Edwardsiella ictaluri (also known as Enteric Septicaemia of Catfish, Hole in the Head Disease, and ESC) is a member of the Enterobacteriaceae

Enterobacteriaceae

The Enterobacteriaceae is a large family of bacteria that includes many of the more familiar pathogens, such as Salmonella, Escherichia coli, Yersinia pestis, Klebsiella and Shigella. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the...

family. The bacterium is a short, gram negative, pleomorphic rod with flagella. It causes the disease enteric septicaemia of catfish

Catfish

Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

 (ESC), which infects a variety of fish species (including many catfish species, knifefish

Knifefish

Knifefish may refer to several knife-shaped fishes:* The Neotropical or weakly electric knifefishes, order Gymnotiformes, containing five families:** Family Gymnotidae ** Family Rhamphichthyidae...

 and barbs). The bacteria can cause either acute septicaemia or chronic encephalitis

Encephalitis

Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...

 in infected fish. Outbreaks normally occur in spring and autumn.

E. ictaluri can be found in Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, being of particular economic importance in the U.S. It is not a zoonosis

Zoonosis

A zoonosis or zoonoseis any infectious disease that can be transmitted from non-human animals to humans or from humans to non-human animals . In a study of 1415 pathogens known to affect humans, 61% were zoonotic...

.

Clinical signs and diagnosis

Acute ESC infection causes an acute septicaemia that presents as multiple petechial haemorrhages

Petechia

A petechia is a small red or purple spot on the body, caused by a minor hemorrhage ."Petechiae" refers to one of the three major classes of purpuric skin conditions. Purpuric eruptions are classified by size into three broad categories...

 that develop into depigmented ulcers. Additional clinical signs include abnormal behavior, exophthalmos

Exophthalmos

Exophthalmos is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral or unilateral . Measurement of the degree of exophthalmos is performed using an exophthalmometer...

, hemorrhagic gastroenteritis

Hemorrhagic gastroenteritis

Hemorrhagic gastroenteritis is a disease of dogs characterized by sudden vomiting and bloody diarrhea. The symptoms are usually severe, and HGE can be fatal if not treated. HGE is most common in young adult dogs of any breed, but especially small dogs such as the Toy Poodle and Miniature...

, edema

Edema

Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

 and ascites

Ascites

Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...

. Chronic ESC infection causes a chronic encephalitis

Encephalitis

Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...

. Clinical signs include abnormal behavior, abnormal swimming patterns, swelling and ulceration of the head and death.

Any fish that survive the infection become latent carriers

Asymptomatic carrier

An asymptomatic carrier is a person or other organism that has contracted an infectious disease, but who displays no symptoms. Although unaffected by the disease themselves, carriers can transmit it to others...

 of the disease.

A presumptive diagnosis can be made based on the clinical signs alone but PCR, indirect immunofluorescence

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...

, bacterial culture and 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...

 can be used to definitively diagnose the disease.

Treatment and control

Several antibiotics can be used to treat the disease, but there are reports of resistance

Antibiotic resistance

Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...

 emerging. Vaccination

Vaccination

Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...

can be used to prevent disease. Management factors such as reducing stocking density and stress should be considered.