[Toxocariasis]

The clinical presentation of toxocariasis, a zoonotic parasitosis transmitted from dogs and cats to humans, can be very diverse, which is one of the reasons why Toxocara-related disease may go unnoticed. This paper gives a brief summary of the various clinical presentations (covert/common toxocariasis, visceral larva migrans, ocular toxocariasis and neurotoxocariasis), diagnostic and differential-diagnostic considerations as well as treatment and prevention. In brief, the diagnosis of human toxocariasis relies mainly on patient data, anamnestic information, symptoms, eosinophil count and total-IgE levels.

Visceral larva migrans among children in Kütahya (Turkey) and an evaluation of playgrounds for T. canis eggs

This research was undertaken to determine the seroprevalence of Toxocara canis (T. canis) in children aged 3-13 years in Kütahya, to determine the presence of infected larvae in playground sandboxes, and to obtain a view of the general situation regarding visceral larva migrans (VLM) in the city. The blood sera of 119 children (54 girls, 65 boys) were tested for T. canis IgG, and 9 (7.6%) were found positive. In sand samples collected from playgrounds in nine different residential areas across the city, only two of them, in Inköy and Zafertepe neighborhoods, had T. canis larvae; in total, 3 of the 30 sand samples (10%) contained larvae. It is concluded that the main factor regarding VLM infection in children is outdoor playgrounds or playing areas.

[Toxocariasis as a cause of hypereosinophilia]

Toxocariasis is one of the causes of eosinophilia in peripheral blood and provokes eosinophilic infiltration in internal organs. In Israel, the number of cases of toxocariasis is very low, 3 cases annually, according to the records at the Ministry of Health. Many cases of eosinophilia might be misdiagnosed as hypereosinophilia syndrome (HES), if serological testing for Toxocara is not conducted, leading to inappropriate treatment. The test is for specific serum IgG antibody of Toxocara canis antigen measured by enzyme-linked immunosorbent assay (ELISA). The authors present a 4 year old girl with hypereosinophilia of 40,000 cell/microl, without involvement of target organs. The authors found that toxocara was the cause of hypereosinophilia. After appropriate treatment the number of eosinophils decreases, presenting a measurement of the parasite activity.

[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.

A familial case of visceral larva migrans after ingestion of raw chicken livers: appearance of specific antibody in bronchoalveolar lavage fluid of the patients

We report a familial case of visceral larva migrans (VLM) caused by Toxocara canis larvae. Patient 1 was a 45-year-old man who presented to our university hospital complaining of mild fever, general fatigue, and headache. Patient 2 was a 71-year-old man and was the father of Patient 1; he presented complaining of cough and hyper-viscous white sputum. Laboratory data from both patients showed extensive eosinophilia, their chest X-ray findings revealed multiple pulmonary infiltrates, and their bronchoalveolar lavage fluid (BALF) showed an elevated eosinophil count. The diagnosis of VLM was made based on a positive result in a serological test using T. canis larval excretory-secretory both in the serum and BALF. T. canis larvae were identified in meat that was prepared from chicken taken from the same source as that ingested. This is the first report to identify antibodies in BALF in patients with VLM.

A Survey of Environmental Contamination with Ascarid Ova, Wallingford, Connecticut

Few studies have been conducted in the United States to quantify the potential risk associated with encountering zoonotic ascarid ova in the environment. In an effort to raise awareness and to better understand the risk of acquiring visceral larva migrans in south central Connecticut, this environmental survey was conducted to determine the prevalence of ascarid ova (Toxocara canis, Toxocara cati, Baylisascaris columnaris, and Baylisascaris procyonis) in public areas of Wallingford, Connecticut, to compare prevalence levels among these public areas, and to determine what host species are primarily responsible for environmental contamination. A preliminary study was conducted to determine if ascarid ova of different species could be identified by size and appearance utilizing light microscopy alone; results did not support the differentiation of species via these methods. To determine the prevalence of environmental contamination with ascarid ova, samples of approximately 250 g of soil were collected from park green areas, playgrounds, public housing areas, parkways, and a school. Ova were detected in 46 (14.4%) of 319 samples collected. Ova were collected from three of the 60 (5.0%) park green area samples, 11 of the 40 (27.5%) playground samples, six of the 98 (6.1%) public housing samples, and 26 of the 96 (27.1%) parkway samples. Public areas of Wallingford, Connecticut are frequently contaminated by potentially infectious ascarid ova. Of particular concern is the high degree of contamination of playgrounds and the potential risk these areas pose to children's health.

[Negligible risk of visceral or ocular larva migrans from petting a dog]

In a recent publication it was suggested that human toxocarosis, including ocular larva migrans, may result from petting dogs infected with Toxocara canis, the dog roundworm. Recalculating the eggs per gram in the dog's coat revealed that in 7 of the 15 positive dogs only one Toxocara egg per dog was found. Only 4% of all eggs were embryonated and hence infectious. It is, however, very plausible that this is contamination originating from the environment. The authors found also many other parasite eggs and free-living larvae in their samples, which points to the dog being merely a passive transport host. The risk to man of acquiring the infection by stroking a dog is therefore considered to be extremely limited.

[Eosinophilia, diarrhea]

A 46-year-old Swiss woman presents with intermittent abdominal pain and persistent eosinophilia that is suggestive of helminthic etiology. Though her stay in Africa goes back > 35 years, an imported disease is a possibility. However, contact with a puppy suggests a locally acquired organism. Antibodies to filariae and Toxocara are demonstrated in the serum. Following treatment with albendazole 400 mg daily for 14 days the patient makes a full recovery, and the final diagnosis is active Toxocara canis infection.

Prevalence of Toxocara spp. eggs in the soil of public parks in Ankara, Turkey

One hundred and seventy soil samples from forty-six public parks in Ankara area were examined to determine the level of contamination with Toxocara spp. eggs. 30.6% of the 170 soil samples were contaminated with Toxocara spp. eggs. The number of eggs in the positive soil samples varied from 1 to 10. A high proportion of the eggs was fully embryonated. The findings demonstrate the common occurrence of these eggs in locations likely to be important in the transmission of visceral larva migrans. Of 19 fecal collected, 5 (26.3%) contained Toxocara spp. eggs. Eggs of Ancylostomidae, Toxascaris leonina, Trichuris spp., Taenia spp. and Enterobius vermicularis were also recovered from 17.6, 4.1, 2.4, 1.8 and 1.2% of soil samples, respectively.

Radiologic-pathologic findings in raccoon roundworm (Baylisascaris procyonis) encephalitis

A 13-month-old boy developed eosinophilic meningoencephalitis, retinitis, and a protracted encephalopathy with severe residual deficits. The initial MR examination revealed diffuse periventricular white matter disease, and follow-up images showed atrophy. Brain biopsy, serology, and epidemiologic studies lead to the diagnosis of Baylisascaris procyonis infection, a parasitic disease contracted through exposure to soil contaminated by the eggs of a common raccoon intestinal roundworm. The pathologic, epidemiologic, and imaging features of this disease are herein reviewed.

[Incidence of Toxocara ova--especially ova of visceral larva migrans in beach sand of Warnemünde in 1997]

Beach sand was examined and analysed in 1997 at several locations in Warnemünde, a North-East German seaside resort, especially for the incidence of the nematode genuo Toxocara. Two of 126 samples contained Toxocara. The author points out measures to decrease the risk of infection.

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.

[Toxocara canis (Nematoda) and toxocariasis of animals and humans]

Some aspects of dog toxocarosis and syndrome of visceral larva migrans in human toxocarosis, particularly in children were presented. In detail the morphological characters and biology of Toxocara canis, its pathogenicity, ways of invasions as well as conditions favouring the spreading of parasites were discussed. Attention was paid to the efficacy of diagnosis of invasions, treatment and prophylaxis. The current toxocarosis threat was analysed and epidemiological prognosis was moved forward.

Human toxocariasis and the visceral larva migrans syndrome: correlative immunopathology

The surface of T. canis is now recognized as a dynamic structure which turns over quite rapidly and serves as a renewable source of large quantities of antigen(s). The major host responses to these antigens include a marked eosinophilia and hyperglobulinemia. Both of these responses are apparently ineffective at ridding the body of infective larvae. Both eosinphils and IgE antibodies are manifestations of the Th2 subset of T helper cells and the cytokines that they secrete. Further, there is reason to believe that the antigens released from T. canis larvae favor the induction of this cellular population. Finally, there is mounting evidence that the chronic production of parasite antigen and its continued stimulation of the host immune system with a concomitant production of eosinophils can lead to a permanent alteration of the normal organization of the cardiopulmonary system. In the absence of any well-documented drugs capable of killing infective larvae, it would seem that immunological intervention may offer the only way to minimize or neutralize this 'gift from man's best friend'. This chapter was not intended to be an exhaustive review of the literature pertaining to toxocariasis. Several other recent publications will hopefully fulfill the need for more detailed information on the biology of this organism and the clinical spectrum of the disease it produces [16, 138-140]. Finally, a MEDLARS search of the current medical literature should bring anyone up to speed in a very short time.

Human toxocariasis

Human toxocariasis is a zoonotic infection which characteristically presents either as visceral or ocular disease. Some patients are asymptomatic. The real incidence of symptomatic infection and its natural history, and the likelihood of congenital infection, are unknown. Collaboration between clinicians, epidemiologists and microbiologists should help to resolve these questions.

Visceral larva migrans: a seroepidemiological survey in five municipalities of São Paulo state, Brazil

An enzyme-linked immunosorbent assay (ELISA), employing antigens from Toxocara canis larvae and the absortion of suspected sera with Ascaris lumbricoides extracts was used in a seroepidemiological study performed in five municipalities of São Paulo State, Brazil (São Paulo, Campinas, Santos, Marília and Presidente Prudente) in order to determine the frequency of antibodies to Toxocara. In 2,025 blood samples collected, 806 proceeded from male subjects and 1,219 from females; 483 samples were collected from subjects under 15 years of age and the remaining 1,542 from subjects aged 15 years or over. Among the 2,025 sera investigated, 3.60% had antibodies to Toxocara at significant levels. A moderate predominance of infection with Toxocara among male subjects (3.72%) was observed, although the difference was not statistically significant when this rate was compared with that for female (3.28%). Related to age, a higher frequency of positive results was detected among subjects under 15 years (6.41%) against the older group (2.53%). A trend of more elevated rates of infection was observed in municipalities with high demographic densities (São Paulo, Campinas and Santos). Nevertheless, such findings only appeared to be statistically significant in subjects younger than 15 years.

[Domiciliary and occupational contact with dogs as risk factors of human infection by Toxocara larvae]

The contact with dogs at home or place of work has been investigated as factors of risk in the occurrence of the visceral larva migrans syndrome caused by Toxocara, in man. Through the E.L.I.S.A. (enzyme-linked immunosorbent assay) technique, the presence of antibodies to Toxocara was searched in the sera of 79 women who have been raising or had raised dogs at home in the last two years and 123 men, who were municipal public employees in charge of the capture and keeping of stray dogs. The control groups were constituted by 205 sera from women who denied domiciliary contact with dogs, at least in the last two years, and 139 sera from men whose occupation did not urge them to contact with dogs. A significant more elevated frequency of antibodies to Toxocara was observed among women with domiciliary contact with dogs; nevertheless, there was not a significant difference in the positive rates in the case of men with occupational contact with dogs.

Visceral larva migrans in French adults: a new disease syndrome?

Visceral larva migrans is apparently an endemic disease among adults in southwest France. Thirty-seven adults living in the Midi-Pyrenees region of France were confirmed as having visceral larva migrans based on an increased specific antibody titer to Toxocara canis as detected by enzyme-linked immunosorbent assay (ELISA) and by the Western blot method. The disease was characterized clinically by weakness, pruritus, rash, difficulty breathing, abdominal pain, and pathologically by allergic manifestations including eosinophilia and increased serum immunoglobulin (Ig) E levels. Conditional logistic regression analysis using a control group of 37 hospital patients with other conditions who were individually matched to patients with visceral larva migrans by age and sex revealed an increased risk for visceral larva migrans associated with hunting or living in a household with a hunter (odds ratio (OR) = 9.0, p = 0.02) and with living in a village of less than 500 persons (OR = 5.7, p = 0.04). Owning two or more dogs compared with owning one or no dogs increased the risk of visceral larva migrans for hunting or living in a household with a hunter (OR = 9.6 vs. OR = 4.5) and for persons living in nonhunting households (OR = 2.1 vs. OR = 1.0). These findings, however, could not be duplicated when 60 age- and sex-matched neighbors were used as a second control group.

[Larva migrans visceralis--occurrence of ascarid eggs in sandboxes in the East German district city of Cottbus]

Between 1982 and 1985 18 sand-pits were examined for Toxocara canis eggs. Eggs were found in 4 sand-pits. This implies a risk of larva migrans visceralis infection for children playing in these sand-pits. Some measures for diminishing the contamination are recommended.

Zoonotic visceral and ocular larva migrans

Infection of children with the larval stage of the dog roundworm Toxocara canis usually produces few, if any, clinical signs. In some children, however, the disease may be severe, with permanent ocular or neurologic sequelae. Because the prevalence of infection may exceed 10 per cent in some population subgroups, it is important to understand the modes of transmission and risk factors for infection. The clinical presentations of toxocariasis as well as recommendations for their prevention are described.

Clinical features of covert toxocariasis

The clinical features found in 14 children with toxocara ELISA titres of greater than or equal to 0.7 were compared with those found in 34 toxocara negative children. Blood eosinophils were elevated in 7 of the 14 patients and the highest eosinophilia was 14%. There was a highly significant association between hepatomegaly, cough, sleep disturbance and a raised titre (p less than 0.01). Behaviour disturbance, abdominal pain and headache were also significantly associated with a raised titre (p less than 0.05). The combination of abdominal pain, headache and cough was even more significantly associated with a high titre (p less than 0.0005) than were individual clinical features. It is suggested that in addition to the two well recognised clinical conditions of visceral larva migrans and ocular toxocariasis the clinical entity of covert toxocariasis should receive recognition. Eosinophilia may or may not be present in this condition.

Human toxocariasis. Review with report of a probable case

A 23-year-old woman with fever, myalgias, stridor, pelvic cramping, lower abdominal pain, and profound eosinophilia was presumed to have toxocariasis. An enzyme-linked immunosorbent assay titer of 1:64 and an elevated IgE level supported the diagnosis. The patient became asymptomatic without treatment, and the eosinophil count returned to normal over several months. A stool sample from her dog was found to contain Toxocara canis ova, but the patient had no history of geophagia. Presumably, she acquired infection by hand-to-mouth transmission of infectious ova after handling the dog. Toxocariasis from this type of transmission is usually not seen in an adult, but it does occur, as this case demonstrates. Thus, the primary care physician should consider toxocariasis in any patient with a suggestive clinical picture and eosinophilia.

[Larva migrans visceralis--occurrence of Toxocara canis in dogs in the East German district of Cottbus]

Larvae of the nematode genus Toxocara are the main causative agents of the L.m.v. syndrom. 5,002 dogs from the Cottbus district aged between 2 and 36 months were examined. 994 animals (19.9%) were found to be infected with Toxocara canis. Dogs from a rural area have a higher infection rate (25.6%) than dogs from an urban area (15.2%). The relatively high infection rate of dogs, high egg-production and the tenacity of the development stages are factors dangerous to human health.

Visceral larva migrans: a risk assessment in Baton Rouge, Louisiana

Visceral larva migrans, VLM, is a disease of young children. Due to lack of awareness of the disease as well as its non-specific symptomology, a survey of the potential risk of acquiring the disease was conducted in the Baton Rouge, Louisiana area. The greatest number of dogs showing positive results to tests for the presence of the eggs of Toxocara canis were those less than one year of age. Very few of the soil samples collected from twenty different parks/playgrounds were found to contain eggs of T. canis. A higher percentage of soil samples from individual yards proved to be contaminated with the eggs of the parasite. Even though the incidence of VLM in Baton Rouge is reported to be quite low, the potential for the infection certainly is present. Veterinarians must be prepared to take a leading role in the education of their clients as to the potential of the disease for the children associated with new puppies, and the measures parents can take to reduce the exposure potential.

[Visceral larva migrans in childhood: report of 2 cases]

Reports of Visceral larva migrans (VLM) are not frequent in Brazil, but the prevalence of this disease may be more common due to poor environmental conditions to which most of the children are exposed. The most common infectious agent is Toxocara canis, a parasite of the intestinal tract of dogs. Children get infected eating contaminated material with feces of dogs. The ova are swallowed and reach the intestinal lumen of the children. Systemic migration occurs by lymphatic or portal circulation to several organs, most frequently, to the liver and lungs, causing hepatosplenomegaly and/or bronchospasm.

[Toxocara canis as a cause of visceral larva migrans. Survival and development of eggs in the environment and potential ways of transmission to man: a review]

A review is given on the occurrence of Toxocariasis, the prevalence of T. canis among dogs and investigations on the prevalence of infective ova in soil- and sandsamples. The resistance of ascarid eggs and larvae against different environmental influences, including various sewage treatment-effects is discussed. The eggs are destroyed in 7 minutes when kept at 55 degrees C in a high humidity, slower when the humidity is lowered. When the temperature is -32 degrees C T. canis eggs are inactivated after 8 hours. Complete embryonation is reached in 4 days when the temperature is 30 degrees C. Potential ways of transmission to man are outlined (pica, vegetables, bathing etc.) and recommendations in order to prevent the disease are given such as deworming of dogs, methods to decimate occurrence of eggs in wastewater and sludge etc.

Toxocariasis in an institution for the mentally retarded

A seroepidemiologic investigation was conducted in order to determine the cause of an apparent increase in rates of eosinophilia among 1400 institutionalized children during 1976-1977. The annual serologic survey during this period revealed 283 (20%) individuals with eosinophilia that exceeded 600 cells/cu mm of blood. During a five-month period in 1977, five patients who were hospitalized in adjacent wards developed acute pneumonia with eosinophilia. Because laboratory tests of sputum, bone marrow, and stool failed to identify the etiologic agent, it was thought that these pneumonia cases might be related to the increased rates of eosinophilia. Analyses of random samples of sera from patients with eosinophilia revealed seroprevalence rates of 12% for Ascaris, 20% for Toxocara canis, 24% for Strongyloides stercoralis, and 32% with increased antibody to Entamoeba histolytica. Further investigation showed a statistically significant positive association between occurrence of eosinophilia and pica behavior, and eosinophilia and contact with dogs. Although the serologic survey showed patients to have had previous exposure to a variety of parasites, we hypothesize that a principal cause of eosinophilia among institutionalized children may be Toxocara infestation, due to their frequent pica behavior and, in this case, contact with resident animals. We recommend that children in similar facilities have limited contact with pet dogs, and only after frequent and vigorous examination of the animals for infectious parasites.

Pica patterns, toxocariasis, and elevated blood lead in children

Blood samples were obtained during a lead screening program from 100 children aged 1-6 years in Allegheny County, Pennsylvania, to determine whether there was any association between specific forms of pica and infection with Toxocara canis, the principal cause of visceral larva migrans in the United States, or elevated blood lead levels. Significant associations were found between: 1) feces, soil, or grass pica and Toxocara infection; 2) paint or plaster pica and elevated blood lead; and 3) dog ownership and Toxocara infection. These findings suggest that an accurate pica history may be useful in identifying potential health problems in children.

Risk factors for toxocaral ocular larva migrans: a case-control study

Twenty-four patients with serologically confirmed toxocaral ocular larva migrans (OLM) and 24 age- and sex-matched controls were the subjects of an epidemiologic study. Information on the exposure to dogs and other factors possibly associated with transmission of toxocariasis was obtained by contacting the parents of the subjects. The odds of having had a dog present in the household within the year previous to onset of illness were 3 to 1 for cases vs controls. An association of pups (< 3 months) in the households of OLM patients within one year of onset was statistically significant (P < .05). Twenty-three of 24 OLM patients had had dogs in their homes some time before their illness, and the twenty-fourth patient had a history of geophagia, a behavioral pattern previously identified as a risk factor for toxocariasis. Exposure to cats and other animals in or outside the home did not differ for patients and controls. Infected dogs, especially pups, in the patients' homes were the most probably sources of infection for this group of OLM patients.

An outbreak of toxoplasmosis linked to cats

Clinical, serologic, and epidermiologic evidence documents an outbreak of toxoplasmosis involving ten of 30 members of an extended family. The index patient had unusual clinical manifestations including brain abscesses, progressive chorioretinitis, seizures, neurologic deficits, hepatosplenomegaly, pneumonitis, and eosinophilia. Toxoplasmosis was confirmed by demonstrating the organism in brain tissue and cerebrospinal fluids; clinical and serologic evidence also indicated infection with Toxocara (viscd children. Of the 11 such children, seven (68%) were seropositive, six of whom had high acute-phase titers (greater than or equal to 1024) to Toxoplasma and a disease consistent with acute toxoplasmosis. All six of the latter group required specific chemotherapy. Geophagia was associated statistically with acute toxoplasmosis among the children; it also increased the risk of infection with Toxocara and enteroparasites. Two school-aged children and two adults had serologic evidence of acute toxoplasmosis, but only one of the group was symptomatic. Epidemiologic evidence indicates that this outbreak was probably caused by ingesting oocysts from cat feces. We suggest that the severe and unusual clinical manifestations of the index patient resulted from simultaneous infection with Toxoplasma and Toxocara.

Prevalence of Toxocara canis in babies and in adults as determined by the ELISA test

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