Spillover - By David Quammen Page 0,95

Institute, a university-affiliated facility near the city of Lelystad, with an annex devoted partly to research on dangerous zoonotic agents. Whatever was happening in the Netherlands to account for these sequential outbreaks, it was clearly a veterinary concern as well as a matter of human health. The CVI annex, tucked among trees off a secondary road, was so discreet that I had to circle the neighborhood twice to find it. There I was welcomed by Hendrik-Jan Roest, a slim veterinary scientist in rimless glasses and a casual blue sweater, tall enough to play forward on the Dutch national basketball team, who led me back outside immediately so we could peer in the window of a BSL-3 lab where he and his technician were growing C. burnetii. Through the little window I could see incubators and a negative-airflow hood, like the fan hood above a stove, meant to suck away ambient bacteria as his technician worked at her bench. In this building, Roest told me, we work also on West Nile virus, Rift Valley fever, and foot-and-mouth disease, among other things. Rift Valley fever, I said, you have that in the Netherlands? Not yet, he said.

Back in his office, Roest sketched a verbal portrait of Coxiella burnetii, listing the traits that make it so unusual and problematic. First of all, it’s an intracellular bacterium, meaning that it reproduces within cells of its host—as does a virus, though by dissimilar mechanisms—not out in the bloodstream or the gut, where it could be more easily targeted by immune response. Furthermore, it exists in two forms of bacterial particle, one large and one small, each with different characteristics suited to different phases of its life history. The large form replicates prolifically inside host cells and then transmogrifies to the small form, which is tougher and more stable. The small form, almost like a spore, is packaged for survival in the external environment. (The smallness of this small form may account for why Macfarlane Burnet and some others mistook it for “a filterable virus,” a microbe so tiny it passed through filters designed to scoop away ordinary bacteria.) It is resistant to desiccation, resistant to acids, resistant to high and low temperatures, and resistant to ultraviolet light. It can live in salt water for more than six months. No wonder it travels so well, not just from host to host but from place to place—even from continent to continent.

“Does anyone know where it came from?”

“I think it was always there,” Roest said.

Always where? Always everywhere? In Montana, where Herald Cox found it, and in Australia, where Macfarlane Burnet found it, and in the Netherlands, where you’re finding it now? No, not quite everywhere, he said. There is no record of Coxiella burnetii in New Zealand. So far.

Then why had the disease just lately—since 2007—become so troublesome in Noord-Brabant? When I asked him about the increase in dairy goats, he brushed that idea aside as too simplistic and began showing me photos and charts on his computer. One image revealed a vast building, like a train depot, filled with white goats.

“This is the way they are goat farming.”

“Wow.”

“They are huge, huge barns.”

“Big barns,” I agreed.

Another shot gave a clearer view of what he called a “deep litter shed,” the standard arrangement for housing hundreds or thousands of dairy goats. The shed had a concrete floor, recessed below ground level so that it could contain weeks’ or months’ worth of bedding straw, goat shit, and urine, a savory mulch of organic waste that grew ever deeper and, warmed by decay, offered a lovely culture medium for microbes. New straw was added regularly, as long as possible, to stiffen and mitigate the mess. “Very slowly the package of manure and straw is getting thicker and thicker,” Roest explained, “and so the level where the animals live on is coming up.” Shin-deep in their own ordure, the nannies milled around, converting their feed to milk. As the manure rose, composting gently, it harbored uncountable abundances of C. burnetii, “alive and kicking, down deep in the litter.” By the time such a shed had filled to its brim, any single infected goat could have passed its infection to many or most of the others. Then the goats were moved out, machinery came in, shoveling began, the valuable manure was transferred to crop fields and pastures—and billions more particles of the bacterium, in its small and resistant form, were launched on the breezes.

High-density dairy-goat husbandry, Dutch style—that’s one factor among several

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