Microscopic and molecular prevalence and associated risk factors with Toxocara and Blastocystis infection in dogs and cats in Mitidja, Algeria

Domestic dogs and cats can serve as a source of environmental contamination with Toxocara spp. and Blastocystis spp., and this represents a neglected public and veterinary health problem. We assessed the microscopic and molecular prevalence of these species in a locality in Algeria and identified the associated risk factors. The faeces of 225 dogs and 78 cats were collected in Mitidja between March and July 2022. The samples were analysed by coproscopy and by polymerase chain reaction (PCR) targeting the Internal Transcribed Spacer 2 (ITS2) and Small Subunit Ribosomal (SSU-RNA) of T. canis and Blastocystis spp. respectively. The overall microscopic prevalence of Toxocara spp. in dogs and cats was 9.78 ± 1.98% and 12.82 ± 7.42%, respectively. The rate of Blastocystis spp. was 15.11 ± 2.39% and 15.38 ± 4.08% in dogs and cats, respectively while the molecular prevalence of T. canis in dogs was 4.89 ± 1.44% and in cats 1.28 ± 1.27%; the prevalence of Blastocystis spp. was 41.78 ± 3.29% and 34.62 ± 5.39% in dogs and cats, respectively. Phylogenetic and phylogeographic analyses identified the presence of the H1 subtype of T. canis in dogs, and the ST1 subtype of Blastocystis in dogs and cats. Dogs with clinical signs were more likely to be infected with T. canis (OR 6.039, P < 0.05) than healthy dogs. This study demonstrates that dogs and cats are carriers of Toxocara spp. and Blastocystis spp. and are therefore a source of environmental contamination. Veterinarians and human health professionals should work together to implement control strategies as part of a "One Health" approach to improving animal health and reducing the risk of transmission to humans.

Molecular characterization of ascaridoid parasites from captive wild carnivores in China using ribosomal and mitochondrial sequences

BACKGROUND

Despite the public health importance of toxocariasis/toxascariasis, only a few species of these ascaridoid parasites from wild canine and feline carnivores have been studied at the molecular level so far. Poor understanding of diversity, host distribution and the potential (zoonotic) transmission of the ascaridoid species among wild animals negatively affects their surveillance and control in natural settings. In this study, we updated previous knowledge by profiling the genetic diversity and phylogenetic relationships of ascaridoid species among eleven wild canine and feline animals on the basis of a combined analysis of the ribosomal internal transcribed spacer region (ITS) gene and the partial mitochondrial cytochrome c oxidase subunit 2 (cox2) and NADH dehydrogenase subunit 1 (nad1) genes.

RESULTS

In total, three genetically distinct ascaridoid lineages were determined to be present among these wild carnivores sampled, including Toxocara canis in Alopex lagopus and Vulpes vulpes, Toxocara cati in Felis chaus, Prionailurus bengalensis and Catopuma temmincki and Toxascaris leonina in Canis lupus, Panthera tigris altaica, Panthera tigris amoyensis, Panthera tigris tigris, Panthera leo and Lynx lynx. Furthermore, it was evident that T. leonina lineage split into three well-supported subclades depending on their host species, i.e. wild felids, dogs and wolves and foxes, based on integrated genetic and phylogenetic evidence, supporting that a complex of T. leonina other than one species infecting these hosts.

CONCLUSIONS

These results provide new molecular insights into classification, phylogenetic relationships and epidemiological importance of ascaridoids from wild canids and felids and also highlight the complex of the taxonomy and genetics of Toxascaris in their wild and domestic carnivorous hosts.

History of Toxocara and the associated larva migrans

This review covers the systematics and nomenclature of the Ascaridoid genus toxocara, and more specifically the species Toxocara canis and Toxocara cati. Also discussed is the discovery of the persistence of these larvae in the tissues of paratenic hosts, and the role that other species of this genus might or could play in other such hosts; including those where the life cycle has been described, i.e., Toxocara vitulorum, Toxocara pteropodis, Toxocara mackerrasae, and Toxocara tanuki. Also examined is the work that led to the realization that the larval stage leaving the egg actually being a third rather than a second stage larva. Also discussed on the work showing that the larvae can persist in paratenic host with remarkable longevity without undergoing any morphological change for years and that these larvae can be transmitted from one paratenic host to another by ingestion. People are usually infected by the ingestion of eggs containing third-stage larvae, but infections also occur on occasions from the ingestion of uncooked paratenic hosts.

Differentiation of Toxocara canis and Toxocara cati based on PCR-RFLP analyses of rDNA-ITS and mitochondrial cox1 and nad1 regions

The definitive genetic identification of Toxocara species is currently based on PCR/sequencing. The objectives of the present study were to design and conduct an in silico polymerase chain reaction-restriction fragment length polymorphism method for identification of Toxocara species. In silico analyses using the DNASIS and NEBcutter softwares were performed with rDNA internal transcribed spacers, and mitochondrial cox1 and nad1 sequences obtained in our previous studies along with relevant sequences deposited in GenBank. Consequently, RFLP profiles were designed and all isolates of T. canis and T. cati collected from dogs and cats in different geographical areas of Iran were investigated with the RFLP method using some of the identified suitable enzymes. The findings of in silico analyses predicted that on the cox1 gene only the MboII enzyme is appropriate for PCR-RFLP to reliably distinguish the two species. No suitable enzyme for PCR-RFLP on the nad1 gene was identified that yields the same pattern for all isolates of a species. DNASIS software showed that there are 241 suitable restriction enzymes for the differentiation of T. canis from T. cati based on ITS sequences. RsaI, MvaI and SalI enzymes were selected to evaluate the reliability of the in silico PCR-RFLP. The sizes of restriction fragments obtained by PCR-RFLP of all samples consistently matched the expected RFLP patterns. The ITS sequences are usually conserved and the PCR-RFLP approach targeting the ITS sequence is recommended for the molecular differentiation of Toxocara species and can provide a reliable tool for identification purposes particularly at the larval and egg stages.

Quantifying the risk of zoonotic geohelminth infections for rural household inhabitants in Central Poland

The objective of this study was to evaluate the risk of soil transmitted zoonotic helminth infections for families with young children, inhabitants of villages in the Mazowieckie Province of Central Poland. Epidemiological survey was conducted at 33 randomly selected households with 2-3 children present. Examination of soil samples from yards surrounding the houses for the presence of geohelminth eggs was conducted, the households were inspected, and family members interviewed using a designed questionnaire. Among 55 localities examined, i.e. 33 backyards, 10 vegetable gardens and 12 sandpits, contamination was found in 2 backyards (6.1%) and 1 sandpit (8.3%) at 3 households (9.1%). Of the total 550 examined soil samples, 4 (0.7%) were found to contain Trichuris and Toxocara eggs, with an average density of 1.5 and 2.0 eggs per sample. The study showed a low level of soil contamination, which was the result of inhabitants care about the sanitation of their domiciles. However, the results of the questionnaire survey demonstrated the need to warn rural residents about the risk factors for zoonotic helmints infections. In particular, parents should be advised how to minimize the threat of parasitic diseases for children in the rural environment. The presented study showed that promotional campaigns implemented in recent years on the prevention of parasitic zoonoses have had little effect to increase the awareness of the rural community. The present results confirmed that Toxocara is the most common zoonotic agent among geohelminths in the rural environment.

Natural infection of free-range chickens with the ascarid nematode Toxocara sp

Human toxocariasis may be acquired by eating raw chicken liver. However, there are no reports on the prevalence of natural infection of chickens with Toxocara. The aim of this study was to evaluate the presence of anti-Toxocara antibodies as indicators of natural infection with Toxocara, in free-range chickens from Espírito Santo State, Brazil. An ELISA test with secretory and excretory Toxocara canis antigens was used. Negative controls were 20 industrial chickens reared in a high hygiene standard environment. Positive control serum was from a chicken infected with embryonated eggs of T. canis. Sera were adsorbed with Ascaridia galli extract to reduce cross-reactivity. Cut-off was the mean plus four times the standard deviation of optical density (OD) in negative group. One hundred and fifty-seven sera from free-range chicken were investigated. Results showed 58.5% of the chickens were positive with ELISA test; 12.7% had OD over the positive control and may be considered as true infected chickens. The results between the cut-off and the positive control may include infections with low titers of antibodies or may represent serum scar of past infection or may be the result of cross-reaction with other nematodes rather than A. galli which is used for the adsorption of sera. In conclusion, high prevalence of Toxocara sp. antibodies demonstrates natural infection of free-range chickens from Espírito Santo State which may represent a risk of infection with this nematode in people who have the habit of eating raw or undercooked chicken meat or viscera. The results also suggest that chickens may be useful as sentinels to detect soil contaminated with Toxocara eggs.

Microarray gene expression analysis reveals major differences between Toxocara canis and Toxocara cati neurotoxocarosis and involvement of T. canis in lipid biosynthetic processes

Toxocara canis and Toxocara cati are globally occurring intestinal nematodes of dogs and cats with a high zoonotic potential. Migrating larvae in the CNS of paratenic hosts, including humans, may cause neurotoxocarosis resulting in a variety of neurological symptoms. Toxocara canis exhibits a stronger affinity to the CNS than T. cati, causing more severe neurological symptoms in the mouse model. Pathomechanisms of neurotoxocarosis as well as host responses towards the respective parasite are mostly unknown. Therefore, the aim of this study was to characterise the pathogenesis at a transcriptional level using whole genome microarray expression analysis and identify differences and similarities between T. canis- and T. cati-infected brains. Microarray analysis was conducted in cerebra and cerebella of infected C57Bl/6J mice 42daysp.i. revealing more differentially transcribed genes for T. canis- than T. cati-infected brains. In cerebra and cerebella of T. canis-infected mice, a total of 2304 and 1954 differentially transcribed genes, respectively, were identified whereas 113 and 760 differentially transcribed genes were determined in cerebra and cerebella of T. cati-infected mice. Functional annotation analysis revealed major differences in host responses in terms of significantly enriched biological modules. Up-regulated genes were mainly associated with the terms "immune and defence response", "sensory perception" as well as "behaviour/taxis" retrieved from the Gene Ontology database. These observations indicate a strong immune response in both infection groups with T. cati-infected brains revealing less severe reactions. Down-regulated genes in T. canis-infected cerebra and cerebella revealed a significant enrichment for the Gene Ontology term "lipid/cholesterol biosynthetic process". Cholesterol is a highly abundant and important component in the brain, representing several functions. Disturbances of synthesis as well as concentration changes may lead to dysfunction in signal transduction and neurodegenerative disease. Overall, only a minor overlap of differentially transcribed genes was observed between the two infection groups in both brain parts. Most genes are regulated individually in each infection group, supporting the evident differences of both roundworm species observed in the paratenic host in previous studies. In summary the present study underlines the differences in pathogenicity of T. canis and T. cati. It furthermore provides a comprehensive basis for future analyses over the course of infection as well as functional tests to identify gene regulatory circuits that are crucial for pathogenesis of neurotoxocarosis. The results of this study provide a promising foundation for further specific research to evaluate the particular pathogenetic mechanisms and to identify possible therapeutic targets.

In vitro effect of Nigella sativa oil on adult Toxocara vitulorum

Since the integrity of Toxocara vitulorum cuticle is essential for the nutritive and protective functions, light and scanning electron microscopic studies were undertaken to assess, for the first time, whether the Nigella sativa oil (NSO) had any effect on the cuticle of adult T. vitulorum following incubation in vitro. Differences in response to NSO action were observed, depending on the used concentration. After 24 h incubation with 0.5 mg mL(-1) NSO, the cuticle of the anterior end of worms appeared to be slightly more swollen than normal. This swelling became pronounced and so severe, with lips showed wrinkled cuticular surface and deformed sensory papillae on increasing the concentration to 1.0 mg mL(-1). With the higher concentration of 1.5 mg mL(-1), extensive and severe disorganization of the cuticle and body musculature was observed. Structural alterations in the cuticle as observed in the present investigation were thus, clear indication of nematocidal activity of NSO that could offer a suitable and cheaper alternative for the more expensive anthelmintics.

Contamination of vegetables, fruits and soil with geohelmints eggs on organic farms in Poland

The objective of this study was to evaluate the contamination of vegetables, fruits and soil with zoonotic parasite eggs on organic and conventional farms in south-eastern Poland. To evaluate the contamination with eggs of zoonotic parasites, examinations were conducted on 8 conventional and 11 organic farms in south-eastern Poland from May-October in 2008 and 2009. The following fruit and vegetables were selected for the experiment: strawberry, leek, onion, carrot, zucchini, beetroot, parsley, potatoes, celery, rhubarb, lettuce, cabbage, broccoli, pumpkin, young beetroot leaves, cauliflower, French beans, turnip, fennel and sorrel. A total of 187 samples of vegetables, fruits and soil were examined by means of a modified flotation method according to Quinn et al. (1980). Contamination with Ascaris, Trichuris and Toxocara eggs was found, with a higher number of positive samples revealed on conventional (34.7%), compared to organic farms (18.9%). The level of contamination in soil samples from conventional farms was higher (88.5% positive samples), than of those from organic farms (32.8%). Of the 15 geohelmints eggs, positive samples were found in vegetables: 9 Toxocara eggs, 4 Ascaris eggs and 2 Trichuris eggs. No geohelmints eggs were observed in the strawberry samples. The consumption of vegetables and fruits contaminated with the eggs of parasites may be the cause of parasitoses in humans. Stricter sanitary standards on farms of all types may limit the incidence of parasitic zoonoses.

[The spread of nematodes from Toxocara genus in the world]

Twenty seven species belong to the genus Toxocara. Most of the species infect Carnivora from families: Canidae, Felidae, Viverridae, Procyonidae, Mustelidae and Herpestidae. The most widespread species are: T. canis, T. cati and T. vitulorum. The life cycle of Toxocara spp. is connected with young animals and adults with the lowered immune response. Three of the Toxocara species: T. canis, T. cati and T. pteropodis are the aetiological agents of human toxocariasis.

Evaluation of the efficacy of emodepside plus praziquantel topical solution against ascarid infections (Toxocara cati or Toxascaris leonina) in cats

Eleven controlled studies were conducted in the United States and Europe to evaluate the efficacy of a topical solution of emodepside (3 mg/kg)+praziquantel (12 mg/kg) (Profender, Bayer AG, Leverkusen, Germany) against infection with various stages of the ascarid nematodes Toxocara cati and Toxascaris leonina. Infections were induced by administration of larvated ascarid eggs, and stage-specific efficacy was evaluated by treating cats at scheduled intervals post-inoculation. All studies featured random allocation to treatment groups, placebo-treated control animals and assessment of outcome measures by masked personnel. The product (emodepside+praziquantel topical solution) was 100% effective against mature adults and immature adult T. cati. In addition, it was 96.8% effective against third stage larvae and at least 99.4% effective against fourth stage larvae of T. cati, respectively. Efficacy against mature, immature adult and L4 stages of T. leonina exceeded 93.4%, but regulatory "adequacy of infection" criteria were not met in some studies. No adverse reactions to treatment were noted in cats treated with the emodepside+praziquantel topical solution.

The effects of benzimidazoles on the larval stage of Toxocara cati in experimentally infected chickens

Toxocara cati (T. cati) and Toxocara canis (T. canis), roundworms of cats and dogs, are zoonotic parasites that cause visceral and ocular larval migrans in human beings. Humans and other paratenic hosts are infected by ingesting the infective Toxocara eggs from contaminated soil, unwashed hands, contaminated raw vegetables or ingestion of under-cooked organs and muscle tissues of infected paratenic hosts such as chickens, cattle and sheep. It has been shown that the seroprevalence of toxocariasis in the rural and urban children of southern Iran is high and more than 50% of cats of this area are also infected with T. cati. It is stated that consumption of raw chicken meat resulted in visceral toxocariasis. It is possible that poultry reared outdoors and feeding in open range system, gain Toxocara eggs from soil and or by eating infected earthworms as paratenic host. The aim of the present study was to investigate the effects of albendazole and febendazole in experimentally infected chickens with eggs of T. cati by histopathological and digestive methods. Pathologic lesions were observed only in the untreated group and larvae were detected in brain of 3 chickens of this group by squash method. No larva was observed at histopathological level in liver, lungs, brain, cardiac and skeletal muscles and other examined organs of either treated or untreated animals. No lesion was seen in other tissues of the infected untreated chickens. Treatment resulted in disappearance of the larvae and disappearance of the gross and histopathologic abnormalities from their organs. No detectable difference was observed in chemosusceptibility of the two drugs.

[Contamination of soil with geohelminth eggs on vegetable organic farms in the Lublin voivodeship, Poland]

Organic farming, despite being more difficult and labour consuming than traditional farming, gains increasingly more followers among farmers. Currently in Poland there are approximately 10 000 organic farms. Pure, uncontaminated soil in the Lublin voivodeship makes this area an ideal location for organic agriculture production. In 2006-2007, 102 soil samples were examined from 40 organic farms specializing in vegetables and berries. Farms for the study were selected by ecology- and food-production specialists from the Lublin Agriculture Advisory Centre in Końskowola. The following plants were cultivated on the farms examined: berry-bearing plants, carrots, parsley, zucchini, cabbage, lettuce, cucumbers, cauliflowers, leeks, onions, kidney beans, beetroots, potatoes, pumpkins, broad beans, rhubarb and herbs. The presently reported parasitological survey was performed on 102 soil samples. Each sample consisted of 100 g of soil and the methodology followed that of the Polish Standard PN-Z-19000-4 (flotation method by Quinn et al.). The survey yielded eggs of parasites representing genera: Ascaris, Trichuris and Toxocara. Contamination with eggs of intestinal parasites was noted in 43 (42.16%) soil samples. Toxocara spp. eggs were found in 24 samples (55.81%). Eggs of Ascaris spp. were detected in 18 samples (41.86%) while eggs of Trichuris spp were present in one sample (2.32%). In total, 29 eggs of Toxocara spp., 19 eggs of Ascaris spp., and 1 egg of Trichuris spp. were found. The largest amount of soil for examination was taken across the plantations of berry-bearing plants - 57 samples. In the group examined, plantations of raspberries and strawberries dominated. The soil was contaminated with the eggs of Toxocara spp. and Ascaris spp. No eggs of Trichuris spp. were detected. The presence of eggs of intestinal parasites in soil poses a threat of geohelminthoses to people who eat contaminated fresh fruits and vegetables.

The comparision of IgG antibodies specific to Toxocara spp. among eosinophilic and non-eosinophilic groups

Toxocariasis is one of the most frequently reported helminth infections worldwide. Eosinophilia is a common finding of parasitic infections. This study assessed the levels of IgG antibodies specific to Toxocara spp. by ES-ELISA method in an eosinophilic (n=350) and non eosinophilic group (n=350). There were IgG antibodies specific to Toxocara spp. in 114 (32.6%) of the eosinophilic group and in 71 (20.3%) of the non-eosinophilic group (p<0.001). Toxocariasis may be an important problem in the region and should be kept in mind for patients with eosinophilia.

Prevalence of Toxocara cati and other intestinal helminths in stray cats in Shiraz, Iran

Toxocariasis is a parasitic zoonosis with worldwide distribution that affects both cats and dogs. Necropsy of 114 stray cats from Shiraz revealed that 106 (92.9%) stray cats were infected at least with one of the intestinal helminth species. The overall infection rates in stray cats infected with cestoda and nematoda were 105(99.1%) and 101(95.3%) respectively. The detected cestodes were Joyeuxiella pasqualei (34.3%), Dipylidium caninum (49.5%), Taenia taeniaeformis (12.3%), Spirometra sp. (3.8%) and the detected nematodes were Physaloptera sp. (44.6%), Toxocara cati (42.6%) and Toxascaris leonina (12.9%). The study revealed that T. cati was one of the most frequently detected intestinal helminths, which is an important source of zoonotic helminths.

[Visceral and cutaneous larva migrans]

The syndrome of visceral larva migrans was described for the first time in 1952 by Beaver. He demonstrated that the presence of nematodes larvae, particularly in the liver, were those of Toxocara canis and T. cati. Baylisascaris procyonis, the common racoon ascarid in the U.S.A. can also cause serious diseases in human. Digestive and respiratory clinical symptoms are usually moderate, however severe disease resulting from invasion of the myocardium or the brain has been reported. A blood hypereosinophilia is usually present the first few years after infection. Diagnosis uses serological methods, among them the ELISA test. Ocular larva is also possible with in that case, immunological modifications of the aqueous. Cutaneous larva migrans characterized by a linear, progressing, serpigenous eruption and intense itching is easy to diagnose. Larva migrans is due to dogs, cats and horses helminths. Dogs and cats (referred here as pets) now receive antihelmintitic treatments and parasites are now in decrease.

Toxocariasis in Japan

Toxocariasis has long been considered a parasitic disease affecting pet owners and children who often play in sandboxes at public parks. Recent cases of this animal-borne infection, however, indicate that its clinical manifestations and etiologies are changing. In this article, we will describe the critical characteristic features of toxocariasis alongside the contributions of Japanese researchers to a better understanding of the disease.

Utilizing a polymerase chain reaction method for the detection of Toxocara canis and T. cati eggs in soil

A polymerase chain reaction (PCR) technique has been used for the differentiation of T. canis and T. cati eggs isolated from soil and previously identified from microscopical observations. The method, using specific primers for the identification of the two Toxocara species, was assessed in both the field and laboratory. Successful results were obtained when only a single or large numbers of eggs were recovered from 40 g soil samples. The method is sensitive, allows analysis of material independent of the stage of egg development and can be adapted for the recovery of other species of parasites from soil.

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.

Identification of tissue-embedded ascarid larvae by ribosomal DNA sequencing

Polymerase chain reaction (PCR) was applied to identify tissue-embedded ascarid nematode larvae. Two sequences of the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA), ITS1 and ITS2, of the ascarid parasites were amplified and compared with those of ascarid-nematodes registered in a DNA database (GenBank). The ITS sequences of the PCR products obtained from the ascarid parasite specimen in our laboratory were compatible with those of registered adult Ascaris and Toxocara parasites. PCR amplification of the ITS regions was sensitive enough to detect a single larva of Ascaris suum mixed with porcine liver tissue. Using this method, ascarid larvae embedded in the liver of a naturally infected turkey were identified as Toxocara canis. These results suggest that even a single larva embedded in tissues from patients with larva migrans could be identified by sequencing the ITS regions.

Eosinophilic granuloma of the liver: a characteristic lesion with relationship to visceral larva migrans

Children with the clinical syndrome of visceral larva migrans as a result of Toxocara species have typical lesions in the liver and other viscera, consisting of palisading granulomas that contain numerous eosinophils and often Charcot-Leyden crystals; recognizable parasites are uncommon. Similar eosinophilic granulomas that are found incidentally in adults often cause diagnostic problems. To define better the clinical, laboratory, and pathologic features of these lesions, we reviewed 43 cases of hepatic eosinophilic granuloma (excluding cases of Langerhans' cell histiocytosis) collected in the files of the AFIP over a period of 31 years. The eosinophilic granulomas were found in patients of all ages (range 12 months to 77 years); 30% were younger than 20 years. There were 26 male and 17 female patients. Most patients (26 of 43; 60%) were asymptomatic, and the lesions were discovered incidentally. Others had fever (20%) or abdominal pain (20%). The granulomas were typically multiple (61%), with central necrosis surrounded by a mixed inflammatory infiltrate with numerous eosinophils and variable numbers of neutrophils. lymphocytes, and a palisade of epithelioid histiocytes and/or giant cells. Charcot-Leyden crystals were present in 19 cases (44%). Remnants of parasites (eight Toxocara sp., two Capillaria sp.) were identified in the tissue in 10 patients. There was a positive serologic test for Toxocara sp. in five additional cases. Immunohistochemical staining using polyclonal antiserum against Toxocara canis larvae demonstrated positivity in macrophages in eight of 13 cases tested. We conclude that identification of an eosinophilic granuloma in the liver should suggest the diagnosis of visceral larva migrans and prompt a search for the causative organism with serial sectioning of the block and serologic tests for Toxocara and other causative parasites.

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.

[Distribution of sources of Toxocara spp. infection in urban and rural environments in Poland]

Soil examinations made in 5 regions of Poland in the 1990s comprised 1184 samples taken from urban areas and 590 samples from suburban and rural areas. Toxocara spp. eggs were found more often in urban areas (14% positive samples) than in suburban and rural once (12% positive samples). The average ratio of positive samples was: in the streets and roads--19.3% (0.36 eggs/100g of soil), near houses (backyards, gardens)--18.6% (1.11 eggs/100g), in sandpits--13.0% (0.23/100g), in parks and public gardens--10.5% (0.46 eggs/100g), on playgrounds and playing fields 9,4% (0,06 eggs/100g) and on the beaches--3.4% (0.03 eggs/100g). In children habitual play areas the prevalence of T. cati eggs was higher than T. canis eggs.

Differentiation of Toxocara canis and T. cati eggs by light and scanning electron microscopy

In this study, we investigated the morphological identification of Toxocara canis and T. cati eggs on the basis of light and scanning electron microscopic (SEM) observations. T. canis and T. cati eggs used in this study were recovered from the uteri of respective gravid female worms. Measurement of egg size was not helpful in the differentiation of these species, because approximately 90% of eggs measured were of similar size. Using SEM, we were able to differentiate T. canis eggs from T. cati eggs based on their respective characteristic surface structures. Both species have subspherical eggs with markedly pitted surfaces like those of a golf ball, but the surface pitting in T. canis is more coarse than that in T. cati. In this study, however, these differences were not absolute, as 16% of T. canis and 29% of T. cati eggs showed surface pitting that was uncharacteristic of their species. Of the 16% of T. canis eggs that could not be differentiated by surface structure, 3% had pitting resembling T. cati, and the remaining 13% showed intermediate type surface pitting. Similarly, 5% of T. cati eggs resembled T. canis, and 25% of these were of intermediate type. Light microscopic observation yielded results similar to those of SEM, indicating that light microscopy is also a useful tool for the identification of Toxocara eggs.

[Soil contamination with Toxocara spp. eggs in the Kraków area and two nearby villages]

The distribution of Toxocara spp. eggs was studied in the Kraków city and nearby villages Grodkowice and Lazkowice. In Kraków out of 80 samples surveyed 30% were positive and the mean egg density was 3.7 eggs/100g soil. Court-yards and squares in the centre of the city were the most heavily contaminated areas (58% samples positive). In two nearby villages Toxocara spp. eggs were present in 16% samples examined and the mean egg density was 0.8 eggs/100g soil. Almost 90% of Toxocara spp. eggs recovered were infective. At least 80% of the eggs were classified as T. cati by egg's morfology.

A new species, Toxocara lyncis, in the caracal (Lynx caracal)

Toxocara lyncis, sp. n. is described from Lynx caracal in Somalia. It most closely resembles T. cati, the only species of Toxocara reported from L. caracal. It differs from T. cati in the comparative length of the spicules and the esophagus, and in the shape of the cervical alae. Cervical alae have a nearly uniform width along their length in T. lyncis, while they are narrow anteriorly and broad posteriorly forming an arrow head shaped cephalic end in T. cati.

[Biological infection of soil on the flooded areas of Wrocław City]

The distribution of geohelminth eggs on the appartment backyards of Wrocław city after flood disaster was studied. Out of 100 soil samples examined 17% were positive. Toxocara spp.eggs were present in 6% samples examined, Ascaris spp. in 2% and other eggs (Capilaria sp. and Trichuris vulpis) in 9% samples examined. Soil contamination of Wrocław area was much less than in other cities of Poland and Europe. The prevalence of geohelminth eggs on flooded areas was very similar to that on the not-flooded areas although the number of eggs recovered was twice as high on flooded areas.

Adult Toxocara cati infections in U.S. children: report of four cases

We report four cases of passage of subadult or adult Toxocara cati worms by young children ages 20 months to seven years. Worms were expelled rectally in two cases and in two cases they were vomited. A single worm was passed in two cases, three worms in one case, and 15 worms in the fourth case. All worms that were available for study were identified as T. cati by morphologic criteria, including the arrow-shaped cervical alae and the digitiform shape of the male tail. None of the four children exhibited clinical signs of ocular or visceral larva migrans, and in two cases where serum samples were available, neither child had a titer to Toxocara. These results further the argument that these children acquired the worms through the ingestion of immature worms passed by infected cats, not through the ingestion of infective eggs. Although the children were generally not ill as a result of these unusual infections, it does serve to reinforce the public health issue that potential serious consequences can occur where children have exposure to an environment that has been contaminated with cat feces, or, more specifically, infective eggs, and could become infected with larval forms of Toxocara.

Molecular characterization of a Toxocara variant from cats in Kuala Lumpur, Malaysia

The ascaridoid nematode of cats from Kuala Lumpur, Malaysia, previously identified morphologically as Toxocara canis, was characterized using a molecular approach. The nuclear ribosomal DNA (rDNA) region spanning the first internal transcribed spacer (ITS-1), the 5.8S gene and the second internal transcribed spacer (ITS-2) was amplified and sequenced. The sequences for the parasite from Malaysian cats were compared with those for T. canis and T. cati. The sequence data showed that this taxon was genetically more similar to T. cati than to T. canis in the ITS-1, 5.8S and ITS-2. Differences in the ITS-1 and ITS-2 sequences between the taxa (9.4-26.1%) were markedly higher than variation between samples within T. canis and T. cati (0-2.9%). The sequence data demonstrate that the parasite from Malaysian cats is neither T. canis nor T. cati and indicate that it is a distinct species. Based on these data, PCR-linked restriction fragment length polymorphism (RFLP) and single-strand conformation polymorphism (SSCP) methods were employed for the unequivocal differentiation of the Toxocara variant from T. canis and T. cati. These methods should provide valuable tools for studying the life-cycle, transmission pattern(s) and zoonotic potential of this parasite.

Detection of sequence variation in parasite ribosomal DNA by electrophoresis in agarose gels supplemented with a DNA-intercalating agent

This study evaluated the use of a commercially available DNA intercalating agent (Resolver Gold) in agarose gels for the direct detection of sequence variation in ribosomal DNA (rDNA). This agent binds preferentially to AT sequence motifs in DNA. Regions of nuclear rDNA, known to provide genetic markers for the identification of species of parasitic ascarid nematodes (order Ascaridida), were amplified by polymerase chain reaction (PCR) and subjected to electrophoresis in standard agarose gels versus gels supplemented with Resolver Gold. Individual taxa examined could not be distinguished reliably based on the size of their amplicons in standard agarose gels, whereas they could be readily delineated based on mobility using Resolver Gold-supplemented gels. The latter was achieved because of differences (approximately 0.1-8.2%) in the AT content of the fragments among different taxa, which were associated with significant interspecific differences (approximately 11-39%) in the rDNA sequences employed. There was a tendency for fragments with higher AT content to migrate slower in supplemented agarose gels compared with those of lower AT content. The results indicate the usefulness of this electrophoretic approach to rapidly screen for sequence variability within or among PCR-amplified rDNA fragments of similar sizes but differing AT contents. Although evaluated on rDNA of parasites, the approach has potential to be applied to a range of genes of different groups of infectious organisms.

Biochemical and immunological systematics of some ascaridoid nematodes: genetic divergence between congeners

Vertical starch gel electrophoresis and trefoil immunodiffusion were used to study the systematics of some ascaridoid nematodes. Within the Ascarididae, the time scale of divergence was too great for intergeneric electrophoretic comparisons. Congeneric electrophoretic comparisons of Baylisascaris procyonis (host--raccoon) versus Baylisascaris transfuga (host--black bear), and Toxocara canis (host--domestic dog) versus Toxocara cati (host--domestic cat) yielded Nei genetic distance coefficients of 1.21 and 1.55, respectively. Estimates of times of divergence made from 1 electrophoretic clock calibration suggest that the Baylisascaris species have not shared a common ancestor for 25 million years (Myr), and that the Toxocara species diverged 33 Myr ago. The Baylisascaris divergence estimate corresponds to host-family divergence estimates based on immunological and paleontological evidence, which suggests that cospeciation has occurred. In contrast to this, Ascaris suum (host--pig) and Ascaris lumbricoides (host--human) have a distance coefficient of 0.09. This indicates that these species diverged comparatively recently and may represent a case of host range expansion. Trefoil immunodiffusion comparisons of ascaridoid albumins yielded reactions of identity for A. suum, A. lumbricoides, Parascaris equorum, B. procyonis, B. transfuga, T. canis, and T. cati. This confirms that these taxa are members of a monophyletic group.

The ascaridoid nematodes of rodents with a redescription of Porrocaecum ratti

Two ascaridoid nematodes occurring in rodents in South-East Asia, namelyPorrocaecum rattiandToxocara mackerrasae, were compared; the former was redescribed. These and other ascaridoid species occurring in rodents were classified and it was suggested that relative to the other mammalian orders, the rodents are well endowed with ascaridoids. There is, as yet, insufficient evidence for conjecture as to whether species occurring in rodents represent primitive forms from which the species occurring in predatory animals may have been evolved through host—succession—extension, or whether they have been secondarily derived through loss of a predatory definitive host through host—succession—reduction.

Toxocara vajrasthirae sp.nov. from the hog-badger (Arctonyx collaris) of Thailand

Toxocara vajrasthirae is described from the hog-badger (Arctonyx collaris) of Thailand. Of the species in the genus Toxocara, it most closely resembles T. canis. It differs in the possession of proportionately shorter and narrower cervical alae, relatively longer spicules, a coarse, reticulate pattern on the eggshell and an undivided part of the uterus which is longer than the divided part.

Two new species of Toxocara from viverrid hosts

Toxocara genettaesp.nov. andToxocara sprentisp.nov. from viverrid hosts in Africa and S.E. Asia respectively are described. SevenToxocaraspp. from viverrid hosts are differentiated. The writer proposes thatToxocara canarisiPuylaert, 1967, from a feline host, become aspecies inquirendaerequiring further study.