Bioterrorism. Clinical recognition and primary management

The recent anthrax attacks in the United States have demonstrated the reality of bioterrorist threats as well as the need for preparedness and planning to mount a successful response to such events. Medical practitioners have a key role in responding to bioterrorist activity because they can contribute to the timely recognition of an event and to the mitigation of morbidity resulting from a bioterrorist attack. The medical community needs to become familiar with how to recognize and manage diseases produced by the biologic agents that might be used by terrorists. This review summarizes the microbiological and clinical aspects of the agents of anthrax, smallpox, plague, and tularemia, which are all considered likely bioterrorist weapons.

Combating high-priority biological agents What to do with drug-allergic patients and those for whom vaccination is contraindicated?

The threat of bioterrorism continues to be a very real one. Regularly, there are news stories on bioterrorism-related topics: What biologic weapons will our enemies likely use to attack the United States? How prepared is our country to successfully counter such attacks? Although these critical questions are being addressed by the leaders of our country, allergists-immunologists, too, will have to grapple with difficult questions during these uncertain and frightening times. We care for a special group of patients with various allergic and immunologic disorders. Some of our patients have immunodeficiency disorders that might preclude them from receiving life-saving vaccines. Our patients with drug allergies are fearful that should they become infected with a biologic agent, they will not be able to receive appropriate treatment. In this article we focus on the various vaccine-related and antibiotic-related adverse effects that the allergist-immunologist might see during treatment of infections caused by Category A agents. Where possible, potential management approaches are outlined.

Prevention and treatment of bacterial diseases caused by bacterial bioterrorism threat agents

There is general consensus that the bacterial agents or products most likely to be used as weapons of mass destruction are Bacillus anthracis, Yersinia pestis, Francisella tularensis and the neurotoxin of Clostridium botulinum. Modern supportive and antimicrobial therapy for inhalational anthrax is associated with a 45% mortality rate, reinforcing the need for better adjunctive therapy and prevention strategies. Pneumonic plague is highly contagious, difficult to recognize and is frequently fatal. Therefore, the development of vaccines against this agent is crucial. Although tularemia is associated with low mortality, the highly infectious nature of aerosolized F. tularensis poses a substantive threat that is best met by vaccine development. Safer antitoxins and a vaccine are required to meet the threat of the use of botulinum toxin as a weapon of mass destruction. In this article, the current status of research in these areas is reviewed.

[Use of monoclonal antibodies to plague microbe antigens at the early stage of infection in white mice for enhancement of the late streptomycin and doxycycline treatment]

It was demonstrated that use for prophylaxy (after 5 h of infection) or for treatment (after 24 h after infection) of the monoclonal antibodies mixture to specific epitops of capsule antigen (fraction 1), lipopolysacharide, murine toxine can prevent development of plague pathogen at 100 of mice infected by approximately 1000 LD50 Yersinia pestis 231. 5-day course of prophylaxy by monoclonal antibodies provided survival of 50 per cent animals. Subsequent use of fraction 1 antigen for 5 days followed by treatment with streptomycin or doxycycline at 6-7-8-9-10 days after infection with Y. pestis 231 prevented infection manifestation at 80 per cent of animals, etiotropic therapy started at the same period was ineffective. When white mice were infected with Y. pestis 231 Fra-, with deleted ability to produce capsule antigen (fraction 1) 80% level of efficacy can be provided by subsequent administration of antibodies to fraction 1 combinated with lipopolysacharide, murine toxine and streptomycin. Use of monoclonal antibodies followed by doxycycline was ineffective.

The usual suspects

Any scientist will think twice before reporting any discrepancy or possible theft of biohazardous material to either his or her institution or to the government.

Pneumonic plague

Pneumonic plague, a disease caused by the bacterium Yersinia pestis, is a rare disease in the United States and carries a high mortality. Health care professionals in the United States are not familiar with the clinical presentation and diagnosis of plague pneumonia. The wide prevalence of the bacterium in different parts of the world, its high virulence, and its ability to spread by aerosolization makes it a potential agent of biological warfare in the hands of terrorists. This review focuses on the prevalence, pathogenesis immunity, clinical manifestations, diagnosis, treatment, and prevention of plague pneumonia, with particular emphasis on the plague bacillus as an agent of biological warfare. Based on available information, we discuss measures that need to be undertaken by health care personnel, public health personnel, and epidemiologists in the event of such an attack.

[The plague, possible bioterrorist act]

PLAGUE AND BIOWARFARE: Plague is an infection caused by Yersinia pestis. This is a major agent that might be used as a biological weapon. If the bacteria is sprayed, the most frequent clinical form would be pneumonia. If contaminated fleas were used, the bubonic and septicaemic forms would be those observed. Suspicious context A biowarfare act by spraying Y pestis must be suspected when a patient without any risk factors presents with a primary pulmonary form of the disease in a non endemic area.

PRACTICAL MANAGEMENT

All the patients presenting with a pulmonary form of plague must be hospitalised and isolated in de-pressurised room, at least for the first three days of antibiotherapy. For the other clinical forms, patients must isolated during the first 48 hours of treatment. Treatment must be initiated as rapidly as possible. Strains of Y. pestis are usually sensitive to many antibiotics (streptomycin, gentamicin, doxycycline, ciprofloxacin, chloramphenicol, sulfadiazin, trimethoprime-sulfamethoxazole...).

PREVENTION

In the case of contact with a spray suspected of containing the plague bacilla, doxycycline or ciprofloxacin can be prescribed. A dead cell vaccine exists, but its efficacy in terms of protection from primary pneumonia appears inadequate.

Recognition and management of bioterrorism infections

Recent events have demonstrated that bioterrorists have the ability to disseminate biologic agents in the United States and cause widespread social panic. Family physicians would play a key role in the initial recognition of a potential bioterrorism attack. Familiarity with the infectious agents of highest priority can expedite diagnosis and initial management, and lead to a successful public health response to such an attack. High-priority infectious agents include anthrax, smallpox, plague, tularemia, botulism, and viral hemorrhagic fever. Anthrax and smallpox must be distinguished from such common infections as influenza and varicella. Anthrax treatment is stratified into postexposure prophylaxis and treatment of confirmed cutaneous, intestinal, or inhalation anthrax. Disease prevention by vaccination and isolation of affected persons is key in preventing widespread smallpox infection. Many resources are available to physicians when a bioterrorism attack is suspected, including local public health agencies and the Centers for Disease Control and Prevention.

Bioterrorism and critical care

A bioterrorist attack of any kind has the potential to overwhelm a community and, indeed, in the case of smallpox, an entire nation. During such an attack the number of patients requiring hospitalization and specifically critical care is likely to be enormous. Intensivists will be at the forefront of this war and will play an important role in dealing with mass casualties in an attempt to heal the community. A high degree of suspicion and prompt recognition of an event will be required to contain it. Specific knowledge of the possible agents that can be used will be key in managing patients and in estimating the needs of a health care facility and community to deal with the future course of events. Intensivists play various roles aside from the delivery of critical care to the patient in the ICU. These roles include making triage decisions regarding the appropriate use of critical care beds (which automatically dictates how other non-ICU beds are used and managed) and serving as a team member of ethics committees (on such issues as dying, futility, and withdrawal of care). Indeed, intensivists are no strangers to disaster management and have served on the forefront of many. A biologic weapons attack, however, is likely to push this multidimensional nature of the intensivist to the maximum, because such an attack is likely to result in a more homogeneous critically ill population where the number of critical care staff and supplies to treat the victims may be limited. One hopes that such an event will not occur. Sadly, however the events of September 11, 2001, have only heightened the awareness of such a possibility.

[The plague]

The word plague evokes associations with old times, but plague actually does still occur all over the world. The survival chances are at the moment much better (antibiotics) than formerly, when half of the patients died; now this figure is 15%. The causal organism is Yersinia pestis, a bacterium in fleas on rodents. This bug is a plausible candidate for attacks by bioterrosists. So, in this time, there is good reason to pay attention to it, as well as to to smallpox and anthrax and their causal organisms.

Bioterrorism: pivotal clinical issues. Consensus review of the Society of Infectious Diseases Pharmacists

OBJECTIVES

To discuss specific facts regarding use as a bioweapon, epidemiology, microbiology, clinical manifestations, diagnosis, antimicrobial therapy, immunization, and isolation precautions for five most likely agents of bioterrorism; to review and provide recommendations for health care clinicians on the management of these bioterrorism agents; and to share information on the pharmacist's role in preparedness and response.

PARTICIPANTS

The manuscript was drafted by the three authors, reviewed by a group of selected members of the Society of Infectious Diseases Pharmacists, and approved by its Board of Directors.

EVIDENCE

The primary focus was to review and summarize recent and key articles on bioterrorism. Preference was given to peer-reviewed journal information and government-sponsored journals, such as the MMWR, Morbidity and Mortality Weekly Report.

CONSENSUS PROCESS

Written comments were requested from each reviewer. Comments were incorporated into the final draft.

CONCLUSION

Pharmacists play an integral role in disaster preparedness and response and should be involved in planning committees. As drug information specialists, pharmacists can assist other health care providers and emergency personnel, as well as provide counseling to calm, comfort, and empower the public.

[Formation of virulent antigen-modified mutants (Fra-, Fra-Tox-) of plague bacteria resistant to rifampicin and quinolones]

Experiments were performed with two strains of plague bacteria--231 (isolated from marmot) and 358 (isolated from human) and their isogenic variants with Fra- and Fra-Tox- phenotype. Mutants resistant to rifampicin (Rifr) and nalidixic acid (Nalr) appeared independently of pathogen phenotype and genotype with frequency n.10(-8)-n.10(-9), subsequently. Rifr mutation influenced on virulence manifestation at albino mice and antigendeficient variants with Fra- and Fra-Tox- phenotype. In every group of strains highly virulent subcultures were registered. Resistance to nalidixic acid mainly was not associated with virulence loss. Nalr mutants of parent and antigenmodified mutants were cross resistant to fluoroqinolones (ciprofloxacin, ofloxacin, pefloxacin, lomefloxacin). LD50 for untreated albino mice did not differ from LD50, for mice treated with rifampicin (when mice were infected with strain resistant to rifampicin) or with nalidixic acid and fluoroquinolones (when animals were infected with Nalr mutants). Antigenmodified strains of plague bacteria and their Rifr, Nalr mutants were able to overcome specific immune reaction. The drugs should be used in synergic combinations (with aminoglycosides or cephalosporines of III generation) to prevent appearance of virulent strains resistant to rifampicin and fluroquinolones.

Therapeutic challenges posed by bacterial bioterrorism threats

The events of the autumn of 2001 in the United States made it clear that the spectre of the use of microorganisms to intentionally harm humans is a reality. The current strategy to control disease outbreaks caused by the intentional release of bacteria is to use antimicrobial agents, both therapeutically and prophylactically. However, multidrug-resistant strains of bacterial bioterrorism agents occur naturally or have been bio-engineered, indicating how vulnerable this strategy is.

Anthrax, tularemia, plague, ebola or smallpox as agents of bioterrorism: recognition in the emergency room

Bioterrorism has become a potential diagnostic consideration in infectious diseases. This article reviews the clinical presentation and differential diagnosis of potential bioterrorist agents when first presenting to the hospital in the emergency room setting. The characteristic clinical features of inhalation anthrax, tularemic pneumonia, plague pneumonia, including laboratory and radiographic finding, are discussed. Ebola vieus and smallpox are also discussed as potential bioterrorist-transmitted infections from the clinical and epidemiologic standpoint. In addition to the clinical features of the infectious diseases mentioned, the article discusses the infectious disease control and epidemiologic implications of these agents when employed as bioterrorist agents. The review concludes with suggestions for postexposure prophylaxis and therapy.

Confronting bioterrorism: physicians on the front line

The events surrounding September 11, 2001, and its aftermath have compelled the public health and medical community to face the hitherto unfamiliar reality of bioterrorism. Physicians and public health personnel are frontline soldiers in this new form of warfare. This article provides a general overview of the pathophysiology, clinical presentation, diagnosis, and management of patients infected with the 6 highest priority agents that could potentially be used in bioterrorism. The diseases discussed include anthrax, smallpox, tularemia, plague, botulism, and viral hemorrhagic fevers. Despite the unpredictable nature of bioterrorism, disaster preparedness and knowledge of essential diagnostic and epidemiological principles can contribute substantially toward combating this new threat.

Biological agents as weapons 2: anthrax and plague

Although most naturally occurring infections with anthrax and plague are cutaneous, both organisms are most likely to be deliberately disseminated in aerosolised form, resulting in severe pulmonary illness. Mortality from both would be high and rapid in the absence of early and effective treatment, making swift and effective liaison between alert clinicians and public health authorities crucial to an effective response. Differentiating features include mediastinal widening (anthrax) and haemoptysis (plague). Doxycycline and ciprofloxacin are effective agents for prophylaxis and treatment for both diseases. Medical advocacy for strengthening the Biological Weapons Convention, particularly with an enforceable protocol including verification and compliance provisions, is needed.

[Evaluation of the effectiveness of antibacterial substances in treating an experimental form of bubonic plague in monkeys]

The modelling of glandular plague and selection of the conditions for estimating the efficacy of new antibacterials for the treatment of the infection were performed on hamadryads (baboons). The experiments showed that the average LD50 of the culture of a highly virulent strain of Yersinia pestis on its subcutaneous administration to the animals was 2089 viable microbes. In 18 per cent of the episodes the experimental glandular plague in the animals was complicated by secondary plague pneumonia. Subcutaneous administration of 2 x 10(7) viable microbial cell of the plague pathogen caused acute sepsis and the animal death. The treatment of the experimental glandular plague in the hamadryads demonstrated that new antibacterials such as amikacin, netilmicin, ceftriaxone, cefotaxime, ceftizoxime, doxycycline, rifampicin, ofloxacin and ciprofloxacin were not inferior in their efficacy to streptomycin and tetracycline successfully used in the therapy of patients with plague.