Toxocara canis

About: Toxocara canis is a research topic. Over the lifetime, 2200 publications have been published within this topic receiving 46640 citations.

Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects

Abstract: Toxocariasis is caused by a series of related nematode species (ascarids) that routinely infect dogs and cats throughout the world. The eggs from these ascarids are common environmental contaminants of human habitation, due largely to the fact that many kinds of dogs and cats serve as pets, while countless others run wild throughout the streets of most urban centers. The eggs, present in dog and cat feces, become infectious within weeks after they are deposited in the local environment (e.g., sandboxes, city parks, and public beaches, etc.). Humans, particularly children, frequently ingest these eggs by accident and become infected. Infection in humans, in contrast to their definitive hosts, remains occult, often resulting in disease caused by the migrating larval stages. Visceral larva migrans (VLM) and ocular larva migrans (OLM) are two clinical manifestations that result in definable syndromes and present as serious health problems wherever they occur. Diagnosis and treatment of VLM and OLM are difficult. These issues are summarized in this review, with emphasis on the ecology of transmission and control of spread to both humans and animals through public health initiatives employing treatment of pets and environmental intervention strategies that limit the areas that dogs and cats are allowed within the confines of urban centers.

Chronic eosinophilia due to visceral larva migrans; report of three cases.

Abstract: Three cases of chronic extreme eosinophilia with granulomatous lesions in the liver have been studied. A larval nematode observed in sections from the liver of one patient has been identified either as Toxocara canis or Toxocara cati, common cosmopolitan ascarids of dogs and cats; available evidence favors the former. The term visceral larva migrans is proposed for this type of parasitism, known in animals but not previously described in humans. It is related to better known cutaneous larva migrans, in that both are usually caused by infective stage larvae of nematode parasites of other animals. Man being an abnormal host, either has unfavorable tissue reactions or otherwise fails to provide stimuli for usual tissue migration and development of the parasite. As a result, larvae remain active for variable periods in various tissues. Similar but less severe and less prolonged reactions occur when the larvae of normal nematode parasites of man invade the tissues of a hyperimmune individual. Visceral larva migrans is usually a relatively benign disease, characterized chiefly by sustained eosinophilia, pneumonitis and hepatomegaly, and probably is due both to direct tissue damage by migrating larvae and to allergic responses to their products. Its severity varies with the number of larvae in the tissues and the immune or allergic state of the infected individual.

Human toxocariasis: diagnosis, worldwide seroprevalences and clinical expression of the systemic and ocular forms

Abstract: Although human toxocariasis ranks among the most common zoonotic infections worldwide, it remains relatively unknown to the public. The causal agents are the nematode parasites Toxocara canis and T. cati, whose definitive hosts are dogs and cats, respectively. When embryonated eggs are accidentally ingested by humans, larvae hatch in the small intestine, penetrate the intestinal wall and migrate, via the bloodstream, to the liver, lungs, muscles, eye and central nervous system. Although most human infections are asymptomatic, two well-defined clinical syndromes are classically recognised: visceral larva migrans (a systemic disease caused by larval migration through major organs) and ocular larva migrans (a disease limited to the eyes and optic nerves). Two less-severe syndromes have recently been described, one mainly in children (covert toxocariasis) and the other mainly in adults (common toxocariasis). Here, the current laboratory diagnosis, epidemiology and main clinical features of both the systemic and ocular forms of human toxocariasis are reviewed. New developments in serological diagnosis are described, the available seroprevalence data are analysed, and the results of relevant clinical studies that have been published over the last decade are explored, to provide an updated overview of this neglected but highly prevalent human infection.