Immune and Lymphatic
Giardia intestinalis, also known as lamblia intestinalis, is a protozoan parasite that colonises and reproduces in the small intestine, causing giardiasis. The organism is most likely to be present in the food as a cyst, the protozoan resting stage equivalent to a bacterial spore. The giardia parasite attaches to the epithelium by a ventral adhesive disc and reproduces via binary fission. Lamblia infection can occur through ingestion of dormant cysts in contaminated water, or by the faecal-oral route. Anyone may become infected, but the disease is more serious in those who are immunocompromised. Infants and children are more susceptible to infection than adults. Symptoms include loss of appetite, lethargy, fever, severe diarrhea, loose or watery stool, stomach cramps, upset stomach, projectile vomiting (uncommon), bloating, and flatulence. Symptoms typically begin 1-2 weeks after infection and may disappear and reappear cyclically. Symptoms are caused largely by the giardia parasite coating the inside of the small intestine and blocking nutrient absorption. Most people are asymptomatic; only about a third of infected people exhibit symptoms.