The number of swine flu cases is continuing to expand in the United States and in the past week has jumped up by another 16.  From July 12 through August 9, 2012, a total of 153 infections with influenza A (H3N2) variant (H3N2v) viruses have been reported in four states (Hawaii [1], Illinois [1], Indiana [120], and Ohio [31]).

This weeks Flu Weekly report shows the uptick in cases.

One piece of good news…there is no evidence of transmission between humans. So far, all the reported cases have been relatively mild, and have passed to humans through direct contact with pigs. Most of the cases were mild and resolved on their own, he said. Two people were hospitalized and have since been released.

Most of those who have gotten sick were children who had been near pigs at agricultural fairs in Indiana and Ohio. Children are particularly susceptible because they have not developed antibodies to fight the virus, H3N2, whose symptoms, including coughing and fever.

The big concern is always that the virus could start to be transmitted from person to person. The swine flu virus shares a gene with the H1N1 virus that caused the 2009 flu pandemic that sickened millions of people around the world and caused what health officials estimated to have been several thousand flu-related deaths. The big question with influenza is “what happens next?”

CDC is required to report all cases of human infection with novel (non-human) influenza viruses – including influenza viruses of swine origin – to the World Health Organization (WHO) as part of the International Health Regulations (IHR). Domestically, CDC reports these cases in this report and on its website. Early identification and investigation of human infections with novel influenza A viruses is critical in order to evaluate the extent of the outbreak and possible human-to-human transmission. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with livestock can be found at

CDC officials are taking appropriate precautions by creating a seed virus — the beginnings of a vaccine — and has shared it with manufacturers who will put it through clinical trials. However, mass production will not happen without evidence of widespread human transmission.

Stay tuned!