The prevalence and genotypic analysis of Toxoplasma gondii in human sera and brain tissue from individuals in Scotland between 2006 - 2012.

Authors: BURRELLS, A - The Moredun Group; OPSTEEGH, M - National Institute For Public Health And The Environment (RIVM); POLLOCK, K - National Health Service Scotland, Health Protection Scotland; ALEXANDER, C - Scottish Parasite Diagnostic And Reference Laboratory; CHATTERTON, J - Scottish Toxoplasma Reference Library; EVANS, R - Scottish Toxoplasma Reference Library; WALKER, R - Quintiles, Inc; MCKENZIE, C - University Of Edinburgh; SWART, A - National Institute For Public Health And The Environment (RIVM); Hill, Dolores; INNES, E - The Moredun Group; KATZER, F - The Moredun Group

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2016
Publication Date: 6/7/2016
Citation: Burrells, A., Opsteegh, M., Pollock, K., Alexander, C., Chatterton, J., Evans, R., Walker, R., Mckenzie, C.A., Swart, A., Hill, D.E., Innes, E.A., Katzer, F. 2016. The prevalence and genotypic analysis of Toxoplasma gondii in human sera and brain tissue from individuals in Scotland between 2006 - 2012. Parasites & Vectors. 9(1):324.

Interpretive Summary: One third of the human population are predicted to be infected with T. gondii. Infection with T. gondii is generally asymptomatic, however those who are immunocompromised are particularly at risk. Women of childbearing age who test seronegative for T. gondii at the beginning of pregnancy are more at risk of miscarriage and future complications with the unborn child, if they become infected with the parasite during pregnancy. With an objective to obtain a more up to date estimate for the prevalence and genotypes of human T. gondii infection in Scotland, the research within the current study examined two different groups of individuals; 1) serum samples from two cohorts of blood donors located in Glasgow and Dundee over a four year period (2006 - 2009), and 2) human brain tissues from individuals who died suddenly in the Edinburgh area over a five year period (2008 - 2012). In addition to providing up to date figures for the prevalence of T. gondii in the Scottish population, the samples provide links between T. gondii infection and age, gender, location or cause of death. The research also identified whether recent infections were due to the tissue cyst or oocyst stage of the parasite. Molecular detection of the parasite from human brains allowed strain genotyping, providing information which was more representative of the general population and provided an indication whether any atypical strains were present.

Technical Abstract: Up to date information about the prevalence of Toxoplasma gondii in humans is lacking for the UK population, with even less information available about the prevalence of the parasite in people in Scotland. To address this, two different study groups were used to determine the prevalence and genotypes of Toxoplasma gondii in the Scottish population. The first study group included serum samples from Scottish blood donors (n=3273) over a four year period (2006 - 2009) and the second study group comprised DNA samples extracted from human brains (n = 151) over a five year period (2008 - 2012). Serological detection of antibodies to T. gondii from blood donors was found to be 13.2%. As this was a longitudinal study individuals could be tracked over time and there was also evidence of seroconversion (n = 10) as well as reversion to sero-negative status (n = 1) amongst donors. An ELISA which incorporates the sporozoite specific antigen (TgERP) (indicating oocyst infection) was performed on the sera from all individuals who had seroconverted, of which one was identified as positive. The molecular detection of T. gondii DNA from human brains highlighted a prevalence of 17.9%, with genotyping by PCR-RFLP at the GRA6 and SAG3 loci identifying alleles for types I and III. Overall correlation between an increase in age and an increase in detection of the parasite was identified within both study groups.