An outbreak in China of a rare strain of avian flu has struck 125 people since February. Known as H7N9, the disease is believed to have caused at least 24 deaths in the People’s Republic of China, with a small number of additional cases reported elsewhere in the region. There are as yet no known instances of human-to-human transmission, but the National Institute of Allergy and Infectious Diseases in the United States believes it is a strong possibility, and an international investigative team called the virus unusually dangerous. The virus was transmitted to humans from live poultry in markets, Chinese scientists say, though there are believed to have been other sources as well. According to the World Health Organization, as many as 40 percent of sufferers claim to have had had no contact with poultry around the time they were infected.
The disease is only just starting to spread internationally, and authorities in Pacific countries—including the U.S.—are recommending vigilance. The international investigators called this one of the most lethal strains ever seen. However, they also note that only the more serious cases have been recognized, and so milder and even asymptomatic cases are not being counted. That means the lethality is quite likely overstated—one in five reported cases have been fatal, but most cases, in particular those most likely to be non-fatal, are not included in that figure.
According to the Centers for Disease Control and Prevention, the primary symptoms are a high fever and cough. While you should seek medical attention if you exhibit those symptoms regardless of what you think is causing them, almost all cases have been in China, and none have been found in the U.S. It has not yet been found to be contagious in humans; some disease transmission thus far has been the result of poorly handled and undercooked meat, and cross-contamination.
Researchers are still trying to identify the specific virus causing the illness so that it can be treated. The best prevention in areas where H7N9 is likely to be present is to avoid live markets. Indeed, these markets have been closed in Shanghai, after which the rate of new infections there slowed significantly.