Spring is an inviting season for outdoor activities. But be careful--the warm weather is also a hotbed for viruses  and disease. This March, the influenza  A(H7N9) virus hit Shanghai, Anhui, Jiangsu and Zhejiang. It was reported that by April 11 at least 35 people had been infected   with the H7N9 virus, and nine of them had died. The influenza A (H7N9) virus is one type of influenza A H7 viruses. Influenza A H7 viruses normally spread among birds. This is the first time human infections with H7N9 viruses have been reported in China. Earlier reports were about H5N1 and H1N1. All the three viruses are influenza A viruses but they are not the same. H7N9 and H5N1 are animal influenza viruses that could infect people. However, H1N1 viruses can be divided into two groups. One group can normally infect people and the other normally infects animals. Also, H1N1 can spread from human to human, but H7N9 probably can't, according to the World Health Organization (WHO). Most people infected with H7N9 looked like they had the common flu. Some people had bad pneumonia . They suffered from a fever, a cough and shortness of breath. But don't be afraid - it is not easy to be infected with the virus. One of the possible reasons is close contact with sick poultry   waste. People may also be infected through breath, according to National Health and Family Planning Commission. Here are some tips from the WHO that can protect you from being infected. Wash your hands with soap and running water before you eat, after you use the toilet, and after touching animals or animal waste. When coughing or sneezing cover your mouth and nose with a mask ,tissue  or a sleeve. Get a good rest and do exercises, which will help make your body strong enough to stand up to the virus. How many people had died by April 11according to the report?
About 35. About 9. About 44. Nobody had died.