Asia offers valuable bird flu lessons – experts
By Tan Ee Lyn
The Star, 22 Oct 2005

HONG KONG (Reuters) - Disease experts gave a critical assessment on Friday of how parts of Asia has handled the deadly bird flu virus, but stressed there are valuable lessons for other continents that will help control a human pandemic. 

After making the first known jump to humans in Hong Kong in 1997, the H5N1 virus has showed up in Indonesia, Vietnam, Thailand and Cambodia, killing more than 60 people out of 118 known cases since 2003. 

The virus began killing wild migratory birds in central China in April and has since been found in flocks as far west as European Russia and Romania. Experts now fear the virus will mutate further into a strain that is easily transmissible among people, setting off a pandemic in which millions could die. 

"Of course it has been a failure. If it was a success, we wouldn't have come to this," said Hong Kong-based microbiologist Guan Yi, pointing to how the virus is now spreading uncontrolled among wild birds and moving into Europe and possibly Africa. 

Paul Chan, a microbiologist at the Chinese University, said the biggest failing in many parts of Asia has been their inability in curbing the spread of the virus, which is now endemic in their domestic flocks. 

"If there is concerted effort, we could control it at this stage, i.e., outbreaks in poultry (through culling). Some countries are putting effort in this, but not all can or are able to," Chan said. He added that mass cullings which are needed to stop the virus in its tracks have simply not been carried out. 

While Guan and Chan declined to name errant countries, there is no question how difficult it is to control the virus in Asia, where there are large poultry industries and many households keep chickens and ducks in their backyards. 

Left to roam freely, these domestic flocks mingle with wild birds, sharing the same water sources -- which also happen to be major avenues of contamination. 

Georg Petersen, WHO's Indonesia representative, acknowledged this problem, saying: "International experts recognize the daunting task of trying to control backyard chickens in large countries ... there are major difficulties in doing things." 

Countries such as Indonesia and Vietnam lack the resources for big operations such as mass culling. Some villagers even go out of their way to hide flocks from authorities because they rely on them for food. 

GENETIC CHANGES  Guan has been tracking the geographical spread of the virus and the genetic changes it has undergone since 1997 and says the failure to halt its spread has allowed it to keep changing. 

He said H5N1 has undergone at least 20 reassortments of its genetic material since 1997. Gene reassortment is more dramatic than mutation and happens when viruses swap genes with other viruses, often allowing them to acquire new abilities overnight. 

For example, H5N1 could acquire genetic material from a human influenza virus when it infects people or even pigs, which are also susceptible to many viruses that infect people. This swapping of genes inside people or livestock could create a version of H5N1 that triggers a pandemic. 

"Reassortments are large changes, larger than mutations. A mutation is a very small, minor change, but reassortment is like changing a person's arm or leg," said Guan. 

Experts said there were still valuable lessons to be learnt from experiences garnered in Asia. 

"When you look at Vietnam, Thailand or Cambodia and Indonesia, what they have done right is that after the initial sort of confusion and not understanding what was going on and perhaps not notifying everyone, there has been a lot of action taken and a lot of openness," said Petersen. 

"In Indonesia on the health side there has been a lot of activity trying to revitalise and use the system that was built up during SARS and improve on it. I see the other countries, too, have done a lot." 

Chan identified Hong Kong and Thailand as positive examples, saying steps they took in controlling the disease through mass cullings and surveillance were extremely important. 

"When you have a system of compensation, it will facilitate culling. You also need to detect outbreaks in poultry through good surveillance. You can't sit there and wait for large numbers of dead birds. You want to detect even small numbers," Chan said. 

While Europe appears to be able to detect the disease so far, Guan said he was most worried about Africa. 

"It has no disease control system. This virus can infect not only birds, but other animals too," Guan said.