Human toxocariasis: contribution by Brazilian researchers

Abstract

SUMMARYIn the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT).

A case report of ocular toxocariasis

“…When OLM is suspected, aqueous or vitreous fluids are the best options for diagnostic samples. Even, testing of ocular fluid sample did not give absolute positive result because approximately 10% of patients with clinical signs of OLM presented negative results by ELISA method [2] .…”

“…Serological diagnosis of OLM is more challenging than serodiagnosis of VLM or "covert toxocariasis", because the levels of antibodies in the serum are usually low or undetectable [2,6] and eosinophilia is often absent. Even low titres of specific antibodies in the serum may be of diagnostic value but there is no consensus about the cut-off titres for diagnosis [6] .…”

“…These nematodes develop the adult stage in the intestines of cats and dogs, where each female produces 200 000 eggs per day. These eggs are eliminated from the body and become infecting after [2][3][4][5] weeks. After being ingested by humans, the larvae go through the intestinal wall, migrating via the veins into the liver and the rest of the body, where they remain as larvae [1] .…”

“…The clinical signs of toxocariasis are not specific and differential diagnosis includes other parasitic diseases characterized by hypereosinophilia, such as allergic reactions, asthma, other helminthiasis, such as filariasis. Peripheral eosinophilia has been constantly associated with VLM but not among patients with OLM, probably due to low larva numbers [1,2] .…”

An evaluation of the dot-ELISA procedure as a diagnostic test in an area with a high prevalence of human Toxocara canis infection

“…An important problem when attempting to evaluate serological tests for human toxocariasis is that there is no reference laboratory test or parasitological method to definitively diagnose the disease (Chieffi et al 2009). …”