Evaluation of the dot enzyme-linked immunosorbent assay in comparison with standard ELISA for the immunodiagnosis of human toxocariasis

Abstract

A dot enzyme-linked immunosorbent assay (dot-ELISA) was standardized using excretory-secretory antigens ofKey words: Toxocara canis -toxocariasis -dot enzyme-linked immunosorbent assay -ELISA Human toxocariasis is a world-wide helminthic zoonosis due to the human infection by larvae of Toxocara canis, the common ascarid of dogs, and also by the cat ascarid T. cati (Schantz & Glickman 1983, Despommier 2003. The incidence of human toxocariasis is unknown because toxocariasis is not a communicable disease in the majority of the countries. However, many cases of this disease have been reported throughout the world (Glickman & Schantz 1981, Despommier 2003.Humans are infected by ingestion of embryonated T. canis eggs. Children playing in areas contaminated with dog faeces are in higher risk, because of their likelihood of ingesting soil. Prevalence of Toxocara infestation of dogs and the resulting contamination of the ground is relatively high in many countries all over the world. Reported data range from 0 to 93% for dog infestation (Glickman & Schantz 1981) and 15 to 78% for soil contamination (Gillespie 1988, Magnaval et al. 2001. It has been determined that in Peru from 24 to 80% of soil samples in public playgrounds and parks are contaminated with Toxocara eggs (Buitrón 1976, Guerrero 1995, Lescano et al. 1998, Chavez et al. 2000, Dávalos et al. 2000.Although the clinical features vary, two syndromes are recognized: visceral larva migrans (VLM) and ocular larva migrans (OLM). VLM is usually detected in young children (1 to 5 years of age) with a history of geophagia and/or exposure to puppies. It is a self-limited, rarely lethal disease characterized by fever, cough, wheeze, pallor, malaise, asthma, weight loss, hepatomegaly, and marked eosinophilia (Schantz 1989 mus and, more rarely, eye pain (Shields 1984). Another clinical manifestations of Toxocara infection are "common toxocariasis" in adults and "covert toxocariasis" in children (Schantz 1989, Magnaval et al. 2001.Diagnosis of toxocariasis is based on clinical and serological data because of the difficulty in detecting larvae from tissues. The test currently employed for the serodiagnosis of toxocariasis is ELISA using excretory-secretory antigens from T. canis second-stage larvae (TES) (De Savigny et al. 1979, Jacquier et al. 1991. However, this technique has some drawbacks, including the need for trained personnel, requirement of special equipment, the lack of reproducible reading due to plate-to-plate variation, and may be troublesome to perform under field conditions. Dot-ELISA test, a modification of the standard ELISA test, offers a simple and less expensive tool for toxocariasis detection. The dot-ELISA has been successfully adapted for the detection of parasitic diseases in humans as leishmaniasis, schistosomiasis, toxoplasmosis, and hydatidosis (Pappas et al. 1984, Boctor et al. 1987, Rogan et al. 1991, Elsaid et al. 1995. A dot-ELISA for diagnosis of human toxocariasis was described (Camargo et al. 1992). The present study was conducted to standa...

Human toxocariasis: a seroepidemiological survey in the Amazonian city of Yurimaguas, Peru

“…Because of the difficulty of detecting Toxocara larvae in biopsy tissues, the diagnosis of human toxocariasis is essentially based on immunological assays such as the ELISA test using the excretorysecretory antigens from infective Toxocara larvae (TES) to detect antiToxocara antibodies, which have good sensitivity and specificity 14,18,29 . With the development of this test, several seroepidemiological studies also have been possible 5,22,33 .…”

“…Anti-Toxocara IgG antibodies were detected in serum samples by ELISA-IgG test using TES antigens and each serum sample was previously absorbed with total Ascaris suum adult extract in order to avoid the crossreactions in the immunoassay 29 . All sera were tested at 1:200 dilutions and all stages of the immunoassay were performed at room temperature.…”

In vitro production of Toxocara canis excretory-secretory (TES) antigen

“…Treatment of eggs with sodium hypochlorite to dissolve chitinous layer tended to mimic physiological conditions (Rajapakse et al 1992). In the present study embryonated eggs were treated with 4 % sodium hypochlorite for 2 h as it was found to be optimal for subsequent hatching whereas Watthanakulpanich et al (2008) reported an optimal timing of 3 h. However varied incubation time with different concentrations of sodium hypochlorite has been reported (Gupta 1984;Bowman et al 1987;Williamson et al 1990;Shobana 2003;Roldan et al 2006).…”

“…Many authors reported about the hatching of decorticated eggs using mechanical force Smith 1989;Crowcroft and Gillespie 1991;Roldan et al 2006;Kim et al 2008). The procedure adopted in the present study avoided the washing step of the collected larvae with the medium before keeping in cultures and also gave a better recovery of larvae when compared to earlier protocols.…”

“…Decortication of larvated eggs using different concentrations of sodium hypochlorite was tried elsewhere (Oaks and Kayes 1979;Maizels et al 1984;Bowman et al 1987;Williamson et al 1990;Crowcroft and Gillespie 1991;Roldan et al 2006 andPonce-Macotela et al 2011) whereas Iddawela et al (2007) used saturated calcium hypochlorite. Treatment of eggs with sodium hypochlorite to dissolve chitinous layer tended to mimic physiological conditions (Rajapakse et al 1992).…”