Toxocaridae is a zoonotic family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of parasitic nematode

Nematode

The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

s that infect canids and felids and which cause toxocariasis

Toxocariasis

-History of discovery:Werner described a parasitic nematode in dogs in 1782 which he named Ascaris canis. Johnston determined that what Werner had described was actually a member of the genus Toxocara established by Stiles in 1905. Fữlleborn speculated that T canis larvae might cause granulomatous...

 in humans (visceral larva migrans and ocular larva migrans). The worms are unable to reproduce in humans.

Three important species include:

• Toxocara canis
  Toxocara canis
  Toxocara canis is worldwide distributed helminth parasite of dogs and other canids. T. canis are gonochorists, adult worms measure from 9 to 18 cm, are yellow-white in color, and occur in the intestine of the definitive host. In adult dogs, the infection is usually asymptomatic. By the...
  
  , which infects dogs,
• Toxocara cati
  Toxocara cati
  Toxocara cati is worldwide distributed parasite of cats and other felids and it is one of the most common nematode of cats. Adult worms are localised in gut of the host. In adult cats, the infection is usually asymptomatic. However, massive infection in juvenile cats can be fatal.-External links:*...
  
  , which infects cats and which lacks intermediate hosts,
• Toxocara vitulorum, which infects buffalo and cattle.

Infection

Infection by T. canis or T. cati can cause various clinical manifestations. One of these is visceral larva migrans, wherein the larvae are unable to develop in humans as they do in cats and dogs, their natural hosts. Arrested development leaves the larvae to wander aimlessly in the body, causing inflammation, most commonly in the liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

 and lung

Lung

The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

s.

Eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 are introduced into the body through ingestion. This can occur when eggs are deposited on the hands or face, after handling infected dog

Dog

The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

s or cats. In children without exposure to animals, eggs can be introduced by directly ingesting egg-contaminated soil while playing in a yard or on a playground. Usually, the scenario involves a young child with a new puppy. Unfortunately, many young children who have been infected with these larvae, causing ocular larva migrans in the eye

Eye

Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

, have been misdiagnosed to have retinoblastoma

Retinoblastoma

Retinoblastoma is a rapidly developing cancer that develops in the cells of retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers , with more than nine out of every ten sufferers surviving into...

 and have had their eyes erroneously removed. Treatment for ocular larva migrans is to kill the larvae with a laser to prevent further damage, although some loss of vision in the affected eye is irreversible.

Diagnosis

Direct identification of larvae in human disease is not feasible, so the diagnosis relies on history supported by serologic ELISA

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

 assay. The most sensitive assay, called E/S (excretory/secretory), contains 96 immunogenic antigens isolated from cultured T. canis larvae.

Prevention and Treatment of infection

There are a number of products supplied by veterinarian

Veterinarian

A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....

s that can prevent or treat infections with this parasite. A great deal of information on this subject can be found on the computer sites maintained by the Companion Animal Parasite Council

Companion Animal Parasite Council

The Companion Animal Parasite Council The Companion Animal Parasite Council The Companion Animal Parasite Council (also commonly referred to as CAPC, pronounced "Cap-C", is a non-profit organization (501c3) composed of practicing veterinarians, academic veterinary parasitologists, veterinary...

.