Introduction

Cryptobia species are protozoa

Protozoa

Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...

 that can lead to disease in fish. C. branchialis is an ectoparasite that lives on the skin or gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s of fish, and the other four pathogenic species are endoparasites that live in the circulatory system or intestines.

Marine and freshwater fish can be infected and the disease is most important in salmonid fish. The disease is observed in most continents including the USA, Eastern Europe and Mexico.

Bloodfeeding leech

Leech

Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Like other oligochaetes such as earthworms, leeches share a clitellum and are hermaphrodites. Nevertheless, they differ from other oligochaetes in significant ways...

es are implicated in the transmission of the disease for those species that reside in the bloodstream.

Clinical Signs and Diagnosis

C. branchialis infects the gills and can lead to skin changes, anorexia and death.

C. iubilans resides in the intestines and leads to granulomatous inflammation in the abdominal organs resulting in weight loss and death.

C. salmositica, C. borreli and C. bullocki are all blood parasites that lead to anaemia and lesions in the haematopoietic

Haematopoiesis

Haematopoiesis is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells...

 tissues.

Skin or gill biopsies

Biopsy

A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 and blood samples can be examined for moving flagellated

Flagellate

Flagellates are organisms with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, some gymnosperms and other closely related plants...

 organisms.

An antibody response can be detected with ELISA

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

 testing and fluorescent antibody testing

Immunofluorescence

Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...

 for certain Cryptobia species.

Treatment and Control

Chemical treatment has been effective using isometamidium chloride

Isometamidium chloride

Isometamidium chloride is a trypanocidal agent used in veterinary medicine....

.

A vaccine

Vaccine

A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...

 against C. salmositica is available and lasts up to 2 years.

Fish can be selected and bred for resistance

Selective breeding

Selective breeding is the process of breeding plants and animals for particular genetic traits. Typically, strains that are selectively bred are domesticated, and the breeding is sometimes done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties,...

as a method of control of the disease.