The first human case of infection with an influenza A (H6N1) virus has been identified in Taiwan. For researchers, “the question of human-to-human transmission” is not excluded.
As the H7N9 bird flu is back in China, with four new patients recently diagnosed, another influenza virus has just emerged. This time it is H6N1! The first human case of infection with this virus has, in fact, been identified in Taiwan, according to results published in The Lancet on Thursday. With 139 people infected with the H7N9 virus since last winter, 45 of whom have died, this new discovery is alarming researchers.
A virus never isolated in humans
Sung-Hsi Wei of the Centers for Disease Control in Taipei and colleagues describe the case of a 20-year-old woman admitted to hospital in May with flu-like symptoms and a lower respiratory tract infection. After two days of treatment with oseltamivir (Tamiflu) and levofloxacin, the patient’s symptoms improved. About ten days after she was admitted to hospital, a chest x-ray showed that she was healed. By sequencing the patient’s influenza virus genes, the team discovered that it was an A (H6N1), a species never before isolated from humans. According to them, this influenza virus is close to a strain A (H6N1) of chicken which has circulated in Taiwan since 1972. Surprising, because once recovered, the patient reported not having been in contact with poultry in the year.
The possibility of human-to-human transmission is a concern
For the researchers, the absence of direct exposure to poultry “raises the question of human-to-human transmission”. However, the team has no evidence to support this. The authors also note that no transmission of an A (H6N1) virus by aerosol has been described between two mammals.
In addition, according to a survey of 36 people who had been in contact with the patient, six had suffered from fever or respiratory infection between the end of April and the beginning of May. They also all indicated that they had not had recent contact with poultry. And, even if the genetic analyzes in these “contact patients” all ruled out an infection with an influenza A (H6N1) virus afterwards, the authors specify that some of them were already cured during the analyzes.
A mutation could make it more infectious in humans
Finally, Dr. Ho-Sheng Wu, main author of the study, confides that “this strain is not very pathogenic, while adding that” this type of virus is constantly evolving, each time increasing the risk of human infections. “Especially since this virus (H6N1) has a mutation (G228S) on a protein on its surface, which allows it to bind to target human cells. This modification of the virus could, by increasing its affinity for a human receptor in the upper respiratory tract, allow it to become much more infectious to humans, the researchers admit. “In all cases, additional investigations must be carried out to identify more clearly the threat that A / H6N1 may constitute”, the team concludes.
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