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Human toxocariasis, a worldwide parasitic disease, is caused by the larval stage of intestinal nematodes of dogs and cats, namely Toxocara canis and Toxocara cati. Human infection occurs by the accidental ingestion of embryonated eggs present in the soil, vegetables or on other contaminated surfaces, as well as via consumption of uncooked paratenic hosts, such as bird meat and giblets. The objective of this study was to evaluate the contamination of soil in public parks and playgrounds in Shiraz using microscopy and molecular methods. A total of 150 soil samples were collected from public parks and playgrounds in various areas of Shiraz, southern Iran. The samples were treated with saturated zinc sulphate solution, and Toxocara spp. eggs were detected by microscopic observation followed by nested polymerase chain reaction (PCR). To differentiate T. canis and T. cati eggs from each other, PCR restriction fragment length polymorphism (RFLP) of the internal transcribed spacer (ITS)-rDNA region by Sal I endonuclease enzyme was used. PCR-sequencing was performed to confirm the results of the PCR-RFLP method. Based on the flotation results of the 150 soil samples, six (4%) were found to be positive for Toxocara spp. eggs, whereas nested-PCR showed 24 samples to be positive (16%). Based on the PCR-RFLP method and the sequence of the ITS-rDNA region, a total of 23 out of 24 isolates were confirmed as T. cati and one out of 24 as T. canis. The results showed a higher number of soil samples to be positive for Toxocara by the molecular method than microscopy, and higher T. cati infection in soil samples, which could have an important role in human infection with toxocariasis in this region. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the sequence variation in two mitochondrial genes, namely cytochrome c oxidase 1 (pcox1) and NADH dehydrogenase 1 (pnad1) within and among isolates of Toxocara cati, Toxocara canis and Toxascaris leonina. Genomic DNA was extracted from 32 isolates of T. cati, 9 isolates of T. canis and 19 isolates of T. leonina collected from cats and dogs in different geographical areas of Iran. Mitochondrial genes were amplified by polymerase chain reaction (PCR) and sequenced. Sequence data were aligned using the BioEdit software and compared with published sequences in GenBank. Phylogenetic analysis was performed using Bayesian inference and maximum likelihood methods. Based on pairwise comparison, intra-species genetic diversity within Iranian isolates of T. cati, T. canis and T. leonina amounted to 0–2.3%, 0–1.3% and 0–1.0% for pcox1 and 0–2.0%, 0–1.7% and 0–2.6% for pnad1, respectively. Inter-species sequence variation among the three ascaridoid nematodes was significantly higher, being 9.5–16.6% for pcox1 and 11.9–26.7% for pnad1. Sequence and phylogenetic analysis of the pcox1 and pnad1 genes indicated that there is significant genetic diversity within and among isolates of T. cati, T. canis and T. leonina from different areas of Iran, and these genes can be used for studying genetic variation of ascaridoid nematodes. [ABSTRACT FROM AUTHOR]