Arch Pediatr Infect Dis. October 2014. 3(4): e17911. DOI: 10.5812/pedinfect.17911 Published online 2014 July 6. Research Article A Comparative Seroprevalence Study of Toxocariasis in Hypereosinophilic and Apparently Healthy Individuals Bahador Sarkari 1,* ; Malihe Lari 2 ; Reza Shafiei 2 ; Seyed Mahmoud Sadjjadi 2 1 Basic Sciences in Infectious Diseases Research Center, Shiraz University of Medical Sciences, Shiraz, IR Iran 2 Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran *Corresponding author: Bahador Sarkari, Basic Sciences in Infectious Diseases Research Center, Shiraz University of Medical Sciences, Shiraz, IR Iran. Tel/Fax: +98-7112305291, E-mail: sarkarib@sums.ac.ir Received: January 28, 2014; Revised: February 28, 2014; Accepted: May 10, 2014 Background: Parasitic invasion of tissues can elicit hypereosinophilia. Among helminthic infections, moderate to severe eosinophilia can be seen in toxocariasis as a pathophysiological response to a worm infection. Objectives: The current study aimed to compare the rate of toxocariasis in normal and hypereosinophilic individuals in Shiraz, southern Iran. Patients and Methods: Serum samples of 100 patients with hypereosinophilia (> 10%) and 100 normal individuals (without eosinophilia) were collected. Demographic information of the participants was recorded in a predesigned questionnaire during sample collection. Anti-Toxocara antibodies in the subjects’ serum were evaluated by an ELISA. Results: In the hypereosinophilic patients, 54 (54%) were male, and 46 (46%) were female, while in the normal individuals, 58 cases (58%) were male, and 42 (42%) were female. The differences in gender and age of the participants were insignificant (P = 0.46 and 0.59 respectively). Range of eosinophilia found in the patients was between 10-77%. Anti-Toxocara antibodies were detected in the serum of 2 (2%) of the hypereosinophilic patients and 3 (3%) of the normal individuals. No significant correlation was found between hypereosinophilia and the presence of anti-Toxocara antibodies in this study (P = 0.65). Conclusions: Hypereosinophilia may be due to a variety of reasons and toxocariasis is just one of these. Appropriate tests should be carried out on patients in order to rule out a Toxocara infection in hypereosinophilic individuals. Keywords: Toxocara; Prevalence; Iran Copyright © 2014, Pediartric Infections Research Center; Published by Kowsar Corp. This is an open-access article distributed under the terms of the Creative Com- mons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. Background Toxocariasis is a zoonotic helminthic infection caused by the larval stages of Toxocara canis and Toxocara cati, which are common roundworms found in dogs and cats (1). The disease mainly affects children under five years- of-age. Human infection occurs through ingestion of embryonated eggs from the soil, dirty hands, uncooked vegetables, and paratenic hosts (2). The most widely rec- ognized source of human infection is ingestion of con- taminated soil followed by paratenic hosts (2-7). The re- leased larvae from the eggs or paratenic hosts enter the circulation which then invade and form granulomas in different tissues, including; liver, lungs, eyes, brain and other tissues (8, 9). The prevalence of toxocariasis due to soil contamination with Toxocara spp. eggs is from 6.6% to 87.1% (10-14). Inflammatory responses and eosinophilia are the most common signs of a Toxocara infection (4, 8). In helmin- thic diseases, moderate to severe eosinophilia occurs as a pathophysiologic response to the parasitic infection and toxocariasis is one of the main causes of eosinophilia, re- gardless of the presence of signs and symptoms or organ injury, in infected individuals (15). However, in many cases a peripheral eosinophilia is not connected to toxocariasis (16). High seroprevalence rates of toxocariasis have been reported in hypereosinophilic patients. Seo and Yoon in a seroepidemiological study in Korea, reported that out of a total of 101 eosinophilic patients, 50.5% were found to be positive by a Toxocara ELISA (17). In another study in Korea, the seroprevalence of toxocariasis among healthy people with eosinophilia was reported to be 67.0% (18). In a relatively similar study, the seroprevalence of toxocari- asis among asymptomatic children with eosinophilia in Croatia was found to be 31% (19). Maraghi et al. in a study conducted in Khuzestan, southern Iran, found that 19% of eosinophilic individuals were seropositive for toxocaria- sis (20). 2. Objectives The aim of the present study was to determinate and compare the rate of toxocariasis in normal and hypereo- sinophilic individuals in Shiraz, southern Iran. 3. Patients and Methods In this cross-sectional study which was carried out dur- ing February 2010 to April 2012, serum samples were col- lected from 100 patients with hypereosinophilia and 100