The only thing worse than a huge stinking pit of manure may be a huge stinking and foaming pit of manure that blows up the barn. Over the past few years, explosions have destroyed several Midwestern pig farms, killing thousands of hogs and causing millions of dollars of damage. Pig farmers and scientists have been at a loss to explain these explosions. Could the culprit be a small microbe?
It’s still out there, you know.
A study out today in the journal Science tracks the path of swine flu, which may have receded from the forefront of humanity’s attention but hasn’t quit mixing and moving and making ready. The scientists led by virologist Malik Peiris say the flu virus that the world feared last year has gone back into pigs in China, where it’s laying down and recombining its genetics with other flu strains. And, they say, we’re not sufficiently monitoring the danger of a new strain jumping back to people.
“Just because we’ve just had a pandemic does not mean we’ve decreased our chances of having another,” said Dr. Carolyn B. Bridges, an epidemiologist in the flu division of the Centers for Disease Control and Prevention. “We have to stay vigilant” [The New York Times].
Canada has approved for limited production a genetically engineered, environmentally friendly pig.
The “Enviropig” has been genetically modified in such a manner that its urine and feces contain almost 65 percent less phosphorus than usual. That could be good news for lakes, rivers, and ocean deltas, where phosphorous from animal waste can play a role in causing algal blooms. These outbursts of algae rapidly deplete the water’s oxygen, creating vast dead zones for fish and other aquatic life [National Geographic].
All living creatures need phosphorus, as the element plays an important role in many cellular and organ functions. Domesticated pigs get their daily dose from corn or cereal grains, but not without a struggle. These foods contain a type of phosphorus that is indigestible to the pigs, so farmers also feed their pigs an enzyme called phytase to allow the animals to break down and digest the phosphorus. But ingested phytase isn’t as effective at breaking down phosphorus as phytase created inside the pig would be, so a fair amount of the element gets flushed out in pig waste. That waste, in turn, can make its way into the water supply [National Geographic].
It was only a few years ago that scientists figured out how to reprogram adult cells to make them act like multipurpose stem cells, but the next discoveries are coming fast and furious. Researchers had previously transformed human skin cells into so-called induced pluripotent stem (iPS) cells that can grow into any type of tissue; now, a new study reports that the same feat has been accomplished with pig cells. The achievement raises the possibility that genetically engineered pigs could be reared as organ donors, researchers say.
The created iPS cells could be genetically altered, and then cloned to produce pigs with certain traits. By adding or deleting certain genes, for example, researchers could produce pigs whose organs can be transplanted into patients without them being recognised and rejected. Efforts to do such xenotransplants have already been under way for at least a decade, but iPS cells are easier to genetically engineer and grow in the lab than pig embryos, opening up new possibilities for xenotransplantation [New Scientist]. Pigs are considered potential organ donors because their organs are already similar to those of humans in size and function.
In an ironic twist to the swine flu epidemic, an infected farm worker has infected a Canadian herd of pigs with the virus, and the development is a bad public relations blow for the pork industry. The outbreak came on an isolated Alberta farm after a farm worker returned from Mexico on April 12 and had contact with pigs on the farm two days later. On April 24, pigs began showing signs of influenza; about 220 of the 2,200 pigs on the farm were found to be infected with H1N1 [The Globe and Mail]. The farm remains quarantined although the human and all the pigs have recovered from the flu.
World Health Officials note that the virus hasn’t yet been found in other pigs, including any pigs in Mexico–although epidemiologists are testing pigs in the towns where the flu first emerged in humans. The WHO has also begun calling the virus by its scientific name, H1N1, to avoid confusing consumers (the virus is passing from human to human with sneezes and coughs, like a seasonal flu virus). There is no risk of contracting influenza from pork products. Flu viruses are fragile: They can survive only hours outside a live body – human or animal – and are easily destroyed in meat by cooking [The Globe and Mail].
Egyptian health officials have just reported two deaths from bird flu within days of each other. The dangerous virus variant H5N1 struck down a six-year-old boy and a young woman, bringing the total death toll in Egypt to 25. While bird flu experts note that Egypt has seen a surge in human cases in recent months, with 16 confirmed since the start of the year, compared to seven cases between January 1 and April 17 last year [Reuters], they also say that the Egyptian people’s level of alarm is out of proportion to the threat.
Rumors have appeared in the Egyptian media that the virus is circulating widely, and that some people get “silent infections” which show no symptoms, but still allow them to pass on the virus. The rumors have been fueled by the pattern of recent infections: Many of the infected patients have been toddlers, leading to the belief that stronger adults are also infected but simply show no symptoms. Although thousands of Egyptians have rushed their children to hospitals this flu season, there is no evidence yet of asymptomatic avian flu cases or any significant mutation in the H5N1 virus. “Right now, it’s all hot air,” said Dr. Robert G. Webster, a flu expert…. “I hope to hell it’s not happening, because it would mean the virus is adapting to humans. But there’s not a shred of data” [The New York Times].
While the H5N1 virus rarely infects people, the looming fear is that the virus may mutate into a form that can be transmitted easily from person to person, which could spark a deadly pandemic. However, an outbreak of swine flu across the world from Egypt, in Southern California, has reminded people of the hazards of overreacting before all the information is in.
The number of people infected with Ebola traced from pigs in the Philippines has reached five, but health officials say there is no cause for panic–although they do advise wary attention. The strain of the disease, Ebola Reston, is thought not to be dangerous to humans, and the first identified case, a pig handler who was infected at least six months ago, is still healthy. But experts say there remains some concern because pigs are mixing vessels for other human and animal viruses, like flu, and because it shows that pigs may also be able to transmit the lethal strains of Ebola. Far more humans are in regular contact with pigs than with apes, monkeys or bats, the other known hosts [The New York Times].
The virus was first identified in pigs in the Philippines last year, at which point two farms were closed and blood samples collected from 6,000 pigs and 50 workers. From those, four pigs and one worker tested positive, says Francisco Duque, the Philippine health secretary. In January, a new round of testing turned up four more infected men who worked on pig farms and in slaughterhouses.
Domesticated pigs got their stripes and spots and other distinctive markings thanks to deliberate breeding efforts by the earliest farmers over the course of thousands of years, according to a new study of pig genetics. While there’s no clear evidence of what motivated those early farmers to change their pigs’ coats, study coauthor Greger Larson says a number of possible reasons present themselves. “One is that it facilitated animal husbandry since it is easier to keep track of livestock that are not camouflaged. Another could be that it has acted as a metaphor for the improved characteristics of the early forms of livestock compared with their wild ancestors.” But another possibility, Larson said, “is that the early farmers were as amused and as taken with biological novelty and diversity as we are today” [HealthDay News].
Novelty may have been the desired characteristic in the first agricultural settlements, but in the wild opposite forces were at work to produce pigs with a consistent brown-black color that served as camouflage. “Every time a gene mutation arose in the wild causing coat colour to change, it was eliminated immediately,” says Greger Larson…. “So if a black piglet showed up, that was the one picked off by a predator” [New Scientist].