An unwelcome Mexican wave
Apr 27th 2009 | NEW YORK
A mysterious new virus is spreading from Mexico. Could it spark a global pandemic?
THE football stadiums and cathedrals in Mexico City were empty this weekend for the first time in living memory. But these are not ordinary times for the nearly 20m chilangos that live in this sprawling metropolis. Mexican officials shut down all schools, banned large public gatherings and otherwise discouraged human interaction in order to control an emerging global viral scourge that by Monday April 27th had claimed over 100 lives. As the threat spread to other parts of North America and beyond, officials at the World Health Organisation (WHO) and at America’s Centres for Disease Control (CDC) declared public-health emergencies.
The culprit is an unusual new virus known as A/H1N1, which is a form of swine flu that has made its way from pigs into humans. Mexican officials began to notice in late March that an unusually high number of patients were suffering from pneumonia and other respiratory illnesses. After preliminary investigations, it was concluded this month that the cause is not seasonal influenza but rather an entirely new hybrid strain composed of pig, bird and human viruses.
They raised the alarm after being flooded with cases that, at least on the surface, appear to be connected with this virus. Over 1,500 Mexicans have been afflicted with symptoms that may be the result of this new virus. But it is not confirmed whether the root cause of most of these cases was A/H1N1 or commonplace strains of influenza. With help from WHO experts, local laboratories are furiously testing genetic samples to verify how many did indeed fall victim to this new virus.
Despite Mexican efforts at containment, five American states—California, Texas, Kansas, Ohio and New York—have confirmed mild cases of A/H1N1. So too has Canada, which was overwhelmed by the deadly SARS (severe acute respiratory syndrome) outbreak a few years ago. Other suspected cases have surfaced in Britain, Israel and New Zealand.
In response, many countries are becoming more vigilant and increasing stocks of antiviral medicines. Some are making noises about banning North American pork, despite assurances from the WHO that eating cooked pork does not transmit swine flu. China and Russia are moving to quarantine visitors with suspicious symptoms. Asian airports have turned on their heat-sensing equipment to detect sick incoming passengers (kit that they had installed after earlier scares resulting from outbreaks of avian flu and SARS). The WHO moved a meeting scheduled for Tuesday to Monday to decide whether to raise its pandemic threat warning level by a notch, from 3 to 4 (on a scale of 6).
It is too early to say whether A/H1N1 is a dangerous pandemic in the making. Until all of the Mexican cases are properly examined, authorities cannot know whether patients suffering from flu-like symptoms actually got this new bug or merely some older, less worrisome one. Without that information, it is also impossible to determine the new disease’s virulence, fatality rates and so on. Officials are likely to make such determinations in coming days, but until then how worried should the globally mobile punter be?
There is both bad news and good news. Unlike typical flus, which usually hit the old and weak, the young and healthy appear to be falling victim to this new disease. Because most people do not have regular contact with pigs, much of the world’s population may lack immunity against swine flu. Those two factors suggest a pandemic, if it happens, may spread easily. There is no vaccine to prevent the spread of A/H1N1, and even if officials were to start work on one today it would take months to produce—by which time the virus may well have mutated.
On the positive side this virus is, at least for now, responding to common antiviral treatments such as Tamiflu. The WHO has an emergency stockpile of 5m or so antiviral drugs, which it plans to make available for the hardest-hit countries. The United States has 50m treatments in its stockpile, and officials have just authorised the domestic release of a quarter of that hoard. Other countries also have their own stocks on hand.
Also encouraging is that all of the cases confirmed outside Mexico seem to be mild ones. Most of the suspected deaths in Mexico appear to be the result of patients waiting until they were very sick before going to hospital. That suggests even if this virus becomes a pandemic, it need not be a deadly one—early intervention may well quash the bug. That points to the most important reason for cheer, even in the midst of uncertainty.
The world is much better prepared today to handle a pandemic than it was just a few years ago. Thanks to the painful lessons learned by Hong Kong, Toronto and other global centres hit by earlier outbreaks, many countries now have emergency protocols in place and are more wary. Also the WHO’s members have agreed on a sensible set of protocols for pandemic preparedness, sharing of genetic samples and other ways of co-ordinating a global response. Thus far, the new system seem to be working well—but it will take some time to know whether it is good enough to cope with A/H1N1.