Detection and genotyping of Toxoplasma gondii strains isolated from birds in the southwest of Iran.

1. The aim of this work was to determine the frequency of occurrence of Toxoplasma gondii and genetically analyse isolates from a number of avian hosts in the southwest of Iran (Khuzestan province). The frequency of T. gondii was determined in free-range chickens (Gallus domesticus), sparrows (Passer domesticus), pigeons (Columba livia) and starlings (Sturnus vulgaris). 2. Isolates obtained from Toxoplasma-infected birds were subjected to molecular typing by PCR-restriction fragment length polymorphism (RFLP) with sequence analysis of the GRA6 gene. 3. The results showed that 41 (16·5%) of 241 samples of avian tissue were infected with T. gondii. Sparrows were most frequently infected (17 out of 64). 4. Analysis of the GRA6 gene by PCR-RFLP and DNA sequencing revealed Type II and III T. gondii were the predominant lineage, accounting for 19·5% and 80·5% of the isolates, respectively. 5. It was concluded that the use of this PCR test facilitated the diagnosis of T. gondii in avian hosts and the GRA6 PCR-RFLP method clearly differentiated between the three different T. gondii lineages. This study showed a higher prevalence of type III compared with type II T. gondii in infected avian hosts in southwestern Iran.