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Title: Waterborne toxoplasmosis investigated and analyzed under hydrogeological assessment: new data and perspectives for further research

item VIEIRA, FLAVIA - State University Of North Fluminense
item ALVES, MARIA - State University Of North Fluminense
item MARTINS, LIVIA - State University Of North Fluminense
item RANGEL, ALBA - State University Of North Fluminense
item Dubey, Jitender
item Hill, Dolores
item BAHIA-OLIVEIRA, LILIAN - Universidade Federal Do Rio De Janeiro

Submitted to: Memorias Do Instituto Oswaldo Cruz
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2015
Publication Date: 12/28/2015
Citation: Vieira, F.P., Alves, M.G., Martins, L.M., Rangel, A.L., Dubey, J.P., Hill, D.E., Bahia-Oliveira, L.M. 2015. Waterborne toxoplasmosis investigated and analyzed under hydrogeological assessment: new data and perspectives for further research. Memorias Do Instituto Oswaldo Cruz. 113(2):398-403.

Interpretive Summary: Toxoplasmosis, caused by the single celled parasite, Toxoplasma gondii, continues to be a public health problem worldwide. This parasites infects all warm-blooded hosts, including humans. It causes mental retardation and loss of vision in children, and abortion in livestock. The ingestion of food and water contaminated with resistant stage of the parasite, the oocyst, is now considered a major mode of transmission of this parasite. Of all the hosts infected, only cats are known to excrete oocysts in feces. Cats can excrete millions of oocysts after eating an infected prey, such as a mouse or a bird. Oocysts can survive outdoors for months. There are no efficient methods to assess the environmental contamination by oocysts. In the present study the authors used chickens as sentinel to detect T. gondii oocysts in water samples. Chickens fed on membranes used to filter large quantities of municipal waters in Brazil developed antibodies to T. gondii. They also found that humans had antibodies to a oocyst-specfic ELISA (developed at the ARS laboratory at Beltsville), indicating that humans had ingested food or water contaminated with oocysts. These results will be of interest to biologists, parasitologists, and epidemiologists.

Technical Abstract: We present a set of data on human and chicken Toxoplasma gondii seroprevalence that was investigated and analyzed in light of groundwater vulnerability information in an area of endemic waterborne toxoplasmosis in Brazil. Hydrogeological assessment was undertaken to conduct water collection from wells for T. gondii oocysts analysis and for blood sampling as well as to analyze both freerange chickens’ and human anti-T. gondii serology. For the human serologic investigation it was used commercial conventional tests and also a sporozoite-specific embryogenesis-related protein (TgERP) which is able to differentiate the origin of the infection if from cysts or oocysts in a time frame until 8 months after initial infection. Water analysis rendered negative results for the presence of viable T. gondii oocysts. However, seroprevalence in free-range chickens was significantly associated with the highest degree of groundwater vulnerability to surface contamination (P<0.0001, odds ratio [OR]: 4.75, 95% confidence interval [CI]: 2.18 to 10.2). Surprisingly serology against TgERP demonstrated a high prevalence of antibodies against it in humans revealing the possibility of a continuous Toxoplasma re-infection phenomenon in endemic settings where the genetic variability of the circulating parasite is high and water has been identified as a risk factor for human toxoplasmosis. Findings are discussed under the perspective for adoption of hydrogeological assessment to conduct waterborne toxoplasmosis research in a global scale as well as for further experimental designs in this research field.