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Toxoplasma gondii infection in pigs is commonly diagnosed using serological tests that detect IgG antibodies targeted against the parasite. Such tests include enzyme-linked immunosorbent assay (ELISA), modified agglutination test (MAT), and western blot (WB), which are commercially available as rapid test kits. In this study, we evaluated the manufacturer recommended cut-off of ELISA-PrioCHECK test kit and determined a new optimal cut-off for identifying T. gondii infections in pigs. Assessment of the commercial ELISA kit was done by including data from two additional serological tests, MAT, and WB, applied to seven pig population categories with varying prevalences. A total of 233 plasma samples that were previously used in other studies for investigating T. gondii seroprevalence in pigs in Denmark were randomly selected for inclusion, including 95 samples that had previously been analysed with all three tests and an additional 138 samples that were analysed using the three serological tests for this study. In the absence of a gold standard test, a latent class model was fit to the data to obtain estimates of sensitivity and specificity for each of the tests along with prevalence in each of the populations. A cut-off that maximized the sensitivity and specificity of the ELISA test was then selected. The optimal cut-off value for percent of positive control (PP) in ELISA-PrioCHECK was estimated to be 27.7 PP, which is higher than the cut-off value of 20 PP that is recommended by the manufacturer. At this cut-off, the estimated sensitivities of ELISA, MAT and WB were 99.2% (96.3-100.0%), 96.3% (88.0-100.0%), and 89.8% (80.0-98.0%), respectively. The estimated specificities of ELISA, MAT and WB were 95.2% (92.5-97.6%), 99.6% (97.5-100.0%), and 98.2% (95.9-100.0%), respectively. Our findings have broad relevance to the use of the ELISA-PrioCHECK test kit for detecting Toxoplasma gondii infection in pigs., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Toxoplasma gondii is found worldwide, and consumption of undercooked meat is considered a significant risk factor for human infections. In Denmark, little is known about the distribution of T. gondii, but a recent study revealed a seroprevalence of 34% in Danish indoor sows. The present cross-sectional study aimed to investigate the role of mice for the transmission of T. gondii in Danish indoor sow herds., Results: In total, 56 sow herds were visited, 137 mice were caught by snap traps from 32 farms, and 52 cat faecal samples were collected from 22 farms. Eight percent of the mice were positive for T. gondii DNA, representing 11% of the farms. Significant associations were found between the presence of T. gondii-positive mice and both open feed systems (P= 0.041) and extra rodent control on the farm (P= 0.024). All cat faecal samples were deemed negative for T. gondii by light microscopy examination and real-time polymerase chain reaction analysis., Conclusion: Mice captured inside Danish sow herds were found to be infected with T. gondii and may thus contribute to the transmission of T. gondii to sows, which may explain the high seroprevalence found in Danish pigs.

In 2015, the World Health Organisation rated toxoplasmosis as one of the most important food borne zoonotic diseases in the world. In addition, recent studies have associated Toxoplasma gondii sero-positivity with severe mental illnesses such as schizophrenia. Intake of raw or insufficiently cooked meat has been suggested to pose a major risk of T. gondii transmission in Europe. The objective of this study was to assess the T. gondii sero-prevalence in Danish pigs divided into sub populations (sows versus finishers, indoor versus outdoor). Serum samples were collected from 89 indoor-reared sows, 128 indoor finishers and 37 outdoor-reared finishers and analysed using an antibody ELISA with a sensitivity of 76.3% and a specificity of 93.7%. It was found that 33.7% indoor-reared sows, 3.1% indoor-reared finishers and 10.8% outdoor reared finishers were T. gondii sero-positive. The sero-positivity of T. gondii was significantly higher for indoor-reared sows compared to indoor-reared finishers (RR=10.9, (P<0.001). Although, the probability of T. gondii sero-positivity for outdoor-reared finishers was 3.5 times higher than for indoor-reared finishers, the difference was not statistically significant (P=0.14). The next step will be to identify specific risk factors for sero-positivity for indoor and outdoor production as well as for finishers and sows, and to use this information to help swine producers to prevent infection in their pigs., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objectives: This paper reports on the national neonatal screening programme for congenital toxoplasmosis (CT) in Denmark conducted from 1999 to 2007, including background, basis for initiation of screening, methods, results, and finally reasons for the discontinuation of the screening., Methods: A nationwide screening was conducted at Statens Serum Institut, including >98% newborns, and using filter paper eluates (Guthrie card, PKU card) obtained from newborns 5-10 days old. These were analysed for Toxoplasma gondii-specific antibodies (IgM), and if positive, then IgM (ISAGA). Confirmatory serology was performed on children and their mothers (IgM, IgG, IgA, dye test) where infection was suspected, and children with suspected or confirmed CT initiated a 3-month treatment regimen with pyrimethamine, sulfadiazine and folinic acid supplements. Selective cohorts were followed with regard to developmental and clinical outcome., Results: A total of 100 children were diagnosed with CT in the screening period, and only 2 cases were detected outside of the screening programme. CT prevalence was 1.6 per 10,000 live-born infants. Follow-up studies showed new retinochoroidal lesions in affected children despite treatment., Conclusion: Screening was terminated August 2007, after it became apparent that no benefit of treatment could be shown. CT was evaluated using a Danish adaptation of the Uniform Screening Panel (ACMG), showing CT as an unlikely candidate for screening today. Whereas results might be comparable with other low-endemic countries with similar strains of T. gondii, neonatal screening and treatment might offer different results in regions with either high prevalence or different strains of T. gondii.

Differentiation between the specific immunoglobulin G (IgG) response to Toxoplasma gondii by a mother and her newborn child is helpful in the diagnosis of congenital infection with T. gondii in newborns without T. gondii-specific IgM and/or IgA antibodies at birth. Previous methods include immunoblotting and complexing T. gondii antigen with the sera from the mother and child and comparing the bands after electrophoresis. We developed a two-dimensional immunoblotting (2DIB) method with T. gondii RH strain tachyzoite antigen and validated the method with sera from 11 children identified through the neonatal screening program for congenital toxoplasmosis in Denmark. The children were identified by using Toxoplasma-specific IgM antibodies at the screening test, but the presence of T. gondii-specific IgM and/or IgA antibodies could not be confirmed at the subsequent serum sample tested. The children were monitored for at least 12 months, and in seven of eight patients monitored for 12 months the results of the 2DIB-predicted congenital infection were confirmed by the presence of persistent Toxoplasma-specific IgG antibodies. 2DIB is a sensitive technique that allows early differentiation between passively transferred maternal T. gondii-specific IgG antibodies and antibodies synthesized by the newborn child.

Background: Congenital toxoplasmosis (CT) causes a substantial disease burden worldwide. The aim of this study was to estimate the disease burden of CT in Denmark, a developed country with free public healthcare and nationwide data available. Methods: Using data primarily from two public health surveillance programmes conducted between 1992 and 2007, we estimated the incidence, occurrence of sequelae, mortality and the burden of disease in terms of disability-adjusted life years (DALYs) of CT in Denmark in 2014. Findings: We estimated that 14 children were born with CT in 2014, of which six will have developed sequelae by the age of 12. CT resulted in a total disease burden of 123 DALYs (95% uncertainty interval [UI], 100–148), of which 78 (95% UI, 64–94) were due to foetal loss and 2 (95% UI, 1–3) were due to neonatal death; the remaining burden was due to moderate to severe life-long sequelae. A comparison of the estimated incidence of CT with the number of reported CT cases in 2008–2014 indicated that for each reported CT case, at least five other CT cases could be expected to have occurred and gone unreported. Interpretation: Early onset, severity, and life-long duration of sequelae have a major effect on the disease burden of CT. Our data suggest that CT is under-diagnosed or under-reported in Denmark. The estimated disease burden and public health impact in Denmark is lower than in other European countries, highlighting the need for country-specific studies. [ABSTRACT FROM AUTHOR]