kdikysts

kdikysts are a rare class of parasitic cysts that appear predominantly in the hepatic and splenic tissues of mammals. They are formed by the obligate intracellular organism Kdikystis major, a single-celled protozoan belonging to the phylum Apicomplexa. Although they were first reported in 1998 in a small population of captive felids, subsequent studies have documented cases in canines, rodents, and occasionally humans.

The life cycle of K. major involves an intermediate host where the organism undergoes merogony and gametogony, producing motile zoites that invade the definitive host. In humans, infection typically occurs through ingestion of contaminated water or arthropod vectors. Once ingested, zoites excyst in the small intestine and migrate hematogenously to the liver and spleen where they encyst within hepatocytes or splenic macrophages. These cysts are usually 0.5–2.0 mm in diameter and can cause localized granulomatous inflammation. Clinical manifestations are often nonspecific, ranging from asymptomatic lesions discovered incidentally on imaging to chronic abdominal pain, fever, and hepatomegaly in severe cases.

Diagnosis relies on serological testing for K. major antibodies and imaging studies such as ultrasound or CT that reveal hypoechoic or hypodense lesions. Definitive identification is achieved by percutaneous biopsy followed by histopathology, showing characteristic parasitic cysts with a laminated wall. Treatment protocols are not yet standardized; however, antiparasitic agents such as clindamycin and azithromycin have been used with variable success. Ongoing research focuses on vaccine development and understanding the molecular mechanisms of cyst formation to improve therapeutic options.