Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Aug 23;18(1):421.
doi: 10.1186/s12879-018-3343-y.

Environmental Risk Factors for Toxoplasma Gondii Infections and the Impact of Latent Infections on Allostatic Load in Residents of Central North Carolina

Free PMC article

Environmental Risk Factors for Toxoplasma Gondii Infections and the Impact of Latent Infections on Allostatic Load in Residents of Central North Carolina

Andrey I Egorov et al. BMC Infect Dis. .
Free PMC article


Background: Toxoplasma gondii infection can be acquired through ingestion of infectious tissue cysts in undercooked meat or environmental oocysts excreted by cats. This cross-sectional study assessed environmental risk factors for T. gondii infections and an association between latent infections and a measure of physiologic dysregulation known as allostatic load.

Methods: Serum samples from 206 adults in the Durham-Chapel Hill, North Carolina area were tested for immunoglobulin (IgG) responses to T. gondii using commercial ELISA kits. Allostatic load was estimated as a sum of 15 serum biomarkers of metabolic, neuroendocrine and immune functions dichotomized at distribution-based cutoffs. Vegetated land cover within 500 m of residences was estimated using 1 m resolution data from US EPA's EnviroAtlas.

Results: Handling soil with bare hands at least weekly and currently owning a cat were associated with 5.3 (95% confidence limits 1.4; 20.7) and 10.0 (2.0; 50.6) adjusted odds ratios (aOR) of T. gondii seropositivity, respectively. There was also a significant positive interaction effect of handling soil and owning cats on seropositivity. An interquartile range increase in weighted mean vegetated land cover within 500 m of residence was associated with 3.7 (1.5; 9.1) aOR of T. gondii seropositivity. Greater age and consumption of undercooked pork were other significant predictors of seropositivity. In turn, T. gondii seropositivity was associated with 61% (13%; 130%) greater adjusted mean allostatic load compared to seronegative individuals. In contrast, greater vegetated land cover around residence was associated with significantly reduced allostatic load in both seronegative (p < 0.0001) and seropositive (p = 0.004) individuals.

Conclusions: Residents of greener areas may be at a higher risk of acquiring T. gondii infections through inadvertent ingestion of soil contaminated with cat feces. T. gondii infections may partially offset health benefits of exposure to the natural living environment.

Keywords: Allostatic load; Biomarkers; Seroprevalence; Toxoplasma gondii; Vegetated land cover.

Conflict of interest statement

Ethics approval and consent to participate

Research reported in this study has been performed with the approval of the ethics committee of the University of North Carolina at Chapel Hill. Human research was carried out in compliance with the Helsinki Declaration. Written consent was obtained from all participants prior to data collection.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


Fig. 1
Fig. 1
Adjusted odds ratios (aOR) of having potentially unhealthy biomarker levels (high level above the 90th percentile or low level below the 10th percentile depending on the biomarker) in T. gondii seropositive individuals vs. seronegative controls
Fig. 2
Fig. 2
Adjusted multiplicative changes in median biomarker levels in T. gondii seropositive individuals compared to seronegative controls

Similar articles

See all similar articles

Cited by 3 articles


    1. Lelu M, Villena I, Darde ML, Aubert D, Geers R, Dupuis E, et al. Quantitative estimation of the viability of Toxoplasma gondii oocysts in soil. Appl Environ Microbiol. 2012;78(15):5127–5132. doi: 10.1128/AEM.00246-12. - DOI - PMC - PubMed
    1. Dabritz HA, Miller MA, Atwill ER, Gardner IA, Leutenegger CM, Melli AC, et al. Detection of Toxoplasma gondii-like oocysts in cat feces and estimates of the environmental oocyst burden. J Am Vet Med Assoc. 2007;231(11):1676–1684. doi: 10.2460/javma.231.11.1676. - DOI - PubMed
    1. Jones J, Lopez A, Wilson M. Congenital toxoplasmosis. Am Fam Physician. 2003;67(10):2131–2138. - PubMed
    1. Robert-Gangneux F, Darde ML. Epidemiology of and diagnostic strategies for toxoplasmosis. Clin Microbiol Rev. 2012;25(2):264–296. doi: 10.1128/CMR.05013-11. - DOI - PMC - PubMed
    1. Jones JL, Parise ME, Fiore AE. Neglected parasitic infections in the United States: toxoplasmosis. Am J Trop Med Hyg. 2014;90(5):794–799. doi: 10.4269/ajtmh.13-0722. - DOI - PMC - PubMed

MeSH terms