Toxoplasma gondii infection: What is the real situation?

The prevalence of chronic Toxoplasma infections reported in the literature varies enormously. We hypothesize that one factor could be due to the different methods used in the evaluation of infections. Serological evidence of Toxoplasma infections in 450 pregnant women (PW) and 300 HIV-infected patients (HIV) were investigated by the Sabin-Feldman dye test and two other commercial ELISA kits (kit1 and kit2). Anti-Toxoplasma IgG antibodies obtained from the Sabin-Feldman dye test, ELISA kit1 and ELISA kit2 in the PW subjects were 14.7%, 29.6% and 38.7%, and in the HIV subjects were 13%, 34.7% and 36.3%, respectively. So there were significant differences in the seroprevalences when different diagnostic tests were used (P<0.05). Regarding Sabin-Feldman dye test as the gold standard for anti-Toxoplasma antibodies detection, we found that the sensitivity and specificity of the ELISA kit1 and kit2 was in the range of their specification. However as the two ELISA kits used in our study identified a much higher prevalence of Toxoplasma infections which indicated that false positive cases were being reported. Based on results obtained, it is therefore highly recommended that research workers should be aware that the reports of serological studies in terms of high positive results should be treated with some skepticism until additional precise diagnostic tools are developed.

Evaluation of Seropositivity of Toxoplasmosis Suspected Patients Admitted to the National Parasitology Reference Laboratory Between 2009 and 2019

Objective: Toxoplasmosis caused by Toxoplasma gondii (T. gondii), which is an obligatory intracellular parasite, is a worldwide zoonotic parasitic disease. In this study, results of T. gondii test conducted between January 2009 and May 2019 were analysed. This study aimed to evaluate the results of T. gondii test of patients who were admitted to the General Directorate of Public Health, National Parasitology Reference Laboratory between 2009 and 2019. Methods: The results of anti-T. gondii IgG, IgM, IgG avidity and Sabin-Feldman dye tests (SFDT), which are used to detect the presence of T. gondii, were examined. ELISA was used for anti-T. gondii IgG, IgM and IgG avidity tests. SFDT, which is the reference test in the diagnosis of T. gondii, is still the gold standard. In addition to laboratory analyses, information on gender, age, city of origin, year distribution of all cases and type of sample sent was also collected. Results: Of the 2.778 patients evaluated, 25.4% were males and 74.6% were females. Moreover, 47.1% and 10.2% of the patients were positive for anti-T. gondii IgG and anti-T. gondii IgM antibodies, respectively. In SFDT, 1.228 (52%) patients were found to be positive, including 319 (59.4%) of 537 men and 909 (49.8%) of 1.824 women. In this 10-year study, the most common seropositivity titre of SFDT was at the level of 1/64. In our study, IgG levels were found to be positive in all cases in which IgG avidity was studied when all the cases in which all three of the anti-T. gondii IgG, IgM and IgG avidity tests were studied together in one patient were evaluated. In addition, of the 293 patients with positive anti-T. gondii IgG, 62.8% had high avidity, 24.2% had a limit value and 13% had a low avidity. In cases involving both mother and baby, anti-T. gondii IgG and IgM seropositivity rates were 80% and 5% for both, respectively. These high rates support the transfer of antibodies from the mother to the baby. Regarding the distribution of provinces from which the samples originated, the highest number of cases came from Ankara (80.7%). Blood is the most predominant sample, followed by cerebrospinal fluid. Conclusion: T. gondii maintains its importance in public health, owing to its high positivity rates. This study, in which 10-year data were collected, showed that despite an increase in awareness, high seropositivity still continues. Therefore, systematic collection and evaluation of laboratory analysis results for toxoplasmosis diagnosis will contribute in taking control measures.

Seroprevalence of Toxoplasma gondii in wild sika deer in Japan.

Toxoplasmosis is a food-borne infection that is widespread around the world, causing congenital disorders and opportunistic infections. Ingestion of undercooked meat is one of the risk factors for infection with the causative agent, Toxoplasma gondii. Japanese people occasionally eat rare meat as a traditional cuisine style called "Sashimi". A rapid increase in venison consumption in Japan has occurred mainly due to enhanced population control of wild Japanese deer (Cervus nippon) in recent decades. In particular, Yezo-sika deer (C. n. yesoensis) in Hokkaido (the northernmost and largest prefecture in Japan) is frequently supplied to markets as branded game/bushmeat. To study the possible burden of Toxoplasma gondii among wild Yezo-sika deer, plasma samples of Yezo-sika deer hunted during two seasons, 2010-2012, in Eastern Hokkaido were investigated. A total 80 samples were examined using the Sabin-Feldman dye test, which is highly specific and sensitive for identifying the development and persistence of antibodies after primary Toxoplasma infection, demonstrating that 38 cases (47.5%) were seropositive (cut-off titer <1:16). Antibody prevalence of T. gondii in female deer was higher than in males. Adult deer aged 3 years or over showed higher seroprevalence compared with younger animals. The overall seroprevalence fluctuated significantly according to the season when the deer were hunted. These results indicated widespread infection of T. gondii among Japanese wild Yezo-sika deer, suggesting that both appropriate handling and treatment of bushmeat are required to prevent food-borne toxoplasmosis in Japan.

Investigation of Anti-Toxoplasma gondii Antibodies in Cats Using Sabin-Feldman Dye Test in Ankara in 2016

Objective: Toxoplasmosis, in which obligate intracellular protozoa Toxoplasma gondii (T.gondii) is the causative organism, is a multisystemic disease that can be seen all over the world and can impair all vertebrates. The only hosts known for T.gondii are members of Felidae family. Our study aimed to determine anti-Toxoplasma gondii antibodies with Sabin-Feldman Dye Test (SFDT) in cats in Ankara. It's aimed to evaluate the current situation in terms of Toxoplasmosis spread by comparing our findings with previous studies in the same region. Methods: Rh strain of Toxoplasma used in our study is maintained in our laboratory. SFDT is still accepted as the gold standard. Material of the study was obtained by taking blood samples from cats who were admitted to the clinics between March 2016 and October 2016 in Ankara. Blood samples were inactivated and measurements were done with SFDT 1/4, 1/16, 1/64, 1/256, 1/1024 titers. Results: SFDT resulted positive in 56 (43.4%) cats at a dilution of 1/16, in 7 (5.4%) cats at a dilution of 1/64, in 23 (17.8%) cats at a dilution of 1/256 and negative in 43 (33.3%) cats. Comparison of demographic data with SFDT results showed that positive test results did not differ according to gender and age (P=0.803 and P=0.991, respectively). Seropositivity was higher in stray cats than house cats (P<0.001). Test results were negative in the cats that fed only by commercial dry food (P<0.001). Positivity in hunter cats was more than in non-hunters (P<0.001). Conclusion: Seropositivity was detected in 66.6% of the cats, which was quite a high rate. As a result, taking precautions in terms of Toxoplasma for stray cats that are hunting and feeding naturally is a necessity for public health.