Unknown age in health disorders: A method to account for its cumulative effect and an application to feline viruses
Eléonore Hellard1, Dominique Pontier1, Aurélie Siberchicot1
1Université de Lyon, Université Lyon1, CNRS, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, 43 Bd du 11 novembre 1918, F-69622, Villeurbanne, France.
Abstract:
Parasite interactions have been widely evidenced experimentally but field studies remain rare. Such studies are essential to detect interactions of interest and access (co)infection probabilities but face methodological obstacles. Confounding factors can create statistical associations, i.e. false parasite interactions. Among them, host age is a crucial covariate. It influences host exposition and susceptibility to many infections, and has a mechanical effect, older individuals being more at risk because of a longer exposure time. However, age is difficult to estimate in natural populations. Hence, one should be able to deal at least with its cumulative effect. Using a SI type dynamic model, we showed that the cumulative effect of age can generate false interactions theoretically (deterministic modeling) and with a real dataset of feline viruses (stochastic modeling). The risk to wrongly conclude to an association was maximal when parasites induced long-lasting antibodies and had similar forces of infection. We then proposed a method to correct for this effect (and for other potentially confounding shared risk factors) and made it available in a new R package, Interatrix. We also applied the correction to the feline viruses. It offers a way to account for an often neglected confounding factor and should help identifying parasite interactions in the field, a necessary step towards a better understanding of their mechanisms and consequences.
Insights
Host age can create false parasite interactions in field studies. A new R package, Interatrix, helps correct for this confounding factor to accurately identify real parasite relationships.
Area of Science:
- Ecology
- Epidemiology
- Parasitology
Background:
- Parasite interactions are well-documented experimentally but rarely studied in natural field settings.
- Field studies are crucial for understanding co-infection dynamics but face challenges, including confounding factors.
- Host age is a significant covariate influencing infection susceptibility and exposure duration, yet difficult to assess in wild populations.
Purpose of the Study:
- To investigate how host age, as a confounding factor, can lead to false parasite interactions in field studies.
- To develop and validate a statistical method to correct for the confounding effect of host age on parasite interaction detection.
- To introduce the R package 'Interatrix' for addressing confounding factors in parasite interaction analyses.
Main Methods:
- Utilized a Susceptible-Infected (SI) type dynamic model for theoretical (deterministic) and empirical (stochastic) analysis.
- Applied the modeling approach to a real-world dataset of feline viral infections.
- Developed a correction method to account for age-related confounding and other shared risk factors.
Main Results:
- Demonstrated that the cumulative effect of host age can generate statistically significant, yet false, parasite interactions.
- Identified that the risk of false positives is highest when parasites induce long-lasting antibodies and share similar infection rates.
- Successfully applied the developed correction method to the feline virus dataset, improving interaction detection.
Conclusions:
- Host age is a critical, often overlooked, confounding variable in field-based parasite interaction studies.
- The 'Interatrix' R package provides a valuable tool for correcting age-related biases and identifying true parasite interactions.
- Accurate identification of parasite interactions in the field is essential for understanding their ecological and evolutionary consequences.
Related Concept Videos
Cytomegalovirus Disease
Pharmacokinetics: Drug–Food and Drug–Viral Interactions
Viral Recombination
Pharmacodynamics in Geriatric Patients: Effects of Age
Factors Affecting the Risk of Infection
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin...
Mechanisms of Retrovirus-induced Cancers


