[health-vn] Swine Flu Shows Need for Better Animal Testing

[Vern Weitzel]

http://www.time.com/time/health/article/0,8599,1895738,00.html

Swine Flu Shows Need for Better Animal Testing
By BRYAN WALSH Tuesday, May. 05, 2009

Given the speed with which the H1N1 flu virus spread around the world — and the 
relentlessness with which it has been tracked by the media — it can be hard to 
believe that less than two weeks have passed since the Centers for Disease 
Control and Prevention (CDC) and World Health Organization (WHO) first responded 
to reports of an unusual respiratory illness.

But even in Mexico City, the epicenter of the global H1N1 outbreak — as of May 
4, the WHO had confirmed more than 1,000 cases in 21 countries — the disease 
seems to be slowing down. The government announced on Monday that restaurants in 
the capital city would reopen by May 6, with churches and museums following soon 
afterward. In the U.S., where the CDC has confirmed 286 cases of H1N1 in nearly 
every state, health officials noted that the illness remained mild. Still, 
officials point out the need to maintain strict surveillance for new cases, in 
the U.S. and especially in countries in the southern hemisphere, where flu 
season is about to begin. (See the top five swine flu don'ts.)

"While we're not out of the woods, we are seeing some encouraging signs," says 
CDC acting director Richard Besser.

As the global panic subsides, scientists will focus on figuring out how to ward 
off the next emerging disease before it lands on our doorstep. "Now is the time 
to take the actions needed to prevent this," says Nathan Wolfe, director of the 
Global Viral Forecasting Initiative, which looks for new pathogens emerging from 
wildlife. One way to start would be to trace how, when and where the H1N1 virus 
emerged from pigs into people (or vice versa — over the weekend, Canada 
confirmed reports that a swine worker in Alberta passed the H1N1 virus to pigs). 
The H1N1 virus contains human, avian and swine flu genes, and genetic analysis 
indicates that it reassorted years ago, meaning it could have been in pig 
populations for some time before the virus gained the ability to transmit easily 
from person to person. If we had had tight surveillance of flu infections among 
swine, we might have noticed that something bad was brewing. (See pictures of 
thermal scanners hunting for swine flu.)

But we don't — unlike diseases like foot and mouth, swine flu is not an 
infection that is automatically reported to national health authorities. Flu is 
common among pigs but not much more deadly than it usually is among people. (The 
H5N1 bird flu virus, by comparison, destroys poultry populations.) That means 
that flu infections in swine herds can easily fall under the radar, as seems to 
have been the case with the new H1N1. Though there were sporadic reports of flu 
infections passing from pigs to people over the past few years, "we hadn't seen 
anything that tipped us off that this was something different," says Tom 
Burkgren, executive director of the American Association of Swine Veterinarians.

A team of scientists from the Food and Agriculture Organization (FAO), the World 
Organization for Animal Health and the Mexican government is now beginning an 
investigation in Mexico, taking blood samples and swabbing the inside of pigs' 
nostrils, looking for H1N1 infection. The hope is to find out how prevalent the 
virus is among Mexican pigs — if at all — and begin to trace back the virus.

It won't be easy. It took years to find the original animal sources of SARS and 
HIV, among other new diseases. What makes tracking emerging viruses inside 
wildlife populations all the more difficult is that animals — even more than 
people — move around a lot, across borders. The U.S. imports live pigs from 
Europe, while Mexico takes in some 600,000 pigs a year from the U.S., so it's 
entirely possible that the virus began in Europe (the H1N1 virus has Eurasian 
genes), then moved to America and Mexico with pigs before infecting the first 
human. "It's going to take several weeks and maybe months to get a clearer 
picture," says Juan Lubroth, a senior officer at the FAO. "There's just a lot 
that we don't know." (Read "Swine Flu: Don't Blame the Pig.")

Although it is too late to put the H1N1 virus back in the bottle, there are 
lessons to be learned for containing future pandemics. One is the need to 
improve monitoring of the trade in live animals, which can spread new diseases 
across borders and even oceans. Peter Daszak, president of the Wildlife Trust, 
notes in a newly published paper in Science that the U.S. alone has imported 
more than 1.5 billion live animals since 2000, the majority of which undergo no 
testing for pathogens before or after shipment. At the height of the H1N1 scare 
last week, many Americans wanted stronger surveillance at the borders to prevent 
the spread of new diseases by foreign travelers — but there has been 
comparatively little attention paid to the live-wildlife trade. "There's a 
backdoor open just waiting for new pathogens to walk in," says Daszak.

In the U.S. and around the world, veterinary health care is the poor cousin to 
human health, chronically underfunded. But if we are serious about heading off 
new infections, we need to increase available resources and make sure that 
veterinarians are looking out for new diseases in livestock and wildlife in the 
same way that the WHO's global flu network is constantly monitoring the world's 
human population for new influenza strains. As we've seen with H1N1, once a new 
flu has emerged and begun spreading among people, it's likely too late to 
contain. "What we need to do is upstream surveillance in animals and wildlife," 
says William Karesh, vice president of the Wildlife Conservation Society's 
Global Health Program. "We've begun to do that with avian flu, but the funding 
isn't available for other species."

In case we had any doubts, the rapid spread of the H1N1 virus should convince us 
that biologically, we live in one world, sharing microbes between species and 
across borders. When it comes to crafting a global early-warning system equal to 
the challenges posed by new pathogens, we're only as strong as our weakest link, 
whether that's the lack of animal-disease surveillance in the U.S. or the 
less-than-ideal laboratory capacity in Mexico. "We have to break down the 
barriers between organizations and agencies," says Lubroth. "It's one world, one 
health."