Thursday, 5 February 2015

H7N9 virus

H7N9 virus
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA). The avian influenza A(H7N9) virus designation of H7N9 identifies it as having HA of the H7 subtype and NA of the N9 subtype.
        Avian influenza A H7 viruses are a group of influenza viruses that normally circulate among birds. H7 influenza infections in humans are uncommon, but have been confirmed world-wide in people who have direct contact with infected birds. Reported in the Netherlands, Japan, and the United States. Until the 2013 outbreak in China, no human infections with H7N9 viruses have ever been reported.

Reported cases in 2014
      On January 21, 2014, it was reported that a 31-year-old thoracic surgeon had died four days previously, the first medical professional to die from H7N9 flu.
     On January 28 it was reported by the Chinese Center for Disease Control and Prevention that the virus had killed 20 people in China in 2014, with the total number of human infections at 102. That compares with 144 confirmed cases, including 46 deaths, in the whole of 2013.

Symptoms and treatment
     According to the World Health Organization, symptoms include fever, cough, and shortness of breath, which may progress to severe pneumonia. 
       The virus can also overload the immune system, causing what is known as a cytokine storm. Blood poisoning and organ failure are also possible. 
         Most of the patients with confirmed cases of H7N9 virus infection were critically ill and that approximately 20% had died of acute respiratory distress syndrome (ARDS) or multi organ failure.
Antigenic and genome sequencing suggests that H7N9 is sensitive to neuraminidase inhibitors, such as oseltamivir and zanamivir.

   The use of these neuraminidase inhibitors in cases of early infection may be effective, although the benefits of oseltamivir treatment have been questioned.
Mortality
     Keiji Fukuda, the World Health Organization's (WHO) assistant director-general for health, security and the environment, identified H7N9 as "...an unusually dangerous virus for humans." By early May the number of new cases sharply declined and the mortality rate remained at about 20%,however as seriously ill patients continued to die, the mortality rate rose to about 33% by July.

Vaccine
On October 26, 2013, Chinese scientists announced that they had successfully produced an H7N9 vaccine, the first influenza vaccine to be developed entirely in China.
 It was developed jointly by researchers from Zhejiang University, Hong Kong University, the Chinese Center for Disease Control and Prevention, China's National Institute for Food and Drug Control, and the Chinese Academy of Medical Science.
 A(H1N1)pdm09 vaccines [about 60% to 70% effectiveness], particularly with regard to vaccine efficacy in persons older than 65 years.