Duck Hepatitis Type 1 in Waterfowl

Disease Summary

Alternative Names (Synonyms)

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Disease Type

Infectious/Non-Infectious Agent associated with the Disease

Infective "Taxa"

• Picornaviridae: Duck hepatitis virus type 1

Non-infective agents

Physical agents

References

Disease Author

Major References / Reviews

Code and Title List

Other References

Code and Title List

Detailed Clinical and Pathological Characteristics

General

Clinical Characteristics

• Rapid onset and spread (mortality mainly in first 3-4 days of an outbreak).
• Listlessness, depression, sit with eyes partially closed, incoordination, fall on sides, kick spasmodically with both legs, develop opisthotonus, die.
• Deaths may occur within approximately one hour to four hours of first signs.

J5.1.w2, B14, B15, B13.46.w1, B32.25.w4.

Incubation

Mortality / Morbidity

• Morbidity 100%, but severity of clinical signs is age-dependent: no clinical signs in ducklings more than six weeks old.
• Mortality varies with age: up to 95 % in ducklings less than week old, up to 50% in 1-3 weeks old, negligible in 4-5 week old ducklings, no deaths in older birds.

(B15, B32.25.w4)

• Higher than expected mortality, and in older ducklings, may be seen with synergistic effect of other pathogens (e.g. avian influenza virus, Chlamydia psittaci) (J3.116.w2, J3.119.w2, B32.25.w4).

Pathology

• Typical opisthotonus posture.
• Liver- Prominent hepatomegaly, petechial to ecchymotic haemorrhages, mottling or reddish discoloration of surface, sometimes extremely friable.
• Spleen - splenomegaly, mottling or haemorrhages sometimes seen.
• Kidneys - frequently swollen; congested renal blood vessels.

Histopathology:

• Necrosis hepatocytes, extensive by 24hrs post infection, widespread bile duct epithelium hyperplasia, variable inflammatory cell (heterophils, mononuclear cells) infiltration and haemorrhage. N.B. regeneration of liver parenchyma reported in ducklings surviving the disease

Biochemistry:

• low total protein and albumen, elevated alkaline phosphatase, GPT (glutamic pyruvic transaminase), bilirubin, creatinine. GPT and GOT (glutamic oxaloacetic transaminase) levels rise correlate with severity of infection.

Electron microscopy:

• cell necrosis liver, spleen, virus-like particles in liver.

J5.1.w2, J5.16.w2, B14, B15, B32.25.w4

Human Health Considerations

Disease / Agent has been reported in either the wild or in captivity in:

• Pekin ducklings (Anas platyrhynchos domesticus) (J5.1.w2, J5.16.w2).
• Mallard Anas platyrhynchos ducklings in conjunction with avian influenza virus infection (J3.119.w2); in experimental infection (J5.16.w2).
• Goslings (experimental infection) (B32.25.w4).

WATERFOWL Host Species List

• Anas platyrhynchos - Mallard
• Anas platyrhynchos domesticus - Domestic duck
• Anser anser domesticus - Domestic goose

Disease / Agent has been specifically reported in Free-ranging populations of:

WATERFOWL Host Species List

General Information on Environmental Factors/Events and Seasonality

Regions / Countries where the Infectious Agent or Disease has been recorded

Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

General Information on Investigation / Diagnosis

• Clinical signs and post mortem examination findings are highly suggestive: acute disease of young ducklings only, with sudden onset, rapid spread and acute course; haemorrhagic lesions in swollen livers. Confirm by serology and virus identification (B15, B32.25.w4):
• Direct fluorescent antibody test on liver, or on inoculated duck embryos.
• Cytopathic effect producing plaques in primary DEK (duck embryo kidney) or DEL (duck embryo liver) cell cultures
• Inoculation of 10-14 day-old duck embryo eggs or 8-10 day-old chicken embryos (die 5-8dpi, cutaneous haemorrhage and oedema, dwarfing enlarged greenish livers with necrotic foci)
• Virus neutralization test, in a plaque reduction assay, chicken embryos, duck embryos or ducklings.
• (J6.11.w1, J6.15.w3, B15, B32.25.w4).
• N.B. In association with other pathogens (e.g. avian influenza virus, Chlamydia psittaci) a synergistic effect may result in higher-than-expected mortality for the virus strain or the age of affected birds (J3.116.w2, J3.119.w2, B32.25.w4).

• Necropsy - General
• Treatment and Care - Euthanasia
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Chapter 5 - B36 Field Manual of Wildlife Diseases - Euthanasia
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

Similar Diseases (Differential Diagnosis)

• Duck hepatitis type 2 (Duck Viral Hepatitis Type 2), Duck hepatitis type 3 (Duck Viral Hepatitis Type 3).
• Other causes of acute mortality in ducklings, particularly salmonellosis (Salmonellosis) and aflatoxicosis (Aflatoxicosis (Mycotoxicosis)) (this may cause ataxia, convulsions, opisthotonus, bile duct hyperplasia, but not hepatic haemorrhages), other bacterial septicaemias, coccidiosis (Intestinal coccidiosis, Renal Coccidiosis), leucocytozoonosis (Leukocytozoonosis) (where this is a problem) duck plague (Duck Plague) (expect deaths in older birds).

(B14, B37.x.w1, B32.25.w1)

Specific Medical Treatment

• Treatment and Care - Injection and Medication Techniques

General Nursing and Surgical Techniques

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Preventative Measures

• Administration of serum from immune ducks (0.5ml DHV type 1 antiserum i/m) or of yolk from eggs of hyperimmunised specific-pathogen-free ducks or hyperimmunised breeder ducks.
• Active immunization with live, avirulent strains of DHV type 1 (produced by passage in duck embryos or chicken embryos) : I/M, intranasal, foot-web stab, aerosol, drinking water (J3.102.w3, J5.13.w2).

• Passively transferred antibodies by vaccination of breeders with live attenuated virus; two or three doses of vaccine required, or live attenuated then inactivated oil-emulsion vaccine (J5.13.w2, J6.20.w2).

N.B. egg-attenuated virus reverts to virulence after serial passage in ducklings: only premises known to be infected should use such vaccination (J3.105.w3).

(B15, B13.46.w1, B32.25.w4)

WATERFOWL

• Treatment and Care - Injection and Medication Techniques
• Preventative Medicine for Birds - General

Environmental and Population Control Measures

WATERFOWL

• Strict hygiene and disinfection.
• N.B. Duck hepatitis virus Type 1 is relatively heat stable and capable of surviving at least 10 weeks in uncleaned brooders, at least 37 days in moist faeces in a cool environment, more than two years at 4ºC and 9years at –20ºC. It is resistant to many chemical treatments, including 30% methanol, ether, chloroform, 2% lysol, 0.1% formalin, 15% creolin, ‘napthalysol’ or ‘xylonaphtha’, 20% anhydrous sodium carbonate, ammonium sulfate, potassium alum, protamine sulfate, Freon 112 Heptane.

• Virus is inactivated by: 62ºC for 30 minutes, 5%phenol, undiluted Wescodyne (inorganic iodine solution), undiluted Clorox (sodium hypochlorite solution), 1% formaldehyde for 2hrs at 15-20ºC, 2% caustic soda for 2hrs at 15-20ºC, 2% calcium hypochlorite for 3hrs at 15-20ºC, 3% chloramine for 5hrs, 0.2% formalin for 2 hrs.

(J5.8.w1, B32.25.w4).

• Environmental and Population Management - General
• Preventative Medicine for Birds - General