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In 2003, there was a huge outbreak of an unknown parasite in China that killed 40 million chickens, affecting food supplies. In 2009, another parasite hit chicken farms in the US- this time it multiplied quickly and spread throughout the country. There has been a lot of interest in whether or not these parasites could be responsible for outbreaks of bird flu in humans which happened in 2003 and 2004. The World Health Organization says it’s possible but they haven’t seen enough evidence to make a statement about what is going on with these two incidents specifically. These recent incidents have heightened interest in this issue and the amount of new research that has been developed for this problem. In 2009, it was discovered that avian influenza (AI) had managed to infect humans. This new class of viruses we call influenza A virus subtype H7N9 does not fit into any of the previous categories of AI, and it remains unknown how humans were infected. The only conclusion people can make is that it must be a new human-to-human transmission and not a natural occurrence. The first case was reported in March 2009 in eastern China, but the majority of cases have been reported in northern China since May 2009. A new threat has emerged for the poultry industry: Enteric Infection. "Enteric Infection" refers to any diseases that originate from and cause illness and death in and through the digestive tract when entering the chicken's stomach. Most of these infections are caused by bacteria such as "Enterobacter" and drug resistant "Salmonella". For example, in 2003 Enterobacter sakazakii was found in a chicken farm in rural China (Chen 2009). Seventy percent of infected chickens were found to be carriers, but they did not show any symptoms; instead they died suddenly. This is known as “clamydia” or "indirect infection" (see Figure 1). Some researchers believe that the outbreak of infectious diseases in poultry is due to environmental determinants (i.e., location). However, another study has found that the Enterobacter sakazakii subspecies is widespread throughout China and it has changed little since 2003. Thus, neither location nor subspecies seem likely to be the cause (see Figure 1). The United States is also having problems with these types of infections. For example, "Salmonella enterica" serovar Kentucky was isolated from pre-weaned calves in eastern Kentucky in 2008 (Snyder 2008). Research has also shown that Enterobacter sakazakii can survive in chickens for more than 10 days, even at temperatures as low as 4 degrees Celsius. Once infected, it can live for more than 48 hours inside eggs. H7N9 is a type of Influenza virus and is a member of the family Orthomyxoviridae. It is genetically similar to other influenza viruses and is one of the few influenza viruses known to infect humans. It has only been seen in people and not in animals or birds. The virus was identified after having caused 18 human deaths and the infection of 36 others since October 2012 (Chen). eccc085e13
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