During the past few months, new cases of the H7N9 avian (bird) influenza virus have surfaced in China. H7N9 is a new strain of avian flu that was transmitted from infected birds to humans for the first time last year. Causing concern: The virus has the potential to spread easily, posing the threat of a pandemic.
In January, the Chinese Center for Disease Control and Prevention (China CDC) reported a spike in new H7N9 cases with 102 people becoming ill. Twenty of them died. The outbreak is expected to increase unless the Chinese government takes serious steps to contain the virus. Most patients come in contact with the virus through poultry or contaminated areas such as live bird markets. The virus spreads quickly, particularly when travelers carry live poultry back to their villages. Unlike the H5N1 virus, the H7N9 virus does not kill the poultry or cause it to become visibly ill. Without any early warning signs of infection, prevention and control are even more difficult.
Human infections were first reported in China in March 2013. Since then, the virus infected 246 people in mainland China. The first case of H7N9 that was documented outside of China occurred in a traveler who carried the virus from an H7N9-affected area of China to Malaysia. Cases have also been reported in Taiwan and Hong Kong, probably transmitted by chickens imported from mainland China. The H7N9 virus has not surfaced in birds or humans in the U.S.
Although the overwhelming majority of cases can be traced to contact with live bird markets, several instances of human-to-human infection are suspected. One of these cases occurred in a 31-year-old surgeon in Shanghai who died from the virus. Because there was no evidence that he had been in contact with live poultry, his case suggests for the first time that perhaps H7N9 can be transmitted from one human to another. Definitive proof has not yet been established. He was the first medical professional to die from this strain of the virus.
H7N9 virus is more serious than the seasonal flu but less deadly than the H5N1 strain. Those infected with H7N9 exhibit fever, cough, and shortness of breath, which may progress to severe pneumonia. Sepsis and organ failure are potential complications. Most patients become critically ill with a mortality rate of about 30 percent. Roughly 20% die of acute respiratory distress syndrome (ARDS). Antigenic and genome sequencing suggests that neuraminidase inhibitors can be effective in treating H7N9 when administered early.
In April 2013, the Centers for Disease Control and Prevention (CDC) activated its Emergency Operations Center (EOC) in Atlanta at Level II, the second-highest level of alert. The activation ensures that the CDC is kept informed of any changes relating to H7N9. To help contain the spread of the virus, live poultry trading in Zhejiang (the Chinese province that has seen the greatest number of H7N9 cases) has been ordered to stop. In Hong Kong, guidelines that detail procedures for cleaning poultry transport cages and a requirement to kill any unsold birds were issued to help limit the spread of the virus.
The CDC is following the situation closely. As with all situations that carry the potential for a pandemic, the CDC routinely develops a candidate virus to create a vaccine in case one is needed. The CDC also posts current information about prevention and treatment.
Sporadic eruptions of H7N9 are likely to continue in China and may spread to poultry in neighboring countries. It is also likely that more cases of infection will be seen in humans in these neighboring countries and in those who travel through infected countries, some of them possibly bringing the H7N9 virus to the U.S. However, provided no evidence of human-to-human contact is uncovered, the public health risk will not be significantly affected.