| The recent "outbreak" of Tularemia (rabbit fever or deer fly fever) in Martha's Vineyard, as documented by its diagnosis in 10 people there, has made this medical researcher/writer a little nervous. Here's why: A year ago in October 1999, I attended a 3 day Bioterrorism Readiness conference for health care professionals held in Detroit at The Veteran's Administration. Hosted by USAMRID, the United States Army Medical Research Institute of Infectious Disease, the conference presented several scenarios of "what if's" concerning the possible bioterrorist release of several lethal and infectious biowarfare elements into an unsuspecting community. These biowarfare elements included anthrax, brucellosis, cholera, glanders, plague, Q fever, and ..Tularemia. Although not listed on the CDC's list of reportable infectious diseases, it is classified in USAMRID's Biological Warfare and Terrorism: The Military Response manual as a bacterial biological warfare agent, right up there with anthrax and bubonic plaque. Why? Because Tularemia, or "rabbit fever", was weaponized as a biological warfare agent by the United States Military in the 1950's and 1960s during the United States offensive biowarfare program. It was long suspected then, and known now, that other countries have also weaponized Tularemia as a bacteriological biowarfare agent. This organism is easily delivered into the atmosphere via aerosolization, i.e., spraying via a small canister, atomizer, etc. Interestingly, although it is most frequently "naturally" transmitted via tick bites to humans, it can also be transmitted to humans via mosquitoes, like West Nile Virus. It's appearance in a fairly pristine place like Martha's Vineyard, in at least 10 documented cases so far, then, is, to say the least, highly unusual and something perhaps we should look askance at as something outside the "natural" transmission of the infection. The typical presentation of Tularemia in a "natural" setting, i.e., nonintentional, nonbioterrorist introduction of pathogen into a community, is the ulceroglandular presentation [skin lesions, or "ulcers" and swollen glands], which is usually treated successfully with antibiotics, if caught in a reasonable period of time, and recovery from the infection usually results in permanent immunity. The case fatality rate for this type of Tularemia presentation is small, only 5%. However, in intentional, bioterrorist introductions of the pathogen into a community via an aerosolized spray mechanism, the presentation of Tularemia is much more severe in the Pneumonic or typhoidal form which would result from inhaling the organisms directly via aerosol. In these cases, the fatality rate of Tularemia is much higher, usually 35% or more. But, like the ulceroglandular type of Tularemia, recovery from the infection, if that occurs, results in permanent immunity as well. A LITTLE HISTORY Tularemia was first recognized in Japan in the early 1800s and then again in Russia in 1926. It showed up in the United States in the 1900s when American healthcare workers investigating an epidemic suspected to be bubonic plague isolated the Tularemia organism, and named it Bacterium tularense after the county in San Francisco where it was first documented, Tulare County, California. Dr. Edward Francis determined the cause of "rabbit and deer fly fever" as this newly categorized Bacterium tularense, and thus it was later renamed for Dr. Francis, becoming Francisella tularensis. CLINICAL FEATURES Tularemia has an incubation period of between 1-21 days, the average being 3-5 days, which is dependent upon the dose of the organisms and the route of delivery. If the delivery was via a mosquito or tick bite, the common presentation of Tularemia would be the ulceroglandular type which comprises 75-80% of Tularemia cases. This presentation is most often acquired through inoculation of the skin or mucous membranes with blood or tissue fluids of infected animals. The symptoms of this type of Tularemia presentation are characterized by fever, chills, headaches, malaise, ulcerated skin lesions and painful swollen glands. However, intentional release of Tularemia "belligerents" (concentrated levels of the organism) via aerosolization of living organisms in a bioterrorist-type of presentation {or a biological warfare "experiment"}, would be a much more concentrated inoculation of the bacteria through inhalation, therefore affecting the pulmonary system first, resulting in severe pneumonia conditions and a much higher and faster death rate amongst its victims. This form of Tularemia (characterized by a severe pneumonia, fever, body aches), would predominate in an intentional release setting. Tularemia is not typically spread person-to-person (there have been some cases of this but it is highly unusual). TREATMENT If Tularemia is caught early, treatment with Streptomycin or gentamycin is usually very effective and are the treatments of choice. Tetracycline and other anti-infectives like chloramphenicol are effective too but they can result in high relapse rates of the disease. SUMMARY The fact that one man died from Tularemia on Martha's Vineyard looms a large question over what exactly was the vector of this bacterial outbreak in Martha's Vineyard? Was it a "natural" transmission via mosquitoes or ticks that bit infected rabbits and/or deer and then bit humans? This could be the likely scenario given the unprecedented proliferation of mosquitoes and ticks from the mid-west to the Eastern states from high rainfall levels and cooler temperatures this summer. However, if a higher level of ticks and mosquitoes was the cause of the Tularemia outbreak on Martha's Vineyards, why haven't we seen more outbreaks of Tularemia in the other mosquito-tick ridden states? My home town of Detroit, Michigan is currently overwhelmed with seemingly attacking mosquitoes, and swarms of other bugs, but to date (that I know of) no cases of Tularemia have been documented in Michigan. Nor have other states similarly afflicted by the mosquito/bug problem this summer reported any outbreaks of Tularemia. Is it possible, then, that this outbreak of Tularemia on Martha's Vineyard is, perhaps, a biowarfare experiment to perhaps test readiness of health care personnel to respond to such outbreaks? With the West Nile Virus on the loose, more and more this question of planned bioterrorism readiness crops up. Is the United States Military "testing the waters" out there in certain venues like Martha's Vineyards, a typically idyllic and peaceful community not used to responding to epidemic medical catastrophic emergencies? In contrast, testing readiness for a bioterrorist event in a big urban city, where medical personnel are more ready and vigilant, might not be the best indicator of how well the rest of the nation, i.e., "hometown" USA communities are able to respond and weather such attacks. As I learned in my 3-day biowarfare conference a year ago, the bioterrorist might not strike in a large city, they just might pick a small, quiet community to release an agent in precisely because they are less likely to be prepared for it and more people would succumb to the attack before anyone knew what exactly had hit them. Health care personnel in Martha's Vineyard reported that the last case of Tularemia there was in 1996. One case. Not ten. With the death of the man who succumbed to his Tularemia infection, are any of Martha's Vineyards local government officials wondering what's going on there and has anyone there contacted the CDC or USAMRID with a few hundred questions? Sources: USAMRID's Biological Warfare and Terrorism: The Military and Public Health Response, 1999.
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