Public health priority: Urgent
PHU response time: Respond to any probable or confirmed cases immediately. Report to CDB on day of identification.
Case management: PHU should identify the likely source of infection. If the case is likely to have acquired the disease in Australia, a thorough assessment of the circumstances and a search for other cases is required.
Contact management: Contacts will be those who may have been exposed to the same source as the case. Management would normally involve collaboration with communicable disease authorities abroad.
To identify cases rapidly in order to control further exposures.
A probable case requires laboratory suggestive evidence AND clinical evidence.
A clinically compatible illness.
A confirmed case requires laboratory definitive evidence.
Isolation of F. tularensis.
CIDM-PH is the only human health laboratory in NSW that can test for F. tularensis. If a case is suspected to have tularaemia or a suspected isolate is cultured from clinical samples by a pathology provider the on-call microbiologist at CIDM-PH should be contacted immediately by the treating physician to determine appropriateness of tests, timelines of testing and specimen transport etc.
Tularaemia is to be notified to the PHU by laboratories (ideal reporting by telephone on same day as notification).
The bacterium Francisella tularensis, a Gram-negative rod.
Two types of F. tularensis occur, A and B. Type A is highly virulent in humans and animals and is the most common sub-type in North America. Type B usually produces a mild ulceroglandular infection, is less virulent, and is thought to cause most of the human cases in Europe and Asia. Both A and B types are found in a diverse range of mammals including rodents and rabbits, and can also be isolated from contaminated water, soil and vegetation.
To date, only Type B (F. tularensis subspecies holarctica) has been isolated from common ringtail possums (Pseudocheirus peregrinus) in NSW. There have been four reported cases of human transmission in Australia. Three occurred after scratches/bites by possums, two confirmed cases of Type B infection in Tasmania in 2011 linked to a ringtail possum and unidentified possum respectively, and a probable case in NSW in 2020 to a ringtail possum. The fourth case, also defined as probable, was likely exposed during necropsy of Australian wildlife, of which the infected animal has not been clearly identified but which was not a possum species.These are the first records of F. tularensis in Australia and the southern hemisphere. In countries where tularaemia is endemic, Type B is also associated with streams, ponds, lakes, rivers and from diseased semi-aquatic animals such as beavers and muskrats, and infected blood feeding arthropods including ticks.
Of the possible agents that could be used in a bioterrorist attack, F. tularensis is included in the high risk category (Tier 2 security sensitive biological agent under the National Health Security Act 2007).
The bacteria can enter the body through the skin, eyes, mouth, throat or lungs. Infection can be acquired by:
F. tularensis is listed by the Centers for Disease Control as a potential agent for bioterrorism.
It is not spread from person to person.
The incubation period for tularemia ranges from 1-14 days, but is usually 3-5 days. F. tularensis bacteria are hardy, and can survive weeks to months in the environment.
Tularaemia can manifest as one or more clinical syndromes. The syndrome depends on the route of transmission, the size of the inoculum, and the virulence of the infecting strain. However, most cases are characterised by a rapid onset of headache, chills, nausea, vomiting, high fever, lymphadenopathy and prostration.
Illness usually falls into one of the following categories:
On the same day as notification of a probable or confirmed case, begin the investigation and telephone the Communicable Diseases Branch (CDB).
In the situation of a suspected deliberate exposure contact CDB immediately.
Within 1 working day of notification, enter probable and confirmed cases on NCIMS.
Given the isolation of F. tularensis in ringtail possums for the first time in Australia in 2016, and the probable case in NSW in 2020 linked to an unidentified Australian wildlife source (that was not a possum), early response to a notification is required to better understand the epidemiology of tularaemia in Australia.
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:
See the latest edition of the Therapeutic Guidelines: Antibiotic.
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission.
Obtain a history of overseas and domestic travel as well as possible exposures to wild or domestic animals (including common ringtail possums and other Australian wildlife), farms, recent tick bites, contact with or drinking water from natural sources including lakes, rivers, streams and ponds, and eating wild game or potentially contaminated imported products, in the two weeks prior to symptom onset.
In the case of local acquisition, environmental evaluation would be recommended in conjunction with officials from NSW Department of Primary Industries, who may need to initiate animal control measures.
Contacts are those who may have been exposed to the same source as the case. If the infection was acquired overseas, communication with the relevant communicable diseases authorities in the country of acquisition would normally be carried out by CDB in collaboration with the Australian Government Department of Health.
For further information please call your local Public Health Unit on 1300 066 055