Watch what you eat. Be careful of where you step.

November 9, 2011

Robert Shope was a highly respected virologist who discovered, among other things, the causative agent of warts, the Shope papilloma virus. He also worked on parasitic worms, and in particular Metastrongylus, a parasitic lung worm often found in farm-raised swine. Pigs get infected by ingesting the embryonated eggs found in fecally-contaminated soil. Shope demonstrated that these long-lived, environmentally resistant ova were capable of harboring swine influenza virus, serving as its “Trojan Horse”. This finding led him to speculate that Metastrongylus might play a role in the transmission of the virus from pig to pig, and perhaps even to people, as well. Swine flu is a life-threatening respiratory infection, so knowing how it is maintained in the environment was an important step in the design of public health programs to limit its spread. The fact that Metastrongylus is found everywhere that pigs are raised is a testament to its simple strategy for transmission. As it turned out, this parasite was not responsible for transmitting swine flu, but Shope’s studies did re-enforce the fact that fecal contamination of pig farms was impossible to control.

Shope was feisty and notorious for his tell-it-like-it-is attitude and “to hell with social protocol”. His laboratory was located at the prestigious Rockefeller University in New York City on the third floor of Theobald Smith Hall. But despite being recognized as a venerable charter member of that “ivory tower” of science, he was compelled to plainly announce to the world his findings regarding the transmission of his now favorite virus, swine flu. Shope created a rather rude saying in bold, easy-to-read lettering and posted it prominently above the entrance to his lab for all visitors to see (much to the chagrin of university officials leading tours of that famous institution, I might add). It read:

The Earth Is Covered With A Thin Layer of Shit

In principle, the World Health Organization agrees with Shope. They state flatly that over half of the world’s farms still use untreated animal waste as fertilizer, and most of it is of human origin. Feces are easy to get and cost nothing. It is also a very good fertilizer! But this creates a real problem, because like the pig parasite story, this unsanitary practice results in the transmission of many fecally-transmitted infectious diseases of humans, as well: a wide variety of dysentery-causing microbes, geo-helminths (intestinal worm parasites that include Ascaris lumbricoides, Trichuris trichiuraStrongyloides stercoralis, and hookworm), and several life-threatening water-borne parasites, the most serious of which is schistosomiasis. These two groups of fecally-transmitted worms infect some 2 billion individuals, and cause serious illness in millions of children, world-wide. Hookworm, alone, infects some 1 billion people. To acquire hookworms, all one has to do is walk around barefoot on ground that is contaminated with human feces that contain the eggs of these parasites. The simple act of swimming in fecally-contaminated fresh water exposes people to the schistosomes. In both of these cases, the parasite does the rest by penetrating our unbroken skin.

Farming facilitates the spread of these parasites, albeit unbeknownst to the farmer. Other microbial infections of animal origin regularly piggy-back on fresh produce, causing outbreaks of serious diseases such as listeriosissalmonella, and E. coli strain 0157.  The prevention of all of these health risks is to isolate our crops from outside sources of fecal contamination. Indoor controlled environment agriculture is the answer. The more we become victimized by preventable outbreaks of food-borne or water-borne illnesses, the easier it is to convince the public as to the value of creating another way of raising food.

Less developed countries are the most affected by these parasites. Eliminate these parasites and the world would be quite a different place. Literacy rates would go up, infant mortality rates would plummet, and the economic picture would go from grim to self-sustainable.  Eventually, birth rates would also drop, and people would now be able to afford so-called “luxury” items like TVs, homes, and cars.

The vertical farm movement is now well underway, and with it the emergence of a new era in food safety and security, whose mantra is avoidance rather than treatment of easily preventable infectious diseases. Millions of lives and billions of health care dollars will be saved when finally everyone can enjoy fresh vegetables and fruits grown under controlled conditions designed specifically to prevent the spread of these insidious microbial infections. Talk about a good return on investment!

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