Seroprevalence of Toxoplasma gondii infection among patients of a tertiary hospital in Guangzhou, Guangdong province, PR China

Abstract

Purpose: This study aimed to explore the prevalence of Toxoplasma gondii (T. gondii) among patients in Guangzhou city, South China, and to identify susceptible patient populations and analyze the causes of infection differences.

Methods: From May 2020 to May 2022, a total of 637 sera were collected from patients, and 205 sera were collected from health participants as health control. All sera were examined by colloidal gold kits to detect the positivity of antibodies against T. gondii. And the positivity of antibodies in sera was confirmed with ARCHITECT i2000SR system.

Results: The prevalence of T. gondii infection in patients was 7.06% (45/637), which was lower than the prevalence in health participants 4.88% (10/205). Among patients, 34 (5.34%) were positive only for IgG, 10 (1.57%) were only for IgM, and 1 (0.16%) was positive for both IgG and IgM. There was a significant difference in prevalence between male and female patients, but not among different age groups or diseases groups. The prevalence of T. gondii infection in diseases groups varied. The prevalence was relatively high in patients with the disorders of thyroid gland and the malignant neoplasms of digestive organs, which suggests that caution should be taken to avoid T. gondii infection in these patients. Surprisingly, the prevalence was quite low in diffuse Large B-cell Lymphoma (DLBC) patients. This may be due to the overexpression of TNF-α in tumor tissues of DLBC patients and the higher protein level of TNF-α in sera of DLBC patients.

Conclusion: This study provides a systematic exploration of the prevalence of T. gondii infection in patients in a tertiary hospital. Our data contributes to a better understanding of the epidemic investigation of T. gondii among patients in South China, which can help the prevention and treatment of the disease caused by T. gondii infection.

Fig 1. Colloidal gold kits used to detect IgG and IgM antibodies against T. gondii.

(A) Modified colloidal gold kits (also known as Rapid diagnostic test (RDT) kits) used in this study. (B) The result was determined as “IgG-IgM-”. (C) The result was determined as “IgG+IgM-”. (D) The result was determined as “IgG-IgM+”. Note: “Control”, a band appears at this position, indicating that the detection is valid; “IgG”, a band appears at this position, indicating that there are IgG antibodies against T. gondii in samples; “IgM”, a band appears at this position, indicating that there are IgM antibodies against T. gondii in samples.

Fig 2. Seroprevalence of T. gondii infection.

(A) Comparison of the seroprevalence of T. gondii among health individuals and patients, χ² = 1.554, P = 0.213. (B) The bar charts show the percentage of test results. The numbers in the light grey boxes in the bar charts represent the number of patients who are tested negative for both IgG and IgM antibody, i.e., “IgG-IgM-”. The numbers in the orange-red boxes in the bar charts represent the number of patients who are tested positive for IgG but not IgM antibody, i.e., “IgG+IgM-”. The numbers in the dark grey boxes in the bar charts represent the number of patients who are tested positive for IgM but not IgG antibody, i.e., “IgG-IgM+”. The numbers in the orange boxes in the bar charts represent the number of patients who are tested positive for both IgM and IgG antibodies, i.e., “IgG+IgM+”.

Fig 3. Seroprevalence of T. gondii in patients by sex.

(A) Comparison of seroprevalence of T. gondii infection between male and female patients, χ² = 3.982, *P = 0.046. (B) The percentage of testing results in different sex groups.

Fig 4. Seroprevalence of T. gondii infection in patients by age.

(A) Comparison of seroprevalence of T. gondii among patients in different age groups, χ² = 3.833, P = 0.802. (B) The percentage of testing results in different age groups.

Fig 5. Seroprevalence of T. gondii infection based on the classification of diseases in this study.

(A) The overall seroprevalence of T. gondii infection in different types of diseases, with a Fisher exact test revealing no significant difference (P>0.05). (B) The percentage of testing results in different types of disease groups.

Fig 6. The expression profile of TNF-α gene expression across tumor samples and normal tissues in GEPIA.

TPM (Transcripts Per Million) values are indicated., Transcripts Per Million. The asterisk (*) indicates statistical significance at P< 0.05. We analyzed five types of malignant neoplasms of digestive organs (Cholangiocarcinoma (CHOL), Colon adenocarcinoma (COAD), Liver hepatocellular carcinoma (LIHC), Pancreatic adenocarcinoma (PAAD), Rectum adenocarcinoma (READ), Stomach adenocarcinoma (STAD)), two types of malignant neoplasms of bronchus or lung (Lung squamous cell carcinoma (LUSC), Lung adenocarcinoma (LUAD)), one type of malignant neoplasms of nasopharynx (Esophageal carcinoma (ESCA)), one type of lymphoma (Lymphoid Neoplasm Diffuse Large B-cell Lymphoma (DLBC)), and one type of breast cancer (Breast invasive carcinoma (BRCA)).

Fig 7. The protein levels of TNF-α and IL-10 in the sera of DLBC patients and health individuals.

The cytokine levels were measured using a commercial ELISA kit, and the results were presented in box plots for comparison. The protein levels of TNF-α (A) and IL-10 (B) were significantly different between the DLBC patients and age-gender-matched healthy individuals.