Anthrax: Public health response plan for Australia

Disease Containment

Page last updated: 05 December 2012

5. Disease Containment


Epidemiological investigation
Containment strategies
Infection control measures
Clinical management of patients
Immunisation
Environmental surveillance

Epidemiological investigation

A single case of anthrax should be considered an outbreak and should be managed with great urgency. If one or more patients seem to have been infected in an unusual way, such as no evidence of exposure to infected animals or their products, a deliberate release of anthrax organisms must be considered. Active case finding would be required.

Containment strategies

Control of case: The treatment advice in the following sections is advisory only. Always consult the most recent edition of Therapeutic Guidelines: antibiotic (Therapeutic Guidelines Limited) and seek the advice of an infectious diseases physician.
  • Control of contacts: Whilst there is no person-to-person transmission of anthrax, State/Territory health authorities will trace and follow up anyone who may have been exposed to the same source. Contacts include workers involved in environmental control.
  • Control of the environment: Samples will be collected from the affected area and tested. The affected area will be quarantined until decontaminated. State/Territory health authorities will notify State Departments of Agriculture if an animal anthrax case is suspected.

Infection control measures

Initial patient presentation

Patients presenting with symptomatic anthrax are unlikely to be harbouring infectious spores unless these are still present in the clothing following, for example, a deliberate release of anthrax spores. Following a suspected deliberate release, the patient’s skin and clothing should be regarded as infectious. The clothing should be removed and double bagged in sealed, tagged plastic bags until either decontaminated or shown to be non-infectious for a BT agent.
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Other items such as watches and jewellery should be stored similarly, in separate sealed, tagged bags. All of the patient’s personal effects should be handled as little as possible before bagging, and by staff wearing PPE, including contact and respiratory protection. The patient should be bathed or showered thoroughly with soap and water as soon as practicable after initiation of antibiotic therapy.

If the patient’s clothing and other personal effects are negative for infectious, radiological and chemical BT agents, the items may be returned. If the patient has been exposed to an agent, their personal effects must be retained as evidence. If an item cannot safely be decontaminated and retain function, the patient should be informed and the item disposed of.

Routine patient management

Standard infection-control precautions are adequate, and should be observed with all patient contact, and when the patient is moved. Standard precautions are standard operating procedures that apply to the care and treatment of all patients, regardless of their perceived infectious risk. These precautions include aseptic technique, hand washing, use of personal protective equipment, appropriate reprocessing of instruments and equipment, and implementing environmental controls. Standard precautions should incorporate safe systems for handling blood (including dried blood), other body fluids, secretions and excretions (excluding sweat), non-intact skin and mucous membranes.

Airborne transmission from person to person does not occur with any form of anthrax. Neither a single room nor a negative pressure room is necessary. Human-to-human transmission of anthrax is extremely rare. There is one published report where community transmission of cutaneous anthrax was associated with sharing a communal loofah [1]. Skin lesions in cutaneous anthrax and faeces in intestinal anthrax may be infectious, but standard precautions will prevent transmission.

Hospital cleaning, disinfection and waste disposal

Contaminated environmental surfaces in health care facilities should be cleaned with 0.5% hypochlorite solution, by staff using standard infection control precautions, including appropriate PPE. Buckets, mops and other equipment should be rinsed thoroughly in tap water, and waste water disposed of according to State regulations.

Clinical management of patients

Most strains of B. anthracis are susceptible to a range of antibiotics, including penicillin, ciprofloxacin and doxycycline. Cephalosporins are ineffective for the treatment of anthrax.

Specimens should be taken for culture and sensitivities before therapy is started (see Appendix 2). For patients with clinical anthrax, these specimens should be regarded as potential forensic evidence, and the chain of custody maintained. If B. anthracis is suspected on the basis of a threat assessment, specimens should be sent immediately to a reference laboratory for detailed characterisation. Empirical antibiotic therapy should commence as soon as possible, and before the results of culture and sensitivity testing are known. A delay in the initiation of treatment may result in a fatal outcome.

Inhalational, gastrointestinal, subcutaneous and meningeal anthrax

Where the diagnosis is suspected but not confirmed, it will be necessary to start empirical treatment to cover the possibility of anthrax. It will also be necessary, however, to treat concurrently for other possible causes of the patient’s symptoms. Recommended antibiotic treatments for inhalational, gastrointestinal, subcutaneous and meningeal anthrax are set out in Table 2.

Repeated drainage of pleural effusions is recommended in inhalational anthrax. Surgical intervention with resection of affected bowel and primary re-anastomosis, as well as antibiotic therapy and resuscitation, has also been advocated in severe cases of intestinal anthrax [19].
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Table 2: Recommended treatment for inhalational, gastrointestinal, subcutaneous and meningeal anthrax. Adapted from reference [28]
Initial therapyDuration
AdultsCiprofloxacin 400 mg IV 12 hourly
PLUS
Clindamycin 600 mg IV 8 hourly
PLUS one or two of amoxy/ampicillin, benzyl penicillin, meropenem, rifampicin, vancomycin
When clinically appropriate switch to oral therapy as for cutaneous anthrax for a total of 60 days
ChildrenCiprofloxacin 10 mg/kg (up to 400 mg) IV 12 hourly
PLUS
Clindamycin 15 mg/kg (up to 600 mg) IV 8 hourly
PLUS one or two of amoxy/ampicillin, benzyl penicillin, meropenem, rifampicin, vancomycin
When clinically appropriate switch to oral therapy as for cutaneous anthrax for a total of 60 days
Pregnant womenSame as for non-pregnant adultsSame as for non-pregnant adults
Immunocompromised personsSame as for non- immunocompromised
adults and children
Same as for non- immunocompromised
adults and children
# Doxycycline may be less effective in anthrax meningitis due to poor CNS penetration. At the time of writing, doxycycline is not registered by the TGA for treatment or prophylaxis of anthrax

Cutaneous anthrax

Recommended treatments for cutaneous anthrax are set out in Table 3. A 60- day treatment period is recommended because of the likelihood of exposure to aerosolised B. anthracis in the context of a deliberate release of spores.
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Table 3: Recommended treatment for cutaneous anthrax. Adapted from reference [28]
Initial therapyDuration
AdultsCiprofloxacin 500 mg oral 12 hourly
OR
Doxycycline 100 mg oral 12 hourly.
After improvement, if sensitive, Amoxycillin 500 mg oral 8 hourly
60 days
ChildrenCiprofloxacin 15 mg/kg (up to 500 mg) oral 12 hourly
OR
Doxycycline, if > 8 yrs, 2.5 mg/kg (up to 100mg) oral 12 hourly.
After improvement, if sensitive, Amoxycillin 25 mg/kg (up to 500 mg) oral 8 hourly
60 days
Pregnant womenSame as for non-pregnant adults60 days
Immunocompromised personsSame as for non- immunocompromised
adults and children
60 days

Potential contacts, and Post Exposure Prophylaxis

Initial patient presentation

Post Exposure Prophylaxis (PEP) may be indicated after the suspected deliberate release of B. anthracis. Whether PEP should be offered will be determined by the level of threat, as assessed by the State or Territory health authority, in consultation with the Australian Government Department of Health and Ageing, and police and national security agencies.

Asymptomatic patients presenting after a credible suspected aerosol release of anthrax should be asked to shower with soap and water, and put on clean clothes. A release of an unidentified suspicious substance will be subject to a rapid risk assessment and on-scene screening analysis by police and emergency services scientific officers. Such screening usually eliminates the requirement for unnecessary decontamination through preliminary identification of hoax or other substances.
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Following an aerosol release, the patient’s clothing and other personal effects should be regarded as contaminated unless the patient has already disposed of clothing worn at the time of the incident. The clothing and other personal effects should be double bagged in sealed, labelled, plastic bags. Staff responsible for these items should also maintain the chain of custody to ensure that they are admissible as evidence in court should criminal proceedings be undertaken. Any vehicle (e.g. car or ambulance) in which the patient has travelled since the suspected exposure should also be regarded as potentially contaminated, and either disinfected or isolated until tests have shown that B. anthracis is not present.

If the patient presents after a suspected food-borne release, clothing and other personal effects would not be infectious.

The treating doctor should contact the relevant public health unit for advice on the level of perceived threat, and whether PEP is indicated. Jurisdictional public health experts should provide advice regarding the exposure zone. PEP, where indicated, should commence as soon as possible, and before the results of culture and sensitivity testing are known. A delay in the initiation of treatment may result in a fatal outcome. The patient should be counselled as to the need for compliance with the recommended regimen.

Informed consent should be obtained where unregistered drugs are used and the patient advised to seek medical advice immediately if symptoms develop. The treating doctor should also consult the relevant public health unit before any diagnostic specimens, whether patient or environmental samples (e.g. suspicious substances or clothing swabs) are sent for laboratory testing. This will minimise the frequency of unnecessary requests for testing in the event of hoax incidents, and ensure that specimens are sent to the appropriate laboratory for diagnosis and characterisation where there is a genuine threat.

Diagnostic specimens

There is little predictive value in assessing whether a patient has been exposed to B. anthracis by taking nasal or skin swabs from persons who are well, but have had possible exposure to aerosolised anthrax. Nasal swabs would need to be collected within 30 minutes of exposure ending and prior to decontamination or blowing the nose. Particles are spontaneously cleared from the nose within this timeframe. However, if obtainable, this information may be useful for epidemiological purposes.

It may be impractical to obtain faecal specimens from an asymptomatic person possibly exposed to food-borne B. anthracis, however a rectal swab and an oropharyngeal swab should be considered.

Test results should be conveyed to the treating doctor, and then to the patient immediately they are available, together with advice as to the need for continued PEP and any changes to antibiotics that may be required. Changing antibiotic as a result of confirmed sensitivity should be managed carefully. Perceptions may develop that authorities are providing a ‘lesser’ antibiotic when changing from ciprofloxacin to amoxicillin. Good communication strategies are required around this issue. Should the specimens be negative for B. anthracis, advice should be sought from the relevant public health unit on the need for continued PEP.

Specific post exposure prophylaxis

When a decision has been taken to offer PEP, antibiotic therapy should commence as soon as possible, as outlined in Table 4 below. Prophylaxis should be continued until exposure to B. anthracis has been excluded. If B. anthracis exposure is confirmed, or remains uncertain, antibiotic therapy should continue for 60 days. The patient should be counselled as to the need for rigorous adherence to the regimen, and given written information about the disease, its epidemiology, symptoms and treatment. The patient should also be advised to seek medical attention immediately if symptoms develop.
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Table 4: Recommended post exposure prophylaxis after exposure to B. Anthracis. Adapted from reference [28]
Initial therapyDuration
AdultsCiprofloxacin 500 mg oral 12 hourly
OR
Doxycycline 100 mg oral 12 hourly
60 days
ChildrenCiprofloxacin 15 mg/kg (up to 500 mg) oral 12 hourly
OR
Doxycycline, if > 8 yrs, 2.5 mg/kg (up to 100mg) oral 12 hourly.
After culture, if sensitive, Amoxycillin 25 mg/kg (up to 500 mg) oral 8 hourly
60 days
Pregnant womenCiprofloxacin, 500 mg bd60 days
Immunocompromised personsSame as for non- immunocompromised
adults and children.
60 days

Amoxycillin may be suitable as an alternative therapy in children if the specific B. anthracis strain has been shown definitively to be sensitive to penicillin/amoxycillin.

Pharmacokinetic studies have shown that ciprofloxacin achieves far higher concentrations in lung macrophages than penicillins, and therefore may be a more effective prophylactic antibiotic. Ciprofloxacin and Doxycycline have the added advantage that they are also effective prophylactic treatments for other potential agents that may be used in deliberate release scenarios such as plague and tularaemia.

Contacts of cases
Generally, there is no need to provide antibiotic prophylaxis to contacts of patients. Exceptions to this would be where the contact:
  • may have also been exposed to the initial release
  • is a member of the same household, and may have come into contact with the patient’s contaminated clothing or other personal effects immediately after the release.

Immunisation

There is no human vaccine currently registered for general marketing in Australia. There are, however, vaccines made and approved for use in the United States of America and the United Kingdom, which may be available for use in Australia under exceptional circumstances.

Other vaccines are also under development including oral vaccines currently being assessed in clinical studies.
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At present, anthrax vaccine is not available for civilian use in Australia. Subject to the availability of a vaccine in the future, it will only be provided under the Special Access Scheme administered by the TGA for those groups at highest risk of infection with B. anthracis, that is, laboratory staff working with cultures of the organism. Vaccination will be offered to these staff only when the threat assessment is sufficiently high. Should this policy change, advice on the place of anthrax vaccination in the prevention of this disease will be available through the relevant State/Territory public health authority (see Appendix 10: Contacts).

Adverse reactions to Anthrax Vaccine Adsorbed (AVA), the US vaccine manufactured by BioPort Corporation, are generally mild and self-limiting. Serious adverse reactions were reported at a rate of 76 per 1.8 million doses in one US study [29], and not all were causally associated with the vaccine. Two deaths were reported in that study but were not proven to be related to vaccine use. In a review of data obtained by the US Vaccine Adverse Event Reporting System (VAERS), six of 602 events judged to be clinically important were considered possibly or probably due to the vaccine [30]. These included aggravation of spondyloarthropathy (2), anaphylactoid reaction (1), arthritis (2) and bronchiolitis obliterans organising pneumonia (1).

Reports of adverse reactions to the UK vaccine, manufactured by the Health Protection Agency, are limited. In one series [31], 18% of military personnel receiving anthrax vaccination suffered incapacitation for up to 120 hours. In 74% of these (13% overall), pain at the injection site prevented lifting or driving for 48 hours. Other adverse reactions reported by the authors were mild. In another series [32], 72 reports of adverse reactions were received from 956 doses of anthrax vaccine (prevalence of 7.5%) and in 11% of recipients. Only mild adverse reactions were observed including flu-like illness, fever malaise, arthralgia, myalgia, gastrointestinal symptoms, sinusitis, headache, paraesthesia or a general feeling of being unwell. No vaccinated person reported having been incapacitated. It is not known why incapacity was reported in one study, but not the other. Although it is possible that this was due to batch variations, there are no data to support this hypothesis.

Further information on vaccines that may be used is contained in Appendix 3. A model consent form for the administration of anthrax vaccine is contained at Appendix 4.

Environmental surveillance

Environmental sampling

Requests for environmental sampling may be made by police or public-health authorities for forensic and/or public health purposes. Initial samples will be collected, packaged and labelled for transport to the testing laboratory by emergency services personnel. Subsequent sampling may be conducted by other personnel, including contractors. Although the agency which collects the material may vary between jurisdictions, the methods used should take into account the need for personal protection and chain-of-custody requirements to be met. A model sampling protocol is outlined in Appendix 5.

Samples will only be accepted by public health reference laboratories for anthrax testing if the correct sampling, labelling and packaging procedures have been observed, approval in writing for the testing has been obtained from the appropriate public health or emergency management unit in the jurisdiction concerned, and an Analysis Request Sheet has been completed for each sample. A model Analysis Request Sheet is at Appendix 6.

Testing of suspicious substances

The extent of testing of suspicious substances will depend on the intelligence report on the possible nature of the threat. The National Counter-Terrorism Committee Suspicious Substances/Packages Assessment Guidelines (September 2011) provides policy and procedural guidelines relating to the testing of suspicious substances. In the absence of specific advice from intelligence agencies, the material should be assessed in the following order for (1) explosives, (2) radioisotopes and (3) toxic chemicals such as cyanide salts or neurotoxins such as cholinesterase inhibitors (nerve gases). In most jurisdictions police will assess the explosive threat. Testing for radioisotopes and chemicals will be undertaken by police, fire or ambulance services depending on jurisdictional policy and prevailing circumstances. If these agents are excluded, or intelligence suggests they are unlikely, the material should then be tested for biological agents such as pathogenic microorganisms and toxins (e.g. ricin), if warranted by the risk assessment.

Laboratories undertaking the microbiological testing should be advised of the results of environmental screening. Analysis of the sample should be undertaken in accordance with an algorithm approved by the laboratory manager.

Chain of custody of forensic evidence

In the event that a criminal prosecution is launched as a result of the incident, it will be necessary to show that the chain of custody has been maintained for all physical evidence tendered to the court. This may include, for example, tissue specimens and clothing taken from a patient. This is to ensure, among other things, that the specimen or personal effects can be identified as coming from a particular person, and that there has been no tampering with the material.
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Each state and territory and the Australian Government has legislation that may vary slightly, but, in general, the collection, custody and presentation in court of evidence must be accompanied by details of the person/persons who collected it, had custody of it and analysed it. States and Territories are encouraged to develop guidelines which will ensure that their respective statutory requirements are met in relation to evidence tendered in court. These guidelines should be consistent with the National Counter Terrorism Committee Protocols for evidentiary recovery by health professionals.

Occupational health and safety issues

First responders to a deliberate release of anthrax spores include all emergency staff at the scene of the incident, those responsible for environmental decontamination, and health-care workers who treat persons exposed to the organism. At the time of the incident, the identity of the agent may not be known, and full protective equipment should be worn. Following an overt aerosolised release of anthrax spores, the area affected by the primary release will depend on factors such as the time and place of release, wind patterns and whether air-conditioning systems were in use. Advice will be provided by jurisdictional public-health experts as to what constitutes the exposed zone.

This zone presents a high risk of infection, and anyone entering it should wear full protective equipment. Health-care workers may be asked to enter this zone to treat casualties e.g. if an explosive device has accompanied the release of a biological agent. In this case full protective clothing should be worn. If there are no injuries, exposed persons will normally be moved from the exposed zone, through decontamination, and into a place of safety for medical assessment and commencement of prophylactic treatment. Those involved in decontamination, and others who have any contact with contaminated clothing and fomites, should observe standard infection-control precautions including appropriate PPE against aerosol contamination.

Emergency staff who attend exposed persons after decontamination has been completed do not need to take any special precautions. For health-care workers involved in the management of hospitalised patients with all forms of anthrax, standard precautions provide sufficient protection, and mortuary staff should use similar barrier protection. More sophisticated countermeasures for airborne protection such as HEPA filter respirators are not required.

Specific pre and post exposure prophylaxis

There is no human vaccine for anthrax currently registered for general marketing in Australia. Emergency services personnel and others who have been inadvertently exposed to environmental sources of B. anthracis, where indicated, should be offered antibiotic PEP as soon as practicable after the incident, in accordance with the schedule in Table 4 Section 5. The initial therapeutic regimen may be modified after the particular strain of B. anthracis has been cultured and characterised.

Environmental decontamination

There are several options for environmental decontamination, including HAZMAT plans and those outlined in AUSVETPLAN, which is available at Animal Health Australia website. Model environmental decontamination protocols are outlined in Appendix 9. state and territory authorities should develop detailed plans based on one or more of these options, consistent with local occupational health and safety and environmental statutory requirements.
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