The Parasite–Disease Connection: How Hidden Infections Can Mimic Mental, Neurological, and Chronic Health Conditions exposes one of modern medicine's most dangerous blind spots—the hidden link between parasitic infections and diseases routinely diagnosed as psychiatric, neurological, autoimmune, or idiopathic. For millions of patients worldwide, the true cause of their depression, brain fog, cognitive decline, seizures, chronic fatigue, or inflammatory symptoms is not stress, aging, anxiety, or hypochondria. It is a hidden parasite their doctors never learned to test for. Written for patients, clinicians, researchers, and anyone seeking answers to unexplained illness, this evidence-based book presents 23 meticulously researched chapters spanning neuroparasitology, immunology, infectious disease, and psychiatry. From Toxoplasma gondii's documented effects on dopamine and behavior, to neurocysticercosis misdiagnosed as schizophrenia for years before anyone checked for a tapeworm in the brain, to Giardia and Blastocystis triggering post-infectious depression and brain fog—the evidence is staggering, robust, and systematically overlooked by mainstream medical training. Inside this comprehensive guide, readers will discover: • Why the standard travel-history question fails patients who acquired parasites decades ago, through unexpected exposure routes, or right at home • How molecular mimicry between parasite antigens and human tissues triggers autoimmune diseases including lupus, multiple sclerosis, and Guillain-Barré syndrome • The cytokine-sickness behavior pathway linking chronic parasitic infection to treatment-resistant depression, fatigue, and anhedonia through IDO activation • Circadian disruption caused by Trypanosoma brucei and Plasmodium parasites—mechanistically proven biological clock hijacking at the suprachiasmatic nucleus • The gut-brain highway: how intestinal parasites alter microbiome composition, vagus nerve signaling, serotonin production, and intestinal permeability • Documented cases of cerebral malaria causing permanent cognitive deficits; sleeping sickness altering personality; Strongyloides stercoralis persisting silently for decades before devastating neurological catastrophe • The helminth paradox: why some parasitic worms protect against autoimmune disease while others trigger it through immune modulation and molecular mimicry • Schistosomiasis eggs migrating to the spinal cord, producing transverse myelitis and paralysis in patient