Wimpy Warmups And Real Deals

A critical lesson of the last few years is that terrorists can rely on simple weapons: box cutters and car bombs. Whether simplicity is a matter of choice or necessity is difficult to know, but the latter is certainly relevant with respect to biological attacks. Without the scientific and technical support of a military-industrial complex, terrorists may be unable to culture and formulate pathogenic organisms into effective weapon systems. Insects, however, offer a low-tech, "safe and effective" alternative: they are easily collected or reared, robust to environmental adversity, and able to disperse on their own. Until recent years, entomological weapons were discounted by some military analysts because of a pair of perceived weaknesses: insect invasions were deemed too slow and too imprecise to alter the course of a modern war. But terrorists are engaged in what we might call postmodern warfare.

For today's radicals, slow-acting agents are not necessarily a problem. Although military planners in industrial nations are not enamored of tactics that take months to play out, terrorists appear willing to engage in interminably protracted conflicts. Blowing up buildings and buses can be a powerful tactic, but there's also a place for low-cost, high-impact operations that take time to unfold. A 1986 report from the Stockholm International Peace Research Institute (SIPRI) provided early glimmers of this realization in noting that, while biological agents had not be considered as effective battlefield weapons because they act more slowly than chemical agents, microbes were judged by military strategists to be suitable weapons for damaging whole populations and agricultural assets.1

As for imprecision, what is a problem for modern militaries may well be a virtue for postmodern terrorists. The SIPRI analysis dismissed conventional military uses of living organisms by reasoning that pathogens were generally uncontrollable and particularly unpredictable when carried by insect vectors.

These limitations echoed the conclusion drawn by Fred C. Iklé, director of the U.S. Arms Control and Disarmament Agency, in the mid-1970s: "The military utility of these [biological] weapons is dubious at best, the effects are unpredictable and potentially uncontrollable."2 Earlier analysts even argued that nations were unlikely to employ insects or other organisms because such weapons would yield high rates of civilian casualties, disrupt vital ecological processes on a large scale, and cause the greatest harm to children, sick people, and older adults. What were once moral disadvantages in conventional warfare have become the very qualities that are sought in today's asymmetrical conflicts. But even the notion that rational analysis can reveal the tactics most likely to be used by an enemy has become problematic in the modern world.

The military historian Alastair Hay has warned that a credible assessment of the vulnerability of the United States to attack cannot rely on our past experience with military tactics or geopolitics.3 Some modern insurgents use unconventional tactics to seek the conventional goal of land, as in Chechnya, Northern Ireland, the West Bank, or the Basque homeland. However, Hay also contends that contemporary enemies may have unusual objectives that preclude western nations from setting aside possibilities, "even if the reasoning behind the attack appears irrational." An act of dubious military value might be favored by the jihadist who seeks to conquer cultures, control minds, and capture souls rather than possess land. And what better weapon to attract attention, disrupt society, or instill fear than insects, the organisms that are consistently one of the frontrunners when pollsters ask what generates the greatest anxiety in people (ironically, according to some studies, more than terrorism itself)?

The vulnerability of the United States and other western nations to terrorist attacks using insects is evident from several incidents in recent years. The most compelling cases concern newly arrived organisms that were not—at least insofar as government officials either know or are willing to admit—introduced by enemy agents. But there is no reason that a moderately educated, reasonably motivated, minimally funded terrorist could not have initiated these outbreaks.

If terrorists were to conduct an entomological attack on an industrialized country, perhaps the greatest impact could be had by using insects to spread disease. Consider what Eric Croddy, one of foremost experts in chemical and biological warfare in the United States, recently listed as the qualities of diseases suitable for weaponization.4 The pathogen should infect the victim in small doses (as with a single bite of a vector); cause acute and severe illness soon after infection (as in many insect-borne diseases); remain potent during production, storage, and handling (as with infected vectors); and survive environmental stresses during dissemination (as within a vector). So what might a terrorist attack with an insect-vectored disease look like? In 1999, the answer was provided in vivid detail.

On August 23, New York City health officials received a call that set into motion a series of events that graphically demonstrated the incapacity of the wealthiest nation on earth to stop an insect-borne disease.5 Deborah Asnis, an infectious disease specialist at Flushing Hospital Medical Center in Queens, reported that she was attempting to diagnose and treat two elderly patients with a mysterious neurological illness. Their fever, confusion, and case histories pointed to mosquito-borne encephalitis, although the victims' severe muscle weakness was rather unusual in such illnesses. Two more patients would exhibit similar symptoms by the end of the week.

Asnis sent tissue samples from her patients to the State Department of Health and called the Centers for Disease Control (CDC, now the Centers for Disease Control and Prevention)—America's frontline defense against new and exotic illnesses. The experts suspected St. Louis encephalitis, and sophisticated tests at the CDC laboratory in Ft. Collins, Colorado, yielded positive results for this disease. Delighted to have an answer, the New York City Department of Health and the CDC announced their finding on September 3. And the Big Apple responded with a flourish.

New York was the best prepared city in the nation to deal with a disease outbreak.6 After the 1993 bombing of the World Trade Center, Mayor Rudolph Giuliani put counterterrorism at the top of his agenda. New York had a cadre of emergency-response officials poised to handle attacks involving unconventional weapons—skills that readily transferred to an outbreak of encephalitis. Jerome Hauer, New York City's head of emergency management, initiated a $6 million insecticide-spraying campaign to quash the mosquitoes and cornered the national market on insect repellent. An army of 500 city employees delivered nearly a half-million cans of repellent to neighborhood firehouses and police precincts for distribution to the citizenry. And a quarter-million brochures printed in eight languages provided residents with vital information about St. Louis encephalitis. There was only one problem—nobody actually had this disease.

While public health officials were worrying about sick people, Tracey McNamara was fretting about dead birds. As the head of the Bronx Zoo's pathology department, she was trying desperately to figure out what was killing her feathered friends. McNamara suspected that eastern equine encephalitis was to blame, but this disease also should have wiped out the emus, which were doing just fine. The perplexed pathologist sent tissues samples to the USDA National Veterinary Services Laboratory in Ames, Iowa. Then she contacted the CDC to call their attention to the possible link between dying birds and sick people.

The CDC laboratory in Ft. Collins, Colorado, was buried under an avalanche of samples from New York City hospitals, and the scientists had no interest in complicating their tidy explanation of the emerging epidemic. So the bird and human investigations proceeded independently. When McNamara learned that the tissue samples she'd sent to the USDA failed to match any pathogen in that laboratory's expansive database, she bypassed the recalcitrant CDC.

The U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID)—the legacy of the military's biological warfare program at Fort Detrick—did not normally involve itself in civilian health matters. But McNamara had a personal connection to a pathologist working at the military facility, who convinced his superiors to make an exception. Within two days, USAMRIID scientists had ruled out St. Louis encephalitis as the culprit.

With this news, the CDC had no choice but to join the army back at the drawing board. And on September 27, the two laboratories announced that a "West Nile—like virus" had been found in the tissue samples. Birds and people were dying from a disease that had never been seen in the Western Hemisphere. Those responsible for biodefense were stunned.

The nation's dress rehearsal for a terrorist attack had been woefully inadequate.7 The public health system had taken 35 days to identify a new disease, and only a stroke of good luck allowed the initial misdiagnosis to trigger an appropriate response—insecticides against the mosquitoes and repellents for the people were the right tools for either St. Louis encephalitis or West Nile virus. One might contend that had New York maintained a more aggressive mosquito-abatement program as part of normal operations, the outbreak might have been avoided, but the city's capacity to respond to a medical (and entomological) emergency arguably made up for the deficiency. The CDC had failed to live up to its motto of "expect the unexpected." The initial screening involved only a half-dozen possible viruses, and there was no consideration that wildlife disease specialists could provide vital clues in solving a human disease mystery.

Nor was the bureaucracy up to the task. Daily conference calls among officials dragged on for hours, so that agencies spent precious time confabulating rather than acting. Biodefense was an "orphan mission" in which dozens of city, state, and federal agencies had say-so but nobody had responsibility. The problem was exacerbated by jurisdictional disputes, which often had to be resolved before anything could be done. But there was little time for agency mea culpas—a city's outbreak was developing into a nation's epidemic.

Despite public health officials having taken impressively, if somewhat fortuitously, swift action to suppress a mosquito-borne disease, West Nile virus moved rapidly beyond the city limits of New York.8 By the end of 1999, the disease had been spread, primarily by infected birds, to four neighboring states. In 2000, cases were reported in 12 states, then 27 states, and by 2002 the disease afflicted people in 44 states. Although fewer than 100 human cases and ten deaths were reported in each of the first three years of the epidemic, this number jumped to 4,156 cases and 284 deaths in 2002. The next year, there were 9,682 cases while the death rate was unchanged. Since that time, morbidity and mortality have declined as people have acquired immunity via low-grade infections, animals capable of serving as reservoirs for the disease have been vaccinated or wiped out, and dry summers in the West have put a damper on mosquitoes. There is precious little evidence that much, if any, credit for this reprieve can be attributed to public health or pest-management programs.

The view among experts in biological warfare that insect vectors would not be effective in disseminating disease was dramatically dispelled. For years, conventional wisdom maintained that biting insects would be too unreliable in locating human hosts, that industrial nations had pest-management systems capable of exterminating any such threat, and that insect-borne diseases were restricted to tropical countries with poor public hygiene. A new disease, carried by indigenous insects, had spread like wildfire across the United States. The public has to wonder whether the government would have been any more capable of suppressing a bioterrorist attack. For that matter, can we be sure that West Nile virus arrived accidentally?

The U.S. intelligence community seriously considered the possibility that this mosquito-borne disease had been loosed upon the American public by the Iraqis.9 And there were reasons for suspicion. In April 1998, the British tabloid Daily Mail published a chilling excerpt from a book entitled In the Shadow of Saddam. The author, Mikhael Ramadan (likely a pseudonym, as nobody has been able to contact him), purportedly served as one of Hussein's doubles. His story is a bizarre account of a madman's plan:

In 1997, on almost the last occasion we met, Saddam summoned me to his study. Seldom had I seen him so elated. Unlocking the top right-hand drawer of his desk, he produced a bulky, leather-bound dossier and read extracts from it. . . . The dossier holds details of his ultimate weapon, developed in secret laboratories outside Iraq. . . . Free of UN inspection, the laboratories would develop the SV1417 strain of the West Nile virus—capable of destroying 97 pc [per cent] of all life in an urban environment. . . . He said SV1417 was to be "operationally tested" on a Third World population centre. . . . The target had been selected, Saddam said, "but that is not for your innocent ears."10

This sounds rather batty, but not completely absurd. Skeptics point out that no strain of West Nile virus has been designated SV1417, but this may well have referred to a code particular to the Iraqi biological weapons pro-gram.11 Furthermore, New York City is not a Third World center, but Hussein was surely capable of changing his mind. And, of course, the fatality rate of West Nile virus is not 97 percent, but Iraqi scientists would have wanted to please their irascible leader.

Various experts, including Ely Karmon, senior researcher at the International Policy Institute for Counter-Terrorism in Herzliya, Israel, have pooh-poohed the notion that Hussein would have used West Nile virus: "There are victims but West Nile isn't one of the biological agents considered to be a warfare or terrorist agent. . . . I don't know what Iraq would achieve from spreading a relatively mild sickness that can be treated. . . . [Hussein] would want to do something more major."12 If Ramadan's account is accurate, then Hussein believed that he was going to accomplish something spectacular. Moreover, Karmon is mistaken about West Nile virus not having been considered as a biological warfare agent.

Ken Alibek, the former deputy chief of research for the USSR's Biopreparat, reported that the Soviet biological warfare program had evaluated West Nile virus because of its potential for mosquito transmission in cities—and the Soviets shared their research with the Iraqis. And members of the U.S. military took seriously the possibility that West Nile virus was used as a simulant by one of America's enemies to assess the nation's vulnerability to insect-borne diseases in preparation for a far more devastating attack.13 But not only are the skeptics' concerns less than reassuring, there are several pieces of circumstantial evidence that make Ramadan's extraordinary claims eerily plausible.

Iraqi scientists had the capability to produce West Nile virus.14 Isolating a virus prior to production can be difficult, but the United States made it easy for foreign researchers by providing pathogens for medical studies. And in 1985, the CDC received a request from Iraq and dutifully supplied samples of West Nile virus. Likewise, building the research facilities to culture viruses is a pretty sophisticated project. However, the French stepped in to help in the 1980s. The pharmaceutical giant Rhône-Poulenc constructed a foot-and-mouth-disease vaccine plant at Al Manal and trained the locals to operate the facility. During the Gulf War in 1990-1991, the Iraqis converted a section of the factory into a production facility for botulism toxin as part of their biological and chemical warfare program. In 1992, the United Nations razed that portion of the plant but left intact the laboratories used for virus research.

A spate of West Nile virus outbreaks in various nations furthered suspicions that something unnatural was afoot.15 While New York was battling its outbreak, the disease struck Volgograd and Rostov, where 600 Russians were sickened and at least 32 died. The next year, simultaneous outbreaks of West Nile virus irrupted in Israel and Saudi Arabia, two of Hussein's top enemies after their duplicity in the Gulf War. The strain of West Nile virus in Israel was apparently the same as that which was sweeping across the northeastern United States. But even if we allow that Hussein's military had the pathogen, did the Iraqis have the capacity to trigger outbreaks in New York City and these other locales?

Experts have been unable to trace how West Nile virus made its way to the United States.16 Some scientists speculate that an infected mosquito or bird might have carried the disease. These creatures could have been stowaways on a ship or plane, or they could have been planted—and nobody would ever know the difference. The CDC has argued that it would require a large number of mosquitoes to trigger an outbreak, which seems unlikely to happen by accident. Other scientists contend that a sick person could have arrived at JFK Airport and then been bitten by a mosquito who spread the virus to local birds. But, again, whether such an individual arrived by accident or was sent by Hussein can't be determined. George W. Bush's secretary of the navy, Richard Danzig, who played a leading role in encouraging the government to prepare for bioterrorism, summarized the problem: "Even if you suspect biological terrorism, it's hard to prove. It's equally hard to disprove."17 But many officials have attempted to deny this essential uncertainty.

In October 1999, the CIA rushed to dismiss the possibility that West Nile virus had arrived via an act of bioterrorism. The agency assured a worried public that "a thorough review of the Iraqi biological weapons program found no evidence that the Iraqis had experimented with West Nile virus at any of the laboratories investigated."18 Of course, absence of evidence is not evidence of absence, and Hussein might have been telling Ramadan the truth when he said that the virus was being produced in laboratories outside of Iraq.

The CDC echoed the intelligence community's claim that the disease was a natural event, and they likewise presented no data in support of their contention. For that matter, neither agency even indicated what direct, empirical evidence could be used in this regard. But the difficulty in sorting out the facts may run deeper than the existence of scientific information, for some bioterrorism analysts contend that the government has good reasons for providing the American public with less than a full account of disease outbreaks. Jason Pate and Gavin Cameron argued in a study published by the prestigious Belfer Center for Science and International Affairs at Harvard's John F. Kennedy School of Government:

Differentiating between naturally occurring outbreaks of disease and those caused purposefully by subnational entities is extremely difficult and may be impossible if no group or individual comes forward to claim responsibility for the outbreak. . . . If it were discovered that a particular outbreak had been intentionally caused, would it be in the public's best interests to make that information widely available? Doing so could create panic and incidentally assist the goals of the perpetrator.19

Based on what we know, it is extremely improbable that West Nile virus was clandestinely loosed on the United States. However, the phenomenal rate at which this disease blanketed the country surely drew the attention of those seeking to harm western nations. Given this lesson, the question becomes, "What insect-borne diseases might yet be used for bioterrorism?"

In 1983, SIPRI published a meticulous analysis of the most likely pathogens to be developed as biological weapons.20 Of the 22 prime candidates, half were arthropod-borne viruses. A similar study in 2000 by the World Organization for Animal Health generated a watch-and-worry roster of livestock diseases, and 6 of the 15 A-list diseases were carried by insects. One disease appearing on both agencies' databases is currently sending chills up the collective spine of U.S. government agencies tasked with protecting humans and agriculture. The virus causing Rift Valley fever might spread as readily as West Nile virus—and the former pathogen makes its African cousin look like a head cold.

After unusually heavy rains in 1930 and 1931, veterinary officers in Kenya began to notice extremely troubling symptoms among sheep in the Rift Valley.21 Within months, thousands of animals were aborting their fetuses, and many of the newborns were dying. The malady started with fever and malaise in the lambs, quickly followed by horrendous bouts of bloody diarrhea, and death within a day or two. These were the first cases of what is now known as Rift Valley fever, a disease that soon afflicted other livestock as well. In cattle, the virus almost invariably caused abortions, and calves suffered 10 to 70 percent mortality; goats, camels, and buffalo were also susceptible.

The pathogen spread within a herd by aerosolized saliva and body fluids, but scientists realized that these forms of transmission could not explain the fast-moving epidemic. The virus' expansion across the countryside would be a slow ramble, rather than a mad dash, if it relied solely on direct transmission. Soon after the disease ravaged Kenya, veterinary scientists grasped the importance of rainfall as a precursor to the epidemic. For a continent in which insect-borne diseases had long been a source of misery, the connections among moisture, mosquitoes, and mortality were all too familiar.

During dry periods, mosquito eggs can survive in a state of suspended animation for months or years, with the Rift Valley fever virus biding its time along with the insect embryo. When the rains return, the infected eggs hatch, the larvae and pupae rapidly mature, and within days a swarm of hungry, disease-carrying adults begins to search for blood. Once the virus infects a mammal, the pathogen replicates at a phenomenal rate. Other mosquitoes then feed on the sick animal—indeed, some species preferentially attack feverish hosts. The infected females pass the virus through their eggs into the next generation and the cycle is complete. With the enormous reproductive potential of the virus and its vectors, Rift Valley fever spreads like living wildfire.

Thanks to a relatively dry period, Kenya was spared another major outbreak until wet conditions prevailed in 1950. Within two years, half a million ewes aborted their fetuses and 100,000 lambs and sheep succumbed to the disease.22 Over the next quarter-century, the disease spread throughout sub-Saharan Africa. The toll on the people of this protein-deficient continent was terrible, but at least the disease was limited to livestock. Or so the experts believed.

In 1977, Rift Valley fever crossed the Sahara, perhaps transported by mosquitoes northward through the irrigated farmlands of Sudan. Whatever the mode of arrival, the disease hammered Egyptian agriculture, sickening a quarter to a half of all sheep and cattle. If the expansion of the disease into northern

Africa weren't bad enough, next came reports of people falling ill with terrible symptoms.

Before the 1977 outbreak, there had been reports of humans suffering from a flulike condition in areas hit by Rift Valley fever. The sick typically recovered within a week. But what the Egyptian medical authorities saw was beyond anyone's experience. Patients were complaining of weakness, back pain, and dizziness. Some victims became anorexic, while others exhibited extreme sensitivity to light, as the virus invaded the retina. Physicians worried that a lethal progression was underway. The retina connects to the optic nerve, meaning that the pathogen had found a bridge into the brain. The doctors' worst fears were realized as patients began to exhibit the classic symptoms of encephalitis: headache, seizure, and coma as their brains became inflamed and then shut down. Others suffered a more grisly fate as the virus infected the liver and other organs, followed by internal hemorrhaging, shock, and death. By the end of the epidemic, 200,000 people had fallen ill, with perhaps 1 percent of the victims becoming blind. In some communities, a third of the populace was afflicted. A virus that previously had not been considered lethal to humans had killed 598 people.23

The outbreak might have been worse, but Fort Detrick's USAMRIID just happened to have 300,000 doses of vaccine for Rift Valley fever on hand. Although the vaccine provided only partial protection, it played a significant role in suppressing the disease among livestock. The stockpile of vaccine left no doubt that the U.S. Army worried about Rift Valley fever being used in a biological attack, at least against the nation's livestock. Whether they knew of its potential to kill people is not entirely clear, but medical experts now peg the expected human mortality during an outbreak at 1 percent (about ten times that of West Nile virus), with 10 percent being possible under some conditions. Among the survivors, as many as one in ten will suffer some permanent loss of vision. The military's concern was validated by subsequent outbreaks in Africa.

The first epidemic of Rift Valley fever in western African was reported in 1987, after construction of the Diama Dam at the mouth of the Senegal River unwittingly created the ideal habitat for mosquitoes. The outbreak wiped out entire herds and killed 200 people. This story was repeated when the Egyptians provided breeding grounds for mosquitoes with the opening of the Aswan Dam. Then, rather than a dam project, an El Niño weather pattern in 1997 created immense tracts of flooded land across Kenya, Somalia, and Tanzania. And this time, along with the tremendous losses of domestic animals and 300

human deaths, devastating economic sanctions were imposed. An embargo by the countries of the Middle East banned exports of meat from eastern Africa for a year and a half. But this effort to keep the disease restricted to the African continent soon failed.

In September 2000, Rift Valley fever struck the Tihama plain of Saudi Arabia and Yemen.24 Tens of thousands of sheep and goats aborted their fetuses, and 855 people suffered from what medical authorities termed "severe cases" of the disease, with one in four dying (see Figure 23.1). A year after this outbreak of Rift Valley fever, exploding planes and collapsing buildings changed how Americans perceived the world. As the pathology of terrorism spread across the world, the potential of insect-borne disease to devastate agricultural production and human health could not be ignored by national security agencies—or, presumably, terrorists.

How difficult would it be to introduce Rift Valley fever to the United States or other western nations? The man with the answer to this question is Colonel Charles Bailey, the director of the U.S. National Center for Biodefense. Nobody in the world is better prepared to assess the matter, given that Bailey earned a Ph.D. in medical entomology, rose from research scientist to commander of U.S. Army Medical Research Institute of Infectious Diseases

Figure 23.1. A pen of goats in Saudi Arabia during the 2000 outbreak of Rift Valley fever. The disease caused tens of thousands of sheep and goats to abort their fetuses, adding the hunger and poverty to villages stricken by the illness. More than 200 people contracted lethal cases of the disease, either via mosquito bites or through contact with the blood or other bodily fluids of infected animals. (Photo by Abigail Tumpey, courtesy of CDC)

at Fort Detrick, served with the Defense Intelligence Agency, and published more than two dozen papers on Rift Valley fever in scientific journals.25

Bailey contends that there are many ways that a would-be terrorist could smuggle the pathogen into a country. The virus is transmissible by aerosols, so a feverish passenger could serve as the carrier, but this tactic would not be terribly efficient. This might be how West Nile virus arrived, but Rift Valley fever has a biological feature that would make it far simpler to introduce: The virus can survive in the dried-out eggs of mosquitoes. According to Bailey:

The easiest [method of introduction] by far—and there's no way authorities would ever detect it—is to simply go to an endemic area during an outbreak, collect floodwater Aedes [mosquitoes] from prime habitats, let them feed on a viremic [infected] animal, collect the eggs, put them on filter paper, let them dry, put them in your shirt pocket, come into the country, go to a suitable habitat, drop the filter paper into the water, and walk away.26

Bailey is not alone in his assessment of the ease with which a bioterrorist could introduce the virus.27

According to Geoff Letchworth—who is a doctor of veterinary medicine and has a Ph.D. from Cornell University, researched insect-borne diseases at Plum Island (the nation's highest biosecurity laboratory, just a mile and a half northeast of Long Island), and recently retired as the research leader of the USDA's Arthropod Borne Animal Diseases Research Laboratory—the challenge for the virus under natural conditions is to overcome several unlikely steps that put the pathogen into intimate contact with its vector and hosts. But Letchworth contends that humans can readily circumvent these limitations:

The terrorist effectively skips the early steps and goes right to the feed lots in the southern U.S. where exposure to mosquitoes is very high, directly inoculates animals and gets it going. I can't believe that you'd be unsuccessful. When Rift Valley fever starts spreading around an area, the attack rates are amazing—20 to 50% of people and animals become infected. The amount of virus that comes out of animals is just amazing. Once it gets cooking it blasts through the whole population.28

Assuming that a terrorist succeeded in initiating a localized outbreak, could the emerging epidemic be contained? Like West Nile virus, the pathogen responsible for Rift Valley fever would find a welcoming committee of native vectors. Nearly every corner of North America harbors a species capable of transmitting the disease. Bailey contends that the staggering reproductive capacity of the pathogen allows it to hijack almost any kind of mosquito. Reaching concentrations in the host's blood that are typically 10,000 times greater than other viruses, the Rift Valley fever virus is ingested by the vector, overwhelms the natural barriers that many mosquitoes have to infection, and then sets up shop in the insect's salivary glands.

Bailey, dismayed with the Department of Agriculture's lethargic and underfunded biodefense program, predicts that the country would be unable to keep the disease from becoming established. Extrapolating from the case of West Nile virus, Rift Valley fever would likely race from coast to coast in five years. Comparing the diseases can be useful, but the tendency to equate West Nile virus, a relatively mild disease, with Rift Valley fever could well cause government agencies to egregiously underestimate the risk.

According to Corrie Brown, who headed the pathology section of the biocontainment facility on Plum Island, Rift Valley fever "would make West Nile look like a hiccup."29 She contends that the disease would shut down U.S. beef exports—a $3 billion loss to the economy. And its impact on people would be painfully evident.

"To say that Rift Valley fever makes West Nile look like a hiccup is an understatement," according to Mike Turell, a USAMRIID specialist.30 He notes that while most people infected with West Nile virus don't even know they have it, 90 percent of those contracting Rift Valley fever are stopped in their tracks by debilitating symptoms. Most survive, but the effect on the nation's health and sense of security would be devastating. Nevertheless, little is being done to prevent or prepare for the arrival of this disease.

According to C. J. Peters, director of the Center for Biodefense at the University of Texas Medical Branch in Galveston, the United States should be aggressively pursuing three lines of defense, none of which is adequately funded or fully under way.31 He argues that the government should be funding the development of an animal vaccine, a human vaccine, and reliable diagnostic tools. What Peters does not include others put front and center: mosquito control.

Based on the fragmented, uncoordinated, and mistimed mosquito programs that typified responses to the outbreak of West Nile virus, the prognosis for curtailing Rift Valley fever by suppressing its vectors is poor. While many communities improved their pest-management systems, the current infrastruc ture is far from sufficient. And with the decline of West Nile virus, control programs are already being dismantled and cannibalized as people, equipment, and funds are directed toward more pressing matters. But this appears to be a very dangerous gamble. Letchworth put the prognosis in starkly unambiguous terms: "If we get Rift Valley fever, we'll forget that West Nile virus ever happened. And taking the long-term view, getting Rift Valley fever in the United States is a matter of when, not if."

Given the expertise that was brought to bear during the National Research Council's study of agricultural terrorism, it is no surprise to find that Appendix E included a scenario exploring the possibility of using Rift Valley fever as a weapon. After conducting a chillingly detailed, hypothetical case study, the scientists concluded that a terrorist would need only a modicum of scientific understanding to select viable times and places for a release of the Rift Valley fever virus. Although Hurricane Katrina struck Louisiana and Mississippi in 2005, which was after the National Research Council's report was published, we can readily apply their analysis to this real-world situation. After the natural disaster, a prospective terrorist would have had no difficulty finding promising mosquito habitat, a collapsed medical system, a shortage of public health providers, a vulnerable human population, and a confused governmental infrastructure.

If there was any doubt as to the vulnerability of this region to mosquito-borne disease, consider that a year after Hurricanes Katrina and Rita hit, the number of West Nile virus cases jumped by 24 percent in Alabama, Louisiana, Mississippi, and Texas.32 A parish in Louisiana reported mosquito populations 800 percent above those prior to the hurricanes.33 With more that 40 percent of the mosquitoes testing positive for West Nile virus,34 there was a silver lining: Rift Valley fever is not yet here.

Having played out a scenario in which Rift Valley fever is introduced to the United States under conditions less opportune than those following the devastation of the Gulf coast, the National Research Council summarized its findings. They concluded that this insect-borne disease is a tempting biological weapon; that the infrastructure of surveillance, diagnosis, communication, and response is inadequate to respond effectively; that the initial outbreak would cause major damage to the nation's economy and human health; that once the disease reached the wildlife population, the virus would be permanently ensconced in this natural reservoir (meaning an unending cost of enhanced pest management and public health programs to prevent major outbreaks); and that—as any good scientific committee is compelled to mention—there should be more research to understand the disease if we hope to prevent or control its spread. In other words, nothing stands between the American public and an epidemic of Rift Valley fever other than a thin membrane of the country's intelligence agencies, the shifting motives and capacities of terrorist organizations, the fickleness of the weather, and the hunger of North American mosquitoes. Fortunately, other insect-borne diseases have a few more obstacles to their being converted into weapons by terrorists.

The most important limitation to a terrorist's launching an insect-borne disease is the mismatch between the exotic pathogen and the native vectors. In many instances, the appropriate six- (or eight-) legged carrier of the disease is not found in Europe or North America, so both the pathogen and its vector would need to be introduced. This would seem to be a rather serious logistical problem, although the hurdle may be lower than one might suppose. The United States and other industrial nations have proved quite susceptible to invasion by biting insects. A sort of blood-filled welcome mat seems to greet the visiting vector.

In August 1985, a mosquito never before seen in the United States was found breeding in Houston, Texas.35 The Asian tiger mosquito (Aedes albopic-tus), named for the impressive pattern of black-and-white striping on its body, was flourishing in the warm stagnant waters found within discarded tires. In fact, the best guess is that the insect arrived as a stowaway on a shipment of used truck tires from Asia, destined for recapping in the United States. Given the 290 million scrap tires in the United States (one for nearly every man, woman, and child in the country), the invader's future was incredibly bright. Within two years, the mosquito had invaded 17 states. So much for one of the most scientifically and technologically advanced nations on earth being able to contain the spread of a blood-feeding insect. But did the lack of control merely reflect a lack of concern among medical experts? Not hardly. This species was a known vector of dengue and was suspected to be a carrier of Western, Eastern, and LaCrosse encephalitis, yellow fever, and dog heartworm.

Developing and deploying a pathogen-vector weapon system might be possible in some cases, but what are a bioterrorist's options when finding, breeding, infecting, and releasing an exotic insect is impractical? In entomological terms, the problem is vector competence. Without an evolutionary association, microbes are not adapted to the unfamiliar species in a target country, so the pathogen is unable to replicate in the insect's tissues and reach levels that allow efficient transmission. Of course, the incompetent vector might carry a few microbes on its mouthparts from the blood of an infected host and function as a flying "dirty syringe," but this is generally an inefficient means of spreading disease. What's needed is a change in the vector's physiology to meet the pathogen's needs. And what evolution might take millennia to develop, scientists can now create in a matter of months.

The dream of engineering insects to do our bidding extends back more than half a century. On the heels of the Cuban missile crisis, President Kennedy ordered an acceleration of biological warfare research, expecting the military to make use of the most advanced technologies available at the time. In response to his commander-in-chief's clarion call, Major General Marshall Stubbs, head of the U.S. Army Chemical Corps, told Congress that research was underway to develop insect strains more resistant to cold and insecticides—presumably to extend entomological weapon systems into the northern reaches of the Soviet Union.36 In 1962, these new strains were almost certainly being developed with tried-and-true artificial selection methods in which those insects that survived exposure to increasingly cold conditions in each generation were mated to boost the frequency of the relevant genes and the cold hardiness of the insects.

A decade later, scientists made the initial breakthroughs that allowed them to imagine a world in which organisms would be genetically tailored to our specifications. In biological factories, stainless steel vats of microbes would produce medicines, nutrients—and toxins. By the 1980s, not only were military scientists talking about making pathogens more deadly and easier to produce, they were beginning to think in terms of creating new insect-microbe associations. SIPRI's experts predicted the development of both more efficient and totally new insect-vector systems for purposes of waging biological war-fare.37 And today, we know that these pioneering scientists were not simply dreaming—nor were the critics of biotechnology merely having nightmares.

A series of breakthroughs beginning in the late 1990s have led to the successful genetic engineering of mosquitoes.38 With methods for inserting genetic material into vectors, the next step was to find and insert a gene that rendered the vector incompetent. Now that we have this creature, the research will culminate with the release of these insects into the wild—where they will, we hope, outcompete the natives. But, of course, the methods that allow genetic engineers to produce a strain of ineffective vectors could well be used by others seeking the opposite result.

According to Letchworth there are no conceptual obstacles to creating some terrifying weapons. He maintains that "there's no reason why a mosquito could not be genetically engineered to transmit, even perhaps produce, the HIV virus."39 And if there were concerns that the insect would not effectively compete with its naturally occurring brethren, Letchworth has the answer: "To allow the new vector to take over, design in some insecticide resistance genes." But to genetically engineer a match between a pathogen and a potential vector, the scientist is not limited to tweaking the insect's DNA.

In terms of a biological weapon system, it would be more promising to alter the genetics of the microbe so that it "fits" into the physiological system of an insect carrier that is already abundant within the enemy's homeland. Although such technological advances are beyond the reach of most terrorists, they are certainly well within the capacity of many nations. And scientific expertise is for sale on the world market. Concerns of blasphemy notwithstanding, playing God may soon be within reach of well-funded terrorist organizations. And the costs are not as high as one might imagine. Letchworth estimates that a facility to tailor-make viruses could be set up for less than $1 million, and the laboratory could be undetectable.

In 1999, New Scientist published an article on biological warfare that portrayed a hellish alliance of entomology, virology, and genetic engineering.40 Imagine a field of corn infested with whiteflies (family Aleyrodidae). These waxy relatives of aphids make the plants appear as if they have dandruff. The farmer's yield is less than stellar, but the insects have not seriously damaged the crop. So the harvest is sent to a brewery, where the corn is used to make beer. The diabolic plot begins to crystallize as hundreds of people become sick. Victims suffer abdominal cramps and vomiting, others have problems breathing, and some die of respiratory arrest.

Faced with public panic, the government tries desperately to track down the cause of the illness and finally identifies botulism toxin. This substance is capable of killing at phenomenally low doses: an amount equal to the weight of a single kernel of popcorn is sufficient to kill 2,000 people. But a critical question looms: What is the source of the toxin? Eventually, researchers trace the origin of the poisoning to the tiny insects that infested the cornfield.

Whiteflies feed by piercing the plant tissues with needlelike mouthparts and in the process transmit microbes in their saliva. A terrorist organization funded rogue scientists to genetically modify a normally harmless plant virus to synthesize botulinum toxin, and the insect dutifully infected fields of corn. In the weeks it took to crack the case, the insects have reproduced and spread at a phenomenal rate. An initial population of six females has the potential to produce 125 billion offspring in a year.

Wave after wave of food scares sweep the nation. As ever more corn is infected, the Department of Agriculture pours billions into an emergency control program. Midwestern skies fill with smoke as enormous tracts of farmland are torched. The credibility of the government is in shambles. The terrorists declare victory.

Such a disastrous chain of events presumes an enemy with the capacity to genetically engineer organisms, or at least to gain access to the requisite methods through a second party. While the necessary training and biotechnology are becoming increasingly available, western scientists are not forfeiting the entomological arms race. Instead, they are turning the tables, enlisting insects for homeland defense. The remarkable abilities of these creatures are being harnessed to protect humans from the dangers posed by modern enemies as well as the buried legacies of past conflicts.

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