Giardia lamblia is a protozoa (an amoebic parasite) and it lives in the water. It is common in the tropics. It can remain viable in water for up to 3 months. Unclean water containing Giardia cysts can cause food poisoning and diarrhoea. The flagellates attach to the mucosa of the duodenum and jejunum and cause inflammation. The patients complain of abdominal pain, anorexia, vomiting and diarrhoea. Prolonged infection can cause malabsorption of vitamin B12.
Good hygienic practices, drinking clean (boiled) water, and avoiding uncooked vegetables are the best preventive measures. Salads should be washed with boiled water. This is the safest way to avoid Giardia because it is highly chemically resistant.
Treatment is with tinidazole 40 mg/ kg body weight or metronidazole 2 g /day for 3 days.