Protozoa are a group of eukaryotic unicellular organisms: with a differentiated nucleus, cytoplasm, mitochondria, plasmatic and nuclear membrane. They have the capacity to phagocytose and are mobile.

They inhabit humid or aquatic environments. They can be free-living or parasitic.

Parasitic protozoa can cause disease in the host. They have the ability to evade innate immune defenses and avoid attack by the host’s immune system mechanisms.

In the swine industry, the effects of infection by protozoa, although they are not clearly visible, cause important losses by decreasing the performance of the animals, and increasing their susceptibility to other pathogens.

They mainly affect piglets, and cause diarrhea, anorexia, weight loss, colitis. They also infect adult pigs, but do not usually show clinical signs. Transmission is via the fecal-oral route, with or without development in the medium, depending on the species.

Among the most common species in pigs, we find:

• Cystoisospora suis

  (formerly known as Isospora suis)

Invades the epithelial cells of the small intestine, where they multiply, damage the epithelium, causing inflammation and loss of absorptive capacity of the intestine. Clinical signs are yellowish, pasty diarrhea, dehydration, and decreased growth.

It mainly affects suckling piglets between 8 and 10 days of age, which makes them susceptible to bacterial pathogens such as Clostridium perfringens. While in piglets of 3 weeks or more, they do not usually show symptoms. It is supposed that due to the immaturity of the immune system of newborn piglets.

• Eimeria spp.

Eight different species of Eimeria have been described in pigs. These mainly affect weaned piglets and adult pigs in a subclinical way, but have a negative impact on the animals performance.

• Cryptosporidium spp

They invade and damage epithelial cells of the small intestine. The infection is usually subclinical, but clinical signs such as diarrhea or weight loss may appear, usually associated with other viral or bacterial enteropathogens.

• Balantidium coli

Found in the cecum and colon as a commensal, it causes clinical symptoms under stress, disease, dysbiosis, or malnutrition. It produces proteolytic enzymes that cause lesions in the colon wall, allowing the entry of pathogenic bacteria.

It affects all pig’s categories, some showing no signs and others experiencing severe diarrhea, loss of appetite, dehydration, loss of body condition and retarded growth.

• Toxoplasma gondii

The infection in pigs is subclinical, but it is one of the main zoonoses. In pigs, they form cysts in muscles and other organs, which later develop into mature parasites.

In sows it can cause abortions, an increase in stillborn, premature or weak piglets.

There are other protozoa that infect pigs, causing neonatal diarrhea in suckling piglets, but little symptomatology in older animals. Some also infect other mammals or birds and cause more or less severe zoonoses.

Protozoa are more difficult for the immune system to detect than other microorganisms. But gut-optimizing pronutrients increase the capacity of the general local mucosal immune system, helping the body against coccidia.

Intestinal optimizer pronutrients are marketed under the name Alquernat Zycox by Biovet S.A.