Detection of Toxoplasma gondii DNA in Brazilian oysters (Crassostrea rhizophorae)

Abstract

ABSTRACT. The aim of this study was to detect evidence of Toxoplasma gondii using polymerase chain reaction (PCR)-based techniques in oysters (Crassostrea rhizophorae) obtained from the southern coastal region of Bahia, Brazil. A total of 624 oysters were collected, and the gills and digestive glands were dissected. Each tissue sample was separated into pools containing tissues (of the same type) from three animals, leading to a total of 416 experimental samples for analysis (208 samples each from the gills and digestive glands). Molecular analysis using PCR-based detection of the T. gondii AF 146527 repetitive fragment yielded negative results for all samples. However, when nested-PCR was used for detection of the T. gondii SAG-1 gene, 17 samples were positive, with the gills being the tissue with maximal detection of the parasite. These positive results were confirmed by sample sequencing. It is therefore suggested that C. rhizophorae oysters are capable of filtering and retaining T. gondii oocysts in their tissue. This represents a risk to public health because they are traditionally ingested in natura.

Impact of environmental factors on the emergence, transmission and distribution of Toxoplasma gondii

“… Whether oocysts can be sporulated or not is partly determined by local climate, particularly temperature and humidity [ 7 ]. The dynamics of oocysts in the environment are influenced by seasonal precipitation, which affects the river flow that can deliver oocysts from the land to the water, including the ocean, leading to water-borne toxoplasmosis and high levels of coastal contamination with this protozoan parasite [ 25 , 39 , 40 ]. Climate may also affect the geographic distribution, population density and migration patterns of rodents, migratory birds and arthropods; animals that act as reservoir hosts or transport hosts and play an important role in the emergence, survival, distribution and transmission of T. gondii [ 41 – 45 ].…”

“…The dynamics of oocysts in the environment are influenced by seasonal precipitation, which affects the river flow that can deliver oocysts from the land to the water, including the ocean, leading to water-borne toxoplasmosis and high levels of coastal contamination with this protozoan parasite [ 25 , 39 , 40 ].…”

Isolation and Genotyping of Toxoplasma gondii in Brazilian Dogs

“…Toxoplasma gondii is a parasite able to infect all warm-blooded animals, including humans, birds, and marine mammals, as well as other marine life, such as bivalve mollusks [1–3]. It is the cause of a worldwide endemic zoonosis known as toxoplasmosis, which has major implications for public health.…”

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

“…The percentage of positive samples for T. gondii (5.8%) observed in the present study was similar to that reported by Esmerini et al (), who analysed oysters acquired from the fish market in the city of Santos (state of São Paulo, Brazil) using molecular methods and observed that 3.3% (2/60) of oysters were positive for T. gondii . Ribeiro et al () analysed oysters cultured in Bahia and detected T. gondii DNA in 8.1% (17/208) of the samples, mainly in the gills. However, in the present study, the largest number of positive samples was observed in the GIT.…”

“…It should be highlighted that bivalve molluscs can filter and retain T. gondii in aquatic environments, and because they are consumed raw, can present a risk to public health. T. gondii DNA has been detected in bivalve molluscs growing under natural conditions in São Paulo, Bahia and China (Cong et al, ; Esmerini, Gennari, & Pena, ; Ribeiro et al, ; Zhang et al, ). However, there are no reports of its presence in oysters in the state of Pará.…”