Acta Tropica 135 (2014) 50–54 Contents lists available at ScienceDirect Acta Tropica jo u r n al homep age: www.elsevier.com/locate/actatropica Molecular characterization of Toxocara spp. from soil of public areas in Ahvaz southwestern Iran Shahram Khademvatan a,b,∗ , Rahman Abdizadeh b , Mahdi Tavalla b a Research Institute for Infectious Diseases of Digestive System, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran b Department of Medical Parasitology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran a r t i c l e i n f o Article history: Received 7 November 2012 Received in revised form 4 March 2014 Accepted 7 March 2014 Available online 30 March 2014 Keywords: Toxocara spp. Eggs Soil PCR a b s t r a c t In the present study, the microscopy and polymerase chain reaction methods were used for detection and identification of soil contamination by Toxocara eggs in squares, streets, public parks, and rubbish dumps in Ahvaz, southwestern Iran. A total of 210 soil samples were collected from different parts of the city and examined by microscopy and polymerase chain reaction (PCR) methods, following sodium nitrate flotation. Nucleotide sequencing was performed to confirm the results of the PCR method. Toxocara eggs were found in 64 and 71 soil sam- ples using the microscopy and PCR methods, respectively. The highest contamination rate was observed in the central part of Ahvaz (39.5% and 46.5% by the microscopy and PCR methods, respectively). Based on internal transcribed spacer 2 (ITS2) PCR identification, 28% of the samples were diagnosed as Toxocara cati and 5.7% as Toxocara canis; no mixed contamination was observed. DNA sequencing of the ITS2 gene confirmed our findings. Compared to the conventional microscopic detection following by flotation, used as the gold standard, the PCR method appears to be rapid and sensitive as well as allows analysis of Toxocara spp. isolated from soil independent of the stage of egg development. Therefore, the PCR method appears to be a valuable tool for the diagnosis and differentiation of Toxocara spp. from soil samples in epidemiological studies, and will help the local health systems in effective prevention and control of disease. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Human toxocariasis is a widespread helminthic zoonotic disease that is caused by the larval stage of Toxocara canis (dog round- worm) and Toxocara cati (cat roundworm) (Despommier, 2003; Fisher, 2003; Lee et al., 2010). Infected cats and dogs pass more than 50,000 eggs/g feces into the environment daily. After 3–6 weeks, depending on the temperature and moisture, eggs become embryonated and infective (Despommier, 2003; Lee et al., 2010). Therefore, these animals play a significant role in the epidemiology of toxocariasis, especially in the tropical, subtropical, and temper- ate regions of the world (Azian et al., 2008; Fisher, 2003). Infections of humans are commonly acquired via accidental ingestion of embryonated eggs in the soil and uncooked vegetables ∗ Corresponding author at: Research Institute for Infectious Diseases of Digestive System and Department of Medical Parasitology, Ahvaz Jundishapur University of Medical Sciences, PO Box: 613715794, Ahvaz, Iran. Tel.: +98 611 3367543x50; fax: +98 611 3332036. E-mail address: khademvatan@yahoo.com (S. Khademvatan). (Akao and Ohta, 2007; De Oliveira and Germano, 1992; Hoffmeister et al., 2007; Lee et al., 2010; Szabová et al., 2007; Uga et al., 2009; Yoshikawa et al., 2008; Zibaei et al., 2010). Depending on the num- ber of ingested eggs, localization of the larvae, and host responses, the infection in humans has four clinical manifestations, namely visceral larva migrans (VLM), ocular larva migrant (OLM), covert toxocariasis (CT), and neurological toxocariasis (NLM) (Azian et al., 2008; Congdon and Lloyd, 2011; Macpherson, 2005; Smith et al., 2009). In Iran, stray animals feast on rubbish and leftover food count- less times and discharge helminth eggs and protozoan cysts into public environments (Khademvatan et al., 2013). The increasing number of stray dogs and cats in urban and rural areas, easy access of animals to public parks, streets, rubbish dumps and increasing popularity of keeping animals as pets may contribute to soil con- tamination and increase parasitic infections, such as toxoplasmosis and toxocariasis (Despommier, 2003). Toxocara eggs remain viable in the soil for a long time depend- ing on several factors, such as climatic conditions, humidity of the soil, and exposure to sunlight (Storey and Phillips, 1985). Consequently, soil contamination seems to be the most direct http://dx.doi.org/10.1016/j.actatropica.2014.03.016 0001-706X/© 2014 Elsevier B.V. All rights reserved.