Use of paired serum sample for the diagnosis of toxoplasma infection in selected population by using elecsys toxo IgG/IgM in HUSM

Introduction Toxoplasmosis is one of the most common worldwide parasitic infection due to Toxoplasma gondii, an obligate intracellular parasite. The mode of transmission is through consumption of food or water or undercooked meat contaminated with the parasite. Maternal infection with vertical transmission depends on age of gestation. Severity of infection is during early gestation, may lead to intense complications such as intrauterine death (IUD) or later with increased risk of congenital infection. In ocular toxoplasmosis, reactivation of infection are common among immunocompromised and immunocompetent patients. Serology is still the mainstay for the diagnosis of Toxoplasma infection. Therefore, this method was applied with paired serum sample in selected population using Elecsys Toxo IgG/IgM assay in HUSM. The paired serum sample was to classify the infection into early, acute, reactivation, recent, latent, possible congenital infection and passive immunity from mother. This study aimed to describe the clinical manifestation, determine the seroprevalence classification of infection among the selected populations, validity of the test and percentage of patient on treatment after first and paired serum sample. Methodology This is a prospective cohort study held in Microbiology Laboratory, Hospital Universiti Sains Malaysia. Paired serum sample with interval of 2 weeks for clinically suspected cases among selected populations were collected from 1st January 2016 till 31st December 2016. Elecsys and cobas e 601 analyser was used to perform the Elecsys Toxo IgG/IgM ECLIA assay. The classification of infection was generated based on the study flow chart. Patients clinical data were obtained from clinical notes or folders. Results A total of 482 patients with paired serum sample were included in the study. The highest seroprevalence was in latent infection, 54%. New born or infants were majority having passive immunity from mother and 4.3% were classified into possible congenital infection. Ocular toxoplasmosis were mainly classified into reactivation and latent infection. Acute infection was successfully detected especially among new born, pregnant women and immune compromised patients. Paired serum sample were compared to clinically confirmed cases as gold standard have given high sensitivity (100%), low specificity (77.1%),high negative predictive value (NPV) (100%), and low positive predictive value (PPV) (53.5%). The ROC curve analyses of paired serum sample showed (AUC) was 0.932 (95% confidence interval between 0.802 and 1.000, p – value 0.001). Majority of patients classified into early, acute and reactivation of infection were treated after the first serum sample. Conclusion Paired serum sample using Elecsys Toxo IgG/IgM assay is a potential diagnostic test for Toxoplasma infection due to high sensitivity and specificity. Furthermore is a good tool to classify the infection among selection populations. The classification of infection is mainly to provide a better understanding regarding the infection and guide the clinician to start treatment promptly