So far, 83 people have been confirmed infected with the H7N9 bird flu (avian flu) virus, of whom, 17 have died. In Shanghai alone, there have been 32 infections and 11 deaths, according to the Chinese Center for Disease Control and Prevention.

Yesterday, the Director of the Shanghai CDC (Center for Disease Control and Prevention) answered some questions that had been circulating in Shanghai.

Wu explained that the rumor that human-to-human transmission occurred at the Fifth People’s Hospital of Shanghai comes from an impossible theory. Six people at the hospital were confirmed with H7N9 bird flu virus infection.

Wu said that the six patients already had pneumonia before being hospitalized – i.e. their infections occurred before being admitted to hospital. She emphasized that the claims the patients infected each other in hospital “are groundless”.

The National Health and Family Planning Commission wrote that it cannot completely rule out the possibility of human-to-human transmission of H7N9. Three family members became ill with H7N9, as did a man and his wife. Poultry may have infected each one of them, they may have infected each other, or it could have been a combination, nobody is certain.

In a telephone interview with the New York Times, World Health Organization spokesman, Gregory Hartl said “Even if two family members are positive, it is not necessarily the case they got it from each other. They may have gotten it from the same bird.” Hartl added that there is no sustained evidence that the H7N9 bird flu virus is human transmissible.

Chinese scientists are also looking at a possible non-bird source for human H7N9 infections – it may have originated in other animals and in environmental sources, Hartl explained.

According to Feng Zijian, from the Chinese CDC, approximately 40% of infected humans have had no contact with poultry or other birds.

China has invited WHO (World Health Organization) experts, as well as scientists from other organizations, such as the CDC (USA), to help investigate the virus. Some of them have already arrived in Beijing.

Last month, thousands of dead pigs were found floating in the Huang Pu river, Shanghai’s main source of drinking water – the river flows through the city.

WHO Representative in China on human infection with influenza A(H7N9), Dr Michael O’Leary, said “There has been some speculation that there could be a link between the death of thousands of pigs in eastern China, influenza in birds, and the human cases.

However the deaths in pigs in the Huang Pu river may be caused by many factors, and we have not connected the pig deaths to human cases of influenza. Those pigs which have been tested were found negative for influenza viruses. The clinical syndrome in pigs is not compatible with influenza infection.”

Other “rumors” say that people were denied tests because they are expensive and health authorities want to keep costs down, or perhaps there are not enough laboratory personnel to deal with them.

Wu answered that certain criteria have to be met before an H7N9 bird flu virus test is performed. A high temperature with no other signs or symptoms is not sufficient reason to order a test.

Wu insisted that Shanghai has the resources in personnel, equipment, knowhow and money to carry out all necessary tests. She added that all costs related to H7N9 tests will be met by the Shanghai government.

After receiving treatment, Beijing’s first confirmed H7N9 infection has recovered well. The 7-year-old girl started receiving treatment on April 11. In Shanghai, a male (66) left hospital after making a full recovery, he was treated for two weeks.

Health authorities say the death rate is now much less than the initial 50%+. They say that the first cases took doctors and hospitals by surprise, and that health care professionals are gaining H7N9 experience, which will result in further declines in mortality.

H7N9, which WHO and various scientific bodies have agreed to refer to as avian influenza A(H7N9) virus, is a serotype (subtype) of Influenzavirus A (avian flu virus or bird flu virus).

Only some strains are known to cause serious disease in humans:

  • H7N9 – the subtype that is infecting humans in China at the moment
  • H7N7
  • H7N3
  • H5N1
  • H9N2

Avian influenza A(H7) viruses are a group of influenza viruses. H7N9 is a subgroup of the H7 group. H7 viruses circulate among bird populations – some variants, such as H7N7, H7N3 and H7N2 have been known to sometimes infect humans (without serious illness).

No human infections with A(H7N9) have ever been reported before these recent cases in China.

The signs and symptoms of A(H7N9) infection include:

  • Cough
  • Fever
  • Shortness of breath
  • Pneumonia (eventually)

The World Health Organization warns that with only eighty-three cases to go by, data on symptoms are limited.

Are there any vaccines against H7N9? – No.

Neuraminidase inhibitors, such as Tamiflu (oseltamivir) and Relenza (zanamivir), may help treat patients who are infected with H7N9.

The World Health Organization says that the number of human infections so far could be much higher. Some relatively mild cases of illness have now been reported, meaning that not all infected people are ending up in hospital or seeing their doctors.

Written by Christian Nordqvist