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Last updated:
03 September 2007
1. Reason for surveillance
- To identify and protect persons at risk of infection, and identify the source of infection (whether natural or deliberate)
- To monitor the epidemiology of anthrax and so inform the development of better prevention strategies.
2. Case definition
A confirmed case requires either:
- Laboratory definitive evidence, or
- Laboratory suggestive evidence and clinical evidence.
Laboratory Evidence
Laboratory definitive evidence
Isolation of Bacillus anthracis-like organisms or spores confirmed by a reference laboratory. Laboratory suggestive evidence
- Detection of B. anthracis by microscopic examination of stained smears, or
- Detection of B. anthracis by nucleic acid test (NAT).
Clinical evidence
- Cutaneous: skin lesion evolving over 1-6 days from a papular through a vesicular stage, to a depressed black eschar invariably accompanied by oedema that may be mild to extensive, or
- Gastrointestinal: abdominal distress characterised by nausea, vomiting, anorexia and followed by fever, or
- Inhalational: rapid onset of hypoxia, dyspnoea and high temperature, with radiological evidence of mediastinal widening, or
- Meningeal: acute onset of high fever, convulsions, loss of consciousness, and meningeal signs and symptoms.
Epidemiological evidence
Not applicable.
3. Notification criteria and procedure
Anthrax is to be notified by laboratories on suggestive or definitive laboratory evidence (ideally by telephone). Confirmed cases should be entered onto NDD.
4. The disease
Infectious agent
Bacillus anthracis, a bacterium. Mode of transmission
Anthrax is acquired in three ways: percutaneously, by inhalation, or by ingestion. B. anthracis spores can remain viable in soil for many years. Humans can become infected with anthrax by handling products from infected animals, by inhaling anthrax spores (especially from contaminated animal products such as hides) or through cuts and abrasions when in contact with contaminated soil. Eating undercooked meat from infected animals can also transmit anthrax. Transmission from person to person has not been reported. Articles and soil contaminated with spores may remain infective for decades. Whilst several cases are reported each year among sheep and other domestic animals mainly in the west of New South Wales (NSW), human cases rarely occur in NSW. In 2001, several people in the USA contracted anthrax from spores maliciously distributed through the mail. Timeline
Symptoms can appear within seven days of coming in contact with the bacterium for all three types of anthrax although incubation periods of up to 60 days are possible. The reported incubation period for cutaneous anthrax ranges from three to ten days (commonly five to seven days). The incubation period for gastrointestinal anthrax is suspected to be three to seven days and respiratory incubation for anthrax has been reported from one to 60 days (commonly one to five days). Clinical manifestations
The symptoms of the disease vary depending on how the disease was contracted. Cutaneous
About 95 per cent of reported anthrax infections occur when the bacterium (or spore) enters a cut or abrasion on the skin, (eg. when handling contaminated wool, hides, leather or hair products of infected animals). Skin infection begins as a small papule and progresses to a vesicle in one to two days. The vesicle then erodes, leaving a necrotic ulcer with a characteristic black centre. Secondary vesicles are sometimes observed. The lesion is usually painless. Other symptoms can include swelling of adjacent lymph glands, fever, malaise and headache. The case fatality rate of cutaneous anthrax can be up to 20 per cent without antibiotic treatment and <1 per cent with antibiotic treatment. Inhalation
Initial symptoms may resemble an influenza-like illness (ILI), which include a sore throat, mild fever and myalgia in the absence of rhinorrhoea. This prodromal phase is characteristically followed by partial resolution of symptoms followed after several days by rapid progression to severe breathing problems and shock. The cardinal feature is a widening mediastinum on chest X-ray without pulmonary infiltrates. Meningitis frequently occurs. Inhalation anthrax is usually fatal even when treated, but commencement of antibiotics during the prodrome may be effective. Gastrointestinal
The gastrointestinal form of anthrax usually occurs after eating contaminated meat and is characterised by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, and fever are followed by abdominal pain, vomiting of blood and severe diarrhoea. Gastrointestinal anthrax results in death in 25% to 60% of cases.
5. Managing single notifications
Response times
Investigation
On same day of notification begin follow-up investigation, and notify CDB of case details. Data entry
Within one working day of notification enter confirmed cases on NDD. Response procedure
The response to a notification will normally be carried out in collaboration with the case's health carers. But regardless of who does the follow-up PHU staff should ensure that action has been taken to:
- Identify likely source of infection (whether natural or deliberate)
- Confirm the onset date and symptoms of the illness
- Confirm results of relevant pathology tests, or recommend the tests be done
- Find out if the case or relevant care-giver has been told what the diagnosis is before interviewing them
- Seek the doctor's permission to contact the case or relevant care-giver
Case managementdure
Investigation and treatment
For treatment recommendations, see Therapeutic Guidelines: Antibiotic. Obtain a history of exposure to infected animals or animal products (e.g. contaminated hair, wool, hides, or products made from them), or anthrax vaccines and trace to the place of origin. In a manufacturing plant, inspect for adequacy of preventative measures. Consider the possibility that the infection arose from deliberate exposure. In the event of a human case occurring in a person in contact with animals or animal products, the Department of Primary Industries Senior Field Veterinary Officer (SFVO) should be informed on the same day (There are 7 SFVO's located at Grafton, Gunnedah, Dubbo, Goulburn, Wagga Wagga and Orange). Where an occupational or other exposure risk factor cannot be identified, consideration should be given to broadening the investigation in consultation with CDB and Reference Laboratories to assist with typing of the organism. Isolation and restriction
Although the lesion is likely to be sterile after 24 hours treatment, dressings soiled with discharges from lesions should be burned and reusable surgical equipment must be sterilized. Standard infection control precautions apply for all direct clinical care. Education
The case or relevant caregiver should be informed about the nature of the infection and the mode of transmission. In particular, emphasis should be placed on careful handling of soiled dressings and contaminated clothing. Education on the handling of carcasses and products of potentially infected animals should be a priority. Environmental evaluation
Identify the likely source of infection in conjunction with the Senior Animal Regulatory Officer at the Department of Primary Industries, who may initiate animal control measures. Contact management
Identification of contacts
Contacts are those who may have been exposed to the same source as the case. Control of human contacts with infectious animals/materials
- Public Health Units should liase with Department of Primary Industries to ensure that all people potentially at risk are provided with information about the disease, including symptoms and decontamination procedures where relevant.
- Contacts should be informed about anthrax and symptoms associated with cutaneous and inhalation disease, and advised to seek medical attention if they develop an illness consistent with anthrax.
- Where exposure to anthrax is considered credible, then recommend post exposure prophylaxis (see Therapeutic Guidelines: Antibiotic http://www.tg.com.au/) and seek expert medical advice. Post exposure prophylaxis for cutaneous anthrax should be considered for contacts of a confirmed anthrax expsoure who were not using personal protective equipment and whose skin was contaminated with fluids from the carcass. The presence of abrasions on the skin would further support chemoprophylaxis.
- The use of anthrax vaccine is not licensed for human use in Australia but may be used in some people with ongoing exposure to anthrax.
Decontamination of clothing and equipment
- All personnel handling potentially contaminated materials should wear gloves and protective clothing and ensure that skin breaks are protected with sealed waterproof dressings. Additional protection such as respiratory masks is NOT required. All personnel should be instructed to shower thoroughly with soap and water.
- Contaminated clothing and items should be minimally handled (to avoid agitation) and stored in labelled double plastic bags until exposure to anthrax has been excluded.
- Material/equipment that requires decontamination following confirmation of anthrax should be either incinerated or sterilized at 121°C for 30 minutes. If this is not possible than liaise with NSW Department of Primary Industries regarding decontamination procedures using chemical disinfectants.
- The Chief Veterinary Officer will determine the method/s of decontamination of a site, facility or any heavy equipment at risk of being contaminated with B. anthracis.
6. Managing special situations
Where a person has been exposed to a suspicious substance, he or she should be advised to call 000, and the NSW Fire Brigades and NSW Police will assess the scene. Where a "high profile" person (from a security point of view) or institution is involved, the NSW Police Forensic Counter Terrorism and Disaster Victim Registration (FCT/DVR) Unit will also attend. The responding agencies will assess the circumstances and determine the priority level and risks associated with the incident. Where the responding agencies assess that an exposure has occurred, the FCT/DVR Unit will obtain a sample of the substance and conduct preliminary testing either on site or at the Forensic Counter Terrorism Laboratory.
The NSW Police Local Area Command Officer is responsible for collecting details of those exposed and providing them with the analysis results (should they be negative). Where samples test negative, post exposure prophylaxis is not recommended. Police may seek the PHU's assistance in counselling exposed people, if required. Positive results
Where preliminary testing by FCT/DVR Unit is positive for anthrax, the Unit will report the result immediately to the State Health Services Functional Area Co-ordinator (HSFAC), who will inform the Director Health Protection, who will in turn inform the Director of the relevant Public Health Unit (PHU), the Director Communicable Diseases Branch and the Director Biopreparedness Unit. Samples that test positive for anthrax on preliminary testing are confirmed at ICPMR at the Emerging Infections and Biohazard Response Unit (EIBRU), Westmead Hospital. Definitive results should be available within 24 hours. EIBRU will report positive results to the Duty State HSFAC and the Public Health Controller. Both a preliminary or definitive finding of anthrax in a sample to which people have been exposed will prompt the Communicable Disease Branch to initiate an urgent teleconference involving the Biopreparedness Unit, local PHU, EIBRU, an infectious disease specialist, the Counter Disaster Unit and the FCT/DVR Unit. The aim of the teleconference will be to assess the risk to exposed people, and to recommend whether antibiotic prophylaxis or further investigations are required. The PHU should ensure that people identified by the Police Local Area Command as having been exposed to material that tests positive for anthrax are contacted, counselled about the risk, provided with the results of the biological testing and - if recommended - receive antibiotic prophylaxis and monitoring.
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