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PubMed1997

Aspects of Toxocara epidemiology: human toxocarosis.

Toxocarosis is the clinical disease in man caused by infection of zoonotic roundworms of dogs and cats, Toxocara canis and T. cati. In this review the mode of transmission to the human by oral ingestion of Toxocara eggs from the environment is discussed. T. cati seems to play a more important role than generally suggested. Direct contact with animals is not considered a potential risk because embryonation of excreted Toxocara ova requires a minimum of 2 weeks. For the same reason there is no relationship expected between infection and exposure to dogs and cats in the household. Children more frequently have clinical symptoms because of the closer contact with contaminated soil in yards and sandpits, the lack of hygiene, and because of eating dirt. Toxocara larval migration in the body can cause various clinical syndromes. Visceral larva migrans, ocular larva migrans, and covert toxocarosis are described. Serodiagnostic techniques are reliable tools to detect antibodies or antigens. Systemic treatment with anthelmintics is described but can result in hypersensitivity reactions caused by dying larvae. For ocular lesions, laser photocoagulation and corticosteroid therapy are described. Preventive measures consist of preventing contamination of the environment with Toxocara eggs and for education of pet owners and non-pet owners to increase awareness about potential zoonotic hazards. Veterinary practitioners, general practitioners, and public health agencies should therefore provide sufficient information and advice.

Animals↗
PubMed1998

[Toxocariasis in dogs and contamination of soil with Toxocara spp. eggs in the Poznań region].

Dogs and soil samples from Poznań city and the nearby small town Murowana Goślina were surveyed for the presence Toxocara eggs. On the areas examined, the range of dog's infections with T. canis and the contamination of the soil with the infective stage of Toxocara spp. were not paralleled. In Poznań city out of 617 dogs examined 11.8% were infected with adult form of T. canis and since 1980th the prevalence has decreased. In Murowana Goślina as much as 35.2% dogs out of 352 examined were infected. On the contrary the range of soil contamination with Toxocara spp. eggs was higher in Poznań (12% positive soil samples) than in Murowana Goślina (7% positive soil samples). The most heavily contaminated areas in both localities were urban backyards with 19% (Murowana Goślina) and 27% (Poznań) of soil samples positive; a mean egg density was 1.98 eggs/100 g and 0.48 eggs/100 g respectively. Contrary to the generally accepted opinion, the study suggests, that exposure of human population to Toxocara spp. infections may be higher in urban agglomeration than in the country. T. cati infections may be an important cause of human toxocarosis and the court yards as a play-grounds may be more risky source of Toxocara spp. infection than sand-boxes.

Animals↗
PubMed2001

Toxocara in the mouse: a model for parasite-altered host behaviour?

The objective of this paper is to critically evaluate the significance of parasite-altered host behaviour in the Toxocara mouse model particularly in the light of the Manipulation Hypothesis. Murine behaviours were examined in both outbred and inbred strains of mice infected with different doses of Toxocara canis ova. Behaviours investigated included activity, exploration, response to novelty, anxiety, learning, memory and social behaviour. Subsequent modifications to the behaviour of infected mice were investigated with respect to dose administered and larval accumulation in the brain. There was substantial variation in the number of larvae recovered from brains of individual mice, which received similar doses of Toxocara ova. Furthermore, the numbers of larvae recovered at different doses differed significantly between an outbred and inbred strain of mouse. Alterations in infected host behaviour occurred and were related to the number of larvae recovered from the brain. For social behaviour in outbred mice, a high infection in the brain reduced levels of aggressive behaviour and increased levels of flight and defensive behaviours. In contrast, outbred mice with a low infection in the brain displayed a greater level of risk behaviour in respect of predator odour and the light/dark box compared to control or high infection mice. Post-infection, outbred mice were more immobile whereas inbred mice showed reduced immobility and increased digging and climbing. Impaired learning ability was observed in outbred mice with moderate and high levels of infection in the brain compared to control and low infection mice. Toxocara infection has an impact upon a diverse range of murine behaviours with little evidence for a specific and hence an adaptive alteration. Many of the effects on murine host behaviour by Toxocara are likely to be pathological side effects of infection rather than as a consequence of adaptive host-manipulation. Observed changes in murine behaviour may be relevant to human toxocariasis.

Animals↗
PubMed2001

Eggs of Toxocara spp. in the environment and their public health implications.

The high prevalence of Toxocara in cats, dogs and foxes results in the contamination of soil with infective eggs of Toxocara spp. which are found in soil samples from public and private places worldwide. In Poland the most contaminated areas were city backyards where 38-53% of soil samples were positive, especially in the spring. Human exposure to infection with Toxocara spp. was proportional to the prevalence of eggs in the samples examined but soil texture was not a critical factor in the degree of soil contamination. Eggs of Toxocara spp. placed on the ground penetrated a sand soil profile slowly. Their presence in the superficial layer of soils and the role of earthworms are instrumental in the dissemination of Toxocara eggs.

Animals↗
PubMed2004

[Use of specific immunoglobulin G antibody avidity in the differential diagnosis of active and chronic Toxocara canis infections].

To differentiate between acute and past Toxocara canis infections, a modified enzyme-linked immunosorbent assay, based on the dissociation of antigen-antibody complex with 6 M urea solution was used to measure levels of avidity of specific immunoglobulin G antibody against Toxocara canis excretory-secretory antigen. IgG avidity index was determined in the sera of 212 patients, divided into two groups with various stages of Toxocara infection. Patients were classified according to time period, from the onset of clinical symptoms or first positive serology result. Low IgG avidity index was found in the sera of 6.6% of patients in the acute phase, and all samples from the chronic stage of infection were characterized by high avidity values above 0.5 (mean 0.74). It was documented, that the avidity test for specific IgG antibodies is a valuable diagnostic method that helps to distinguish the early from the later phase of Toxocara canis infection. Indications for anti-parasitic treatment according to immunological activity of Toxocara infection were discussed.

Adolescent↗
PubMed2004

[The prevalence of Toxocara canis (Werner, 1782) in dogs and red foxes in north-west Poland].

One of the most dangerous parasites, not only for carnivores but also for human being is Toxocara canis. It is presented very commonly all over the world, so spread its into the humans organisms, especially childrens is very easy. The aim of this study was to determine the prevalence of Toxocara canis in dogs and red foxes in area of north-west Poland. The dog coproscopy was provided according to Willis-Schlaff method. Post mortem examination of red foxes was conducted according to Eckert and Amman (1990), Eckert et al. (1991) and Ewald (1993). In examined area dogs were infected with Toxocara canis from 2.67 to 55% (Table 1). The highest prevalence was observed in Gorzów Wielkopolski in its neighborhood (villages) and in urban places. The lowest extensity (2.67%) was determined in urban area of Słupsk city. In examined forest regions the prevalence of Toxocara canis in red foxes was 43% (Table 2). To sum up, north-west Poland is a region where Toxocara canis is common, both in domesticated and wild environment. There should be provided regular monitoring of this zoonozis as well as pharmacological treatment of dogs.

Animals↗
PubMed1993

Prevalence of Toxocara eggs in sandpits in Tokushima city and its outskirts.

To demonstrate the prevalence of Toxocara eggs in sandpits in Tokushima Prefecture, Japan, sand samples were examined. Of 46 sandpits surveyed, 29 sandpits (63.3%) had Toxocara eggs. Sandpits in public parks and playgrounds in residential areas were more contaminated (87.5%) with the eggs than those in kindergartens, schools, and children's centers (36.4%). To examine the seasonal change in the contamination, sand samples obtained from five sandpits were examined monthly from May 1990 to April 1991. Toxocara eggs were found in the majority of sandpits (3/5-5/5) in the spring, early summer, and autumn. In the summer and winter, the rates of sandpits contaminated were lower (2/5-3/5) than in other seasons. Egg counts became smaller in the summer and winter, especially in summer. The ratio of T. canis to T. cati eggs recovered was 2:3. Fecal examination of 144 puppies revealed that 98 (68.0%) were positive for T. canis eggs. These findings show that Toxocara eggs, a possible causative agent of visceral larva migrans, commonly present in sandpits of the urban area. To prevent the contamination of sandpits with these eggs, control measures are needed.

Animals↗
PubMed1993

[Toxocara ova in parks and sand-boxes in the city of Utrecht].

An investigation was carried out for the presence of Toxocara spp. eggs in public parks and children's sand-boxes in the city of Utrecht. The pollution of parks with the eggs of the dog's ascarid Toxocara canis is comparable with reports from other European cities. The eggs of Toxocara cati were found in small numbers only. Interestingly there was no difference between parks with or without formal exclusion of dogs. Most sand-boxes are polluted with the eggs of the ascarid of cats T. cati. Incidentally eggs of T. canis were found. Sand-boxes which were obviously kept clean or could be closed contained lower numbers of eggs. As children playing in sand-boxes have far more chances to contaminate themselves with Toxocara eggs than when playing in parks or on playgrounds, the question arises if not T. cati eggs constitute a greater menace, at least in urban areas, to public health than T. canis eggs.

Animals↗
PubMed2005

Comparison of IgG-ELISA and IgG4-ELISA for Toxocara serodiagnosis.

Diagnosis of human toxocariasis, caused by Toxocara canis or Toxocara cati, normally relies on a combination of the presence of clinical signs and symptoms backed by positive serology. The use of Toxocara excretory-secretory antigen (TES) in ELISA assays increases the test specificity. However, in tropical countries where soil-transmitted helminths are endemic, cross-reactivity from antibodies to these intestinal parasites poses a significant limitation for Toxocara serodiagnosis. To increase the specificity of serodiagnosis, we compared the use of IgG-ELISA to the use of IgG4-ELISA using commercially manufactured TES-coated plates. The sensitivity of the IgG-ELISA was 97.1%, while that of the IgG4-ELISA was 45.7%; the specificities were 36.0 and 78.6%, respectively. The study shows that employing both assays can improve the serodiagnosis of toxocariasis. An IgG4 immunoassay would also be useful in the secondary screening of antigen clones in the effort to develop improved serological tests for toxocariasis.

Animals↗
PubMed2006

O-methylated glycans from Toxocara are specific targets for antibody binding in human and animal infections.

The parasitic helminth Toxocara canis is a widely distributed nematode of mammals. Larval parasites, which infect a wide range of hosts including mice and humans, export glycosylated macromolecules bearing novel methylated oligosaccharide structures, similar to the mammalian blood group antigen H but bearing one or two O-methylated substitutions on the terminal fucose and subterminal galactose residues. We have studied the reactivity of synthetic forms of these glycans to parasite-specific antibodies and mammalian immune system lectins. Murine antibodies, generated to T. canis infection, predominantly recognise the mono-O-methylated form with the beta-configuration of the GalNAc residue (MoMbeta), and antibodies are entirely IgM isotype. The mAb Tcn-2 reproduces this pattern, and shows little reactivity to either the alpha isomer (MoMalpha) or the di-O-methylated form (DiM). Antibodies generated to helminth infections other than T. canis were unreactive with the glycans, except antibodies to other members of the Toxocara genus. Hence, the carbohydrate structures represent immunogenic, genus-specific antigens. Antibodies from human toxocariasis patients are reactive with the same sugars, although preferentially towards DiM. Sera from unrelated helminth infections do not react, confirming the status of these structures as Toxocara-specific glycans. The human dendritic cell lectin, DC-SIGN, was found to bind both Toxocara excretory/secretory products and mammalian blood group antigen H3. However, DC-SIGN did not bind the synthetic glycans, indicating additional non-methylated carbohydrates may also play a role in the interaction between T. canis and its host.

Animals↗
PubMed1998

Antistriational antibodies during Toxocara canis, Trichinella spiralis infections.

The parasitic infections (Toxocara can is, Trichinella spiralis) are characterized by general and local symptoms including fever, muscle pain and swelling. The question was asked whether the muscle changes that occur due to larva migrans give rise to the autoimmune response. The presence of antistriational antibodies (aStrAbs) was determined in the following groups of patients: group 1--66 patients with toxocariasis and the presence of anti-Toxocara antibodies, group 2--22 patients suspected of Toxocara canis infection without anti-Toxocara antibodies, group 3--20 patients with active trichinellosis confirmed by anti-Trichinella antibodies. As control 25 healthy persons (group 4) were studied. The aStrAb were tested by the indirect fluorescence using unfixed cryostat sections of human striated muscle. The following results were obtained: group 1--42 sera positive, group 2--5 sera were weakly positive, group 3--all sera showed the presence of aStrAbs, group 4--no aStrAbs. The presence of aStrAbs in patients with parasitic infections may suggest the occurrence of anti-muscle autoimmune response.

Animals↗
PubMed1991

Comparison of isolates and species of Toxocara and Toxascaris by biosynthetic labelling of somatic and ES proteins from infective larvae.

Infective-stage larvae of three different isolates of Toxocara canis were intrinsically ([35S]methionine) labelled in culture, to determine the presence of similarities or differences in the somatic and ES antigens expressed between larvae derived from different hosts and different geographical regions. Two other closely related ascaridids, Toxascaris leonina which infects cats and dogs, and Toxocara vitulorum (Neoascaris vitulorum) which infects cattle, were also compared to T. canis larvae by this method. Overall comparisons were made by 1- and 2-dimensional electrophoresis, while immunological cross-reactivities between the different species were analysed by radio-immunoprecipitation. Our results show that extensive physicochemical characteristics are shared between T. canis isolates, both from different hosts and different geographical locations. A substantial overlap was revealed when T. canis and T. vitulorum antigens were compared, whereas Toxascaris was found to produce a distinct antigen profile: this result was independent of whether methionine- or Iodogen-labelled products were being considered. Antigen recognition by polyclonal antibodies raised to all three species and to the cat ascaridid Toxocara cati, revealed considerable cross-reactivities. The cross-reactions were especially prominent between the Toxocara species, a fact further substantiated when reactivity of T. canis ES-specific monoclonal antibodies were tested against T. leonina and T. vitulorum antigens. The ES antigens of T. leonina were not recognized by the T. canis monoclonals, whereas the majority of these antibodies precipitated antigens of T. vitulorum. One which did not react with T. vitulorum was monoclonal antibody Tcn 2, indicating its species-specific reactivity and therefore its potential for the specific diagnosis of human toxocariasis.

Animals↗
PubMed1987

Use of bronchoalveolar lavage to compare local pulmonary immunity with the systemic immune response of Toxocara canis-infected mice.

Following infection of mice with larvae of the canine roundworm Toxocara canis, there is a persistent pneumonitis. Heretofore, nothing was known about the immunologic potential of the cells that constitute this inflammatory exudate. By performing bronchoalveolar lavage (BAL), enough inflammatory cells were obtained to compare the local pulmonary immune response to T. canis infection with the systemic immune response as reflected in the peripheral blood and spleen cells of the same mice. Groups of C57BL/6J female mice were given 100 infective ova and BAL, peripheral blood, and spleen cells collected on days 8, 11, 14, and 17 postinfection. The percentage of eosinophils in the BAL averaged about 80% and was four to five times as great as that in the peripheral blood at all times assayed. Use of concanavalin A (ConA)-elicited lymphocyte blastogenesis to evaluate T-lymphocyte activity revealed that BAL T-cell activity was low on day 8 and peaked on day 11. When the B-cell mitogen lipopolysaccharide was used in the assay, there appeared to be far less BAL cell reactivity compared with BAL T-cell activity. Both B- and T-cell responses of the BAL cells were only a fraction of the responses seen concurrently in spleen cells. Use of Toxocara exoantigens in the blastogenesis assay revealed that Toxocara exoantigens could elicit between 20 and 95% of the ConA response in BAL cells, while in spleen cells Toxocara exoantigens could only elicit 1 to 5% of the ConA response. These results suggest that BAL is a useful method for recovering local inflammatory cells that possess detectable immunologic activity. In the case of pulmonary toxocariasis, eosinophils account for the majority of the cells that are present, with most of the remaining cells being T. canis antigen-specific T lymphocytes.

Animals↗
PubMedDate not supplied

Persistence of specific antibody response in different experimental infections of mice with Toxocara canis larvae.

Anti-Toxocara antibody production and persistence were studied in experimental infections of BALB/c mice, according to three different schedules: Group I (GI)-25 mice infected with 200 T. canis eggs in a single dose; Group II (GII) 25 mice infected with 150 T. canis eggs given in three occasions, 50 in the 1st, 50 in the 5th and 50 in the 8th days; Group III (GIII)-25 mice also infected with 150 T. canis eggs, in three 50 eggs portions given in the 1st, 14th and 28th days. A 15 mice control group (GIV) was maintained without infection. In the 30th, 50th, 60th, 75th, 105th and 180th post-infection days three mice of the GI, GII and GIII groups and two mice of the control group had been sacrificed and exsanguinated for sera obtention. In the 360th day the remainder mice of the four groups were, in the same way, killed and processed. The obtained sera were searched for the presence of anti-Toxocara antibodies by an ELISA technique, using T. canis larvae excretion-secretion antigen. In the GI and GII, but not in the GIII, anti-Toxocara antibodies had been found, at least, up to the 180th post-infection day. The GIII only showed anti-Toxocara antibodies, at significant level, in the 30th post-infection day.

Animals↗
PubMedDate not supplied

Toxocara spp. eggs in public squares of Sorocaba, São Paulo State, Brazil.

The visceral larva migrans (VLM) is a syndrome observed in human infection with helminth larval eggs such as the Toxocara spp. that usually infects dogs and cats. Among the risk factors involved in the occurrence of VLM, particularly important is the size of these animal populations. Sorocaba is a city with a dog population twice as large as that recommended by the World Health Organization. This fact has led to a survey of the presence of Toxocara spp. eggs in public square soils of this city. Thirty squares were selected, fifteen located in the outskirts of the city and fifteen downtown. Soil samples were collected from five distinct sites in the same area. The material was homogenized and drained and 100 g was mixed with a saturated solution of magnesium sulfate and 5% potassium iodine. The floating material was analyzed under the light microscope. Toxocara spp. eggs were found in 16 squares, nine of which were located in the outskirts of the city and seven downtown. It was concluded that Sorocaba squares present a high rate of contamination with Toxocara spp. eggs. The squares in the outskirts of the city presented a higher occurrence of these eggs in comparison with those downtown, although the difference was not statistically significant (p > 0.05).

Animals↗
PubMed2004

The frequency rate of Toxocara species contamination in soil samples from public yards in a urban area "Payathai", Bangkok, Thailand.

Toxocara species are most common roundworms of Canidae and Felidae. Human toxocariasis develops by ingesting of embryonated eggs in contaminated soil. There is no previous report of Toxocara contamination in the soil samples from the public areas in Bangkok. For this reason our study have been carried out to examine the frequency of Toxocara eggs in public yards in Bangkok, Thailand. A total of 175 sand and clay samples were collected and examined for parasite eggs. According to this study, Toxocara eggs were detected from 10 (5.71%) of 175 soil samples. The high rate of contamination in this study implies the importance of the control of this possible zoonotic disease: control of abandon of dogs and cats, is still necessary.

Animals↗
PubMed2005

Environmental contamination by Toxocara sp. eggs in Ribeirão Preto, São Paulo State, Brazil.

Toxocariasis is a zoonosis mainly caused by Toxocara canis, an intestinal nematode of dogs. Man acquires the infection through accidental ingestion of viable eggs, and the toxocariasis clinical manifestations may vary from an asymptomatic infection up to the Visceral Larva Migrans syndrome. Seventy eight public squares of Ribeirão Preto, São Paulo, Brazil, including Bonfim Paulista district were visited aiming to evaluate the soil contamination by Toxocara eggs. The squares were divided in five different areas corresponding to the Sanitary Districts of the city. From May to December 2003, soil samples weighting about 250 g each were collected from five distinct sites of each public square. The laboratory analysis was done by centrifugal-flotation techniques in magnesium sulphate solutions with 5% of potassium iodide (d = 1.33) and zinc sulphate (d = 1.20), and by the sedimentation- flotation in conic chalices with zinc sulphate (d = 1.20). Toxocara sp. eggs were found on 16 (20.5%) squares, with the lowest prevalence (12%) at the central area. From these results, it is expected that the legal authority will adopt protection measures for the city public areas, reducing thus the contamination risk by Toxocara sp. eggs.

Animals↗
PubMed2001

Toxocara malaysiensis n. sp. (Nematoda: Ascaridoidea) from the domestic cat (Felis catus Linnaeus, 1758).

Toxocara malaysiensis n. sp. from the small intestine of the domestic cat (Felis catus L.) in Malaysia is described and illustrated. This ascaridoid nematode was previously assumed to be Toxocara canis, which it superficially resembles, or designated Toxocara sp. cf. canis. The new species differs from T. canis in the shape of the cervical alae in cross section, spicule length, and the lip structure. It is also distinct from other species assigned to Toxocara.

Animals↗