Protist (Coccidia) and Related Diseases

Coccidia of the genus Aggregata is the most widely distributed coccidian in cephalopods. Damages caused to the hosts include mechanical (tissue injury), biochemical (malfunction of digestive enzymes), and molecular (affects cellular immune response) effects. However, coccidiosis is not a fatal disease to the cephalopod host; it severely weakens its innate immunity making it vulnerable to secondary infections. Therefore, coccidia of the genus Aggregata are considered the most dangerous parasite for cephalopods affecting wild species of notable economic importance for fishery and aquaculture activity. The pathology caused by coccidiosis to the most important European cephalopod species is the subject of the present chapter.