Detection of Toxoplasma gondii in chicken and soil of chicken farms in Nanjing region, China

BACKGROUND Soil is increasingly recognized as an important source in the transmission of Toxoplasma gondii (T. gondii). The aim of this study was to investigate the presence of T. gondii in the soil and to grasp the relationships between the contamination of soil and chicken infections. METHODS PCR method based on T. gondii-conserved gene internal transcribed spacer 1 (ITS-1) as target gene and ELISA method (sGRA8-ELISA) using the recombinant protein of shortened GRA8 gene of T. gondii as antigen were developed and applied. From April 2013 to March 2014, a total of 700 soil samples were collected at various sites located in thirty farms categorized as free range farm and scale farm in Nanjing, Jiangsu, China, in different seasons. Additionally, a total of 350 sera of chickens were collected from free range farms to determine the presence of antibodies against T. gondii using sGRA8-ELISA. RESULTS The serological results showed that, antibodies were found in 194 of 250 (67.14%) samples from farms with T. gondii positive in soil and 41 of 100 samples from farms with T. gondii negative in soil (41.00%) (P < 0.01). The PCR detection of soil samples showed that, 7 (2.0%) of 350 samples collected from feeding zone in free range farms were found positive of T. gondii, whereas no sample was positive in scale farms. In the seasonal detections, T. gondii was found in 6 (3.33%) samples collected in autumn and 1 (0.56%) collected in winter. CONCLUSIONS The results indicated that the contamination of T. gondii in soil in the free range farms was higher than that in the scale farms and seroprevalence of T. gondii in chickens in the farm with soil contamination was higher than that with no soil contamination. The soil contamination might be an effective indicator of T. gondii infection in chickens.