By Tan Ee Lyn
HONG KONG, March 30 (Reuters) - An influenza pandemic can be avoided if proper disease surveillance and control measures are carried out promptly and thoroughly, leading bird flu expert and microbiologist Yi Guan said.
Guan, who studied the H5N1 bird flu virus after it showed up in people in Hong Kong in 1997 and has tracked its footprints all over the world ever since, is convinced that the world can stop the bug in its tracks if it has enough resolve.
"If proper surveillance is in place for animals and humans, yes, we can stop pandemic influenza forever. Not just for H5N1, it may also work for other subtypes of viruses," he said in an interview over the weekend.
"We have the ability to remove pandemics if we have a long-term strategy."
Guan, a professor at the University of Hong Kong, knows just how backbreaking and mundane surveillance work can be.
He and his researchers have tested more than 200,000 stool samples of chickens, aquatic and wild birds collected from various parts of China since 2000, screening them for the H5N1 virus which experts say could cause the next flu pandemic, killing millions of people.
The university laboratory where Guan works is a World Health Organisation reference facility that also helps to analyse H5N1 samples from other parts of the world, particularly Asia.
Here, Guan has been able to compare H5N1 samples, trace mutations in the virus and track its footprints.
Last week, he and his colleagues published a paper in the Journal of Virology hypothesizing that the H5N1 strains which showed up in Vietnam, Thailand and Malaysia in late 2003 probably originated in China’s southwestern Yunnan province.
"Based on their genetic inter-relationships, they are likely from Yunnan. We detected almost identical viruses in Yunnan in late 2002 and early 2003," he said.
The paper said poultry trade might have been responsible for the introduction of the virus into Vietnam.
"As for the Indonesian virus (which showed up in November 2003), that was detected in (China’s central) Hunan province in 2002 and 2003," Guan added.
The paper did not postulate how the virus got into Indonesia.
Guan said all the years of H5N1 surveillance in Hong Kong and China, and many other parts of the world had paid off.
Although experts have warned of an H5N1 pandemic for years now, the virus remains largely a bird disease. Since late 2003, it has infected only 373 people, although its substantial killing power has left 236 of them dead.
"For disease control, surveillance must be a long term effort. You know where it is and you know it is coming, like a spark of fire you can extinguish it," Guan said.
"If not for all this surveillance and detection ability, the pandemic would probably have already come."
Drawing from what is known of past pandemics, Guan believes that surveillance and strict control measures are the answers.
"Pandemics don’t happen suddenly, they have an early phase, mature phase, outbreak phase. The virus changes step by step, it takes a long cooking time," he said.
"If a virus gets into humans in the early phase, the transmission ability is very low. At most, they infect their families, but it can’t go further into the community.
"This phase is the golden point to control. Once it matures and becomes (efficient in) human-to-human (transmission), it will be too late." (Editing by Alex Richardson)