should be scrutinized. “We found it everywhere,” de Bruin repeated. “There was no secure/unsecure area because the whole farm was infested.”
On the basis of this field sampling and the lab results, he told me, some health officials became overly eager, inclined toward concluding too much. “They said immediately, ‘Oh, that’s the source!’ And we said, ‘Well, it is a source.’ ” But no one had checked the other farms in the neighborhood, any of which might also have been leaking Coxiella burnetii into the air. You should test those too, de Bruin advised. Meanwhile his team worked on other aspects of the outbreak-response study.
They gathered blood samples from 443 people in the Herpen area and, in 73 of those individuals, found evidence of recent infection with C. burnetii; another 38 had been infected sometime in the past. From questionnaire information, the study team matched positives against different forms of potential exposure. The most revealing result from this analysis was that direct contact with animals was not a significant risk factor for infection. Nor was drinking raw milk. Some of the cases—but only a minority, less than 40 percent—involved contact with agricultural products such as hay, straw, and manure. From these data, the team narrowed it down to “windborne transmission” as the most likely source of Q fever in the area. The high incidence of infection among goats, the cascade of abortions, the practice of fertilizing fields with manure from the kidding sheds, the nature of the bacterium itself (more on this below), the dry April weather, and the easterly winds had combined to becloud the village of Herpen with Coxiella burnetii.
De Bruin himself, having helped gather and analyze these data, was acutely aware how well the bacterium went airborne. Later, as the epidemic continued into 2008 and 2009, he grew more wary about field sampling. “I said, ‘Hey, we’re not going anymore without protection—because we’re lab people, we’re not immune.’ ” If you’re a farmer, he said, you may have developed immunity from prior exposure to Q fever at a level that never caused overt illness. That turns out to be quite common among Dutch farmers and veterinarians—but not among molecular biologists. “So we went with masks.” Still, it’s hard to work in a mask—your breathing constrained, your glasses or goggles fogging up—and you find that you don’t want to wear such gear a minute longer than necessary. De Bruin saw more dark amusement in the absurdity of drawing a line between what was impracticable and what was safe. He recalled driving down to another major outbreak site in the south. “I came to that farm, and the only place I could park my car was in front of the stable. So I opened my car, and there was a big wind blowing through the stable.” He got out. He breathed the wind. He thought, “And now I’m going to put on my mask?” This time we both laughed.
The outbreak continued, growing worse in 2008, worse still in 2009. By the end of that year, 3,525 human cases had been recorded since the first alerts in May 2007, most of those still in Noord-Brabant. The infection generally made itself manifest as fever, pneumonia, and in some cases hepatitis. At least twelve people died—not a high lethality compared to some of the grisly viruses, but fairly severe when you remember that this is a bacterial infection, supposedly treatable with antibiotics.
One cluster of cases, in 2008, occurred at a psychiatric care institution in the town of Nijmegen. After three of the psychiatric patients came down with atypical pneumonia and were hospitalized, the Municipal Health Service screened patients, employees, and visitors, finding twenty-eight cases of C. burnetii infection. What was the source? A goat farm near Nijmegen had suffered a storm of abortions, and Q fever was confirmed from vaginal swabs. The bacteria could have traveled downwind from those aborted kids. But in this instance, there was also a more immediate possibility. The psychiatric institution maintained a small flock of sheep on a meadow within the premises. During that year’s lambing season, one lamb had been abandoned by its mother—and was then adopted by a patient, who took it into her bedroom and bottle-fed it six times a day. The pet lamb was also cuddled consolingly by several other patients. This seems to have been somebody’s idea of therapy, until the lamb tested positive for Q fever.
On the day after my conversation with Arnout de Bruin, I drove north to the Central Veterinary