Anew strain of bird flu has surfaced in China and it has health officials alarmed. While the death toll has reached double digits, the real cause of concern is the fact that it was previously not known to affect humans. Health officials in China and elsewhere are closely monitoring hospitals and clinics, as well as the close contacts of confirmed cases.
Surveillance is critical, not only of people, but also of poultry to trace the source of the outbreak and identify its vectors, as well as isolate the strain and prepare a vaccine.
The new flu comes from the H7N9 virus, a variant that has long been in pigeons but has never been found in humans. Apparently, the virus has mutated and now affects mammals. Thus far, Chinese health authorities report it has infected at least 84 people in the cities of Shanghai and Beijing plus four Chinese provinces, killing 17 people over the last two months, all in eastern China.
The victims include men and women, young and old. All the victims had pre-existing health conditions, suggesting that the disease may not be a killer in isolation.
Several had visited poultry markets before they got sick, but the actual source of the infection remains uncertain. Chinese experts believe that the virus originated in migratory birds that mixed with domestic fowl in China’s heavily populated Yangtze River delta.
As a result, many bird markets in eastern China have been shut down and culls are under way. Shanghai has banned the sale of all live poultry. It was reported Tuesday that the virus was detected in a wild pigeon caught in Nanjing.
Officials are also monitoring the close contacts of confirmed patients to ensure that they are not carrying the disease. The World Health Organization (WHO) says there is no evidence of human-to-human transmission. But cases were reported in which family members of bird flu patients became infected. Samples from three patients show that the new strain has genetic characteristics that make it well suited to move from person to person. Mutations in the new virus are similar to those in other viruses that increase transmissibility and make it easier to survive in a mammal’s respiratory tract.
One of the mutations was in the H5N1 bird flu virus and was responsible for much of the alarm surrounding that outbreak. The same mutation was found in viruses that caused two earlier flu pandemics.
Another type of mutation allows the virus to grow in lower temperatures. This, too, is worrisome as the human respiratory tract has lower temperatures than the natural environment of the virus, the avian gastrointestinal tract. Other mutations of the virus that were discovered prompted one research scientist to say this particular strain can no longer properly be called “bird flu.”
Many questions still swirl around the outbreak, not least of which is its extent. China seems to be responding quickly to the appearance of the disease, with health officials stepping up surveillance and sharing results with international counterparts. Four of the viruses have been sequenced and posted on websites for international scrutiny.
People’s Daily, the mouthpiece of the Chinese Communist Party’s Central Committee, has called on officials to publicize information to avoid panic. In Shanghai a microblog is providing real-time updates. Daily email updates are also being sent.
This contrasts sharply with the past. In 2002 and 2003, local officials were slow to report outbreaks of Severe Acute Respiratory Syndrome (SARS), and as a result, the disease spread worldwide, triggering a global scare.
Of special concern is the disease’s high lethality. Thus far, virtually all victims have become extremely ill and about one-fifth of them have died. This leads to speculation that the number of reported infections is too low.
If the numbers are not under-reported, then this is a powerful strain and the causes of infection must be better understood. If the number of infections is much higher, then the urgency of a vaccine is less pressing (because the lethality of the virus is lower) — but the reliability of Chinese reporting is again called into question.
One writer has speculated that under-reporting could be high because of air pollution: The discomfort caused by the recent smog in China may be obscuring reporting of bird flu cases.
One concern can be put to rest: Chinese officials insist that there is no connection between the mysterious appearance of more than 11,000 dead pigs in the Shanghai water supply last month and this virus. This is almost certainly a coincidence, but the two incidents — three, if air pollution is included — are an uncomfortable reminder of the many health concerns of everyday life in China.
Scientists must find the origin of the disease and quickly. If it did originate in migratory birds, then the odds are high that cases will soon be appearing in other countries.
We need a better sense of the lethality to know how to respond. It is reckoned that a vaccine will not be available for several months at the earliest.
China should be applauded for its about-face in responding to this outbreak, but the test is not over. The challenges will intensify if the disease spreads. China should be encouraged to maintain its transparency and its neighbors, along with relevant international institutions, should be vigilant and prepared to cooperate to contain, control and ultimately defeat this disease.