At the UN Food and Agriculture Organization (FAO) it’s referred to as the Economy of the Chicken and it goes a long way to explaining why China may be wedded to avian influenza for quite some time.
The standard cost of a hen in Vietnam is US$2.50. Each hen will produce about 70 eggs per year and half of those eggs will be eaten at home. Of the remaining eggs, 60% will produce chicks and of those six will grow into chickens to be sold at the end of the year for a total of US$15. Add the savings in egg purchases (US$3.06) and the return on the original US$2.50 is seven fold.
Given the significant rates of urban poverty in China and the rest of Southeast Asia, it is easy to see why poultry breeding is a popular choice for families looking to supplement their income.
What’s worrying is that the US National Academy of Sciences found that 3% of these healthy looking creatures in wet markets in southern China have and excrete the avian influenza virus.
The result is almost constant and widespread contact between the virus and people. Outbreaks of avian influenza are tied directly to high concentrations of poultry which are tied directly to poor households. In a sense, it could be argued that the widening income gap in China is a factor aggravating the current crisis.
Hippocrates, the father of modern medicine, described the virus in 412 BC and the first pandemic among humans was recorded in 1580. Since then, there have been about three outbreaks per century.
Perhaps the deadliest was the 1917 Spanish flu, caused by a strain of the virus called H1N1, which killed 20-100 million people around the world. In recent decades, the virus has reemerged as Asian flu (1957), Hong Kong flu (1968), Swine flu (1976) and Russian Flu (1977).
The current H5N1 strain first surfaced in 1997 in Hong Kong. New strains of this appeared in 2001 and 2002.
"The avian virus turned out to be a new strain – one that the human population had never seen before," Dr Robert G. Webster, a US epidemiologist, wrote in 2003. "These deadly new strains arise a few times every century, the next one may arrive any day now."
H5N1 is a tricky virus that keeps altering its genetic makeup to best attack potential hosts. Every small change it goes through is called an "antigenic drift". The more drastic change required to enable the virus to transmit itself from human to human is called an "antigenic shift".
If an antigenic drift is like a piece of glass breaking, a shift is like an earthquake. It is a massive event, and one that has already happened.
As things stand now, H5N1 is going through the motions of finding a genetic makeup that can make it through the cracks of the human immune system. The changing nature of the virus means a vaccine can only be developed after the fact.
Before 2015, China plans to spend about US$1 billion to "eradicate" avian influenza and "severe animal diseases".
There are 12 private companies and 17 governments working on developing pre-pandemic vaccines for humans. Some 28 different clinical trials are in progress.
Seeking a cure
The most effective treatment and prevention vaccine currently in the market is tamiflu. Although there are already several production bases in China, the supplies are likely insufficient to cope with a fully fledged outbreak.
Australian company, CLS, says it has developed a vaccine that can be in production just three weeks after the outbreak of a new, deadlier strain of H5N1. It couldn’t be used to treat anybody already infected but it would significantly heighten the body’s ability to defend itself.
With 15 types of influenza virus out there, each of which can be subdivided into multiple strains, a cure-all remains elusive. Things aren’t helped by a very low human resistance to the virus, while poultry have virtually no resistance at all.
"The influenza vaccine that protected humans against infection last year may be ineffectual this year," Webster wrote.
China learnt a lot of lessons during SARS – Hong Kong, in particular, now has a world-class monitoring and response system. The country can mobilize enormous amounts of people in the event of an outbreak and, if necessary, shut down all entries and exits from a specific area. More than that, it has the resources to do this.
In June 2006, China and the World Health Organization (WHO) put in a place a key piece in the outbreak reaction infrastructure with the opening of the Guangdong Centre for Disease Control and Prevention. It is the first line of defense.
Monitoring can only go so far, though. Of the 22 human avian influenza cases found in China last year, only one was preceded by an outbreak in birds. This could mean that vaccination programs are working but also that animal testing may no longer be enough to track the progress of the virus.
"The moment you vaccinate you need to strengthen your animal surveillance system," said Dr Henk Bekedam, chief China representative for the WHO. "The virus is still circulating somehow, but it is more difficult to detect."