quarantine researcher checks on a chicken
© CHINA STRINGER NETWORK/REUTERS/NewscomA quarantine researcher checks on a chicken at a poultry farm in Hubei province in China earlier this month.
An avian influenza virus that emerged in 2013 is suddenly spreading widely in China, causing a sharp spike in human infections and deaths. Last month alone it sickened 192 people, killing 79, according to an announcement this week by China's National Health and Family Planning Commission in Beijing.

The surge in human cases is cause for alarm, says Guan Yi, an expert in emerging viral diseases at the University of Hong Kong in China. "We are facing the largest pandemic threat in the last 100 years," he says.

As of 16 January, the cumulative toll from H7N9 was 918 laboratory-confirmed human infections and 359 deaths, according to the World Health Organization (WHO). Despite its high mortality rate, H7N9 had gotten less attention of late than two other new strains—H5N8 and H5N6—that have spread swiftly, killing or forcing authorities to cull millions of poultry. But so far, H5N8 has apparently not infected people; H5N6 has caused 14 human infections and six deaths.

All human H7N9 cases have been traced to exposure to the virus in mainland China, primarily at live poultry markets. The strain likely resulted from a reshuffling of several avian influenza viruses circulating in domestic ducks and chickens, Guan's group reported in 2013. Studies in ferrets and pigs have shown that H7N9 more easily infects mammals than H5N1, a strain that sparked pandemic fears a decade ago. There have been several clusters of H7N9 cases in which human-to-human transmission "cannot be ruled out," but there is "no evidence of sustained human-to-human transmission," according to an analysis of recent developments that WHO posted online last week. WHO's analyses of viral samples so far "do not show evidence of any changes in known genetic markers of virulence or mammalian adaptation," WHO's China Representative Office in Beijing wrote in an email to Science.

Still, there are worrisome riddles. One is that H7N9 causes severe disease in people but only mild or even no symptoms in poultry. The only previous example of that pattern, Guan says, is the H1N1 strain responsible for the 1918 flu pandemic, which killed 50 million to 100 million people.

A menace again

After two quiet years, human cases of the H7N9 bird flu virus in mainland China spiked sharply at the end of last year, provoking renewed fears of an influenza pandemic.
human cases of the H7N9 bird flu virus chart
© G. Grullón/Science
Because poultry infected with H7N9 show few symptoms, the virus has spread stealthily, coming to the attention of authorities only after human victims appeared. Determining where the virus is circulating requires testing chickens and collecting environmental samples from live poultry markets.

Human infections have followed a consistent pattern, dropping to zero during summer, picking up in the fall, and peaking in January. During the fifth wave of H7N9 that began last fall, authorities noticed an early and sudden uptick in cases, with 114 human infections from September to December 2016, compared with 16 cases during the same months in 2015 and 31 in 2014, according to a surveillance report. The report notes that the virus has spread geographically, with 23 counties in seven eastern Chinese provinces reporting their first human cases last fall.

"It is too late to contain the virus in poultry," Guan says. He predicts that the virus will continue to spread in China's farms, possibly evolving into a strain that would be pathogenic for poultry. Authorities have culled more than 175,000 birds this winter to stamp out local outbreaks of H7N9 and other avian flu strains. Further spread of H7N9 "will naturally increase human infection cases," Guan says.

H7N9 may also spread beyond China's borders, either through the poultry trade or through migratory birds. The virus has not been reported in poultry outside China. However, warns WHO's Beijing office, "continued vigilance is needed."


Comment: We've collected some related stories from the past couple months below:


Bird flu detected in Japan's Gifu, 80,000 chickens culled - Jan. 26, 2017

At least 80,000 chickens were culled at a poultry farm in central Japan's Gifu subdivision, where the highly pathogenic H5 bird flu strain had been detected, local authorities said.

Over 100 chickens were found dead at the farm in Yamagata city in the prefecture. Among seven of those carcasses sent for a preliminary test, six tested positive for bird flu, authorities said on Sunday.

The local government started culling the chickens at the farm Saturday night following the H5 virus was confirmed in further tests, Xinhua news agency reported.

Local authorities have ordered farms within 10 km of the affected poultry farms to stop transporting eggs and poultry out of the areas, while checking whether the virus has spread to neighbouring farms.

Bird flu cases have been reported at farms in Japan's central Niigata subdivision, southwestern Miyazaki prefecture, northeastern Aomori prefecture and Hokkaido since November last year.

A New, "Highly Aggressive" Bird Flu Has Been Found in Germany - Jan. 30, 2017

The Friedrich Loeffler Institute, Germany's national institute for animal health, discovered H5N5 on Jan. 21 at four different locations, all owned by the same company, in Steinburg, in the state of Schleswig-Holstein. First, a farmer found a number of dead turkeys at a site housing 3,400 birds. The virus then spread to a larger facility housing 15,000 birds, according to the news agency Kieler Nachrichten. The birds were culled in an attempt to stop the virus virus, but on Thursday, the Schleswig-Holstein Agriculture Minister Robert Habeck stated that two more nearby farms with another 15,000 birds had been infected and would also have to be culled. Preventive measures, including closing down the sites, have been put in place to contain the virus, according to Habek.

Habek described the new subtype, which has never been found in European poultry, as "highly aggressive," noting that it killed more than half of the flock of 3,400 birds where it was first discovered within 48 hours with the rest of the turkeys having shown disease symptoms. H5N5 had already been found in wild geese in Germany and in wild birds in the Netherlands, Italy, Montenegro, Italy, Croatia and Israel.

"This discovery shows how dynamic the bird flu is. The virus is still present and is changing," Habeck told Deutsche Welle.

There hasn't been a known case of H5N5 being contracted by humans, according to the Friedrich Loeffler Institute. In China, a different subtype of the virus, H7N9, has jumped to humans, sickening more than 1,000 people, and killing nearly 40 percent of those who contracted the illness.

Since October, poultry flocks in 23 European countries have been hit by a different subtype of avian influenza, H5N8, which led to the culling of more than 1.5 million poultry so far, according to Reuters.

Fifth case of bird flu confirmed in Ireland - Jan. 30, 2017

A fifth case of bird flu has been identified in Ireland.

The latest bird to test positive for H5N8 is a whooper swan in Ballinturley, Roscommon.

It is the third swan to have been found to be infected with the virus - the other cases were on the Longford-Leitrim border and in Tipperary.

The other two cases occurred in a species of duck known as wigeons.

In December, the Department of Agriculture activated regulations requiring all poultry and captive birds to be kept within a secure building amid concerns over bird flu.

The public is advised not to handle dead or sick birds.

Czech Republic Reports H5N5 In Dead Swans At Liberec Zoo - Feb. 13, 2017

Although still greatly outnumbered by reports of HPAI H5N8, we continue to see an expansion of reassorted HPAI H5N5 detections across Europe, with this new virus previously reported in The Netherlands, Italy, Montenegro, Germany, Greece, Slovenia, Poland, and Macedonia.

Today it is the Czech Republic's turn, as their Státní Veterinární Správa (State Veterninary Administration) reports their latest findings on their website.
Published: February 13, 2017
Vysocepatogenní avian influenza in the Czech Republic; current information as of February 13, 2017
13. 2. 2017 yesterday evening confirmed 28 outbreak of bird flu in backyard poultry in Volyn district. Strakonice. The farm has about 100 pieces of water and gallinaceous poultry to be killed during the day.
Laboratory results of examinations of dead swans from the Liberec Zoo, confirmed the H5N5 subtype of bird flu, which was recently captured in Germany.
In connection with bird flu have been in the country since the beginning of the year so far killed more than 58,000 birds. Bird flu has also yet to be proven in 50 wild birds in 12 regions (especially swans, but also ducks, geese and herons).
Human cases of bird flu are surging, alarming public health officials - Feb. 28, 2017

ATLANTA — Scientists and public health authorities are expressing alarm about an extraordinary surge in bird flu infections among humans.

The H7N9 bird flu virus, which has sickened and killed several hundred people in China for the past four winters, had seemed over the past couple of years to be diminishing as a threat.

But a resurgent wave of activity this winter has produced more than a third of all infections recorded since the first human case was hospitalized in February 2013. And with this large burst of cases, H7N9 has overtaken another bird flu, H5N1, which has been causing sporadic human infections at least a decade longer than H7N9.

Changes in the virus are also worrying, said Dr. Daniel Jernigan, director of the Centers for Disease Control and Prevention's influenza branch. Jernigan noted Tom Price, the new health and human services secretary, has been briefed on the situation.

"We're concerned about the uncertainties here and the number of changes that are happening at this point. We are monitoring this closely," Jernigan told STAT.

France detects possible bird flu outbreak on northern farm - March 1, 2017

French authorities reported a possible outbreak of bird flu on a poultry farm in the far north of the country on Wednesday, which could mark a spreading of the disease beyond the southwest foie gras producing region where millions of birds have been culled.

Traces of a severe bird flu virus were found on chickens at a farm near the port town of Dunkirk, which is close to the Belgian border, local authorities said in a statement, adding that further tests were being conducted to confirm the outbreak.

The type of bird flu was not indicated.

The farm saw some 10,000 chickens out of a flock of 27,000 die last month but initial testing did not detect bird flu.

France, alongside Hungary, has been the country most affected by a wave of highly contagious H5N8 bird flu in Europe. The virus is deadly for poultry but not known to be transmissible to humans.

The government has been trying to contain the virus in southwest France, where more than 3 million birds have died or been preventively culled in a region known for its production of foie gras, the specialty made from duck and goose liver.

A case of H5N8 bird flu was detected in the far north late last year but among wild birds rather than on a farm.

Medical experts urge action after H7N9 virus shows resistance to Tamiflu - March 1, 2017

Medical experts have called for a swift investigation into the possibility that a mutation of the H7N9 bird flu virus in China was becoming resistant to a drug commonly used to treat infected people.

Two patients in Guangdong province with the new and more virulent strain of the virus have shown signs of failing to respond to Tamiflu, the Nanfang Daily reported this week, citing Zhong Nanshan, an expert in respiratory diseases.

As bird flu spreads, US concludes its vaccine doesn't provide adequate protection - March 1, 2017

With human infections from a bird flu virus surging in China, US officials charged with preparing the country for influenza pandemics have been assessing the state of an emergency stockpile of vaccines against that strain. The conclusion: The stored H7N9 vaccine doesn't adequately protect against a new branch of this virus family, and a new vaccine is needed.

Rick Bright, who heads the Biomedical Advanced Research and Development Authority, or BARDA, said the H7N9 vaccine in the stockpile would not fend off a new family of these viruses that has emerged in China, known as the eastern or Yangtze River Delta lineage of the viruses.

Bird flu limits egg purchases at US commissaries in South Korea - March 3, 2017

Commissary customers in South Korea are facing limits on the number of U.S. eggs they can purchase as the country suffers from its worst-ever outbreak of bird flu.

Signs went up last week announcing a limit of one carton containing 12 U.S. eggs per purchase, but on Thursday the limit was raised to three cartons per purchase.

South Korea has killed more than 33 million poultry since the first case of avian influenza was reported in November, double the previous record of nearly 14 million destroyed in a 2014 outbreak, according to the Ministry of Agriculture, Food and Rural Affairs. That has sharply driven up local market prices, and authorities imported more than a million eggs from the United States to make up for shortages.

The crisis has also affected commissary supplies, the Defense Commissary Agency said.

New bird flu outbreak as 55,000 ducks to be destroyed at farm to prevent further spread of virus - March 3, 2107

Around 55,000 ducks are to be destroyed after a bird flu outbreak was discovered at another farm in south-eastern England.

The Department of Food And Rural Affairs (Defra) announced on Friday that avian influenza H5N8 has been found on a farm near Redgrave, Suffolk.

Officials detected the highly pathogenic virus while investigating a separate poultry farm nearby where chickens were confirmed to be infected last month.

A protection zone measuring nearly two miles and a six-mile surveillance zone are already in place following the earlier case, although officials say the threat to humans is "very low".

The raging bird flu in China is a good reminder the US isn't prepared for a pandemic - March 3, 2017

A strain of deadly bird flu that has a high risk of becoming a pandemic is surging in China, and experts are warning that the US isn't making the necessary preparations.

According to an assessment from the World Health Organization this week, China had 460 lab-confirmed human cases of the H7N9 bird flu virus since last October — the most of any flu season since the virus was first reported in humans in 2013.

This makes the current outbreak the largest on record for H7N9, a virus that typically circulates around poultry markets and can cause pneumonia or death when it spreads to people. Forty percent of those with confirmed H7N9 infections have died — including at least 87 people this year alone. That's a very deadly pathogen.

Global poultry industry shaken by bird flu situation - Rabobank - March 4, 2017

The outlook for the global poultry industry in 2017 has been shaken by the bird flu situation, according to a Rabobank report.

The bird flu situation has significant implications, both locally and globally, according to RaboResearch's Global Poultry Quarterly for the first quarter of 2017.

The Chinese market has been worst affected, due to a sharp increase in the number of human bird flu cases in the country, the report says.

It has dramatically changed Chinese market conditions, as prices have fallen sharply to historic lows.

Despite the spread of the disease across other parts of the world, including Europe, Africa, and the rest of Asia, most of these markets have continued to perform relatively well, it added.

UTA Professor Invents Breath Monitor To Detect Flu - March 4, 2017

It's a revolutionary device that makes it possible to diagnose flu cases at home.

University of Texas Arlington Professor, Dr. Perena Gouma, invented a flu breathalyzer.

"I think it's going to save a lot of people a lot of trouble, and a lot of money," says Dr. Gouma. "Now, someone has to go to the doctor's office, and the virus can infect other people. It might be an unnecessary visit if they don't have the flu."

Methodist Mansfield Medical Center ER Physician Ashkan Bidgoli says the method to diagnose the flu virus takes around half an hour.

"Right now basically we're using a nasal swab to detect the flu in all ages," says Dr. Bidgoli. "It can be uncomfortable and cumbersome, especially for younger kids."

With the breathalyzer, sensors (smaller than a grain of rice) zero in on a chemical in the breath. Dr. Gouma says it can pinpoint the virus in just milliseconds.

Bird flu found in Tennessee chicken flock on Tyson-contracted farm - March 6, 2017

A strain of bird flu has been detected in a chicken breeder flock on a Tennessee farm contracted to U.S. food giant Tyson Foods Inc, and the 73,500 birds will be culled to stop the virus from entering the food system, government and company officials said on Sunday.

The U.S. Department of Agriculture said this represented the first confirmed case of highly pathogenic H7 avian influenza (HPAI) in commercial poultry in the United States this year. It is the first time HPAI has been found in Tennessee, the state government said.

Tyson, the biggest chicken meat producer in the United States, said in a statement it was working with Tennessee and federal officials to contain the virus by euthanizing the birds on the contract farm.