TULARAEMIA

Last updated: 06 September 2004

1. Reason for surveillance

To identify cases rapidly in order to control further exposures.

2. Case definitions

Probable case
A probable case requires laboratory suggestive evidence AND clinical evidence.

Laboratory suggestive evidence

• Isolation of a Gram-negative bacillus suggestive of Francisella tularensis where the organism identity and pathogenicity have not yet been confirmed by a reference laboratory, OR
• Detection of F. tularensis by nucleic acid testing, OR
• Detection of characteristic Gram-negative rods suggestive of F. tularensis, confirmed by a reference laboratory.

Confirmed case
A confirmed case requires laboratory definitive evidence.

Laboratory definitive evidence
Isolation of F. tularensis.

Factors to be considered in case definition

• As natural, locally acquired cases of tularaemia have not been reported, deliberate release of the organism should be a consideration in case investigation. Early identification of cases is therefore vital
• Due to the low index of suspicion for tularaemia in Australia by clinicians, and the lack of specialised diagnostic testing techniques such as NAT, direct fluorescent antibody (DFA), and immunohistochemistry tests, diagnosis of early cases is likely to be delayed. Suspicion may be triggered by the identification of a cluster of cases of atypical pneumonia. Serendipitious discovery of the organism in the laboratory is another possibility and this is more likely to occur as a result from direct examination of specimens or by culturing the organism. F. tularensis is only occasionally isolated from blood so positive cultures are more likely result from respiratory specimens
• Handling F. tularensis can represent a biosafety hazard and specialised laboratory safety procedures are required.

3. Notification criteria and procedure

Tularaemia is to be notified to the PHU by laboratories (ideal reporting by telephone on same day as notification).

4. The diseases

Infectious agent
The bacillus 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 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.
Of the possible agents that could be used in a bioterrorist attack, F. tularensis is included in the highest risk category.

Mode of transmission
F. tularensis can enter the body by ingestion, inoculation, inhalation, or by direct contact. It can penetrate apparently unbroken skin, but may actually enter through microlesions. It is not directly transmitted from person to person.

Timeline
The incubation period for tularaemia ranges from 1-14 days, but is usually 3-5 days. F. tularensis is quite hardy, and can survive weeks to months in the environment.

Clinical Presentation and Course
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 characterized by a rapid onset of headache, chills, nausea, vomiting, high fever, lymphadenopathy and prostration.

Illness usually falls into one of the following categories:

• Ulceroglandular:(80% of cases) this is the commonest type and follows inoculation via a skin lesion. Patients present with a primary local ulcerative lesion and tender, regional lymphadenopathy. Systemic symptoms are prominent
• Pneumonic (pulmonary): occurs as a primary infection following inhalation of organisms, and in 10-15% of those with ulceroglandular tularaemia and 50% of those with typhoidal tularaemia. The presenting symptoms are those of atypical pneumonia. This form is the most probable one in the event of a bioterrorist attack. Untreated, it has a 30-60% mortality rate
• Typhoidal: (10% of cases)a severe form of tularaemia, with prominent systemic and gastrointestinal symptoms. Half the cases will develop pneumonic tularaemia
• Oculoglandular: (1% of cases) a combination of painful conjunctivitis (usually unilateral) with local lymphadenopathy. Follows inoculation via the conjunctiva
• Glandular: similar to ulceroglandular form but without skin lesions
• Oropharyngeal: a rare form that occurs after ingestion of organisms. The patient develops stomatitis or pharangitis accompanied by regional lymphadenopathy.

5. Managing single notifications

Response time

Investigation
On the same day as notification of a probable or confirmed case, begin the investigation and telephone the Communicable Diseases Branch (CDB).

Data entry
Within 1 working day of notification, enter probable and confirmed cases on NDD.

Response procedure
As locally-acquired cases of tularaemia have not been reported, key to the early response to a notification is to ascertain whether that the case is a result of a deliberate release of the organism.
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:

• 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 beginning the interview
• Seek the doctor's permission to contact the case or relevant care-giver
• Determine the likely source of infection, such as a laboratory that handles infectious specimens, or exposure overseas.

Investigation and treatment
See the latest edition of the Therapeutic Guidelines: Antibiotic.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. Although bodies of patients who die of tularemia should be handled using standard precautions, autopsy procedures likely to produce aerosols or droplets should be avoided.

Exposure investigation
Obtain a history of overseas and domestic travel as well as possible exposures to wild or domestic animals, farms, recent tick bites, and eating wild game or potentially contaminated imported products, in the two weeks prior to symptom onset.

Isolation and restriction
Standard precautions.

Environmental evaluation
As local acquisition would be a novel event, environmental evaluation would be recommended in conjunction with officials from the Department of Primary Industries, who may need to initiate animal control measures.

Contact management

Identification of contacts
Contacts are those who may have been exposed to the same source as the case. If the case is an imported one, communication with the relevant communicable diseases authorities in the country of acquisition would normally be carried out by CDB in collaboration with the Commonwealth Department of Health and Ageing.