duck virus hepatitis

Identity

Preferred Scientific Name

• duck virus hepatitis

International Common Names

• English: duck hepatitis

English acronym

• DH
• DVH

Pathogen/s

Overview

Duck hepatitis (DH) or duck viral hepatitis (DVH) is a highly fatal viral infection of ducklings, characterized by rapid onset of high mortality, opisthotonos and hepatitis. The potential for high mortality if not properly controlled makes DH an economically important disease in all duck-growing areas.

Duck hepatitis is caused by at least three different viruses, previously referred to as types I, II and III (Tseng and Tsai, 2007; Wang et al., 2008). Genome sequencing studies have revealed a great deal about them (Kim et al., 2006, 2007a; Tseng et al., 2007; Fu et al., 2009; Todd et al., 2009; Yun et al., 2010; Wei et al., 2012), including that type III is not a picornavirus, as once thought, but an astrovirus, now called duck astrovirus-2 (DAstV-2; Todd et al., 2009). Type II is also an astrovirus (subsequently renamed as duck astrovirus 1 (DAstV-1; Todd et al., 2009), and type I is a picornavirus. DHV I, the most common of the three viruses, with international distribution, is now known as duck hepatitis A virus (DHAV) in the new genus Avihepatovirus.

Duck viral hepatitis should not be confused with duck hepatitis B infection caused by a member of the hepadnavirus group (hepatitis B viruses) that are also found in wild and domestic ducks.

Please see the AHPC library for further information on this disease from OIE, including the International Animal Health Code and the Manual of Standards for Diagnostic Tests and Vaccines. Also see the website: www.oie.int

Host Animals

Systems Affected

Distribution

Duck hepatitis A virus (DHAV) was first described in young White Pekin Ducks on Long Island, New York (Levine and Hofstad, 1945; Levine and Fabricant, 1950). Since then, DHAV has been reported in duck-raising areas worldwide (Woolcock, 2008), and most recently in China (Guo and Pan, 1984) and Korea (Park, 1985; Woo et al., 2000).

DHV type II (DAstV-1) was originally reported in Norfolk, England (Asplin, 1965). A duck astrovirus with very high sequence similarity to DAstV-1 (Todd et al., 2009) has been detected and sequenced in China (Fu et al., 2009), associated with very high mortality in 1- to 2-week-old commercial ducklings.

DHV type III (DAstV-2) is only known to have occurred in the USA.

For current information on disease incidence, see OIE's WAHID Interface.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Pathology

Gross lesions are predominately found in the liver, which is enlarged and displays distinct punctuate or ecchymotic haemorrhages. Spleen enlargement and swelling of the kidneys, with congestion of renal blood vessels is also observed. Occasionally, small haemorrhages are seen in the intestinal wall, and on the heart fat with DAstV-1 infection. Gross pathological changes with DAstV-2 are similar to those caused by DHAV.

Histopathological changes in DHAV infection consist of necrosis of hepatic cells and varying degrees of inflammatory cell infiltration. In survivors, more chronic lesions showed regeneration of liver parenchyma and widespread bile duct hyperplasia. All microscopic changes associated with DHAV infections were analyzed in experimentally induced DHAV infection (Fabricant et al., 1957). Peng showed by electron microscopy that DHAV invades many tissues in the duckling, and causes swelling, haemorrhage and necrosis of the liver, spleen, kidneys, and pancreas. Pathological changes are also seen in the central nervous system and the bursa of Fabricii in infected ducklings (Peng, 1998). Lesions are similar with DAstV-1 and DAstV-2 infection.

Diagnosis

DHV type I (DHAV)

The clinical and pathological observations are highly indicative of a DHAV infection. Preparing 20% (w/v) liver homogenate suspensions, from birds that are thought to have had the infection, in buffered saline and inoculating the allantoic sac of 8- to 10-day-old chicken embryos can isolate the virus. Infected embryos will die within 5 to 8 days post infection and exhibit gross lesions, including dwarfing, enlarged greenish livers with necrotic foci, and cutaneous haemorrhage and oedema. Embryo mortality and lesions will occur sooner after inoculation, in 10- to 14-day-old duck embryos from susceptible breeder ducks. The presence of DHAV can be confirmed by one of more of the following tests: 

1. Subcutaneous or intramuscular inoculation of the isolate into 1- to 7-day-old susceptible ducklings results in death 18 to 48 hours post-infection. Gross lesions should be consistent with DHAV infection and the virus should be re-isolated from the livers.
2. Inoculation of serial dilutions of the liver homogenate into the allantoic sac of duck or chicken eggs and observation of clinical changes as described above.
3. Inoculation of liver homogenate suspensions into primary cultures of duck embryo liver cells. DHAV will cause a cytopathic effect (CPE) in the cells. Recently, an attenuated strain of DHAV was reported to replicate in chicken embryo fibroblasts (Zhang et al., 2000). A duck embryo fibroblast cell line has been developed, in which DHAV replicates with cytopathic effect (Fu et al., 2012).
4. An accurate diagnosis of DHAV can be made using direct immunofluorescence on livers from naturally occurring infections or inoculated duck embryos (Maiboroda, 1972; Vertinskii et al., 1968).
5. An ELISA for antibodies to DHAV has been developed using virus protein 1 (VP1) produced in bacteria as antigen (Liu et al., 2010).
6. Reverse transcriptase polymerase chain reaction (RT-PCR) test have been developed for DHAV (Kim et al., 2007b, 2008; Cheng et al., 2009) and reverse transcription loop-mediated isothermal amplification tests (Song et al., 2012; Yang et al., 2012).

DHV type II (DAstV-1)

The virus may be recovered in a 20% (w/v) homogenized liver suspension and can be used to inoculate susceptible ducklings, and embryonated chicken eggs. An outbreak of DAstV-1 in China in 2008 killed approximately 50% of 1- to 2-week-old commercial ducklings (Fu et al., 2009). As sequence data is now available for DAstV-1, RT-PCRs can be used to detect the virus (Todd et al., 2009; Fu et al., 2009).

Gross lesions will be similar to field cases. Chicken eggs can also be inoculated, either by the amniotic cavity or the yolk sac. This results in very little mortality and stunted green necrotic livers are the only observable pathology. There are no cell culture systems for DAstV-1.

DHV type III (DAstV-2)

The virus can be recovered from homogenized liver suspensions and isolated by duckling inoculation, or inoculation onto the chorioallantoic membrane of 10-day-old embryonated duck eggs. There will be some embryo mortality 7 to 10 days post-inoculation, and the membrane will appear dry and crusty. DAstV-2 is less virulent than DHAV.

Serologic tests

Serologic tests have not been useful because of the acute nature of the clinical disease. However, various virus neutralization (VN) assays have been described that are useful for virus identification, titration of serologic response to vaccination, and epidemiologic surveys. The VN tests may achieve greater significance if DAstV-1 and DAstV-2 become more widespread. The VN tests described include a DHAV neutralization test in chicken embryos (Hwang, 1969), an agar gel diffusion precipitin (AGDP) test for identification of type I (Murty and Hanson, 1961) and a plaque-reduction test for VN antibodies (Woolcock et al., 1982). A duck embryo fibroblast cell line has been developed, in which DHAV replicates with cytopathic effect (Fu et al., 2012).

Differential Diagnosis

Although the sudden onset, rapid spread, and acute course of the disease are characteristic of DHAV, the virus must be isolated or demonstrated by RT-PCR to confirm DHAV infection. Other potential causes of acute mortality in ducklings include salmonella and aflatoxin. Neither of these causes the liver lesions characteristic of DHAV infection, but will produce rapid onset mortality and ataxia, convulsions, and opisthotonos in the case of aflatoxicosis.

List of Symptoms/Signs

Disease Course

DHAV causes a highly contagious, often-fatal infection of ducklings, especially in those under 6 weeks of age. The onset and spread of DHAV is very rapid and is initially characterized by lethargy and ataxia. Within a short time, ducklings stop moving and squat with their eyes partially closed, this is followed by loss of balance, spasmodic kicking of both legs and death. At death, the head is usually drawn back in the opisthotonos position. Death occurs very rapidly, often within 1 to 2 hours after the onset of clinical signs. Morbidity is 100% and mortality is variable depending on the age at infection. DAstV-1 and DAstV-2 cause similar clinical signs and disease course as DHAV. An outbreak of DAstV-1 in China in 2008 killed approximately 50% of 1- to 2-week-old commercial ducklings (Fu et al., 2009).

Epidemiology

DHV type I (DHAV)

In naturally occurring outbreaks, DHAV occurs only in young ducks. Experimentally, infection of goslings, mallard ducklings, turkey poults, quail, young pheasants, geese and guinea fowl with DHAV have been reported (Hwang, 1974; Woolcock, 2008). DHAV will rapidly spread to all susceptible ducklings in a flock. Recovered ducks may excrete the virus in their faeces, and the virus remains viable in the faeces for many weeks. It is probable that infection follows the ingestion by susceptible ducklings of virus-carrying particles from the environment. Variants of DHAV have been described in South Korea (Kim et al., 2007a, 2008). There is no evidence of egg transmission. There are reports suggesting that wild birds (Asplin, 1961) or brown rats (Demakov et al., 1975) may serve as mechanical vectors or host reservoirs for DHAV.

DHV type II (DAstV-1)

Only ducks appear to be affected by DAstV-1. The earliest described outbreaks occurred in ducks kept on open fields in eastern England, initially reported in 1965 and up to 1969, then again in 1983/84, which were the last reported outbreaks in England. However, the role of wildfowl, wild birds, and wildlife reservoirs or vectors is unknown (Gough, 1986; Woolcock. 2008). In 2008 there was a severe outbreak of duck hepatitis in China. Virus present in liver extracts had very high amino acid sequence identity (Fu et al., 2009) to the DAstV-1 sequenced by Todd et al. (2009) and very different to DAstV-2 (Todd et al., 2009).

DHV type III (DAstV-2)

There is little known about the epidemiology of DAstV-2, which has only been described in the USA (Woolcock, 2008).

Impact: Economic

Duck hepatitis is recognized as an economically important disease in all duck-growing areas because of the potential for high mortality if not controlled.

Zoonoses and Food Safety

There is no known zoonotic threat of duck hepatitis virus.

Prevention and Control

Husbandry Methods and Good Practice

DHAV can be prevented by strict isolation during the first 4 to 5 weeks of life. In areas where the disease is prevalent, achieving the necessary degree of isolation may be very difficult and vaccination may be required.

Immunization and Vaccines

DHV type I (DHAV)

Resistance against DHAV in ducklings can be achieved through three methods:

1. Injection of immune serum or yolk from eggs produced by hyperimmune breeder ducks, or yolk from eggs produced by specific-pathogen-free-chickens hyperimmunized with DHAV.


2. Immunization of breeder stocks with a live-attenuated-virus-vaccine. The vaccine is produced in embryonated chicken eggs to ensure high levels of passively transferred antibodies in ducklings. Alternatively, breeder ducks can also be vaccinated with an inactivated vaccine if they have already been primed with, or exposed to, live DHAV.


3. Direct immunization of ducklings with live avirulent strains of DHAV by foot web-stab, intramuscular, intranasal or subcutaneous injection. DHAV-1 vaccines may not be fully effective against type 2 and 3 types of DHAV. Kim et al. (2009) have produced an attenuated DHAV-3 vaccine using a strain that had been circulating in South Korea and China.

DHV type II (DAstV-1)

A live virus, DAstV-1 vaccine, protected ducklings under experimental conditions but has never been used commercially.

DHV type III (DAstV-2)

Experimentally, an attenuated live-virus vaccine given to breeder ducks confers immunity to hatchling ducklings. Also convalescent sera obtained from DAstV-2-infected ducks effectively controlled outbreaks in the field.

National and International Control Policy

Duck Hepatitis is defined as a List B disease by the Office des International Epizooties. As defined by the OIE the incubation period for DVH is seven days. The Veterinary Administrations of importing countries should require the presentation of an international veterinary certificate attesting that:

• The ducks showed no clinical signs of DVH on the day of shipment


• The ducks come from establishments that are free from DVH


• That the ducks are either vaccinated or not vaccinated against DVH.

There are further requirements for the importation of day-old ducks and duck embryonated eggs.

References

Asplin FD, 1961. Notes on epidemiology and vaccination for virus hepatitis of ducks. Off. Int. Epizoot. Bull., 56:793-800.

Asplin FD, 1965. Duck hepatitis: vaccination against two serological types. Vet. Rec., 77:1529-1530.

Cheng AnChun; Wang MingShu; Xin HongYi; Zhu DeKang; Li XinRan; Chen HaiJuen; Jia RenYong; Yang Miao, 2009. Development and application of a reverse transcriptase polymerase chain reaction to detect Chinese isolates of duck hepatitis virus type 1. Journal of Microbiological Methods, 76(1):1-5. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T30-4T2M5S0-4&_user=6686535&_coverDate=01%2F31%2F2009&_rdoc=2&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234932%232009%23999239998%23758070%23FLA%23display%23Volume)&_cdi=4932&_sort=d&_docanchor=&_ct=19&_acct=C000066028&_version=1&_urlVersion=0&_userid=6686535&md5=7aaab2a486ff4608681192ab2ec767fa

Demakov GP et al., 1975. Infection of brown rats with duck hepatitis virus. Veterinariya, 3:57-58. Abstr. Vet. Bull., 45:4375.

Fabricant J; Rickard CG; Levine PP, 1957. The pathology of duck virus hepatitis. Avian Diseases, 1:256-275.

Fu Yu; Pan Meng; Wang XiaoYan; Xu YongLiang; Xie XiaoYu; Knowles NJ; Yang HanChun; Zhang DaBing, 2009. Complete sequence of a duck astrovirus associated with fatal hepatitis in ducklings. Journal of General Virology, 90(5):1104-1108. http://vir.sgmjournals.org

Fu YuZhi; Chen ZongYan; Li ChuanFeng; Liu GuangQing, 2012. Establishment of a duck cell line susceptible to duck hepatitis virus type 1. Journal of Virological Methods, 184(1/2):41-45. http://www.sciencedirect.com/science/journal/01660934

Gough RE, 1986. Duck hepatitis type 2 associated with an astrovirus. Acute virus infections of poultry, 223-230; [Current Topics in Veterinary Medicine and Animal Science volume 37]; 9 ref.

Guo YP; Pan WS, 1984. Preliminary identifications of the duck hepatitis virus serotypes isolated in Beijing, China. Chinese Journal of Veterinary Medicine (Zhongguo Shouyi Zazhi), 10(11):2-3; 5 ref.

Haider SA; Calnek BW, 1979. In vitro isolation, propagation, and characterization of duck hepatitis virus type III. Avian Diseases, 23:715-729.

Hwang J, 1969. Duck hepatitis virus-neutralization test in chicken embryos. Am. J. Vet. Res., 30:861-864.

Hwang J, 1974. Susceptibility of poultry to duck hepatitis viral infection. Am. J. Vet. Res., 35:477-479.

Kim MC; Kwon YK; Joh SJ; Kim SJ; Tolf C; Kim JH; Sung HW; Lindberg AM; Kwon JH, 2007. Recent Korean isolates of duck hepatitis virus reveal the presence of a new geno- and serotype when compared to duck hepatitis virus type 1 type strains. Archives of Virology, 152(11):2059-2072. http://springerlink.metapress.com/content/lr4r87u143tl0723/?p=4c5a0dcd7b2d4452a896ae294250bb57&pi=8

Kim MinChul; Kim MinJeong; Kwon YongKuk; Lindberg AM; Joh SeongJoon; Kwon HyukMan; Lee YounJeong; Kwon JunHun, 2009. Development of duck hepatitis A virus type 3 vaccine and its use to protect ducklings against infections. Vaccine, 27(48):6688-6694. http://www.sciencedirect.com/science/journal/0264410X

Kim MinChul; Kwon YongKuk; Joh SeongJoon; Kwon JunHun; Kim JaeHong; Kim SunJoong, 2007. Development of one-step reverse transcriptase-polymerase chain reaction to detect duck hepatitis virus type 1D. Avian Diseases, 51(2):540-545. http://avdi.allenpress.com/avdionline/?request=get-abstract&doi=10.1637%2F0005-2086(2007)51%5B540:DOORTC%5D2.0.CO%3B2

Kim MinChul; Kwon YongKuk; Joh SeongJoon; Kwon JunHun; Lindberg AM, 2008. Differential diagnosis between type-specific duck hepatitis virus type 1 (DHV-1) and recent Korean DHV-1-like isolates using a multiplex polymerase chain reaction. Avian Pathology, 37(2):171-177.

Kim MinChul; Kwon YongKuk; Joh SeongJoon; Lindberg AM; Kwon JunHun; Kim JaeHong; Kim SunJoong, 2006. Molecular analysis of duck hepatitis virus type 1 reveals a novel lineage close to the genus Parechovirus in the family Picornaviridae. Journal of General Virology, 87(11):3307-3316. http://vir.sgmjournals.org

Levine PP; Fabricant J, 1950. A hitherto-undescribed virus disease of ducks in North America. Cornell Vet., 40:71-86.

Levine PP; Hofstad MS, 1945. Duck disease investigation. Annu. Rep. New York State Vet. Coll. Ithaca, 55-56.

Liu Ming; Zhang TingTing; Zhang Yun; Meng FanYi; Li XiaoJun; Hou ZhenZhong; Feng XinChang; Kong XianGang, 2010. Development and evaluation of a VP1-ELISA for detection of antibodies to duck hepatitis type 1 virus. Journal of Virological Methods, 169(1):66-69. http://www.sciencedirect.com/science/journal/01660934

Lu YS; Lin DF; Lee YL; Liao YK; Tsai HJ, 1993. Infectious bill atrophy syndrome caused by parvovirus in a co-outbreak with duck viral hepatitis in ducklings in Taiwan. Avian Diseases, 37(2):591-596; 11 ref.

Maiboroda AD, 1972. Formation of duck hepatitis virus in culture cells. Veterinariya, 8:50-52. Abstr. Vet. Bull., 42:6905.

Murty DK; Hanson LE, 1961. A modified microgel diffusion method and its application in the study of the virus of duck hepatitis. Am. J. Vet. Res., 22:274-278.

Office International des Epizooties, 1999. World Animal Health in 1999. Paris, France: OIE.

OIE Handistatus, 2002. World Animal Health Publication and Handistatus II (dataset for 2001). Paris, France: Office International des Epizooties.

OIE Handistatus, 2003. World Animal Health Publication and Handistatus II (dataset for 2002). Paris, France: Office International des Epizooties.

OIE Handistatus, 2004. World Animal Health Publication and Handistatus II (data set for 2003). Paris, France: Office International des Epizooties.

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (data set for 2004). Paris, France: Office International des Epizooties.

OIE, 2009. World Animal Health Information Database - Version: 1.4. World Animal Health Information Database. Paris, France: World Organisation for Animal Health. http://www.oie.int

Park NY, 1985. Occurrence of duck virus hepatitis in Korea. Korean Journal of Veterinary Research, 25(2):171-174; 12 ref.

Peng NaXiu, 1998. Dynamic pathological study on viral hepatitis in ducklings. Chinese Journal of Veterinary Science and Technology, 28(8):22-23.

Rao SBV; Gupta BR, 1967. Studies of a filterable agent causing hepatitis in ducklings, and biliary cirrhosis and blood dyscrasia in adults. Indian J. Poult. Sci., 2:18-30.

Sandhu TS; Calnek BW; Zeman L, 1992. Pathological and serologic characterization of a variant of duck hepatitis type I virus. Avian Diseases, 36(4):932-936; 11 ref.

Shalaby MA; Ayoub MNK; Reda IM, 1978. A study on a new isolate of duck hepatitis virus and its relationship to other duck hepatitis virus strains. Vet. Med. J. Cairo Univ., 26:215-221.

Song CuiPing; Wan HongQuan; Yu ShengQing; Han XianGan; Qiu XuSheng; Hu QingHai; Tan Lei; Ding Chan, 2012. Rapid detection of duck hepatitis virus type-1 by reverse transcription loop-mediated isothermal amplification. Journal of Virological Methods, 182(1/2):76-81. http://www.sciencedirect.com/science/journal/01660934

Tauraso NM; Coghill GE; Klutch MJ, 1969. Properties of the attenuated vaccine strain of duck hepatitis virus. Avian Diseases, 13:321-329.

Todd D; Smyth VJ; Ball NW; Donnelly BM; Wylie M; Knowles NJ; Adair BM, 2009. Identification of chicken enterovirus-like viruses, duck hepatitis virus type 2 and duck hepatitis virus type 3 as astroviruses. Avian Pathology, 38(1):21-29.

Tseng ChunHsien; Knowles NJ; Tsai HsiangJung, 2007. Molecular analysis of duck hepatitis virus type 1 indicates that it should be assigned to a new genus. Virus Research, 123(2):190-203. http://www.sciencedirect.com/science/journal/01681702

Tseng ChunHsien; Tsai HsiangJung, 2007. Molecular characterization of a new serotype of duck hepatitis virus. Virus Research, 126(1/2):19-31. http://www.sciencedirect.com/science/journal/01681702

Vertinskii KI et al., 1968. Pathogenesis and diagnosis of duck viral hepatitis. Veterinariya, 7:27-30. Abstr. Vet. Bull., 39:2074.

Wang LiYan; Pan Meng; Fu Yu; Zhang DaBing, 2008. Classification of duck hepatitis virus into three genotypes based on molecular evolutionary analysis. Virus Genes, 37(1):52-59. http://springerlink.metapress.com/link.asp?id=103010

Wei ChunYa; Su Shuo; Huang Zhen; Zhu WanJun; Chen JiDang; Zhao FuRong; Wang YanJing; Xie JieXiong; Wang Heng; Zhang GuiHong, 2012. Complete genome sequence of a novel duck hepatitis A virus discovered in southern China. Journal of Virology, 86(18):10247. http://jvi.asm.org/content/86/18/10247.full

Woo SH; Hong KJ; Sung HW; Kim JH, 2000. Isolation of duck hepatitis virus and its attenuation in chicken embryos. Kor. J. Vet. Res., 40(1):101-109.

Woolcock PR, 2008. Duck Hepatitis. In: Diseases of Poultry, 12th edition [ed. by Saif, Y. M. \Fadly, A. M. \Glisson, J. R. \McDougald, L. R. \Nolan, L. K. \Swayne, D. E.]. Ames, Iowa, USA: Blackwell Publishing, 373-384.

Woolcock PR; Chalmers WSK; Davis D, 1982. A plaque assay for duck hepatitis virus. Avian Pathol., 11:607-610.

Woolcock PR; Fabricant J, 1997. Duck Hepatitis. In: Calnek BW, ed. Diseases of Poultry. Ames, IA, USA: Iowa State University Press, 661-673.

Yang LiMin; Li Jing; Bi YuHai; Xu Lei; Liu WenJun, 2012. Development and application of a reverse transcription loop-mediated isothermal amplification method for rapid detection of Duck hepatitis A virus type 1. Virus Genes, 45(3):585-589. http://rd.springer.com/article/10.1007/s11262-012-0798-6/fulltext.html

Yun T; Ni Z; Liu GQ; Yu B; Chen L; Huang JG; Zhang YM; Chen JP, 2010. Generation of infectious and pathogenic duck hepatitis virus type 1 from cloned full-length cDNA. Virus Research, 147(2):159-165. http://www.sciencedirect.com/science/journal/01681702

Zhang XF; Xie QF; Pan XC; Zhao RH, 2000. Culture of attenuated A66 strain of duck hepatitis virus in chicken embryo fibroblast. Chinese J. Vet. Sci., 20(1):19-21.

Distribution References

Asplin F D, 1965. Duck hepatitis: vaccination against two serological types. Veterinary Record. 1529-1530.

CABI, Undated. Compendium record. Wallingford, UK: CABI

CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Guo Y P, Pan W S, 1984. Preliminary identifications of the duck hepatitis virus serotypes isolated in Beijing, China. Chinese Journal of Veterinary Medicine (Zhongguo Shouyi Zazhi). 10 (11), 2-3.

Haider S A, Calnek B W, 1979. In vitro isolation, propagation, and characterization of duck hepatitis virus type III. Avian Diseases. 23 (3), 715-729. DOI:10.2307/1589748

Lu Y S, Lin D F, Lee Y L, Liao Y K, Tsai H J, 1993. Infectious bill atrophy syndrome caused by parvovirus in a co-outbreak with duck viral hepatitis in ducklings in Taiwan. Avian Diseases. 37 (2), 591-596. DOI:10.2307/1591694

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (dataset for 2004)., Paris, France: Office International des Epizooties.

OIE, 2009. World Animal Health Information Database - Version: 1.4., Paris, France: World Organisation for Animal Health. https://www.oie.int/

Park N Y, 1985. Occurrence of duck virus hepatitis in Korea. Korean Journal of Veterinary Research. 25 (2), 171-174.

Rao S B V, Gupta B R, 1967. Studies on a filterable agent causing hepatitis in ducklings, and biliary cirrhosis and blood dyscrasia in adults. Part I. Indian Journal of Poultry Science. 2 (2), 18-30 pp.

Shalaby MA, Ayoub MNK, Reda IM, 1978. A study on a new isolate of duck hepatitis virus and its relationship to other duck hepatitis virus strains. In: Vet. Med. J. Cairo Univ. 26 215-221.

Woolcock PR, Fabricant J, 1997. Duck Hepatitis. In: Diseases of Poultry, [ed. by Calnek BW]. Ames, IA, USA: Iowa State University Press. 661-673.

Distribution Maps