Which organism is responsible for causing Giardiasis?

Giardiasis is an intestinal infection caused specifically by the protozoan parasite Giardia lamblia, also known as Giardia intestinalis. This organism is generally found in contaminated water, food, or surfaces and can lead to gastrointestinal symptoms like diarrhea, abdominal pain, and nausea. Giardia lamblia has a distinctive pear-shaped appearance and can exist in both cyst and trophozoite forms, contributing to its ability to survive in various environments.

The other organisms listed do cause diseases but are responsible for different conditions. Entamoeba histolytica causes amoebic dysentery, which leads to severe diarrhea and can sometimes affect other organs, while Cryptosporidium parvum causes cryptosporidiosis, characterized by watery diarrhea, primarily affecting immunocompromised individuals. Ascaris lumbricoides is a type of roundworm responsible for ascariasis, which leads to intestinal obstruction and malnutrition due to its large size and lifecycle. Understanding the specific agents that cause these different parasitic diseases is crucial for proper diagnosis and treatment.