Detection of Toxoplasma gondii in Crassostrea spp. oysters cultured in an estuarine region in eastern Amazon

Abstract

The aim of the present study was to detect DNA of Toxoplasma gondii in Crassostrea spp. oysters cultured in the state of Pará, Brazil. A total of 400 oysters were directly collected from a fixed rack system. Gills, gastrointestinal tract (GIT) and intervalvular liquid were separated and grouped into pool samples of 10 animals, resulting in 40 samples each of gills, GIT and intervalvular liquid. DNA extraction was performed using a commercial kit, and T. gondii DNA was detected by nested PCR using the primers Toxo3 and Toxo4, which produced an amplification product of 155 bp of the T. gondii gene B1. Nucleotide sequencing was performed for positive samples, and the obtained sequences were identified by comparison with sequences in GenBank. The DNA of T. gondii was detected in 5.8% (7/120) of the pool samples, of which 7.5% (3/40) was in the GIT, 5% (2/40) in the gills, and 5% (2/40) was in the intervalvular liquid. The obtained sequences presented 100% identity and overlap with T. gondii DNA sequences. This is the report of detection of T. gondii DNA in oysters from genus Crassostrea spp. originating from the state of Pará, eastern Amazon.

Molecular investigation of Toxoplasma gondii in oysters (Crassostrea spp.) sold on beaches in the State of Pará, Brazil

“…Studies on bivalve mollusks are relevant in terms of aquatic environment contamination considering that these organisms obtain nutrients from filtration. Some studies have reported a low occurrrence of T. gondii DNA in oysters (Esmerini et al, 2010;Ribeiro et al, 2015;Monteiro et al, 2019;Silva et al, 2020). Monteiro et al (2019) detected T. gondii in oysters from northeastern Pará.…”

“…The Norgen® stool extraction kit (Biotek Corp.) and IllustraTM Tissue and Cell Prep Mini Spin kit (GE Healthcare, Little Chalfont, UK) were used to extract DNA from the samples as described by Monteiro et al (2019).…”

“…Ultrapure water was used as the negative control. The molecular analyses were performed as per the methods described by Monteiro et al (2019).…”

“…In Southern Italy, protozoans were detected in oysters farmed under natural conditions (Putignani et al, 2011). Likewise, there have been reports of protozoan contamination in oysters farmed in Brazil, in southern Bahia (Ribeiro et al, 2015), Pará (Monteiro et al, 2019), and Maranhão (Silva et al, 2020), as well as in oysters sold in the fish market in São Paulo (Esmerini et al, 2010). However, no studies have focused on screening for T. gondii in oysters sold on the beaches in the Amazon region.…”

The life-cycle of Toxoplasma gondii reviewed using animations

“…felines, can be infected by carnivorism (both mammals and birds), or ingestion of sporulated oocysts. Oocysts can also survive in oysters and mussels retaining its infectivity [ 30 – 32 ]. Ingestion of non-pasteurized milk or milk products is a potential source of transmission, although not common [ 8 , 33 ].…”