The World Trade Center and Pentagon disaster and the bioterror- ist events of 2001 have dramatically advanced the need for veterinari- ans, physicians, all other allied- health professionals, livestock and poultry producers and the general public to become more knowledge- able about possible biologic agents that terrorists might release. While direct exposure to disease agents in human beings from bioterrorist attacks has been in the spotlight, livestock and the nation’s food and water supplies are also possible targets. Why Anthrax? Of all the biologic agents, why might anthrax be the first choice? Anthrax could be a desirable agent to a terrorist because it is cheap, effective, easy to produce and simple to store (the highly resistant and dormant spores have been shown to survive at least 60 years in soil in a laboratory). From an economic viewpoint, bio- logical weapons are a very inexpen- sive way to inflict casualties. Research conducted during the cold war era found that the costs per square kilometer to deliver weapons of mass destruction for civilian targets (in 1969 US dollars) was $2,000 for conventional weapons, $800 for nuclear, $600 for chemical and $1 for biological weapons. It is expected that today’s costs could likely be extrapolated with similar cost ratios. (Note: the United States ceased the produc- tion of biological weapons in 1972, after the world’s nations signed a treaty banning them. Consequently, there is a dearth of research in recent years.) Studies performed in the 1970s comparing brucellosis, Q-fever, tularemia and anthrax found that after a hypothetical airplane release of 50 kg of agent along a 2 km line upwind of a population center of 500,000, all agents caused incapacitation of 100,000 or more inhabitants and reached downwind for at least 10 km. Anthrax killed 95,000 people and incapacitated another 125,000 inhabitants and ranged downwind for more than 20 km, further than any other agent in this simulation. Anthrax in People Symptoms Depending on the route of entry into the body, infection by anthrax organisms produces three recog- nized forms of disease in human beings — cutaneous, pulmonary and gastrointestinal anthrax. Rare cases of anthrax meningitis have also been documented. The cutaneous form is the most common and accounts for more than 90 percent of the cases in peo- ple. It has an incubation period of 2 to 6 days after inoculation of a spore or vegetative bacilli into a wound. A reddened, raised lesion develops that may be mistaken for an insect bite. It develops into a blister that later becomes black and very obvious. Edema (swelling or accumulation of fluid) often extends to the associated lymph nodes and beyond. A lesion on the head or neck can produce throat swelling so severe that a tracheal tube must be placed to insure a clear air passage. Mortality is low if treated but can approach 20 per- cent in untreated cases. The pulmonary form has an incu- bation period of 1 to 6 days after inhaling the anthrax spores. It begins like many common respira- tory infections with fever, malaise, muscle pain and coughing. In the second phase, 3 to 5 days later, the patient suddenly develops respira- tory distress, sweating, cyanosis and shock. Death may occur within 24 hours. Mortality is close to 100 percent if untreated and may be as high as 80 percent, even with treat- ment. The incubation period of the gas- trointestinal form is 12 hours to 5 days after eating contaminated L-5418 4-02 Bioterrorism Preparedness — Anthrax D. Bruce Lawhorn Professor and Extension Swine Veterinarian, Texas Cooperative Extension The Texas A&M University System
Transcript
The World Trade Center andPentagon disaster and the bioterror-ist events of 2001 have dramaticallyadvanced the need for veterinari-ans, physicians, all other allied-health professionals, livestock andpoultry producers and the generalpublic to become more knowledge-able about possible biologic agentsthat terrorists might release. Whiledirect exposure to disease agents inhuman beings from bioterroristattacks has been in the spotlight,livestock and the nation’s food and water supplies are also possibletargets.
Why Anthrax?
Of all the biologic agents, whymight anthrax be the first choice?Anthrax could be a desirable agentto a terrorist because it is cheap,effective, easy to produce and simple to store (the highly resistantand dormant spores have beenshown to survive at least 60 yearsin soil in a laboratory).
From an economic viewpoint, bio-logical weapons are a very inexpen-sive way to inflict casualties.Research conducted during the coldwar era found that the costs persquare kilometer to deliverweapons of mass destruction forcivilian targets (in 1969 US dollars)was $2,000 for conventionalweapons, $800 for nuclear, $600 for
chemical and $1 for biologicalweapons. It is expected that today’scosts could likely be extrapolatedwith similar cost ratios. (Note: theUnited States ceased the produc-tion of biological weapons in 1972,after the world’s nations signed atreaty banning them. Consequently,there is a dearth of research inrecent years.)
Studies performed in the 1970scomparing brucellosis, Q-fever,tularemia and anthrax found thatafter a hypothetical airplanerelease of 50 kg of agent along a 2km line upwind of a populationcenter of 500,000, all agents causedincapacitation of 100,000 or moreinhabitants and reached downwindfor at least 10 km. Anthrax killed95,000 people and incapacitatedanother 125,000 inhabitants andranged downwind for more than 20km, further than any other agent inthis simulation.
Anthrax in People
Symptoms
Depending on the route of entryinto the body, infection by anthraxorganisms produces three recog-nized forms of disease in humanbeings — cutaneous, pulmonaryand gastrointestinal anthrax. Rarecases of anthrax meningitis havealso been documented.
The cutaneous form is the mostcommon and accounts for morethan 90 percent of the cases in peo-ple. It has an incubation period of 2to 6 days after inoculation of aspore or vegetative bacilli into awound. A reddened, raised lesiondevelops that may be mistaken foran insect bite. It develops into ablister that later becomes black andvery obvious. Edema (swelling oraccumulation of fluid) oftenextends to the associated lymphnodes and beyond. A lesion on thehead or neck can produce throatswelling so severe that a trachealtube must be placed to insure aclear air passage. Mortality is low if treated but can approach 20 per-cent in untreated cases.
The pulmonary form has an incu-bation period of 1 to 6 days afterinhaling the anthrax spores. Itbegins like many common respira-tory infections with fever, malaise,muscle pain and coughing. In thesecond phase, 3 to 5 days later, thepatient suddenly develops respira-tory distress, sweating, cyanosisand shock. Death may occur within24 hours. Mortality is close to 100percent if untreated and may be ashigh as 80 percent, even with treat-ment.
The incubation period of the gas-trointestinal form is 12 hours to 5days after eating contaminated
L-54184-02
Bioterrorism Preparedness —
Anthrax
D. Bruce Lawhorn
Professor and Extension Swine Veterinarian, Texas Cooperative ExtensionThe Texas A&M University System
meat. The patient develops fever,vomiting, bloody diarrhea andmalaise. Mortality can be close to50 percent if untreated.
After an airplane release of anthraxspores, exposure of human beingsthrough dermal (skin cuts and abra-sions) routes would likely cause anestimated 20 percent mortality ratein untreated cases; oral routes, 25to 60 percent; and inhalation, ashigh as 100 percent. The mortalityrate from an individual with multi-ple exposure routes would be moredifficult to predict.
Treatment and Prevention
Treatment is with ciprofloxacin,doxycycline or penicillin. Cipro-floxacin is used as the antibiotic of choice for possible geneticallyengineered, biologic warfare strainsof anthrax that are resistant topenicillin and doxycycline.
Also, inhalation anthrax is very difficult to treat, especially aftersymptoms are apparent. Even highdose antibiotic therapy may reducethe mortality rate only to 80 per-cent. In addition, an extendedduration of therapy (60 days) is recommended for inhalation exposure because of the persistenceof spores that are resistant toantibiotics. Even with long termantibiotic therapy, persistent sporesin the respiratory tract may germi-nate after treatment has ended tocause anthrax many weeks afterthe initial exposure. No evidencesupports the existence of persistentspores associated with the gastroin-testinal form of anthrax.
After a terrorist attack, possibly the best case management optionfor physicians is an extendedcourse of ciprofloxacin, combinedwith administration of humananthrax vaccine.
Members of the U.S. armed forcesand emergency essential Depart-ment of Defense employees andcontractors assigned to high threat
areas may have been immunizedwith human anthrax vaccine. Thecurrent vaccination schedule isthree subcutaneous inoculations 2weeks apart, followed by doses at6, 12 and 18 months and annualboosters. This vaccine is not avail-able to the general public.
Human anthrax vaccine informa-tion is available from the TexasDepartment of Health(http://www.tdh.state.tx.us/) or at theCenters for Disease Control andPrevention’s Morbidity and MortalityWeekly Report (http://www.cdc.gov/),“Use of Anthrax Vaccine in theUnited States — Recommendationsof the Advisory Committee onImmunization Practices,” Dec. 15,2000, Vol.49, No. RR-15 (404-639-3158 [p]) andhttp://www.anthrax.osd.mil.
Anthrax Signs
in Animals
Animals would also be casualties of a terrorist attack. Livestock, deerand other wild ruminants usuallybecome infected when they ingestanthrax spores while grazing or incontaminated feed (e.g. domesticand feral swine). The incubationperiod is 3 to 7 days and can beperacute, acute or chronic. In theperacute form, an animal that wasnormal just a few hours earliermay be found dead. Cattle, sheep,goats and deer typically have theperacute form.
Animals with the acute form mayrapidly develop fever (up to 107.6degrees F), stagger, tremble andhave signs of abdominal pain andrespiratory distress. They may haveblood-tinged diarrhea, blood in theurine and milk and hemorrhagingfrom the mouth and nose. Pregnantanimals may abort. Animals maydie within 24 hours, with convul-sions in the terminal stage of thedisease. The acute form is morecommon in cattle, sheep, horsesand deer.
In swine, the disease tends to bechronic. Swelling in the head andneck often interferes with breath-ing and swallowing and may causedeath by asphyxiation. There maybe blood-tinged mucous dischargefrom the mouth and snout. Someaffected swine may recover with-out treatment. The chronic form isalso seen in horses and dogs.Chronic cases of anthrax are moreresponsive to antibiotic treatment.
Although cats and dogs may devel-op anthrax from ingesting contami-nated meat, both species seem tobe resistant to inhalation anthrax.Isolation, decontamination andmedication of cats and dogsexposed to anthrax spores would beimportant procedures after a bioter-rorist event.
Anthrax can resemble other condi-tions that cause sudden death. Incattle and sheep, this includesclostridial infections, bloat, light-ning strike, acute leptospirosis,bacillary hemoglobinuria, anaplas-mosis, babesiosis, and acute poison-ing with bracken fern, sweetclover, lead or blue-green algae. Inhorses, acute equine infectious ane-mia, colic, lightning strike, lead poi-soning and blue-green algae poison-ing may resemble anthrax. Inswine, classical swine fever (hogcholera), African swine fever, andpharyngeal malignant edema symp-toms are similar to anthrax.Poisoning and non-fatal vehicle col-lision could mimic anthrax in deer.
Containment and Treatment
The carcass of an animal killed byanthrax generally shows little or norigor mortis, and there is usuallydark blood oozing from the mouth,nose and anus (the blood may notclot). The body will be bloated andwill decompose rapidly. Do notcut into a suspicious carcass!Veterinarians are trained to collecta blood sample from a large veincollected through the unopenedskin for submission for laboratoryconfirmation.
Treatment in naturally occurringcases is more successful if it occursearly in the course of the disease.The recommended twice daily doseof penicillin IM (intramuscular) forlivestock is 22,000 units/kg (10,000units/pound) for 5 days. The dailyoxytetracycline dose is 5 mg/kg (2.3 mg/lb) for all species. It maybe given as an IM or by IV (intra-venous) injection (slowly) in divid-ed doses for at least 5 days (up to26 to 28 days withdrawal time,depending on the product used).An alternative antibiotic such asciprofloxacin may be used if antibi-otic resistant anthrax is used in aterrorist attack. Extra-label usage ofpenicillin as indicated above orciprofloxacin would require anextended withdrawal time of atleast 30 days in food animals.Extra-label use means for purposesor at dosages not approved. Onlyveterinarians can prescribe extra-label drugs — when aveterinary/client-patient relation-ship exists. On their own, produc-ers cannot prescribe or use drugsin an extra-label manner.
The disease management techniqueof isolating sick animals under-going treatment from healthy-appearing animals should be prac-ticed at the immediate premise.Animals should not be moved offthe premise until at least 10 daysafter all livestock are vaccinatedand after proper disposal of all carcasses. The number of quaran-tine days may be extended in thespecial case of terrorist attack,when livestock (and many otheranimals, pets, etc.) may be exposedby unnatural routes of infection(e.g. inhalation, cutaneous or combinations).
Veterinarians are required to reportsuspected cases to their respectivestate animal health agency anddepartment of human health. Ifanthrax is confirmed, the prelimi-nary quarantine issued by the stateanimal health agency will be fullyenforced.
Anthrax Vaccinationin Animals
In anthrax outbreak situations, live-stock deaths should start to subsideat about 10 days after vaccination.A second dose of vaccine should begiven 2 to 4 weeks later. Areas sub-jugated to terrorist attack and seed-ing of the ground with anthraxspores may be sources for anthraxinfection for a long time (depend-ing on soil type and seasonal envi-ronmental conditions). In thosecases, it will be necessary toadminister vaccine to livestock inthese geographic locations at leastonce yearly, 4 weeks before thestart of environmental conditionsthat foster seasonal anthrax out-breaks. These are the same recom-mendations for areas of the UnitedStates currently having seasonalendemic anthrax outbreaks (e.g.Southwest Texas).
Reactions to anthrax vaccine mayinclude swelling at the injectionsite, fever for several days, loweredmilk production and abortion. Milkfrom dairy cows developing feverafter vaccination should bedestroyed. Antibiotics given within7 days of vaccine administrationcan make the vaccine ineffectivesince it is a live attenuated biologic(formulated with live organisms).Animals should not go to slaughteruntil at least 60 days after vaccina-tion.
Environmental Cleanup
The best ways to prevent futureanthrax outbreaks is to keep fromreleasing more spores into the envi-ronment and to destroy existingspores. Anthrax bacteria-contami-nated carcasses, bedding, soil andother materials should be burnedas soon as possible. Burn carcasseswhere they lie. If carcasses must bemoved, use a sled so as not tospread anthrax organisms by drag-ging the carcass across the ground.Remember, do not open the car-cass. The vegetative form of the
anthrax bacteria in the carcass iskilled by burning. If the carcass isopened and vegetative forms areexposed to air, the transformationto the spore form will be a futuresource of infection. Thorough burn-ing kills spores.
In the event of a terrorist anthraxattack that kills livestock and con-taminants pets, personnel in respi-rators and protective clothing willperform environmental clean up,decontaminate pets and burn deadanimals. (Anthrax vaccination alonein clean up workers may not pro-vide complete protection if work isperformed close to the releasepoint, so personal protective gearand respirators are a necessity).Contaminated equipment will thenhave to be sanitized with a sporoci-dal disinfectant, such as 5 percentsodium hydroxide (lye).Usual con-centrations of many common disin-fectants are not effective againstanthrax spores.
Successful Anthrax
Release Depends on
Many Variables
Fortunately for livestock, pets andpeople — the potential targets —successful attack with biologicalweapons hinges on many variables.In the case of anthrax spores dis-persed by airplane, any carrier thatcontains anthrax spores must becorrectly formulated, and theweather conditions must be stable.
Mini-environments, such as windcurrents between and among build-ings in large population centers,make even distribution of agentsunpredictable. Rainfall and changein wind directions also affect distri-bution. Remember that the sameterrorists who successfully killedJapanese citizens with Sarin gaswere unsuccessful with anthraxspores and botulinum toxin releas-es. Researchers know that evenunder the most controlled condi-tions, it is sometimes very difficult
to consistently cause experimentaldisease from various bacterialagents by direct animal inoculation.Aerosol exposure might be evenless reliable.
Although anthrax spores deliveredby postal letters have recentlycaused successful human expo-sures, mass exposure throughaerosol release might not be as suc-cessful.
A bioterrorist attack might beattempted indirectly through foodor water. Any food product suspect-ed or found to be contaminatedwith anthrax organisms should bedestroyed, preferably by incinera-tion. Livestock producers should bealert to never send to slaughter anyanimal showing possible signs ofanthrax. Also, do not touch, fielddress or process the carcass of deer,other wild ruminants or livestockthat may have been incubating orshowing symptoms of anthrax prior to harvest. Do not eat themeat or use other products fromsuch animals.
Attempts to cause anthrax throughcontamination of water may not bevery successful. Within 24 hours ofexperimental inoculation intowater, vegetative anthrax organismswere undetectable. Less informa-tion seems to be available on thepossible transmission via spores
through contaminated water.Testing for the presence of Bacillusanthracis by experts would be thefirst step for evaluation of such ascenario.
Be Prepared
In summary, what can people do toprepare for the possibility of a ter-rorist attack by anthrax or otherbioterrorist agents? They can
� Know the clinical signs for andcountermeasures against themost probable bioterroristagents.
� Talk to neighbors and becomeacquainted with their pets andlivestock.
� Report any suspicious behaviorin people or any increase in ani-mal deaths anywhere and every-where you go.
� Become involved in local, stateor national efforts to prepare forthese possible emergencies.
For more information
Bruce Lawhorn, “Anthrax” factsheet (L-5402, July 2001), TexasCooperative Extension, The TexasA&M University System, CollegeStation, Texas, Web site http://texaserc.tamu.edu.
Centers for Disease Control andPrevention (CDC) Web sitehttp://www.bt.cdc.gov.
Judith Miller, Stephen Engelbergand William Broad. Germs:Biological Weapons and America’sSecret War. Simon and Schuster,Inc. Rockefeller Center, 1230Avenue of the Americas, New York,NY 10020, 2001, (800) 456-6798.
Frederick R. Sidell, William C.Patrick, III, and Thomas R.Dashiell, Jane’s Chemo-BioHandbook 2000, Jane’s InformationGroup, 1340 Braddock Place, Suite300, Alexandera, VA 22314, (703)683-3700, e-mail [email protected].
The Journal of the AmericanMedical Association (JAMA)Consensus Statement, “Anthrax as aBiologic Weapon,” Medical andPublic Health Management, JAMAWeb site http://jama.ama-assn.org/.
U.S. Department of Health andHuman Services (HHS) Web sitehttp://www.hhs.gov/news.
