Interesting Article About Flu

[davidm]

From today's copy of the Economist:

Averting a global plague

Jan 29th 2004

From The Economist Global Agenda

UN agencies have appealed for funds to halt the rapid spread of a lethal strain of bird flu, which they fear could soon evolve into a deadly human disease. Is a global pandemic far worse than the SARS outbreak on the way?

THE great influenza pandemic at the end of the first world war is estimated to have killed up to 50m people worldwide—a far higher toll than even that of the war itself. Besides being highly contagious, flu viruses mutate rapidly, which means that new versions can quickly emerge, against which the body’s immune system may be powerless. Especially deadly are flu strains in birds and animals that have jumped the species barrier to become virulent human diseases, transmissible from person to person.

Now, three United Nations agencies fear that a strain of bird flu, known as H5N1, which has been spreading like wildfire across Asia and is already thought to have killed ten people, could become pandemic in humans if not stopped quickly. On Tuesday January 27th, the World Health Organisation (WHO), UN Food and Agriculture Organisation and the World Organisation for Animal Health jointly issued an urgent plea for funding to halt the new bird flu, which they said could quickly evolve into “an efficient and dangerous human pathogen”. And on Wednesday, an emergency summit on the outbreak was held in Bangkok, with representatives from 13 countries, the three UN agencies and the European Union (EU). On the same day, it was announced that the epidemic itself had arrived in the Thai capital from outlying provinces.

The summit’s host, Thailand’s prime minister, Thaksin Shinawatra, admitted that his government had made errors in handling the outbreak, but his officials denied accusations of a cover-up: last week Mr Shinawatra’s cabinet staged a lavish chicken lunch to reassure both locals and the foreigners who buy more than $1 billion-worth of Thai poultry a year. The two largest importers of Thai chicken, Japan and the EU, have since imposed temporary bans on it. The virus is believed capable of surviving for years in deep-frozen poultry but can be killed by cooking the meat thoroughly.

The countries represented at the summit pledged a co-ordinated fight against the disease and issued a declaration that mass culling of infected poultry flocks was the best way to control its spread. This prompted Indonesia to drop its earlier argument that it could not afford to compensate its poultry farmers for a mass culling.

There had been no recorded cases of bird flu infecting people until an outbreak of H5N1 among poultry in Hong Kong in 1997. Eighteen people suffered severe respiratory illness after contact with infected birds; six of them died. A decision was taken to cull Hong Kong’s entire poultry flock of about 1.5m birds in just three days. By denying the flu strain further opportunities to infect humans, this swift action may have prevented a pandemic, says the WHO.

The WHO has said that the current outbreak of H5N1 in birds started in South Korea in December. However, New Scientist, a British magazine, said experts had told it that the outbreak probably began a few months earlier in China. The Chinese government angrily denied the allegation of a cover-up. Whatever its origin, the disease has spread rapidly and is now believed to be affecting ten Asian countries.

As with the 1997 outbreak in Hong Kong, those people who have so far been struck by H5N1 seem to have picked it up from direct contact with infected birds. As yet, there is no evidence that the virus can pass from person to person. But flu viruses can swap genes with each other, so if someone carrying a human flu virus catches the new bird flu, the two strains could mingle inside the victim’s body, creating a new, highly contagious and lethal human plague. Fortunately, such a doomsday scenario is unlikely: none of the other recent outbreaks of avian flu resulted in human epidemics. But it is not impossible. Two flu pandemics (in 1957 and 1968) that caused large numbers of human deaths were caused by human and animal viruses mingling to form hybrids.

The alarming statements by the WHO and other UN agencies this week may in part have been prompted by a widespread feeling that health authorities in Asia failed to act quickly enough last year to contain the SARS virus, a hitherto unknown human infection. Eventually, the outbreak was largely contained, with about 8,000 people becoming infected, of whom about 800 died (though fresh cases have been reported in China this month). However, there were severe economic side-effects: the Asian Development Bank reckons SARS cost Asia $60 billion in lost revenues, with airlines and tourism especially hard hit.

SARS was a completely new disease in people, whereas any new, human version of H5N1 would be merely a new strain of an old enemy. This ought to be of help in combating it. Already, there are diagnostic tests for the flu strain and effective (though costly) antiviral drugs to treat it. Even so, says the WHO, it would take at least four months to create and start mass-producing a vaccine against a new, human-to-human version.

According to the WHO, public-health experts are agreed that another worldwide flu pandemic is “inevitable and possibly imminent”. But there is no need to panic, yet. Unlike at the end of the first world war, there is now a global disease-surveillance system which would sound the alarm if H5N1 showed signs of being able to pass from person to person. Even if it does, it may evolve into only a mild ailment that most healthy people would survive. Still, the spread of the disease, and the authorities’ response to it, need to be monitored carefully.