Highly pathogenic fowlpox virus in cutaneously infected chickens, China

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We investigated an acute outbreak of the cutaneous form of fowlpox among chickens in China in November 2009. Using pathologic and virologic methods, we identified a novel type of fowlpox virus that carried an integrated genomic sequence of reticuloendotheliosis virus. This highly pathogenic virus could lead to severe ecologic effects and economic losses. Fowlpox has been reported worldwide as a mild to severe poultry disease. Caused by fowlpox virus (FWPV), the disease is primarily found in 2 forms, cutaneous and diphtheritic. The cutaneous form is usually mild and characterized by multifocal cutaneous lesions on unfeathered areas of the skin. The more severe diphtheritic form is characterized by fibrous necrotic proliferative lesions on the mucous membranes of the respiratory and gastrointestinal tracts and causes more deaths than the cutaneous form, usually resulting from asphyxiation. In recent years, fowlpox outbreaks in poultry flocks have been gradually increasing because of an emerging novel type of FWPV. The pathogenic traits of this virus type are likely enhanced by integrated reticuloendotheliosis virus (REV) sequences of various lengths in the FWPV genome. Although this variant FWPV has been found widely, the reported illness and death rates from the cutaneous form of fowlpox in chickens have not reached 100%. We investigated a severe outbreak of cutaneous fowlpox in a poultry flock in northeastern China in which all infected chickens died. The flock had not been vaccinated with an FWPV vaccine. Clinical signs, including listlessness, anorexia, and typical skin pock lesions, were observed in all infected chickens. Lesions types varied in size and type: ulcerated, multifocal, or coalescing proliferative cutaneous exanthema variolosum. The lesions appeared on the skin in unfeathered areas of the backs, the eyelids, and the wings. All of the birds died within 10 days after clinical signs first appeared. Postmortem examinations were performed for      pathologic evaluation. Samples submitted for histopathologic examination included skin from the varioliform exanthema areas, trachea, thymus gland, bursa of fabricius, and internal organs. Microscopic examination of skin lesions showed swelling, vacuolation, and characteristic eosinophilic cytoplasmic inclusion bodies in the stratified squamous epithelial cells of the folliculus pili. No obvious lesions were observed in other organs. Read more: http://wwwnc.cdc.gov/eid/article/20/7/13-1118_article

http://wwwnc.cdc.gov/eid/  Emerging Infectious Diseases

July 22, 2014

http://wwwnc.cdc.gov/eid/article/20/7/13-1118_article  Original web page at Emerging Infectious diseases

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