An outbreak of type C botulism in waterbirds: Incheon, Korea.

Five outbreaks of botulism in waterbirds were encountered over a 5-yr period from 2004 to 2008 in Korea. In October 2008, an outbreak of avian type C botulism affected approximately 2,000 wild waterbirds in the Namdong flood control basin, Incheon, South Korea. Ecologic conditions, clinical signs exhibited by moribund birds, and lack of gross pathology and microbial evidence of infectious disease, suggested botulinum intoxication. Type C botulinum toxin was demonstrated in duck sera, liquid culture of intestinal tissue, and an extract of maggots taken from the carcasses. Additionally, 34 of 40 (85.0%) sediment samples from the same area were positive for botulinum toxin by mouse bioassay using multivalent (types A-F) antiserum, indicating that toxigenic Clostridium botulinum was present in the environment. This is the most severe case of avian botulism documented in Korea.

Evaluation of neuraminidase antigen based competitive enzyme-linked immunosorbent assay in chickens vaccinated with avian influenza inactivated vaccine.

A competitive enzyme-linked immunosorbent assay (c-ELISA) was developed as a serologic diagnostic tool to detect antibodies against NA subtype 3 of avian influenza virus (AIV). The NA antigen used in this c-ELISA was obtained by pronase treatment of allantoic fluid of specific-pathogen-free (SPF) eggs infected with AIV. The NA specific monoclonal antibodies were produced from purified NA. The N3 c-ELISA was carried out on serum samples collected from both SPF chickens and commercial layers to confirm whether the N3 c-ELISA was capable of detecting specific N3 antibodies. The positive cutoff percentage inhibition value was 6.13%. The sensitivity and specificity of the N3 c-ELISA were 83.7% and 95.6%, respectively, which indicated that N3 c-ELISA can detect the antibodies from SPF chickens or commercial chickens vaccinated with H9N3 subtype of AIV.

Outbreaks of hydropericardium syndrome and molecular characterization of Korean fowl adenoviral isolates.

Outbreaks ofhydropericardium syndrome (HPS), caused by fowl adenovirus serotype 4 (FAdV-4), have occurred in Korea and caused severe economic loss due to mortality and weight loss. From these outbreaks, several adenoviruses were isolated and identified in samples from broilers, layers, breeders, and native Korean fowl. In pathologic examinations, hydropericardium and multifocal hepatic necrosis, with an intranuclear inclusion body in hepatocytes, were observed. Specific adenovirus particles were also observed in the nucleus of hepatocytes, by electron microscopic examination. Polymerase chain reaction (PCR) analysis of the hexon gene identified all of the isolates as FAdV, serotype 4 and genotype C. To reproduce FAdV-4 field cases, 8- and 52-week-old specific pathogen free (SPF) chicks were infected intramuscularly with the field isolate CBU070244. The mortality rate of infected chicks ranged from 10%-40%, and specific pathologic lesions, such as swollen livers and hydropericardium, were observed. Further studies to determine the prevalence of infection, and analysis of the economic impact to the poultry industry, are needed in the near future.