Frequency of anti-Toxoplasma gondii IgG antibodies and associated variables among veterinary clinic personnel in Medellín, Colombia

Introduction

Toxoplasmosis is a globally distributed zoonotic disease caused by the obligate intracellular protozoan Toxoplasma gondii, a parasite belonging to the phylum Apicomplexa and the family Sarcocystidae (1). T. gondii infects a broad range of warm-blooded vertebrates. Domestic and wild felids are the definitive hosts, whereas humans, birds, and numerous domestic and wild mammals serve as intermediate hosts (2). Among felids, domestic cats (Felis catus) play a pivotal role in the epidemiology of toxoplasmosis because they shed environmentally resistant oocysts in their feces, contaminating soil, water, and food and thereby facilitating parasite transmission to humans and other animals (3).

In humans, toxoplasmosis is usually asymptomatic or associated with mild clinical manifestations in immunocompetent individuals, after which the parasite establishes a lifelong latent infection. However, in immunocompromised individuals, latent infection may reactivate and lead to severe manifestations, including encephalitis, myocarditis, polymyositis, lymphadenitis, and chorioretinitis (4). In recent years, increasing attention has also focused on the potential association between chronic T. gondii infection and several neuropsychiatric disorders, further highlighting the public health relevance of this parasite (5). Serological methods, particularly enzyme-linked immunosorbent assays (ELISA), remain the most widely used approach for detecting previous exposure to T. gondii. In contrast, molecular techniques such as polymerase chain reaction (PCR) have improved the diagnosis of active infection and epidemiological surveillance because of their high sensitivity and specificity (6).

In Colombia, the epidemiology of toxoplasmosis has not been fully characterized across different population groups. A comprehensive review by Cañón-Franco et al. reported seroprevalence estimates ranging from 24% to 71.8% in studies conducted between 1944 and 2014 (7). More recently, anti-T. gondii IgG seropositivity of 38.5% was reported among blood donors in Cúcuta, providing additional evidence of widespread human exposure (8). Furthermore, T. gondii has been detected in meat intended for human consumption, highlighting the circulation of the parasite in the food chain and reinforcing its importance as a foodborne zoonotic pathogen (9).

Several studies have evaluated populations with potential occupational exposure to T. gondii. Anti-T. gondii antibodies have been detected among veterinary students exposed during their professional training (10), while slaughterhouse workers in Colombia have shown seropositivity rates of up to 71.8% (11). These findings suggest that occupational groups with frequent contact with animals, animal tissues, or contaminated biological materials may be at increased risk of previous exposure to the parasite. Nevertheless, exposure to T. gondii is likely influenced by both occupational and non-occupational factors. Occupational exposure may occur through contact with animals, biological samples, or contaminated materials during veterinary practice. In contrast, domestic exposure may result from household contact with cats or environments contaminated with feline feces. Distinguishing these potential exposure pathways is relevant for understanding infection patterns and for designing appropriate preventive strategies. Consequently, toxoplasmosis is recognized as one of the most important zoonotic diseases worldwide because of its impact on human and animal health, as well as its economic and ecological consequences (12). Moreover, the disease represents a clear example of the One Health concept, given the close interaction among humans, domestic animals, wildlife, and the environment in its transmission cycle (13).

Veterinary clinic personnel constitute an occupational group with frequent exposure to companion animals, biological samples, and potentially contaminated environments. Nevertheless, information regarding T. gondii exposure and associated factors among veterinary clinic personnel in Colombia remains scarce. Identifying factors associated with previous exposure in this population is essential for strengthening biosafety practices and improving preventive strategies against zoonotic diseases. Therefore, this exploratory analytical cross-sectional study aimed to determine the frequency of anti-Toxoplasma gondii IgG seropositivity and identify factors associated with previous exposure among personnel working in companion-animal veterinary clinics in Medellín, Antioquia, Colombia.

Materials and Methods

Study design, setting, and population

An exploratory analytical cross-sectional study was conducted between May and December 2023 among personnel from seven companion-animal veterinary clinics located in Medellín, Antioquia, Colombia. Veterinary clinics were selected by convenience according to their willingness to participate during the study period. The study population comprised veterinarians, veterinary assistants, veterinary medicine interns, laboratory personnel, administrative staff, and general services personnel who had direct or indirect occupational contact with companion animals.

Eligible participants were adults (≥18 years old) who voluntarily agreed to participate and provided written informed consent. Individuals who declined to participate or whose blood samples were insufficient for serological analysis were excluded.

Epidemiological survey

Each participant completed a structured questionnaire designed by the research team to obtain information on sociodemographic characteristics, occupational activities, behavioral habits, biosafety practices, animal exposure, and epidemiological variables potentially associated with T. gondii infection. The questionnaire also included items evaluating participants' knowledge of toxoplasmosis, potential routes of transmission, contact with companion animals, dietary habits, hygiene practices, previous medical history, and occupational exposure during veterinary clinical practice.

Blood sampling and serum processing

Approximately 5 mL of peripheral venous blood was collected from each participant using sterile vacuum collection tubes following standard biosafety procedures. Blood samples were centrifuged at 3,500 rpm for 5 min to obtain serum, which was aliquoted into sterile microtubes and stored at −80 °C until serological analysis.

Detection of anti-Toxoplasma gondii IgG antibodies

Previous exposure to T. gondii was determined by detecting anti-T. gondii IgG antibodies using a commercial enzyme-linked immunosorbent assay (TOXO IgG ELISA, Diagnostic Bioprobes, Italy), following the manufacturer's instructions (14). Positive and negative controls supplied with the kit were included in each analytical run to ensure assay validity. Optical density values were measured using an ELISA microplate reader, and serum samples were classified as positive or negative according to the cutoff values established by the manufacturer. The presence of anti-T. gondii IgG antibodies was interpreted as evidence of previous exposure to the parasite.

Statistical analysis

Data were entered into Microsoft Excel 2019 and analyzed using IBM SPSS Statistics version 22.0 (IBM Corp., Armonk, NY, USA). Descriptive statistics summarized the characteristics of the study population. Categorical variables were expressed as absolute frequencies and percentages. Educational level and occupation were reported descriptively. Because several categories contained very small numbers of participants, no inferential comparisons were reported for these variables. Associations between anti-T. gondii IgG seropositivity and explanatory variables were initially evaluated using Pearson's chi-square test or Fisher's exact test, as appropriate. Crude odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were estimated by bivariate analysis.

Variables with a P value <0.25 in the bivariate analysis were considered candidates for inclusion in a multivariate logistic regression model to identify factors independently associated with seropositivity. Adjusted odds ratios (aORs) with 95% CIs were estimated, and statistical significance was established at P <0.05. Considering the convenience sampling strategy, the relatively small sample size, and the exploratory nature of the study, the multivariate analysis was performed to identify potential factors associated with previous exposure rather than to establish causal relationships or generate population-level estimates. Therefore, the findings should be interpreted as hypothesis-generating and warrant confirmation in larger multicenter studies.

Results

Anti-T. gondii IgG antibodies were detected in 22 of 71 participants evaluated, corresponding to a seropositivity frequency of 30.99%. The sociodemographic and occupational characteristics of the study population are presented in Table 1. Most participants were women (81.7%). Veterinarians represented the largest occupational group, followed by administrative personnel and veterinary assistants. Professional and technical training were the most frequent educational levels among participants.

Knowledge and epidemiological characteristics related to toxoplasmosis are summarized in Table 2. Nearly half of the participants reported having only limited knowledge of toxoplasmosis (47.9%), whereas 43.7% considered themselves knowledgeable about the disease. Considerable variability was observed regarding the recognition of the clinical consequences of toxoplasmosis, susceptible populations, and transmission routes. More than half of the participants (54.9%) reported routine occupational contact with both cats and dogs.

The associations between anti-T. gondii IgG seropositivity and the evaluated variables are presented in Table 3. In the bivariate analysis, cat ownership was positively associated with seropositivity (crude OR = 4.37; 95% CI: 1.14–16.75; P = 0.02), whereas consistent use of personal protective equipment (PPE) during work was associated with lower odds of seropositivity (crude OR = 0.20; 95% CI: 0.06–0.71; P = 0.01). No statistically significant associations were observed for sex, dietary habits, occupational activities, history of needle-stick injury, contact with cat feces, or the remaining evaluated variables.

Variables with P <0.25 in the bivariate analysis were included in the exploratory multivariate logistic regression model (Table 4). After adjustment, cat ownership remained the factor most strongly associated with anti-T. gondii IgG seropositivity (adjusted OR = 9.41; 95% CI: 1.60–55.23; P = 0.013). In contrast, consistent use of PPE during work remained independently associated with reduced odds of previous exposure (adjusted OR = 0.10; 95% CI: 0.02–0.54; P = 0.007). None of the remaining variables included in the model reached statistical significance.

Discussion

Anti-T. gondii IgG antibodies were detected in 30.99% of the veterinary clinic personnel included in this study, indicating previous exposure to the parasite within this occupational group. Although the convenience sampling strategy and relatively small sample size do not allow extrapolation to all veterinary personnel in Colombia, the results provide novel epidemiological information for a population that has been scarcely investigated in the country. Furthermore, they contribute to identifying behavioral and occupational factors that may influence previous exposure to T. gondii in veterinary clinical settings.

The frequency of anti-T. gondii IgG seropositivity observed in this study is comparable to that reported by Corrales (15) and Roncalla Marroquín (16), who found a seropositivity of 36.7% and 26%, respectively, among personnel working in companion-animal veterinary facilities in Arequipa, Peru. Similar frequencies have been described among veterinarians in Portugal (26%) (17) and Finland (14.6%) (18), whereas a substantially lower anti-T. gondii IgG seropositivity of 8.78% was reported among veterinary personnel in Punjab, India (19,20). These differences probably reflect variations in environmental conditions, dietary habits, hygiene practices, climatic factors, and local epidemiology rather than occupational exposure alone.

Although veterinary personnel are considered an occupational group with potential exposure to T. gondii because of their frequent contact with animals and clinical environments, occupational exposure itself is unlikely to be the only determinant of infection. Previous studies have shown that exposure to T. gondii results from the interaction of occupational, environmental, and behavioral factors, including food consumption habits, hygiene practices, and environmental contamination (17,18).

One of the principal findings of this study was the positive association between cat ownership and anti-T. gondii IgG seropositivity. Participants who owned cats had significantly higher odds of previous exposure than those who did not. This finding is biologically plausible because domestic cats are the definitive hosts of T. gondii and are responsible for shedding environmentally resistant oocysts capable of contaminating soil, water, and household environments (1). Similar observations have been reported among veterinary students, in whom frequent contact with cats was associated with the presence of anti-T. gondii antibodies (21).

However, cat ownership should not be interpreted as an isolated causal factor. Human infection is recognized as a multifactorial process in which exposure is also influenced by environmental contamination, food handling practices, consumption of undercooked meat, inadequately washed fruits and vegetables, untreated water, and inadequate hygiene after contact with soil or cat litter boxes (22–24). Therefore, cat ownership may represent a marker of cumulative environmental exposure rather than the direct source of infection.

Another important finding was the inverse association between the consistent use of personal protective equipment and anti-T. gondii IgG seropositivity. Participants who consistently reported using personal protective equipment had substantially lower odds of previous exposure than those who did not. Although the cross-sectional design precludes establishing causality, this finding supports the biological plausibility that appropriate biosafety practices may reduce occupational exposure to potentially contaminated biological materials encountered during routine veterinary activities (25).

Comparable observations have been reported by Retmanasari et al. (26), who described a higher frequency of toxoplasmosis among individuals with limited adherence to personal protective measures. Similarly, Troncoso et al. (10) found that veterinary students who did not consistently use personal protective equipment while cleaning animal feces showed higher seropositivity than those who routinely adopted these protective measures. Collectively, these findings reinforce the importance of maintaining appropriate biosafety protocols in veterinary clinical practice.

Despite the high educational level of most participants, nearly half reported having only limited knowledge of toxoplasmosis. This finding agrees with that reported by Suárez-Hernández et al. (27), who identified important knowledge gaps regarding zoonotic diseases among veterinary professionals. These results highlight the need to strengthen continuing education programs on zoonotic diseases, transmission routes, and preventive measures for veterinary personnel.

Most participants reported routine occupational contact with both dogs and cats, a finding similar to that described by Alemán (28), who reported that 57.1% of veterinary personnel routinely handled these animal species. Participants also recognized several potential routes of T. gondii transmission, including contaminated meat, inadequately washed fruits and vegetables, untreated drinking water, and contact with cat litter boxes. These observations are consistent with current evidence demonstrating the environmental persistence of T. gondii oocysts and their importance in foodborne and waterborne transmission (22).

From a diagnostic perspective, ELISA remains one of the most widely used methods for detecting anti-T. gondii IgG antibodies in epidemiological studies because of its good sensitivity, specificity, and suitability for identifying previous exposure in large populations (29,30). Using this technique in the present study allowed reliable identification of individuals previously exposed to the parasite.

Interestingly, no statistically significant associations were observed between anti-T. gondii IgG seropositivity and most demographic, dietary, behavioral, and occupational exposure variables evaluated in this study. Although these findings may partly reflect the limited statistical power resulting from the sample size, they should not be interpreted as evidence of the absence of associations with demographic or occupational variables. Evaluating these variables remains epidemiologically relevant because they represent potential confounders that should continue to be assessed in future occupational studies.

Several limitations should be considered when interpreting these findings. First, the convenience sampling strategy and the relatively small sample size limit the external validity of the results. Second, the sample size was also constrained by the analytical resources available for serological testing, which limited the number of participants that could be included in the study. Third, the cross-sectional design does not allow temporal or causal relationships to be established. Fourth, the limited number of seropositive participants reduced the statistical power of the multivariate model; therefore, the identified associations should be interpreted as exploratory and hypothesis-generating rather than definitive. As reflected by the wide confidence intervals observed for some variables, the precision of the estimated odds ratios was limited. Nevertheless, this study provides the first evidence of anti-T. gondii IgG seropositivity among veterinary clinic personnel in Medellín and identifies potentially modifiable factors that may contribute to strengthening occupational biosafety strategies and guiding future multicenter investigations.

Conclusion

Overall, this study provides evidence of previous exposure to T. gondii among veterinary clinic personnel in Medellín and identifies cat ownership and consistent PPE use as variables associated with the observed seropositivity pattern. Strengthening biosafety practices and educational strategies on zoonotic diseases may help reduce potential occupational exposure and improve preventive practices in veterinary clinical settings.

Acknowledgments

The authors thank the Remington University Corporation, particularly the Faculty of Veterinary Medicine, for its institutional support throughout all stages of this project. We also express our sincere gratitude to the Colegio Mayor de Antioquia University Institution for providing access to its facilities, especially the Ángela Restrepo Moreno Research Laboratory.

Conflict of Interest

The authors declare no conflicts of interest that could have influenced the results or interpretation of this study.

Ethical approval

The study protocol was reviewed and approved by the Ethics Committee of the Faculty of Health Sciences of Remington University Corporation (Approval No. 092022). All participants provided written informed consent before enrollment. Personal information was treated confidentially and analyzed exclusively for research purposes in accordance with national and international ethical guidelines for research involving human participants.

Artificial Intelligence Statement

During the preparation of this work, the authors used ChatGPT (OpenAI) to assist with English language editing, grammar correction, and improvement of text clarity. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the published article.