First report of detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão

Abstract

The aim of this study was to report on detection of Toxoplasma gondii DNA in oysters (Crassostrea sp.) in the state of Maranhão. To conduct this study, 200 farmed oysters were acquired in the municipality of Raposa and 100 in Paço do Lumiar; and a further 100 oysters were taken from the natural stock in the municipality of Primeira Cruz. This total of 400 specimens sampled was divided into 80 pools composed of five animals each. The gills and visceral mass of each oyster were removed for DNA extraction (per pool of oysters), using a commercial kit. The nested PCR technique (with the primer SAG-1) was then used to investigate any presence of protozoa. This molecular technique demonstrated the presence of DNA of T. gondii in 2.5% of the pools of oysters (n = 2/80): these oysters were exclusively from farms. The results from this study allow the conclusion that oysters of the genus Crassostrea that are farmed in the state of Maranhão are capable of filtering oocysts of T. gondii and maintaining them in their tissues. They are therefore potential sources of contamination for humans and other animals.

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.…”

“…These include the presence of felids in the environment, the impact of human activity on the natural habitat, as well as rains, which increase the movement of contaminants. All these factors have been reported to affect the prevalence and dissemination of the protozoan across rivers and seas (Silva et al, 2020).…”

“…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.…”

Contamination of Soil, Water, Fresh Produce, and Bivalve Mollusks with Toxoplasma gondii Oocysts: A Systematic Review

“…Finally, the presence of T. gondii oocysts in bivalves was reported in 19 out of 22 studies in Brazil ( n = 4), China ( n = 2), France ( n = 1), Italy ( n = 3), New Zealand ( n = 1), Tunisia ( n = 1), Turkey ( n = 2), and the United States ( n = 5), with detection rates that varied from 0.1% (1/1109) [ 21 ] to 46.3% (19/41) [ 53 ], both in the United States, and from 1.3% (2/160) to 31.0% (19/60) in pooled samples from Brazil [ 54 ] and the United States [ 55 ], respectively. In most studies, the detection rates were below 7% ( Table 4 and Figure 2 , Supplementary Table S5 ).…”

Potential Risk of Three Zoonotic Protozoa (Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii) Transmission from Fish Consumption

“…In coastal environments, oocysts can be accumulated by bivalves. This bioaccumulation has been demonstrated experimentally [109][110][111] and has been detected in wild and cultivated bivalves [24][25][26]85,[112][113][114][115][116][117][118][119][120][121]. Nonetheless, this cannot explain how offshore cetaceans that do not feed on bivalves come into contact with these parasitic oocysts and acquire the infection.…”