Once again, bird flu is in the air

As spring approaches, there are reports of outbreaks of avian flu throughout Northeast Asia. Again, China appears to be the source of the contagion, although strains have been detected in various countries. Fortunately, the virus does not appear to be more virulent than it was in previous outbreaks. That is no reason to be complacent, however: Viruses are always mutating and the current strain could quickly become more dangerous.

There have been five annual epidemics of the H7N9 avian flu virus since it was first identified in 2013. That year, 135 people were infected. The following year, infections peaked at 320 people and the numbers have decreased each year since then. Until now. Thus far, 460 people have been reported to have been infected with the virus between October and February, one-third of the entire number of cases reported over the five-year period.

The virus is powerful. During the first four epidemics, 88 percent of people infected developed pneumonia, 68 percent were admitted to hospital intensive care units and 41 percent of those admitted died. Symptoms start with high fever and cough, progress to pneumonia and terminate in multiple-organ failure. While that progress is worrisome, scientists are quick to note that the vectors of transmission are largely restricted to contact with infected poultry. There are some reports of human-to-human spread, but they are limited and generally occur among sick people and their caregivers. This means hospitals and medical personnel need to be especially cautious, but the risk of a widespread pandemic remains low. Researchers warn that the virus could mutate, however, and surveillance agencies need to be especially attentive to that possibility.

One mutation has made the virus more dangerous to birds, which carry the disease (hence the name), but that could be a good thing. A more potent virus will either kill the carrier or make it visibly sicker, which allows reservoirs to be more easily detected and the birds culled. That can be more expensive for bird farmers — and the governments that pay them to compensate for lost revenue — but it should help control the disease.

Culls are already underway. China confirmed five bird flu outbreaks during the winter, which has led to culling of more than 175,000 birds. Authorities in Guangzhou, China’s third-largest city, warned that about one-third of its live poultry markets were contaminated with the virus; live poultry trade in Zhejiang province has been halted as well. For some, this comes too late: China has already experienced 100 deaths as a result of the disease, nearly three times the number that accompanied the first outbreak in 2013.

In Japan, the H5 strain of the avian flu virus has been detected in farms in Niigata, Aomori, Hokkaido, Gifu and Miyazaki prefectures since November. Nearly 70,000 chickens were culled in Saga Prefecture in early February. Taiwan last month reported its first case of the H5N6 virus, although there have been a dozen cases of less virulent strains. The H5N6 strain has been detected at 340 farms in South Korea; 34 million birds — nearly a fifth of the country’s poultry population — have been killed to try to contain the spread of the disease. No cases of human infection of avian flu have ever been detected in South Korea.

Researchers around the world have been working on a vaccine against H7N9; efforts have begun to develop a second vaccine in response to observed mutations. What is most important in this effort is complete transparency among authorities regarding any outbreaks of the disease and the sharing of genetic sequences of any virus strains that they can identity.

China is central to the success of this effort and its record is troubling. Beijing has been reluctant to acknowledge the severity of previous bird flu outbreaks. This occurred most notably during the SARS (severe acute respiratory syndrome) outbreak in 2002-2003 that resulted in 8,098 cases, and 774 deaths in 37 countries. Concerned about the negative impact of reporting the disease, health officials covered up the outbreak, which, ironically, facilitated its spread. Chastised by the international criticism that followed, China has been more transparent in subsequent outbreaks, but even now it is not sharing samples of the virus that have been collected — it has published genetic sequences — which limits the ability of foreign researchers to assess the strain itself.

Given the origin of so many of the bird flu strains in China’s bird population, the sheer number of live birds in city markets and the density of Chinese cities, the government must more actively promote transparency and cooperation among health researchers. The inclination to cover up bad news will grow as the 19th Party Congress, scheduled for later this year, approaches; the SARS outbreak occurred at the same time as the 16th Party Congress. Hopefully, the Chinese authorities have learned their lesson and will be on the leading edge of efforts to combat and contain this disease, rather than trying to cover it up.