Several days after news broke of a possible link between Mexico-based hog CAFOs and the rapid spread of a novel swine-flu strain, what have we learned?

• Clarifying details about respiratory ailments in the Perote area of Vera Cruz State — where U.S. pork behemoth Smithfield Foods raises nearly a million hogs a year in large confinement buildings, under a subsidiary called Granjas Carroll — have emerged. In my original post on this topic, I didn’t fully understand that the outbreak of a virulent respiratory condition in the town of La Gloria — located near Smithfield’s farming operations — wasn’t initially identified as swine flu. The disease emerged as early as February and infected 60 percent of the town’s 1,800 inhabitants, according to the widely cited blog Biosurveillance, run by the U.S. disease-tracking consultancy Veratract (which claims the CDC, the World Health Organization, and the Pan-American Health Organization as clients). Three children died during the outbreak, Veratract reports. Residents blamed the Granjas Carroll confinements for the outbreak; and local authorities evidently agreed. “Health workers soon intervened, sealing off the town and spraying chemicals to kill the flies [which grew in swarms on Granjas Caroll’s manure lagoons] that were reportedly swarming through people’s homes,” according to a Monday account in the Guardian.

There was evidently much confusion about the cause of the disease. “According to residents, the [Granjas Carroll] denied responsibility for the outbreak and attributed the cases to ‘flu,'” Veratract reports. And “State health officials also implemented a vaccination campaign against influenza.” However, “physicians ruled out influenza as the cause of the outbreak.” Yet the symptoms experienced in La Gloria closely resemble those that would later be diagnosed as swine flu, according to several accounts. The Guardian quotes a La Gloria resident:

The symptoms were exactly like the ones they talk about now [with swine flu] …. High fevers, pain in the muscles and the joints, terrible headaches, some vomiting and diarrhoea. The illness came on very quickly and whole families were laid up.

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• On Monday, Mexican authorities revealed that at least one victim of the original outbreak definitely had the same strain of swine flu now wreaking havoc in Mexico City — and his is the earliest known case of the disease. The Associated Press reported Monday that:

Mexican Health Secretary Jose Angel Cordova said tests now show that a 4-year-old boy contracted swine flu in Veracruz state, where a community has been protesting pollution from a large pig farm, at least two weeks before the first death confirmed by the Mexican government. The farm is run by Granjas Carroll de Mexico.

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The question now becomes: Did the outbreak that started in February and killed three kids involve swine flu — or was the 4-year-old boy’s infection an isolated case? If not — if the La Gloria epidemic turns out to be ground zero of the infection — could the swine-flu outbreak have originated literally in the shadows of Granjas Carroll’s hog confinements, and not have some tie to intensive hog farming? That’s a question that health authorities have to vigorously pursue.

• In a statement issued late Sunday, Smithfield said it had “found no clinical signs or symptoms of the presence of swine influenza in the company’s swine herd or its employees at its joint ventures in Mexico.” The wording is interesting here — “no signs or symptoms,” but no information about actual testing of pigs for flu strains. Could pigs carry a flu virus without being visibly ill? Tara Smith, an epidemiologist at the University of Iowa who has done groundbreaking work around hog confinements and the emergence of the deadly, antibiotic-resistant MRSA staph infection, told me in an interview that one would expect to see at least some sign of sickness in hogs carrying a flu bug. Of course, precisely for biosecurity reasons, CAFO operators rabidly resist visitors. When I toured a CAFO-intense county in Iowa a couple of years ago and approached a massive, reeking hog building, an employee rushed to intercept me, claiming that germs from a single healthy human could wipe out an entire 10,000-hog confinement. Confined hogs, you see, are extremely immune-compromised. One hopes that health authorities have been allowed to inspect the Granjas Carroll facilities. 

It’s important to note as well that non-symptomatic pigs can carry flu. Here is a line from the World Health Organization’s recently posted FAQ on swine flu: “The virus is spread among pigs by aerosols, direct and indirect contact, and asymptomatic carrier pigs” (emphasis mine).

• Citizens of La Gloria, as well as some Mexican public-health workers, have pointed to flies congregating on manure piles as a possible vector for the flu, as I reported in my earlier post. Several commenters dismissed that possibility, denying that flies can carry flu viruses. From what I can tell, those folks are wrong. I recently got my hands on a paper by an international team of scientists — including Jay Graham and Ellen Silbergeld of Johns Hopkins — published in the May-June 2008 Public Health Reports. The paper, “The Animal-Human Interface and Infectious Disease in Industrial Food Animal Production: Rethinking Biosecurity and Biocontainment” (PDF), points to a concrete example of flies acting as a flu vector:

[R]esearch conducted during an HPAI outbreak in Kyoto, Japan, in 2004 found that flies caught in proximity to broiler facilities where the outbreak took place carried the same strains of H5N1 influenza virus as found in chickens of an infected poultry farm.

• The public-health scientific community has been sounding the alarm for years about the potential for bio-catastrophe brewing on industrial animal farms. The Graham/Sibergeld paper crystallizes those concerns. I’ll tease out a few key themes.

Untreated manure in lagoons, pointed to by La Gloria residents as a health hazard, can indeed contain flu strains.

Animal biosolids contain a range of pathogens that may include influenza viruses, which can persist for extended periods of time in the absence of specific treatment.

Regulatory regimes, in the U.S. and elsewhere, tend to be lax. Sanitary laws demand the treatment of human sewage; animal waste is a different story:

Apart from some use in animal feeds and aquaculture, poultry and swine wastes are almost entirely managed by land disposal. Pathogens can survive in untreated and land-disposed wastes from food animals for extended periods of time—between two and 12 months for bacteria and between three and six months for viruses. [emphasis mine]

The amount of untreated waste allowed to fester in CAFOs globally is stunning.

The volume of animal wastes is significant, reflecting the considerable expansion of food animal production globally. In the U.S., it is estimated that 238,000 CAFOs produce 314 million metric tons of waste per year, which is 100 times as much biosolids produced by treating human wastewater. Global estimates suggest that 140 million metric tons of poultry litter and 460 million metric tons of swinewaste were produced in 2003, based on data from the Food and Agriculture Organization. [Emphasis added.]

And of course, this vast amount of manure is highly concentrated geographically. For example, the bulk of pork consumed in the United States comes from a handful of counties in Iowa and North Carolina. In Mexico, the Perote region of Vera Cruz carries the burden of intensive hog production. The relatively few workers who staff these industrial farms, as well as the residents who live nearby, are vulnerable to the pathogens — and can carry them to far-flung populations.

Workers involved in removing the wastes from animal houses, transporting wastes, and spreading wastes on land are especially at risk of exposure to pathogens through inhalation, dermal contact, and hand-to-mouth transfers.

Regulations for protecting those workers tend to be … not so strict.

In the U.S., as in much of the world, there is little regulation of occupational conditions or worker exposures in most high-density animal houses. The conditions of work … provide many opportunities for both worker infection and transfer to others in the community. With the exception of concerns about disposal of dead chickens during an outbreak, there has been minimal attention to animal-human interactions associated with the operation and management of broiler poultry houses. Many workers are provided little or no protective clothing or pportunities for personal hygiene or decontamination on-site. Our studies of poultry house workers in Maryland indicate that workers take their clothes home for washing. Thus, it is not surprising that increased risks of pathogen exposure and infections, both bacterial and viral, have been reported among farmers, their families, and farm workers at poultry and swine operations. [again, my emphasis]

• Vera Cruz authorities are suddenly scrambling to deny any link between the Granjas Carroll confinements and the outbreak. Instead, they claim, the flu came from Asia. Say they’re right and the outbreak near the Granjas Carroll confinements is traced directly to an Asian source. Even under that scenario, as the Graham/Silbergeld paper shows, the globe’s rapidly growing meat industry is creating conditions for virulent pathogens, both viral and microbrial, to thrive. As they write:

Industrial-scale poultry production is expanding rapidly in Asia, Africa, Latin America, North Africa, and the Near East. Concerns have been raised over the relatively weak veterinary and public health infrastructure in some of these countries. Swine production is also increasing; for example, in China, pork production increased from 42 million tons to 51 million tons from 2001 to 2006. This increase is largely related to the expansion of the integrated or industrial model of production led by both national  and multinational corporations for expanding markets of increasingly urban consumer populations within these countries as well as exports.

The results of this trend — in Chinese pork production, at least, driven in large part by Smithfield — threaten to be dire.

These new methods of food animal production generate many routes of pathogen transfer among wild and domesticated species and from animals to humans through occupational, peri-occupational, and environmental pathways. At the animal-human interface in these operations, there is inadequate protection of workers and their communities, and, more generally, there is incomplete biocontainment to prevent transfers from the animal house to the general environment.

For more background on confinement operations, see my 2007 special report — “Sow what? On food and farming.”