Toxocariasis
Overview
Toxocariasis or toxocarosis is a helminthic infection of humans caused by the dog or cat roundworm, Toxocara canis or Toxocara cati, respectively. Humans can become infected by ingestion of embryonated eggs (containing fully developed larva, L3) from contaminated sources. There are two main syndromes: visceral larva migrans (VLM), which encompasses diseases associated with major organs; and ocular larva migrans (OLM), in which toxocariasis pathological effects on the host are restricted to the eye and the optic nerve.[1]
Symptoms
Many kids won't have symptoms, but if they do, they can include fever, cough or wheezing, abdominal pain, enlarged liver or spleen, poor appetite, a rash that sometimes looks like hives, and enlarged lymph nodes ("swollen glands"). Toxocariasis also may affect the eyes, causing decreased vision, swelling around the eyes, or a cross-eyed appearance. Untreated toxocariasis can cause retinal damage and decreased vision. Most cases go undiagnosed and do not cause problems. Some toxocariasis cases are diagnosed during a routine eye exam or an X-ray study done for some other reason.
Causes
* Toxocara cati * Toxocara canis * Loa loa * Baylisascariasis * Toxocariasis * Diffuse unilateral subacute neuroretinitis * Gnathostomiasis * Strongyloidiasis
Prevention
The eggs of Toxocara species are widespread in parks, playgrounds, yards, and in homes and apartments where the occupants have dogs or cats. Elimination of eggs from the environment is not possible; therefore, prevention depends on proper hygiene, including handwashing after contact with pets. Public policies that have attempted to eradicate Toxocara infection in dogs and cats have had limited success.
Diagnosis
In suspected cases, diagnosis is confirmed by: an increase in the anti-Toxocara excretory-secretory antigen IgE level; a recent history of exposure to susceptible dogs and cats; sustained eosinophilia, hyperglobulinemia, and hepatomegaly; and liver biopsy demonstrating degenerated larvae at the centre of eosinophilic granulomas.
Prognosis
Toxocariasis is always a benign, asymptomatic, and self-limiting disease, although brain involvement can cause brain damage, meningitis, encephalitis, or epilepsy. Ocular involvement, also known as 'ocular larvae migrans,' may cause loss of visual acuity or unilateral blindness. Pulmonary and hepatic forms can cause protracted symptoms if the patient does not receive treatment.
Treatment
General anthelmintic treatments (mebendazole, thiabendazole and diethylcarbamazine) are common; albendazole is the more modern form of treatment. Management with anti-inflammatory steroids is also an option.