The past week, the Netiverse has erupted with stories linking the Granjas Carroll confined animal feeding operations (CAFOs) near La Gloria, Vera Cruz, Mexico, with the outbreak of a strain of H1N1 influenza, commonly called “swine flu,” that has triggered concerns about possible flu pandemic reminiscent of the one that claimed tens of millions of lives between 1918 and 1920. Outlets such as Grist, Huffington Post, and Daily Kos have contributed to the eruption, as have some members of the old-line print and broadcast media, but I find much of the reportage at this point troubling.

Why? Because I don’t see any beef — or pork — yet.

What I see is proximity, coincidence, and correlation being confused with causality, but without any evidence that the virus has been present in any of Granjas Carroll’s CAFO sites, we have nothing to support the hypothesis that the current outbreak started there.

Granjas Carroll is a subsidiary of Smithfield Foods, which is based in my current home state of Virginia (full disclosure). Smithfield Foods is notorious for its CAFO operations, which I am firmly convinced by a substantial amount of evidence is responsible for a lot of environmental problems in the regions where they occur. The CAFO operations may even be “breeding grounds” for a variety of diseases. This is not the question at hand.

The question at hand is whether the Granjas Carroll CAFO operations in Vera Cruz are responsible for this disease outbreak. The distinction is important. Our highest priority — in the immediate term — is not eliminating the possibility of any possible disease outbreak in the future. The highest priority is in stopping the potential pandemic in front of us now — the outbreak that is spreading and sickening and killing. To do that, it helps to know where and how it started.

Mind you, the Granjas Carroll CAFOs are legitimate suspects. It is possible that the H1N1 strain of concern emerged there and spread to the surrounding human population via sick workers, contaminated waste, or flies that pick up virus particles from fecal matter in waste pools and deposit them on someone’s dinner nearby. The fact that Patient Zero, 4-year-old Edgar Hernandez, lives in a town near one of the suspect CAFOs adds a plausible connection. In addition the fact that hundreds of people came down with a flu-like illness in the past two months likewise lend credence to the Smithfield connection. The hypothesis looks about as solid as any hypothesis can be.

Nevertheless, in science and medicine, a researcher has to put his pet hypothesis to the test. Hypotheses are tested against evidence, and those that don’t fit — cannot explain — the evidence must be cast aside. A researcher has to reject all alternative hypotheses before being able to accept, or at least get other researchers to accept, his or her preferred hypothesis. Journalists covering scientific and medical matters should keep this fact in mind.

What are some alternative hypotheses here?

* The outbreak may not have originated in La Gloria, Vera Cruz, or Mexico. Hernandez can only retain his Patient Zero title as long as no earlier case of this strain of virus can be found. Given that these searches for Patient Zero are conducted after the fact, it can be difficult, if not impossible, to identify the index (first) case. Hernandez’s mother said that dozens, if not hundreds, of people in the La Gloria area fell ill before Hernandez did. It is likely, then that he is merely the first confirmed case, not the first case. If we cannot be sure he is the first person to be infected by this particular strain of influenza, we likewise cannot be sure that anyone in La Gloria was the first person infected. The search thus expands throughout Vera Cruz, throughout Mexico, throughout the world. Only time and a lot of detective work will tell if the outbreak started in Smithfield’s neighborhood.

* Despite the moniker “swine” flu, this particular strain may not have originated in swine. Reports about the genetic characteristics of this strain are rather confusing, but reports from people actually sequencing the virus (and posting their data on the mailing list ProMED-mail) suggest a mix of swine viruses only — with an mixture of genetic material from both North American strains and Eurasian strains. (This information is subject to change, though, as more samples are sequenced.) So far, the evidence seems to point solely toward pork, except for a basic fact of influenza biology. The flu viruses can often infect multiple species — such as pigs, birds, and humans — and the have a tendency to swap genetic material with other viruses also present in host cells. It is entirely possible that the mutations that produced the H1N1 strain involved in this outbreak originated in a species other than swine. We could be the source.

There is also some contrary evidence to consider. Smithfield Foods officials and Mexican agriculture officials all say there has been no evidence of swine flu in either the animals or the workers at the Granjas Carroll CAFOs. This leads to the following hypotheses: 1) they are lying; 2) they are telling the truth, but they had not been looking for the right evidence; or 3) they are telling the truth.

Personally, I’m not inclined to embrace hypothesis No. 1 until someone finds evidence of deceit. I could accept No. 2, but it is pretty damned unlikely that a flu outbreak could happen at operations as large as the ones near La Gloria without somebody noticing something. If hypothesis No. 3 survives all challenges, it rules out any connection with this particular flu outbreak.

Finally, why is this important?

My colleague Merritt Clifton, in an essay published yesterday, discussed the importance of credibility among journalists. If all the hype proves a bust — if Granjas Carroll is exonerated — the journalists look like unethical, scandal-mongering, can’t-get-their-facts-right fools. In addition, environmental and animal-rights activists who talk up the story — even if motivated by sincere concern about the environmental effects of CAFOs — will look like a bunch of Chicken Littles crying out “The Sky is Falling!” and passing the hat for contributions from the faithful, or at least the very, very nervous.

Michael Crichton, in his book, “State of Fear,” made a lot of money making environmentalists look like greenie-weenie-psycho-terrorists bent on the destruction of civilization as we know it. Far too many people in our society believe that, too. Those concerned about the environmental effect of CAFOs should not reinforce that impression. If the accusations turn out to be wrong now, people are less likely to listen to legitimate allegations in the future.

Some of my colleagues have argued that journalists could use the flu outbreak as a peg to discuss the perils of CAFOs. I argue, however, that if the news peg proves to be faulty, then readers will question everything else in the story that follows. Personally, I would rather not have mistakes in my work inoculate an industry against legitimate criticism for its environmental malpractice.

Journalists should investigate. Journalists should ask hard, unpleasant questions. But journalists should retain (and display) a healthy dose of skepticism until they turn up evidence to back up a connection between an industry practice and an environmental or health problem in question.

Consider this analogy: Anyone can call a politician a crook. It means nothing. A good journalist, however, waits until he catches the politician paying for private expenses with public funds – and runs a photo of the paycheck on the front page. The journalist won’t even need to use the “c” word. The appropriate conclusion will be obvious.

The worst consequence has nothing to do with credibility, however. It has to do with lives. Preoccupation with a false lead in a disease outbreak like this distracts researchers from finding the source of the illness.

Preoccupation with a false lead delays adequate or appropriate actions that could slow or stop the outbreak; likewise it may prompts people to take inadequate or inappropriate defense measures that may make the outbreak worse. I’ll close with a cautionary example.

In 1854, a cholera outbreak that sickened hundreds in a matter of days terrified the city of London. A physician, Dr. John Snow, and clergyman, the Rev. Henry Whitehead, determined — with damning evidence — that the outbreak was triggered by contaminated water from a pump in the Soho neighborhood. Most public health officials at the time, however, were convinced that cholera was caused by miasma — “bad air.” Acting under the belief that “all smell is disease,” they blamed living conditions (and moral failings) of the working poor — the group most heavily affected by the epidemic — for the epidemic. The emphasis on smell placed the focus on obvious nuisances rather than the more subtle, actual cause.

Unfortunately, policies designed to remove the smelly air — by collecting sewage and dumping it into the Thames — made cholera outbreaks more likely by contaminating the drinking water of millions of city residents.

Let’s not make a similar mistake in Vera Cruz. Millions of lives may be at stake.