First human-to-human transmission of deadly strain of bird flu in China

Virus transmitted from infected father to daughter who cared for him in hospital; both die

By Kundan Pandey
Published: Wednesday 07 August 2013

The first case of human-to-human transmission of the H7N9 strain of bird flu has been found in China. In a paper published in the British Medical Journal on Tuesday, researchers from various organisations in China confirmed that a woman who had no contact with poultry but was caring for her infected father in hospital developed symptoms. Neither patient survived, say media reports.

In April, the World Health Organization (WHO) convened a team of experts to visit areas affected by H7N9 in China  in order to make recommendations on the prevention and control of the disease. At the time the global health body termed the virus as mysterious because its sources were not clear. The organisation found that there were many patients who had no contact with poultry. The organisation said that strain transmission was not human-to-human.

Limited human-to-human transmissibility

The researchers collected samples in March after a family cluster of patients were reported. They say the father fell ill five or six days after his last exposure to poultry. His 32-year-old daughter, who provided him with unprotected bedside care in hospital, had no known exposure to poultry. However, she developed symptoms six days after her last contact with her father. Both patients died in hospital because of multiple organ failure.

The researchers isolated samples from both father and daughter. The genome sequence and analysis of phylogenetic trees showed that both viruses were almost genetically identical. The researchers concluded that the infection of the daughter was probably a result of unprotected exposure due to contact with her father. This suggested that in this cluster the virus was able to transmit from person to person. However, they said that the transmissibility was limited and non-sustainable.

The novel avian influenza A H7N9 virus was identified in the beginning of the year in Eastern China. Till May 30, a total of 132 cases were reported including one in Taiwan. In most of the laboratory-confirmed cases, the patients developed severe pneumonia and acute respiratory distress syndrome (ARDS) and needed intensive care. Thirty-seven died of respiratory failure or other complications.


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