What is Giardiasis ?

Giardiasis is a disease caused by the Giardia protozoan. Giardia has a flagellated structure. It is a zoonotic disease. Giardia lamblia lives in the small intestine of humans, domestic and wild animals (e.g., cats, dogs, cattle, deer, and beavers). Van Leeuwenhoek discovered trophozoites in his own diarrhoeal stool in 1681. This was one of the first protozoans to be identified. Leeuwenhoek mentioned that he had seen moving creatures and that they were bigger and smaller than blood globules, but that they all had the same structure.

Epidemiology and Morphology

G. lamblia is the most commonly isolated intestinal parasite throughout the world and is especially prevalent in children in developing countries.
●10% in adult dogs
●33-50% in puppies
●4-11% in cats
Infection begins with ingestion of the cyst form and the adult form in the intestines is the trophozoite form. Cyst form transmitted by the fecal-oral route through contaminated food and water. Infected animals also play a role in transmission to humans.
It has an incubation period of 3-25 days

Clinical Symptoms

Clinical signs are seen in young, especially in puppies. Generally, cases are asymptomatic, but symptoms may be observed in some cases.
●weight loss
●abdominal pain
●diarrhea
●foul-smelling stools

Diagnosis

Microscopic examination of faces for cysts and trophozoites is usually the first diagnostic test.
Stools must be fresh for trophozoite detection. A drop of Lugols solution is used to kill the trophozoite form and make it easier to look through the microscope. ELISA test can also be applying.

Public Health

Giardia is well-known food- and waterborne protozoa affecting humans and a wide range of domestic and wild animals. In recent decades, the scientific community has focused on Giardia to understand how it spreads and whether infected animals can infect humans.

This blog post has been verified by Prof. Dr. Ahmet DENİZ

Sources

ScienceDirect. Veterinary Parasitology. 20.04.2025
Giardia in symptomatic dogs and cats in Europe—Results of a European study – ScienceDirect

Springer Nature Link. Parasitology Research. 20.04.2025
  https://rdcu.be/eiuvF

AYTUĞ N. Köpek ve Kedilerin İç Hastalıkları. Türkiye.Medipres

RODNEY D. ADAM. The Biology of Giardia spp. .