AS bird flu spread across China this winter, Shanghai stood at the forefront of disease control and prevention efforts.
“More than 62 percent of the emerging diseases in the world originate from wildlife,” said Wang Tianhou, director of the ecology program at East China Normal University.
For Shanghai, that means birds. The city sits along the East Asia-Pacific Flyway, one of the world’s major bird tracks. Two-thirds of the 445 species of birds recorded in Shanghai are migratory, passing through the city twice a year.
“Shanghai is an essential stopover for birds in migration journeys, and millions of them stop here awhile to refuel and rest,” said Wang. “Some can carry pathogens like avian influenza.”
China has reported more than 340 cases of human infections from H7N9 avian influenza since last autumn, with a death toll of at least 108.
The outbreak among domestic poultry led to the culling of more than 175,000 poultry in China, and some live poultry markets have been closed.
In 2006, the Shanghai Wildlife Epidemic Disease Monitoring Platform was created at East China Normal University to provide analysis and policy advice on viruses spread from wild animals.
There are three types of influenza viruses. Influenza A infects humans and many different animals; type B circulates only among humans and causes seasonal epidemics; and type C infects both humans and pigs, but infections are generally mild and rarely reported. H7N9 bird flu is a type A influenza.
“Not all avian influenza viruses are contagious,” Wang explained. “Certain highly pathogenic strains can infect humans, but the animals may not show any symptoms before passing the virus to humans. Before we can conduct disease prevention and control, we must know all about the source.”
Avian influenza is closely monitored nationwide and worldwide. In China that is particularly critical given high population densities in urban areas on migratory routes.
The Shanghai Municipal Administration of Landscaping and City Appearance has 58 stations that form a monitoring and early-warning alert system. Among the sites are state-level outposts at the Chenhang Reservoir, Shanghai Zoo, the Sheshan Hill forest area, Chongming Dongtan and Jiuduansha wetland.
The Shanghai Wildlife Conservation Management Station is also involved in the effort.
Every year more than 2,000 samples are sent to the Shanghai Wildlife Epidemic Disease Monitoring Platform labs to be tested and analyzed. The results go back to the Shanghai Municipal Administration of Landscaping and City Appearance which in turn works with the Center for Disease Control, the Institute of Animal Husbandry and Veterinary Science and the Shanghai Academy of Agricultural Science.
“We cover the stations every year, taking samples for testing,” Wang said. “We sometimes find different subtypes of the virus in the same sample because the virus can recompose and lead to mutation. Mutation is not like evolution, which is a long-term process. Mutation of viruses can develop very rapidly.”
Wu Di, a senior staff member of the Shanghai Wildlife Conservation Management Station who has been working in wildlife borne disease surveillance and control since he graduated from East China Normal University in 2011, replied to questions from Shanghai Daily about the work of the agency.
Q: What is the day-to-day work at the station?
A: It involves monitoring and prevention in the field of wildlife epidemic diseases, by building new stations, maintaining the existing ones and providing staff training.
One of our key priorities now is providing health alerts from information we collect from wild birds or their faeces. We test for avian influenza viruses in the hope that we can give advance warning of possible outbreaks.
We also receive faxed reports from the various stations on population counts, and deaths and abnormalities found in birds along designated surveillance routes.
We also deal with public calls about abnormalities and deaths of wild animals, and carry out quarantine, bio-safety disposal and disinfecting procedures.
Q: What is the routine process for collecting samples?
A: At the beginning of the year we make specific plans for sampling at each of the participating offices. We mainly focus on collecting samples in areas where bird species gather in numbers, like Chongming Dongtan, Jiuduansha, Nanhui Dongtan, Shanghai Zoo and the Shanghai Wild Animal Park. We target geese and ducks, shorebirds and land birds.
The process starts with acquiring a special permit to capture some birds in their active season. Labs at East China Normal University come to collect cloacal and throat swabs. For larger birds like geese and ducks, blood samples are also taken.
The samples are then transported back to the labs for testing and storage. It’s very crucial to prevent contamination when collecting samples and to store them in low temperatures.
Q: Where are the key monitoring locations for species during the peak winter season in Shanghai?
A: Our current monitoring is focused on geese, ducks and shorebirds. The stations cover Shanghai’s outskirts and areas with more intense bird activities, including Chongming Dongtan, Nanhui Dongtan, Fengxian and Jinshan near shores, as well as lakes and forests.
Q: What happens when samples test positive?
A: Because it takes time to process the samples, we don’t know what kind of virus the bird may be carrying when samples are first taken. In positive tests for avian influenza, we use the results to issue alerts and try to trace how the virus may spread to humans.
For example, we can forecast the epidemic potential of a virus according to its subtype and its pathogenicity. We also carry out related gene research.
In the peak season when humans are most likely to be infected, we intensify monitoring in concentrated bird habitats, and often aviaries in zoos are closed to prevent humans coming into contact with wild birds.
Q: What are the common misunderstandings about avian influenza?
A: The public doesn’t have to become overly worried, but the risk can’t be ignored either.
Many people don’t realize the role wild birds play in spreading the flu. Wildlife conservation workers often find wild birds captured in nets in the city suburbs, which is not only illegal but also dangerous. If someone captures a bird carrying the virus and is in direct contact with it without adequate protection, there is a greater risk of infection.
Also, people raising free-range poultry need to be aware of the risks when migrating birds stop over in fields.
Spring is a great time for outings and picnics, but people should keep a safe distance from forests and lakes where birds are most active, and they avoid touching any bird faeces.
If you may be exposed to avian influenza, it’s important to wash the hands thoroughly with flowing water and soap or disinfectant, and to avoid using shared towels in public places.
Poultry meat and eggs are safe to eat when they are completely cooked. The avian flu virus is killed when exposed to heat of at least 100 degrees Celsius for two minutes. But it’s very important to be careful when handling raw poultry because the virus could spread through contact between a bird’s respiratory and digestive tracts and human air passageways or skin wounds.
There is no need to be panic when someone close to you is infected by bird flu. So far, the H7N9 virus has not been shown to spread from human to human. The majority of cases involve direct human contact with live poultry.
Q: What can the public do to assist in the fight against avian flu?
A: The first thing is to maintain a scientific and rational attitude instead of creating panic when reports of cases surface. Pay attention to personal hygiene and avoid contact with wild birds or live poultry to lower the risk of infection.