Black disease

From Cow
Scleral oedema in a bovine with Black Disease[1]

Black disease (Infectious necrotic hepatitis) is a relatively sporadic bacterial infection of cattle worldwide caused by Clostridium novyi.

This soil-borne bacteria, which normally resides in the intestine and liver of cattle, primarily causes disease in sheep but also infects cattle by causing subacute or acute necrotic hepatitis with a high mortality rate[2].

Fecal contamination of pastures by carrier animals is the primary route of infection. It is usually associated with pre-existing liver disease, especially flukes such as Fasciola hepatica and Dicrocoelium spp.

Necrotising lesions in cattle as a result of this bacteria are caused by release of an α toxin which is highly toxigenic to hepatic[3] and renal parenchymal tissue[4].

Clinical signs

In many cases, sudden death syndrome occurs as a result of toxemia[5], with one or a number of cattle found dead in the pasture.

Affected cattle often present acutely with anorexia, fever, recumbency, icterus, gas gangrene[6] and scleral oedema. Many present with no clinical signs before death. As this disease is usually associated with a pre-existing fluke infestation, it is rare to see in catle under 2 years of age, and a history of fascioliasis is common on the property.

In some acutely infected cattle, subcutaneous skin in amelanistic areas may appear black and subcutaneous edema and hemorrhage may also be observed.

Diagnosis

Diagnosis is often difficult antemortem. Confirmation usually requires postmortem findings which are usually characteristic; grayish yellow, necrotic foci in the liver along migratory tracks of the young flukes. The peritoneal and thoracic cavities are often filled with copious straw-colored fluid.

Submitted samples are usually sent to laboratory for confirmation of acute fascioliasis with secondary bacterial involvement. Histology often confirms a central eosinophilic inflammation (fluke induced) surrounded by coagulation necrosis with an outer rim of neutrophils[7].

Confirmation of Clostrium novyi is usually ascertained by bacterial culture, ELISA and PCR assays[8].

filled with straw-colored fluid and excess fluid in the peritoneal and thoracic cavities. Usually, there is extensive rupture of the capillaries in the subcutaneous tissue, which causes the adjacent skin to turn black (hence the common name, black disease).

A differential diagnosis would include other causes of acute death such as brisket disease, tetanus, blackleg and snake bite.

Treatment

Treatment in affected cattle is usually limited to broad-spectrum antimicrobial therapy and supportive therapy. Penicillins are usually the drug of choice, in high parenteral doses.

Control of fluke burdens and reduction of snail populations in surrounding waterways and streams is essential to minimize further outbreaks of this disease.

In outbreaks, vaccination of at-risk cattle with C. novyi toxoid seems prudent[9], especially young calves in herds where Black Disease is prevalent[10].

References

  1. Dept of Agriculture, Ireland
  2. Hang'ombe BM et al (2000) Detection and characterization of Clostridium species in soil of Zambia. Comp Immunol Microbiol Infect Dis 23(4):277-284
  3. Borrmann E & Schulze F (1999) Detection of Clostridium novyi type B alpha toxin by cell culture systems. FEMS Immunol Med Microbiol 24(3):275-280
  4. Kanoe M et al (1998) Detection of cytotoxic effects of Clostridium novyi type A on bovine kidney cells. Microbios 95(380):7-13
  5. Kelch WJ et al (1977) Suspected infectious necrotic hepatitis (black disease) in Oregon cattle. J Am Vet Med Assoc 171(5):431-432
  6. el Sanousi SM & Musa MT (1989) Note on an association of Clostridium novyi type A and Clostridium sordellii with a case of gas-gangrene in a Zebu cow. Rev Elev Med Vet Pays Trop 42(3):391-392
  7. Merck Vet Manual
  8. Thomas RJ et al (1991) Detection of Clostridium botulinum types C and D toxin by ELISA. Aust Vet J 68(3):111-113
  9. Woolums AR et al (2011) Humoral immunity and injection-site reactions in cattle vaccinated with a multivalent clostridial vaccine administered via subcutaneous injection or via transdermal needle-free injection. Am J Vet Res 72(8):1124-1129
  10. Troxel TR et al (2001) Clostridial antibody response from injection-site lesions in beef cattle, long-term response to single or multiple doses, and response in newborn beef calves. J Anim Sci 79(10):2558-2564