of the disease. Hair was collected from 60 dogs from various places in Ireland and the UK and examined for the presence of Toxocara canis eggs. T. canis eggs were found in the hair of 25 per cent of the dogs; in total, 71 eggs were recovered, of which 4.2 per cent were embryonated and 23.9 per cent were embryonating. The maximum densities of the embryonating and embryonated eggs were 180 and 20 eggs per gram of hair, respectively, much higher than the densities reported for soil samples. It is suggested that dogs infected with T. canis may infect people by direct contact.

Toxocara cati: an underestimated zoonotic agent

The role of Toxocara cati as a zoonosis is reviewed. It is suggested that, despite case histories of human infection in the literature, historical factors have led to T. cati being under-recognized as a zoonosis, particularly when compared with the prominence given to Toxocara canis in dogs. Differentiation of the two infections remains challenging even today. It is recommended that further work be conducted to facilitate differentiation so that the importance of T. cati as a zoonosis can be clearly defined.

Toxocara canis: egg presence in Melbourne parks and disease incidence in Victoria

PURPOSE

Toxocara canis can cause blinding eye disease. This study assessed the presence of T. canis eggs in soil from parks in Melbourne and also the incidence of presumed ocular toxocariasis in Victoria.

METHODS

One hundred and eighty soil samples were collected from nine suburban locations in Melbourne, Australia. These were analyzed for the presence of T. canis eggs. A search of laboratory records of T. canis serology requests from Victorian patients over an 8-year period was performed.

RESULTS

Only one soil sample was positive for T. canis eggs. Positive T. canis serology was reported in 13 samples from patients. These patients all had ocular features suggestive of T. canis infection.

CONCLUSION

Toxocara canis eggs are rare in public parks in Melbourne and symptomatic ocular toxocariasis is uncommon in the Victorian population. The acquisition of the disease is unlikely to be from public parks.

The changing epidemiology of echinococcosis in Kazakhstan due to transformation of farming practices

In recent years there has been a substantial increase in cystic echinococcosis in Kazakhstan. There are several factors that have contributed to this change in the epidemiology of the disease. The primary reason was the degradation of traditional nomadic system of livestock breeding and closing of large collective farms. Small private farms have started to keep stock year round in closer proximity to permanent human habitation. Furthermore, routine anthelmintic prophylaxis of dogs has been abandoned and there is inadequate control over the use and disposal of animal carcasses. Large mechanized slaughterhouses are no longer operational. Now more people (7-8 times) and more dogs (8-10 times) participate in the husbandry of 1000 sheep, than during Soviet administration. Because of the close association of dogs with man there is the potential for a substantial increase in eggs and of Echinococcus in immediate environment of inhabited houses. Soil samples taken from 61% of yards of village homes contained taeniid eggs and from 35% of yards from around farmsteads. During an examination of 1464 village dogs the average rate of infection with Echinococcus granulosus was 5.8%, whilst the prevalence in 607 shepherd dogs was 23.2%. At present, these dogs represent a major source of infection for people with this dangerous parasite. Examination of hospital records suggested that children and people in occupations associated with animal husbandry were at most risk of infection.

Environmental and serological evidence for the presence of toxocariasis in the urban area of Ancona, Italy

To evaluate the Toxocara spp. eggs environmental contamination of the soil of the urban or suburban area Ancona (Italy), 22 public playgrounds were selected and several cores of soil were taken from any selected areas. To study the Toxocara seroprevalence in the inhabitants of Ancona, blood samples were collected from selected groups of individuals. One hundred and sixty-three blood samples were tested using an enzyme linked immunosorbent assay (ELISA) technique (Lofarma Lab, Milan, Italy) for the detection of IgG-specific antibodies to T. canis excretory-secretory antigens. Toxocara spp. eggs were found in the soil samples from 14 (63.6%) playgrounds. Toxocara seroprevalence was detected in blood specimens from six (8.1%) out of 74 symptomatic individuals and from one (1.1%) out of 89 asymptomatic controls. Among symptomatic individuals, the association between Toxocara seroprevalence and eosinophilia resulted statistically significant (p = 0.029). The high environmental contamination frequency found make necessary to prompt preventive public health measures, such as control of stray animals, treatment of infected pets and hygiene education of the population.

Improved methods for recovering eggs of Toxocara canis from soil

The ingestion of soil in parks and public places containing eggs of Toxocara may constitute a significant health risk, particularly to children. To determine the most efficient method for extracting eggs from experimentally contaminated soil, two consecutive studies were undertaken. Four techniques, including washing, sieving, vacuum, and the one recommended by the World Health Organization, were evaluated. Recovery rates of over 85% were recorded with both washing and sieving methods. Using the washing technique, all combinations of the four pre-treatment solutions, distilled water, acetoacetic solution pH 5, 0.1 n sodium hydroxide and 1% Tween 20, and seven flotation fluids with different specific gravities (S.G.) ranging from 1.20 to 1.35 were assayed. The association of distilled water and saccharose solution with an S.G. of 1.27 showed the best results, with a recovery rate of 99.91%.

Contaminação, por ovos de Toxocara spp, de parques e praças públicas de Botucatu, São Paulo, Brasil

A freqüência de contaminação de parques e praças públicas de Botucatu, São Paulo, Brasil, por ovos de Toxocara spp foi estudada durante 12 meses, com colheitas mensais de amostras de solo de dez praças, que foram processadas pela técnica de concentração em solução decinormal de hidróxido de sódio. Das 120 amostras analisadas, 21 estavam contaminadas, correspondendo a 17,5%, em um total de seis praças. A maioria desses ovos porém apresentaram características de inviabilidade infectiva. Embora a chance de aquisição dessa zoonose nas praças estudadas seja pequena, existe o risco de infecção da população.

Specific gravity of Opisthorchis viverrini eggs

The specific gravity of the eggs of the liver fluke Opisthorchisviverrini was determined using a sucrose gradient centrifugation and found to range from 1.2713 to 1.3043. The peak egg count was located at the sucrose fraction with a specific gravity of 1.2814. An attempt to float eggs in saturated sodium nitrate solution, sp.gr. 1.4, failed. Examination of human stool specimens for Oviverrini eggs by simple flotation in saturated sodium nitrate solution and the formol-ether sedimentation technique revealed that the flotation technique was not as efficient as the sedimentation technique. It was suggested that the flotation techniques were inappropriate for the detection of Oviverrini eggs in faeces or contaminated soil.

Comparison of methods of sampling for Toxocara species and fecal coliforms in an outdoor day care environment

OBJECTIVE

To compare three sampling methods and to pretest methods for the determination of fecal coliform (FC) counts and Toxocara species from sand in the day care outdoor environment.

DESIGN

The sand samples were obtained from the play area and the sandbox of a day care centre and examined for the presence of FC and Toxocara species, the common roundworm of dogs and cats. The sampling methods included random selection and two types of judgement methods. The latter included one method where domestic animals were judged to be likely to defecate and the other where children would be likely to be playing. In addition, to obtain a global estimate of contamination, the entire areas of both the sandbox and the play area were sampled on the last day.

SETTING

Outdoor day care environment.

MAIN RESULTS

The most representative levels of bacterial contamination and Toxocara species originated from the combined sample of the entire surface areas rather than from any separate random or judgement method of sampling. FCs were found in all sampled areas of the sandbox (median 910 FCs/g of sand) and of the play area (median 350 FCs/g of sand). Toxocara species were recovered from a number of areas in both the sandbox and the play area.

CONCLUSIONS

Research on environmental microbial contamination of outdoor day care settings would benefit from the application of standardized and validated sampling and laboratory methods.

Aspects of Toxocara epidemiology: toxocarosis in dogs and cats

Toxocara canis and Toxocara cati are common roundworms of dogs and cats. In this review the life cycles of these parasites are described, including the various routes of transmission, such as transplacental, transmammary infection, and infection through paratenic hosts. The somatic and tracheal migration in the body of the hosts after infection with Toxocara eggs or larvae is discussed, with special reference to age resistance and differences between dog and cat. The clinical symptoms and pathology in adult and young dogs and cats are given. Diagnosis of patent infections can be obtained by fecal examination, and treatment consists of the use of anthelmintics. Control of the infection and disease is achieved by prevention of contamination of the environment, anthelmintic treatment strategy, and education. Special attention is given to the efficacy of anthelmintics against adult worms and against somatic larvae. It is concluded that education on the life cycles of the parasites, hygiene, and anthelmintic treatment schedules is required because of the zoonotic risks of Toxocara spp. Deworming of pregnant dogs and cats is not recommended.