to account for the recent outbreaks, Roest said. Factor two was concomitant to factor one: proximity of humans. The Netherlands is a crowded country, containing 16 million people within an area half the size of Indiana, and many of those high-density goat farms are sited near towns and cities. Factor three was the weather: Yes, very dry springtime conditions, during each year since 2007, had doubtless exacerbated the airborne spread of the bacterium. And Roest suspected a fourth factor: It might be, he said, that the nature of the bug itself had changed. An evolutionary twitch could have enabled an ecological leap.
His molecular data showed that one particular genetic strain of the bacterium—one among fifteen that his team identified—had come to predominate. “On all farms in the high-risk area,” by which he meant Noord-Brabant and some adjacent zones, “and on the two dairy farms outside,” which also tested positive, “there is one genotype present in 90 percent of all samples. And that is what we call the CbNL-01.” CbNL-01 seems a fancy cryptogram but it connotes simply “Coxiella burnetii, Netherlands, genotype #1.” Such disproportionate representation suggested that a mutation in that strain might have made it especially aggressive, efficient, transmissible, and fierce.
Dutch officials tried to cope with this crisis by means of some forceful, if inconsistent, regulatory measures. In June 2008, shortly after the outbreak among patients at the psychiatric facility in Nijmegen, Q fever became a “notifiable” disease for dairy goats and dairy sheep, meaning that veterinarians were required to notify the government about any abortion storms. (It had been a notifiable disease with regard to human cases since 1975.) Another regulation, issued the same day, prohibited farmers from removing manure from an infected stable or deep litter shed for three months following notification of an outbreak. Almost a year later, in April 2009, as the pattern of outbreaks continued on dairy-goat farms and the number of human cases ascended faster than ever, a program of mandatory vaccination against Q fever went into effect. This order applied to all dairy goats and sheep on farms with more than fifty animals, and to zoos and “care farms” such as the one at Nijmegen, where the general public might come into close contact with infected animals. By November 2009, more than a quarter million goats and sheep had been vaccinated, at government expense—but the human case count for the year was alarmingly high, and concern had spread widely through the Dutch media. So in early December 2009, a ban was decreed on the breeding of goats: no more pregnant nannies allowed until further notice. Closer consideration revealed that was too little, too late. Many females had already been bred. One week later, on advice from an expert panel, the government announced that all currently pregnant goats and sheep (including those recently vaccinated) on affected dairy farms would be culled.
Veterinary teams went out to do the deeds. One dairyman, awaiting the cullers, told a reporter that his animals would be less agitated if he remained with them, but “I just don’t know if I can watch it.” The eventual toll included about fifty thousand dead goats and scores of angry, frustrated farmers, who were compensated for the value of each animal but not for lost revenue as they faced rebuilding their herds, nor for emotional stress. “It was also distressing for the veterinarians,” Hendrik-Jan Roest told me—and distressing too, as he could say from experience, “for the veterinary advisors.”
Despite all these measures, and the disappearance of pregnant goats from the Dutch landscape, Q fever did not disappear—not entirely, not at once. The bacterium was still out there in some abundance. In its small, sturdy form, it could survive in the fetid wastes on infected farms for as long as five months. In its large form, it could replicate in a variety of animals. Highly robust but not too specialized, it was capable of invading a wide range of hosts, and had been found not just in goats and sheep but also in cattle, rodents, birds, amoebae, and ticks. An enterprising organism and, as Macfarlane Burnet had noted, quite versatile.
In time the regulatory measures had some effect, and another spring passed, this one without many newborn or aborted kids. The rate of new human cases declined from its 2009 peak. By the middle of July 2010, only 420 more Netherlanders had been diagnosed with Q fever. The ministry officials could feel guardedly optimistic that their public health crisis had been brought under control.