Terrorist Use of Biological Weapons - Deadly Cultures: Biological Weapons Since 1945 - page 287

contrast to the current focus on bioterrorism, involving aerosols of le-
thal agents causing mass fatalities, these attacks used food contamination
at restaurant salad bars, with an agent of low lethality but capable of
causing mass morbidity. The success of this technologically undemanding
method of attack is worth noting, especially as some lethal agents could
be disseminated in the same fashion.
Interestingly, the outbreak was not recognized as a deliberately insti-
gated event, although there was ample evidence to support such a con-
clusion. Only later was it discovered to have been an attack.
The Outbreak
In the fall of 1984 there was an outbreak of restaurant-acquired sal-
monellosis in The Dalles, Oregon, the county seat of rural Wasco County.
With 751 identified cases, it was the largest outbreak of food-borne dis-
ease in Oregon's history, and the largest in the US for 1984. 5 However, it
undoubtedly afflicted many more than the Centers for Disease Control
and Prevention (CDC) reported. The Dalles is on a major highway out of
Portland, a heavily used scenic tourist route along the Columbia River.
The town, with a population of only about 10,000, had almost 40 restau-
rants in 1984; clearly, most meals were served to travelers, and thus most
cases must have occurred in travelers. The geographic dispersal of restau-
rant patrons, coupled with the fact that most cases of salmonellosis are
never detected—as few as 1 percent of cases may be reported 6 —makes it
certain that a large number, perhaps thousands, of cases among travelers
were missed.
Salmonellosis is normally a brief illness, lasting a few days. It can pres-
ent a variety of symptoms, but is usually associated with diarrhea and fe-
ver, often preceded by vomiting. Symptoms can range from barely detect-
able to fatal. Transient, asymptomatic infection occurs. In the outbreak in
The Dalles, 45 of the 751 known victims were sick enough to be hospital-
ized, but none died.
The Wasco-Sherman Public Health Department began receiving physi-
cian reports of gastrointestinal illness on 17 September 7 and rapidly asso-
ciated them with consumption of meals in one of two restaurants. By 25
September the Oregon Health Division and local authorities had identi-
fied hundreds of cases, the number of restaurants involved had increased