Evolving: Deadly H7N9 virus develops drug-resistance to Tamiflu

With new H7N9 cases waning, the worst thing humans can do right now is let their guard down about the potential dangers of this deadly new virus. The microbe is always mutating and evolving, as a virulent living force of nature and natural selection.

TAIPEI, Taiwan – The only H7N9 patient so far in Taiwan was carrying two strains of the same virus, with one being drug resistant and the other not, making it tricky to treat to him, doctors said. Huang Li-min, a doctor from National Taiwan University Hospital (NTUH), explained that it was possible the avian flu virus was not drug resistant when the patient was first infected, but mutated later to become resistant to Tamiflu.

With Tamiflu failing, NTUH later switched to another intravenous drug, Huang said. Because of the presence of the two strains simultaneously, it was difficult for doctors to determine how much the virus’ drug resistance had undermined the therapy Chou Chi-hao, deputy director-general of the Centers for Disease Control (CDC), said it is natural for viruses to mutate, saying the H1N1 flu strain mutated after infecting human beings.

But Huang said H7N9 has limited chances of human-to-human transmission through respiratory secretions because the virus has difficulty surviving the environments of human upper respiratory systems. Patients do not have symptoms of a runny nose or sneezing. The patient, surnamed Lee, got sick on April 12, three days after returning from a business trip in China. His condition was initially critical, but has improved much.

He has already been transferred from the intensive care unit to an ordinary ward at NTUH. The findings by the NTUH and CDC about H7N9 are to be published in a local medical journal next month. Resistance is of concern in the scenario of an influenza pandemic (Wong and Yuen 2005), and may be more likely to develop in avian influenza than seasonal influenza due to the potentially longer duration of infection by novel viruses.