Field and his colleagues looked, the more evidence of Hendra they found. After the early bat surveys, about 15 percent of their flying foxes had tested positive for Hendra antibodies. This parameter—the percentage of sampled individuals showing some history of infection, either present or past—is called seroprevalence. It constitutes an estimate, based on finite sampling, of what the percentage throughout an entire population might be. As the team continued testing, the seroprevalence rose. At the end of two years, having sampled 1,043 flying foxes, Field and company reported Hendra seroprevalence at 47 percent. In plain words: Nearly half of the big bats flying around eastern Australia were present or former carriers. It almost seemed as though Hendra virus should have been raining down from the sky.
While the scientists published their findings in periodicals such as Journal of General Virology and The Lancet, some of this stuff got into the newspapers. One headline read: BAT VIRUS FEAR, RACING INDUSTRY ON ALERT. The crime-scene tape and the dismembered horses at Rail’s place had been an irresistible starting point for television crews, and their interest continued. A few of those journalistic reports were accurate and sensible, but not all, and none were soothing. People became concerned. The identification of flying foxes as reservoir hosts, plus the high levels of seroprevalence within those bat populations, caused public-image trouble for a group of animals that had a legacy of such trouble already. Approval ratings for bats are never high. Now in Australia they went lower.
One eminent racehorse trainer gave me his view of the matter at a track in Hendra on a sunny Saturday during an interlude between races. Hendra virus! This man exploded at the mention. They shouldn’t allow it! “They” were unspecified governmental authorities. They should get rid of the bats! Those bats cause the disease! They hang upside down and shit on themselves! (Can that be true? I wondered. Seemed biologically unlikely.) And they shit on people! It’s backwards—let the people shit on them! What good are they? Get rid of them! Why doesn’t that happen? Because the sentimental Greenies won’t have it! he groused. We were in the Members Bar, a social sanctum for track professionals, to which I had been admitted in company with Peter Reid. The government should protect people! Should protect vets, like our friend Peter here! Harrumph, harrumph, and furthermore harrumph! et cetera. This trainer, a legendary figure in Australian racing, was a short, bantam-cocky octogenarian with gray hair combed back in dandy waves. I was a guest in his clubhouse and owed him a little respect—or anyway, a little slack. (In fairness, too, he was speaking not long after still another human victim, a Queensland veterinarian named Dr. Ben Cunneen, had died of Hendra contracted while treating sick horses. The mortal risk to horse people, and the economic risk to the entire Australian racing industry, were undeniably large.) When I showed genial interest in quoting this trainer on the record, he spoke more temperately but the gist was the same.
Among the “sentimental Greenies,” he would have included bat carers. But even some of those softhearted activists, the carers, grew concerned as evidence piled up. They had two worries, uneasily counterbalanced: that the virus would make bats even more unpopular, leading to calls (like the trainer’s) for bat extermination, and that they themselves might become infected in the course of their well-meaning work. The second was a new sort of anxiety. It must have caused some reexamination of commitment. They were bat lovers, after all, not virus lovers. Does a virus constitute wildlife? Not in most people’s minds. Several such carers asked to be screened for antibodies, which opened doors for a broad survey, quickly organized and led by a young epidemiologist from the University of Queensland named Linda Selvey.
Selvey tapped into the wildlife-carer networks in southeastern Australia, eventually finding 128 bat carers willing or eager to be tested. She and her field team drew the blood and asked each participant to complete a questionnaire. The questionnaires revealed that many of these people had had prolonged and close contact with flying foxes—feeding them, handling them, not infrequently getting scratched or nipped. One carer had been bitten deeply on the hand by a Hendra-positive bat. The most unexpected finding of Selvey’s survey was the percentage of those 128 carers who tested positive for antibodies: zero. Despite months and years of nurturing, despite scratches and bites and cuddling and drool and blood, not one person showed immunological evidence of