Measuring the Prevalence of Toxoplasmosis and Its Socio-economic Consequences

NCT ID: NCT05860998

Last Updated: 2023-05-18

Basic Information

• Recruitment Status: UNKNOWN
• Total Enrollment: 120 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2023-06-26
• Study Completion Date: 2023-07-30

Brief Summary

The investigators propose a fast and inexpensive procedure to determine the prevalence of the Toxoplasmosis infection (Toxoplasma Gondii) in the general population, using response times in a cognitive task instead of costly medical tests. Therefore, the investigators aim to measure the prevalence of Toxoplasmosis and its socio-economic consequences in the general population.

Detailed Description

An estimated 2 billion humans worldwide are affected by the protozoan Toxoplasma gondii. The resulting Toxoplasmosis is considered one of the most important but most neglected parasitic infections. Toxoplasmosis has been linked to behavioral alterations in humans. While rarely resulting in an acute pathology, latent infections have been associated with non-clinical outcomes such as car accidents, impulsiveness, and suicides through the pathology's influence on personality and risk-taking behaviors.

Given the economic and social impact of these consequences, it is important to have reliable estimates of Toxoplasmosis prevalence. However, current methods involve costly, time-expensive medical tests, which are not always available, especially in developing countries. Therefore, simpler, inexpensive, and easily-scalable diagnostic methods would be highly valuable. For this reason, both the CDC and the WHO consider it a priority to improve diagnostic testing of Toxoplasmosis. This includes obtaining reliable and easily-implementable estimates at the population level, which is essential to gauge the magnitude of the problem and to inform and design health policy aimed at reducing the number of infections in the population.

Therefore, the investigators aim to determine the frequency of latent Toxoplasmosis infections in the general population in a simple, quick, and inexpensive way.

The key idea of simplifying the diagnosis of this infection is that Toxoplasmosis induces specific behavioral and physiological changes. It alters the levels of neurotransmitters such as dopamine and causes a delay in muscle response time. In particular, people with RhD-negative blood type become slower when afflicted by Toxoplasmosis, while the RhD-positive sub-population does not experience a change in response times. This relation is important because, while the distribution of blood types can be determined in an inexpensive way and is already commonly known at the aggregate level (RhD-negative are 15% in Caucasians, 8% in Africans, and 1% in Asians), the actual prevalence of the Toxoplasmosis infection is underinvestigated, and the respective tests are costly and not easily deployable in large numbers (especially in developing countries). The investigators aim to leverage on the differential effects of Toxoplasmosis on response times across blood types to estimate its latent diffusion.

Response times (RT) are known to be log-normally distributed [22]. This is crucial because mixtures of log-normally distributed variables are identifiable through standard statistical methods as e.g. finite mixture models [23]. The distribution of RTs in the population is a mixture of two different types, afflicted vs. non-afflicted, and the first group should show a systematic delay in RTs compared to the latter group. A finite mixture model can then be applied to a sample of RhD-negative individuals to estimate the characteristics of the two distributions and hence quantify both the magnitude of the delay in response times as well as the size of the afflicted group.

The investigators already obtained data showing that the proposed method is able to capture interesting and economically-relevant individual characteristics between those who are imputed to be afflicted by this parasite compared to those who do not. This first investigation also passed some preliminary validation. For example, those estimated to be afflicted by Toxoplasmosis are also those who are more likely to have a cat, which is the main vector of contagion for this parasite.

In this study the investigators propose a systematic validation of the proposed method. In particular, the investigators aim to compare it agrees with a standard medical test for Toxoplasmosis infection, e.g., compare it to the presence of Toxoplasma gondii IgG Antibodies. The latter medical test requires a blood sample.

Conditions

Toxoplasmosis; Rhd

Study Design

• Observational Model Type: CASE_CONTROL
• Study Time Perspective: CROSS_SECTIONAL

Study Groups

Toxoplasmosis positive

Healthy students with RhD-Negative blood with Toxoplasma gondii IgG Antibodies

Presence of Toxoplasma gondii IgG Antibodies

Intervention Type: DIAGNOSTIC_TEST

Testing for the presence of Toxoplasma gondii IgG Antibodies in participants blood.

Toxoplasmosis negative

Healthy students with RhD-Negative blood without Toxoplasma gondii IgG Antibodies

Presence of Toxoplasma gondii IgG Antibodies

Intervention Type: DIAGNOSTIC_TEST

Testing for the presence of Toxoplasma gondii IgG Antibodies in participants blood.

Interventions

Presence of Toxoplasma gondii IgG Antibodies

Testing for the presence of Toxoplasma gondii IgG Antibodies in participants blood.

Intervention Type: DIAGNOSTIC_TEST

Eligibility Criteria

Inclusion Criteria

• Ability and willingness to participate in the study.
• Declaration of consent.
• Having RhD-Negative blood. This is because only RhD-negative blood type become slower when afflicted by Toxoplasmosis. Hence, the proposed analysis can only be performed on RhD-Negative people.
• Good English language skills (at least C1, to ensure understanding of all instructions and the declaration of consent).

Exclusion Criteria

• Inability to give the declaration of consent.
• Any neurological disorders
• Reduced general health / chronic diseases (e.g. autoimmune disease, severe cardiovascular diseases, insulin-dependent diabetes, severe depression); chronic pain disorders

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 35 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

University of Zurich

OTHER

Sponsor Role: lead

Responsible Party

Carlos Alós-Ferrer

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Central Contacts

Carlos Alós-Ferrer, PhD

Role: CONTACT

carlos.alos-ferrer@econ.uzh.ch

798667160 ext. +41

Other Identifiers

2023-00366

Identifier Type: -

Identifier Source: org_study_id