Propagation of avian influenza virus in embryonated ostrich eggs.

Influenza A viruses (IAVs) are typically isolated and cultured by successive passages using 9- to 11-day-old embryonated chicken eggs (ECEs) and in 14-day old ECEs for virus mutational studies. Real-time reverse transcription-polymerase chain reaction tests (RT-PCRs) are commonly used for IAV diagnosis, but virus isolation remains invaluable in terms of its high sensitivity, providing viable isolates for further studies and the ability to distinguish between viable and nonviable virus. Efforts at isolating ostrich-origin IAVs from RT-PCR positive specimens using ECEs have often been unsuccessful, raising the possibility of a species bottleneck, whereby ostrich-adapted IAVs may not readily infect and replicate in ECEs, yet the capacity of an ostrich embryo to support the replication of influenza viruses has not been previously demonstrated. This study describes an optimised method for H5 and H7 subtype IAV isolation and propagation in 28-day old embryonated ostrich eggs (EOEs), the biological equivalent of 14-day old ECEs. The viability of EOEs transported from breeding sites could be maximised by pre-incubating the eggs for 12 to 14 days prior to long-distance transportation. This method applied to studies for ostrich-adapted virus isolation and in ovo studies will enable better understanding of the virus-host interaction in ostriches and the emergence of potentially zoonotic diseases.

National surveillance and control costs for highly pathogenic avian influenza H5N1 in poultry: A benefit-cost assessment for a developing economy, Nigeria.

We conducted benefit-cost analysis of outbreak and surveillance costs for HPAI H5N1in poultry in Nigeria. Poultry's death directly cost US$ 939,734.0 due to outbreaks. The integrated disease surveillance and response originally created for comprehensive surveillance and laboratory investigation of human diseases was adapted for HPAI H5N1 in poultry. Input data were obtained from the field, government documents and repositories and peer-reviewed publications. Actual/forecasted bird numbers lost were integrated into a financial model and estimates of losses were calculated. Costs of surveillance as alternative intervention were determined based on previous outbreak control costs and outputs were generated in SurvCost® with sensitivity analyses for different scenarios. Uncontrolled outbreaks will lead to loss of over US$ 2.2 billion annually in Nigeria with 47.8% of the losses coming from eggs. The annual cost of all animal related health activities was