The two patients were aged 87 and 27 years. The Xinhua News Agency reported that the younger man, surnamed Wu, became ill on February 19th, 2013 and died just over three weeks later on March 4th. The older man, surnamed Li, became sick on February 27th and died on March 10th.
The older patients' two sons became ill with flu and were hospitalized. The younger son, aged 55, developed severe pneumonia and died. The older son, aged 67, recovered and is no longer in hospital. Chinese health authorities say that neither son had the H7N9 virus.
A third patient, in Chuzhou in the eastern province of Anhui, also became infected with the H7N9 virus strain and became ill on March 10th. The woman, surnamed Han, aged 35, is reported to be in a critical condition in hospital in Nanjing, capital of Jiangsu Province.
Little is known about how H7N9 spreads among humansHealth experts in China say they do not know how the virus strain has spread. They are certain that the three infected people did not transmit H7N9 to each other. Tests on 88 close contacts of the three infected people found no abnormalities.
The National Health and Family Planning Commission (the Commission) in China says that the three patients started off with coughs and fever, which then developed to pneumonia with breathing difficulties.
Commission laboratories confirmed that all three were infected with H7N9, an avian influenza (bird flu) strain known to affect birds, but not humans.
The World Health Organization (WHO) says there is no vaccine to protect humans from H7N9 infection.
H7N9 does not appear to be highly human transmissibleThe Commission emphasized that there is no evidence indicating that H7N9 is highly transmissible from human-to-human. However, it is not possible to draw any conclusions from just three cases.
The Chinese CDC (Center for Disease Control and Prevention) says that it has a team of experts studying the toxicity and human-infection potential of the virus.
Shanghai Daily quotes Jiang Qingwu, dean of Public Health School of Fudan University, as saying "So far, it is still an animal virus not a human virus".
Timothy O'Leary, of the World Health Organization, said in an interview with the Associated Press:
"There is apparently no evidence of human-to-human transmission, and transmission of the virus appears to be inefficient, therefore the risk to public health would appear to be low."
Health departments throughout China have been urged to step up supervision and monitoring of all cases involving flu symptoms, respiratory problems, and pneumonia.
People with fever, coughing, and breathing problems have been told to visit their doctors immediately.
What is bird flu (avian influenza)?Avian influenza, also known as avian flu or bird flu, is a flu caused by viruses that infect birds and make them sick. It is an infectious disease of birds caused by influenza virus strains type A. Highly pathogenic avian influenza (HPAI) is the more aggressive one.
Avian influenza affects several types of birds, including farmed poultry. In December 2012, pigs in China were found to be infected with the bird flu virus.
Bird flu (avian flu) is the illness, which is caused by the avian influenza virus.
Avian influenza can be transmitted from wild birds to farmed livestock or pet birds, and the other way round. The infection spreads via the saliva, feces, nasal secretions and the feed of infected birds.
Since December 2003, there have been many bird flu outbreaks, which have directly killed or caused the culling of millions of farmed poultry and wild birds in Europe, Asia and Africa.
Scientists have identified over 16 different bird flu types. The one that causes the most concern is the H5N1 strain, because it can make humans very ill, and even kill them. Fortunately, H5N1 does not infect humans easily. However, some highly virulent strains have caused severe respiratory diseases in humans.
In the vast majority of human infections, the person was in contact with infected birds or surfaces/objects contaminated with their secretions or feces.
H5N1 kills 60% of humans who become ill after being infected. According to WHO, so far during this millennium H5N1 has killed 359 humans in twelve countries.
Experts worry that an avian influenza virus may one day mutate and become easily human-transmissible.
Scientists reported in the journal mBio last year that a new bird flu virus had infected harbor seals and could pose a threat to human health as well as wildlife.
Written by Christian Nordqvist