Detection of Toxoplasma gondii oocysts in environmental soil samples using molecular methods

Abstract

Infections caused by Toxoplasma gondii are prevalent in humans and animals throughout the world. So far, there is no sufficient information concerning T. gondii oocysts prevalence in the environment, especially in soil. Therefore, the aim of this study was to estimate occurrence of T. gondii oocysts in soil and determine the genotype of detected parasites. A total of 101 soil samples were taken from different sites (sand-pits, "farming ground", areas around rubbish dumps) located in the Tri-City (Poland). Oocysts were recovered using the flotation method. Then, PCR reactions targeting the B1 gene were performed for specific T. gondii detection. The positive samples were further confirmed by PCR amplification of a repetitive element (REP) sequence [GenBank accession number AF146527]. Toxoplasma DNA was found in 18 samples. Among them, seven samples were successfully genotyped at the SAG2 locus. They were classified as SAG2 type I (5 samples) and SAG2 type II (2 samples). This is one of the first investigations describing T. gondii oocyst detection in environmental soil samples with rapid molecular detection methods and genotyping. The results of our findings showed that soil contaminated with T. gondii oocysts may play a role in the epidemiology of human toxoplasmosis in Poland.

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…A study of a cat population living in the Croix-Rousse hospital (Lyon, France) showed that defecation sites were the areas most often found to be positive for T. gondii DNA, and may be viewed as hot spots of environmental risk to humans [50]. Similarly, in Poland and in China, contaminated soil samples have been found in public parks and sand pits [67,68]. Contact with soil, and particularly gardening and consumption of raw vegetables have been demonstrated to be significant risk factors for toxoplasmosis in humans [69,7,70].…”

“…Contact with defecation sites is thus expected to result in a high risk of infection, but, because contaminated sites represent a low proportion of the area, only a few humans are likely to be directly exposed. These persons include children playing in sand pits, persons feeding the cats, gardeners, maintenance workers in these sites and also dog owners who allow pets to roam in these sites and become indirectly exposed through contact with dogs [71,67,68].…”

Great efficacy of sulfachloropyrazine-sodium against acute murine toxoplasmosis

“…Then the mixtures were sonicated to produce a smooth dispersion and the desired concentration was prepared daily in physiological saline and administered to mice at a dosage of 250 mg/kg/day, according to the animal's body weight, for 5 or 10 days, 24 h after infection.…”

“…Other members of the same phylum, Apicomplexa, include the human pathogens Plasmodium and Cryptosporidium, and the animal pathogens Eimeria and Sarcocystis [3][4][5] . T. gondii has become a model organism for the study of the Apicomplexa, as it is the most experimentally tractable organism in this important group of intracellular parasites that includes Plasmodium, Eimeria, Cryptosporidium, Neospora, and Theileria.…”

“…Felids are the key animal species in the life cycle of this parasite because they are the definitive hosts that can excrete the environmentallyresistant stage, the oocyst [6] . According to the serological investigations, about 30% of the human population is infected with this parasite [5] . A recent serosurvey using samples from the population-based National Health and Examination Nutrition Study found a decrease in the ageadjusted T. gondii prevalence in USA-born persons, of years of age, from 14.1% in [1988][1989][1990][1991][1992][1993][1994] to 9% in [1999][2000][2001][2002][2003][2004] [6,7] .…”