Giardia and Its Influence on Neurotransmitter Systems

Abstract

Giardia duodenalis is one of the most prevalent gastrointestinal parasites worldwide, affecting a wide range of hosts, including both dogs and humans. Several studies have shown that Giardia infection significantly alters the composition of the gut microbiota. Disruption of the gut microbiota can have profound consequences, as the gut microbiota plays a key role in maintaining homeostasis, regulating immune responses, and contributing to overall health. Recent research highlights the role of the gut microbiota in influencing not only gastrointestinal function but also the gut microbiota-brain axis, a bidirectional communication network connecting the gut and central nervous system. This axis is involved in regulating digestive processes, mood, and cognitive function. Thus, alterations in microbial populations induced by Giardia may impact not only digestion and nutrient absorption but also neurological and behavioural functions. Several gut-resident bacterial taxa are known to produce key neurotransmitters, including dopamine, serotonin, gamma-aminobutyric acid (GABA), acetylcholine, and norepinephrine. Dysbiosis caused by Giardia duodenalis infection may disrupt the balance of these neurotransmitters, potentially contributing to changes in mood and behaviour. Interestingly, the co-evolution of dogs and humans has led to notable similarities in their gastrointestinal microbiomes. Given this parallel, research on the interactions between Giardia and the gut microbiota in humans can offer valuable insights for understanding its effects in canine populations. By integrating findings from human studies, veterinary research can further elucidate the complex interplay between Giardia, the microbiome, and host health, ultimately improving therapeutic and preventive strategies for both species.