Giardiasis is a globally prevalent intestinal infection caused by the protozoan parasite Giardia duodenalis (also known as G. lamblia or G. intestinalis). This flagellated protozoan is the most frequently identified intestinal parasite in the United States and worldwide. Transmission primarily occurs via the fecal-oral route, with infection arising from ingestion of water or food contaminated with cysts. Individuals in low-resource settings, international travelers, outdoor enthusiasts, daycare...

Gastritis is marked by disruption of the mucosal barrier that usually protects the stomach tissue from digestive juices and manifests in acute and chronic forms.
In acute gastritis, the gastric mucosa becomes swollen and red and undergoes superficial erosion. Superficial ulceration may lead to bleeding.
In chronic gastritis, persistent or repeated insults lead to chronic inflammatory changes and, eventually, thinning or atrophy of the gastric tissue.
Gastritis can stem from various causes, each...

The gastrointestinal tract is susceptible to various disorders. If the lower esophageal sphincter is damaged, stomach acid can flow back into the esophagus, causing irritation and inflammation of the lining. This condition is called gastroesophageal reflux disease (known as heartburn) and may cause chest pain and difficulty swallowing. In the stomach, prolonged use of nonsteroidal anti-inflammatory drugs like aspirin, chronic alcohol consumption, bacterial infections such as Helicobacter...

The disease process of myasthenia gravis begins at the neuromuscular junction, where antibodies attack key proteins needed for muscle activation. This immune reaction weakens signal transmission, leading to the characteristic muscle fatigue and weakness that define the condition.Immune-Mediated DamageIn most individuals, antibodies target acetylcholine receptors (AChRs) on the postsynaptic membrane of muscle cells. By blocking acetylcholine binding, these antibodies prevent the nerve signal...

Graves' disease is an autoimmune disorder that causes hyperthyroidism, or overactivity of the thyroid gland. It results from autoantibodies called thyroid-stimulating immunoglobulins (TSIs), which bind to thyroid-stimulating hormone (TSH) receptors, leading to overstimulation of hormone production and a hypermetabolic state.EtiologyAlthough considered idiopathic, Graves’ disease has well-established contributing factors. There is a strong genetic component, with increased prevalence in...

Graves’ disease is an autoimmune disorder characterized by the production of thyroid-stimulating immunoglobulins (TSI) that activate TSH receptors, leading to excessive synthesis and release of thyroid hormones (T3 and T4) and resulting in hyperthyroidism.Among all causes of hyperthyroidism, Graves’ disease is the most common and can happen at any age, though it is more frequent in women. It produces a hypermetabolic state with features such as weight loss, tachycardia, tremor, and heat...