Toxoplasma gondii seropositivity and substance use in US adults

The Relationship of Latent Toxoplasmosis and Cigarette Smoking: Seroprevalence, Risk Factor, and Case-Control Study in Fars Province, Southern Iran

Toxoplasmosis is a parasitic disease with worldwide prevalence. Despite the relatively similar effects of toxoplasmosis and smoking on alteration in neurotransmitters, especially dopamine, little is known about the relation of Toxoplasma gondii infection and addiction to cigarette smoking. Therefore, the main objective of this study was to assess the relationship between latent toxoplasmosis and smoking. Through a case-control study, 216 regular cigarette smokers and 324 nonsmoker age- and gender-matched subjects were evaluated for anti-T.gondii IgG antibodies with enzyme-linked immunosorbent assay (ELISA). During the sampling, a structured questionnaire was used to obtain the demographic information of participants and the risk factors of acquired Toxoplasma. The median ages of case and control groups were 51.04 ± 18.1 (22-97 years) and 51.03 ± 16.5 (21-89 years), respectively (p = 0.99). Anti-T.gondii IgG antibodies were detected in 44 (20.37%) cases and in 135 (41.67%) controls. There was a statistically significant difference for the positivity rate between the smokers and the control group (OR = 0.35; 95%CI: 0.19-0.65; and p = 0.001). The overall prevalence was 33.14%. This study indicated the inverse association between seropositivity to Toxoplasma infection and cigarette smoking. This relationship could be due to the changes that latent toxoplasmosis has on the neurotransmitters, especially dopamine, which needs more research.

Cross-sectional association of Toxoplasma gondii exposure with BMI and diet in US adults

Toxoplasmosis gondii exposure has been linked to increased impulsivity and risky behaviors, which has implications for eating behavior. Impulsivity and risk tolerance is known to be related with worse diets and a higher chance of obesity. There is little known, however, about the independent link between Toxoplasma gondii (T. gondii) exposure and diet-related outcomes. Using linear and quantile regression, we estimated the relationship between T. gondii exposure and BMI, total energy intake (kcal), and diet quality as measured by the Health Eating Index-2015 (HEI) among 9,853 adults from the 2009–2014 National Health and Nutrition Examination Survey. Previous studies have shown different behavioral responses to T. gondii infection among males and females, and socioeconomic factors are also likely to be important as both T. gondii and poor diet are more prevalent among U.S. populations in poverty. We therefore measured the associations between T. gondii and diet-related outcomes separately for men and women and for respondents in poverty. Among females <200% of the federal poverty level Toxoplasmosis gondii exposure was associated with a higher BMI by 2.0 units (95% CI [0.22, 3.83]) at median BMI and a lower HEI by 5.05 units (95% CI [-7.87, -2.24]) at the 25^th percentile of HEI. Stronger associations were found at higher levels of BMI and worse diet quality among females. No associations were found among males. Through a detailed investigation of mechanisms, we were able to rule out T. gondii exposure from cat ownership, differing amounts of meat, and drinking water source as potential confounding factors; environmental exposure to T. gondii as well as changes in human behavior due to parasitic infection remain primary mechanisms.

Toxoplasmosis gondii (T. gondii) is a parasite that infects over 10 percent of the US population. T. gondii infection can cause serious health problems for some people, but most infections remain undiagnosed and subclinical. When an individual is infected, T. gondii can chronically reside in muscle and central nervous system (including brain) tissue. Previous studies have found that individuals with prior exposure to T. gondii may engage in more risky and impulsive behaviors, and risk tolerance and impulsivity may be related with individual’s diet. Our study examines whether individuals with T. gondii exposure have higher body mass index (BMI) and worse diets. We further discuss and test for alternative explanations that prevent us from establishing a causal relationship between T. gondii and BMI/diet. Overall, our results show that T. gondii exposure is related with higher BMI and worse diets among lower-income females in the US. Our results uncover a novel correlate of BMI and diets, and suggest the importance of investigating the broader public health impacts of chronic T. gondii infection.

Latent Toxoplasma gondii infections are associated with elevated biomarkers of inflammation and vascular injury

BACKGROUND

Toxoplasma gondii is a protozoan parasite that infects cats as definitive hosts and other warm-blooded animals including humans as intermediate hosts. It forms infectious cysts in the brain, muscle and other tissues establishing life-long latent infection. Approximately 10% of the US population is infected. While latent infections are largely asymptomatic, they are associated with neurological deficits and elevated risks of neuropsychiatric diseases.

METHODS

This cross-sectional epidemiological study investigated associations of T. gondii infections with biomarkers of inflammation and vascular injury: soluble intercellular adhesion molecule 1 (ICAM-1), soluble vascular cell adhesion molecule 1 (VCAM-1), C-reactive protein (CRP), and serum amyloid A (SAA). Serum samples from 694 adults in the Raleigh-Durham-Chapel Hill, North Carolina metropolitan area were tested for IgG antibody response to T. gondii, and for the above biomarkers using commercially available assays.

RESULTS

T. gondii seroprevalence rate in this sample was 9.7%. Seropositivity was significantly associated with 11% (95% confidence limits 4, 20%) greater median levels of VCAM-1 (p = 0.003), and marginally significantly with 9% (1, 17%), and 36% (1, 83%) greater median levels of ICAM-1, and CRP, respectively (p = 0.04 for each) after adjusting for sociodemographic and behavioral covariates, while the 23% (- 7, 64%) adjusted effect on SAA was not statistically significant (p = 0.15).

CONCLUSIONS

Latent infections with T. gondii are associated with elevated biomarkers of chronic inflammation and vascular injury that are also known to be affected by ambient air pollution.

Seroprevalence of Toxoplasma gondii in the U.S.: Evidence from a representative cross-sectional survey

The National Health and Nutrition Examination Survey (NHANES) evaluates the epidemiology in the U.S. population of certain infectious diseases, including Toxoplasma gondii (T. gondii), a protozoan parasite. This study aims to evaluate the seroprevalence of T. gondii -IgG antibodies using NHANES data to identify risk factors related to T. gondii. Using NHANES 2009-10, 2011-12, and 2013-14 cycles, univariate analyses and logistic regression models were conducted to determine the relationship between T. gondii seropositivity and various risk factors. Across the three cycles, 13.3% of participants tested positive for T. gondii-IgG seroprevalence, with a significant decrease in seroprevalence from the earlier to later cycles. 53.4% of individuals with positive serology were male. The probability of testing positive for T. gondii -IgG significantly increases between four and five times from the 18-29 age group to 70-79 age group. Seroprevalence also differed by ethnicity, with Latinos of any race having two times higher odds of testing positive for T. gondii compared to other ethnicities. Other sociodemographic factors were associated with lower odds of T. gondii seropositivity, including college education, higher household income, and health insurance. Most clinical conditions were not significantly associated with T. gondii, excluding depression, which was observed in 25% of patients positive for T. gondii-IgG. Further research on the influence of this parasite on infected individuals, including predispositions for risk-taking, is needed to better understand the relationship between Toxoplasma gondii, depression, and other mental illnesses.

An association between latent toxoplasmosis and substance abuse: an Egyptian Center Study

Infection of toxoplasma gondii (TG), an intracellular neurotropic parasitic protozoon, has been associated with various neuropsychiatric disorders. TG is usually diagnosed from serological sample in which a positive test for Anti-TG immunoglobulin G (IgG) indicates TG infection (toxoplasmosis). The research was conducted to test the hypothesis that TG infection may be associated with substance abuse. Anti-TG (IgG) was screened in 444 participants (350 abusers and 94 controls) who attended the Psychiatry Department of Mansoura University Hospitals. All participants were screened for different class of abused substances (tramadol, cannabis, opiates, barbiturates and benzodiazepines) using enzyme multiplied immunoassay technique and positive cases were confirmed using gas chromatography-mass spectroscopy (GC-MS). Substance users were also diagnosed according to DSM IV criteria. GC-MS assays revealed that 116 cases (33.1% of users) had documented use of more than one substance. Tramadol was the most common abused substance [86 cases (24.6%)]. About 56% of the participants were sero-positive for anti-TG IgG. Toxoplasmosis sero-positivity was significantly higher among substance abusers (P < 0.0001) irrespective of the class of substance used. There was a significant relationship between toxoplasma sero-positivity and occurrence of convulsions among tramadol users (P = 0.0007) and those relapsing (P < 0.0001) following short periods of abstinence. The data collected suggest that TG infection is significantly associated with the high incidence of substance use, irrespective of the drug class. These preliminary findings warrant further larger multicenter clinical studies to test the robustness of this association.