Public health priority: Routine.
PHU response time: Respond to confirmed cases within 3 working days. Enter confirmed cases on NCIMS within 5 working days.
Case management: Responsibility of the treating doctor. Case should receive appropriate antibiotics. Identify likely source, and institute control measures if possible.
Contact management: Encourage vaccination of persons at risk.
Last updated: 01 July 2012
1. Reason for surveillance
- To monitor the epidemiology and so inform the development of better prevention strategies.
2. Case definition
- A confirmed case requires laboratory definitive evidence, or
- Laboratory suggestive evidence and clinical evidence.
Laboratory definitive evidence
- Detection of Coxiella burnetii by nucleic acid testing, or
- Seroconversion or significant increase in antibody level to Phase II antigen in paired sera tested in parallel in the absence of recent Q fever vaccination, or
- Detection of C. burnetii by culture (note this practice should be strongly discouraged except where appropriate facilities and training exist.)
Laboratory suggestive evidence
Detection of specific IgM in the absence of recent Q fever vaccination.
Clinically compatible disease.
3. Notification criteria and procedure
Q fever is to be notified by:
- Laboratories on microbiological confirmation (ideal reporting by routine mail).
Confirmed cases should be entered onto NCIMS.
4. The disease
The rickettsia Coxiella burnetti.
Mode of transmission
Q fever is transmitted by airborne dissemination of the organism from placental tissues, birth fluids and excreta of infected animals and by direct contact with infected animals and other contaminated materials such as wool, straw or clothing. The organism is stable in the environment and has a small infective dose; it is believed that infection can result from inoculation with a single organism.
Q fever is found widely across animal species. Animals are commonly chronically infected but often do not show any signs. Ruminants including cattle, goats and sheep are common sources of Q fever. Consumption of unpasteurised dairy products is suspected to be a minor factor in the transmission of Q fever. Other animals including domestic companion animals such as cats and dogs, wild animals such as kangaroos and bandicoots, and birds can also carry Q fever. Ticks and other arthropods can potentially be infected and may serve as vectors.
The occupational groups at the highest risk for Q fever infection are: abattoir workers and meat processing workers (including visiting contractors), and agriculture related occupations, such as farmers, shearers, livestock handlers and livestock transport drivers.
Q fever has been reported in veterinary workers and wildlife handlers who can get infected by breathing in contaminated aerosols or dust when working with infected animals, animal tissues (such as placental tissues), or animal products (such as birth fluids and other excreta). The risk of transmission from infected pregnant and birthing animals is significant due to high levels of Coxiella in the birth fluids and tissues. For further information for veterinary staff, see: Q Fever and Veterinary Staff factsheet.
Cases unrelated to direct contact with animals
Occasionally, infections occur in people who have not had any direct contact with animals but have been exposed to aerosolised Q fever organisms in other ways, eg by mowing lawns contaminated by marsupial excreta. Outbreaks have occurred in eg people living near livestock transport routes who have presumably been exposed to contaminated dust from the animals as they pass nearby.
Person-to-person transmission is very rare but has been reported, eg transmission through blood and bone marrow transfusion, intradermal inoculation, human autopsies and infection of an obstetrician who performed an abortion on an infected patient. It is hypothesised that transmission could occur sexually.
The typical incubation period depends on the size of the infecting dose, but is usually 14 to 21 days.
Clinical presentation is highly variable. It is estimated that 50-60% of cases are asymptomatic. Acute cases may present with fever, sweating and chills, sever headache, myalgia and arthralgia, extreme fatigue, weakness and malaise.
Clinical syndromes associated with acute Q fever include pneumonia, hepatitis, osteomyelitis and meningitis or encephalitis.
Chronic Q fever, defined as an infection lasting more than 6 months, is estimated to occur in 1 - 5% of those infected. Chronic Q fever presents most commonly as endocarditis or hepatitis and can occur up to two years after initial infection. Persons with underlying valvular heart disease have a significantly higher risk of developing chronic Q fever endocarditis. Due to its indolent progression and poor outcome when diagnosis is delayed, a thorough cardiac assessment of all patients with suspected or confirmed Q fever is important.
5. Managing single notifications
Within 3 working days of a confirmed case begin followup investigation.
Within 5 working days of notification enter confirmed cases on NCIMS. Ensure that the question packages relating to occupation, likely source of infection and vaccination status in NCIMS are completed for all cases.
The response to a notification will normally be carried out in collaboration with the case's health carers. 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 likely source of infection
- Review case management. This may include encouraging the clinician to evaluate the patient for valvular heart disease which is a risk factor for development of Q fever endocarditis
- Consider prevention initiatives.
Treatment and investigation
Refer to: Therapeutic Guidelines: Antibiotic.
The case or relevant caregiver should be the NSW Health Q fever factsheet and informed about he nature of the infection and the mode of transmission.
The case or relevant caregiver should be given the NSW Health Q fever factsheet and informed about the nature of the infection and mode of transmission.
A history of possible exposures should be sought. Attempt to identify the source of infection, such as exposure to products of animal conception. Ensure that likely source of infection and occupation fields are completed in NCIMS.
Where the investigation identifies an ongoing source of infection there may be an ongoing risk, ascertain whether additional preventative activities such as infection control or immunisation are warranted.
Q fever vaccination
Q fever vaccination is recommended for those at risk of infection with C.burnetii. Detailed information on Q fever vaccination can be found in the Australian Immunisation Handbook.
Isolation and restriction
When a cluster of cases occurs, ascertain animal and / or environmental risk factors for infection and advise on control measures.
Identification of contacts
Contacts are those who may have been exposed to the same source as the case.
In occupational settings, active case finding among identified contacts should be considered.
Q fever information should be provided to contacts with advice to seek medical attention should they develop symptoms. Q fever vaccination should be recommended to all non-immune workers in high-risk occupations.
- Notify Communicable Diseases Branch.
- Initiate an investigation, perform a risk assessment and control the risk where possible.
- For clusters related to agriculture, seek advice from the local Livestock Health and Pest Authority. Contact details available at: http://www.lhpa.org.au/contact.
- Liaise with WorkCover regarding prevention strategies in the workplace when responding to outbreaks associated with occupational settings. Contact: 13 10 50.