ANALYSIS – Research from Cambridge University has changed assumptions about Salmonella and how it infects human cells, writes Jackie Linden. From July, the EU will reopen to imports of frozen uncooked chicken from Thailand, the first shipments since 2004, when highly pathogenic avian influenza (HPAI) bird flu was first detected in the country. Chicken processing plants there are said to be able to export 50,000 metric tons of uncooked chicken meat to the EU in the second half of 2012. New outbreaks of H5N1 bird flu have been reported in China and Bhutan.
Researchers at Cambridge University have shed new light on Salmonella, a common food poisoning bug. Using real-time video microscopy, coupled with mathematical modelling, they have changed assumptions about Salmonella and how it infects human cells.
Dr Bryant, from the University of Cambridge, said: "Understanding how these bacteria invade, survive, proliferate and kill vital macrophage cells provides a wealth of knowledge to help improve our health. For the first time, we have been able to calculate the rate at which Salmonella can infect macrophages and we have also seen evidence of dual infection and reinfection of a single cell."
Their research found that many incorrect assumptions had been made about Salmonella infection, particularly that macrophages are highly susceptible to infection. Their data showed that infection occurrences after initial contact between a bacterium and macrophage were low. The probability of that bacterium infecting the cell is less than five per cent. However, they also showed that an infected macrophage can be reinfected by a second bacterium. The concept of reinfection by Salmonella had not been considered before and this previously overlooked mechanism may make an important contribution to total bacterial numbers in infection studies.
The study also highlighted the fact that some cells are far more susceptible to infection than others. Rather than grouping all macrophages together in terms of their susceptibility to infection, the research shows that there is a spectrum of susceptibility.
Thai chicken exports to the EU are to go ahead from July. On 3 April, Thailand’s Agricultural Affairs Office in Belgium notified its Minister of Agriculture that the EU’s Standing Committee on the Food Chain and Animal Health reached a consensus to reopen the imports of Thai frozen uncooked chicken, beginning on 1 July 2012. Thailand’s uncooked chicken has been banned since 23 January 2004 when an outbreak of highly pathogenic avian influenza (HPAI) bird flu was detected.
Trade sources reported that the EU directives on the decision should complete the required legislative process by early May. The EU allocates Thailand a quota of 92,610 metric tons of its total quota of 264,245 metric tons for uncooked salted poultry meat. The in-quota tariff rate is 15.4 per cent while the out-of-quota rate will be €1,300 per ton.
A few large export-orientated chicken processing plants have indicated that Thailand would be able to export 50,000 metric tons of uncooked chicken meat to the EU in the second half of 2012.
More samples have been tested in Dubai in order to improve biosecurity further in the country. As part of raising biosecurity and safety from biological risks in the Emirate of Dubai, many more samples have been tested the Veterinary Services Section of Dubai Municipality (DM) has completed the examination of approximately 26,232 samples received during the first quarter of this year from various farms – an increase of 30 per cent from last year.
The head of veterinary services, said the section works in line with the strategic plan and strategic objective of the Emirate of Dubai in order to raise the biosecurity and ensure the safety from biological risks arising from diseases that affect animals and birds as well as common diseases among humans and animals.
In the UK, the Food Standards Agency is launching enhanced molecular-based surveillance and source attribution of Campylobacter infections in the UK.
Turning to bird flu news, new outbreaks of H5N1 have been reported in the last week in China and Bhutan. In Bangladesh, almost two-thirds of poultry farms have been closed down over the last two years due to highly pathogenic avian flu.