Such fears stem from a long list of attempted cover-ups, including that of an epidemic of Severe Acute Respiratory Syndrome (SARS), which emerged in China in 2002 and killed about one in 10 of the 8,000 people it infected worldwide.
Suspicions are also tied to an HIV/AIDS scandal in the 1990s, when officials tried to suppress information of thousands of villagers who were infected through blood donation stations.
But both of those scandals came before the advent of popular local microblog sites; these now have millions of Internet-savvy users who, despite heavy online censorship, have managed to whip up public awareness over galling health and food-safety issues.
The difficulty of keeping a lid on information is one reason China has increased transparency about H7N9, said Jia Xijin, an expert on civil society at Tsinghua University in Beijing.
"Concealing the information is impossible," Jia said. "If they keep the information it will only increase criticism."
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Still, Chinese Internet users and newspapers question why it took weeks for the government to announce cases of the bird flu strain, especially as two of the victims fell ill in February.
Health officials said it took time to identify the virus, which was previously unknown in humans. Senior officials are acutely aware of the mistrust, and on Monday Vice Premier Liu Yandong called for greater transparency surrounding the virus.
Searching for Answers
In a sign of the intense public concern surrounding H7N9, people in China are making a record number of online searches for "bird flu", according to a Google tracking tool. Search volumes are higher now than at any time in the past nine years.
The results, calculated on a comparable adjusted basis, take into account growing Internet use in the country. More Chinese people use the Chinese-language search engine Baidu, but the spike in Google searches is still significant.
With the Internet at their fingertips, many Chinese are not holding back. Jia, the Tsinghua professor, said the government's tight grip on information made transparency seem unattainable, leading to constant criticism and occasional wild rumors - among them talk of the flu being the result of a U.S. attack.
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Listening to the public, Chinese authorities have been quick to counter speculation that the H7N9 outbreak is related to more than 16,000 pig carcasses found dumped in rivers around Shanghai. The World Health Organization (WHO) has said some dead pigs from the rivers tested negative for influenza infection.
State media reported some Chinese consumers are making their own decisions, leading to a rush on pharmacy sales of isatis, a herb used in traditional Chinese medicine to cure fever.
While skeptics in China have taken to social media to speak their minds, flu scientists and global public health experts are heaping praise on Beijing for its efforts so far.
Chinese doctors and officials, they say, appear to have learned in the past decade that seeking to cover up a public health threat is more likely than not to backfire and create more panic and worry than publicizing what is known.
"Things have improved tremendously," said Ab Osterhaus, a flu expert at the Erasmus Medical Centre in the Netherlands.
"What's important is that communication with the WHO and the international scientific community is happening."
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Michael O'Leary, the WHO's representative in China, confirmed his team was getting at least daily updates from China's National Health and Family Planning Commission and from the country's Centre for Disease Control and Prevention.
Within a day or two of the first cases of the new strain being identified and reported in humans, scientists had posted gene sequence data from virus samples on the website of GISAID, the Global Initiative on Sharing All Influenza Data, which makes such data available to flu researchers worldwide.
That swift publication has allowed flu experts in laboratories across the world to start picking through the DNA sequence data to try to assess H7N9'S potential for developing into a human pandemic.
China's official Xinhua news agency said on Tuesday that the H7N9 virus had not triggered an epidemic among poultry. With no evidence of transmission between humans, experts say the H7N9 flu outbreak merits close watching, but so far does not present an immediate pandemic risk.
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Jeremy Farrar, a leading expert on infectious diseases and director of Oxford University's research unit in Vietnam, told Reuters that China had done "a fantastic job" so far: "In a way, the West could perhaps learn from the way they have truly integrated the public health and clinical response to this."