This week has seen one of the leading events in the global calendar - the International Production & Processing Expo (IPPE) in Atlanta, US.

Among other reports from the event, a leading international researcher said that vaccination can make viruses “hot” - or more dangerous.

Using the example of Marek’s disease in poultry, Dr Andrew Read of Pennsylvania State University said that some vaccines drive the evolution of more virulent pathogens.

He was presenting his Milton Y. Dendy keynote address, part of the International Poultry Scientific Forum on the day before IPPE started.

Another speaker, Dr Franco Mussini, explained to the audience the concept of Life Cycle Analysis and its role in estimating the environmental impact of a particular activity, such as poultry production. An online tool has been developed to make this calculation for feed production. It can also be used to assess the likely effects of any change in the feed formulation or source of an ingredient.

In news of avian flu this week, the H5N8 strain of the virus has been detected in a turkey flock in California - the first commercial poultry in the country flock to have been affected in this latest wave of the disease. There are also new outbreaks in Nigeria.

Taiwan, meanwhile, has reported almost 200 new outbreaks of the disease affecting more than a million birds in the last week alone. The most affected species there is geese, in which the H5N2, H5N3 and H5N8 viral variants have been detected, simultaneously in a single outbreak in several cases.

Further human cases have been reported in Egypt, China, Hong Kong and Canada. The latter case was in a person who had recently returned from a visit to China.