Last updated:
06 September 2004
1. Reason for surveillance
- To monitor the epidemiology of tuberculosis
- To identify and treat infectious cases
- To identify infected contacts and reduce their risk of developing active tuberculosis
- Help develop better prevention strategies.
2. Case definition
A confirmed case requires a diagnosis accepted by the Public Health Unit Director based on:
- Laboratory definitive evidence, or
Laboratory definitive evidence
- Isolation of Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis or M. africanum) from a clinical specimen by culture, or
- Detection of M.tuberculosis complex by nucleic acid testing EXCEPT where this is likely to be due to previously treated or inactive disease.
Clinical evidence
A clinician experienced in tuberculosis makes a clinical diagnosis of tuberculosis including clinical follow-up assessment to ensure a consistent clinical course. Epidemiological evidence
Not applicable.
3. Notification criteria and procedure
Tuberculosis is to be notified by:
- Laboratories on diagnosis (ideal reporting by telephone on diagnosis)
- Medical practitioners on diagnosis (ideal reporting by telephone on diagnosis)
- Hospital CEOs (or delegates) on diagnosis (ideal reporting by telephone on day of diagnosis).
Only confirmed cases should be entered onto NDD.
4. The disease
Infectious agent
Tuberculosis is almost always caused by the bacterium Mycobacterium tuberculosis. Rarely, the bacteria Mycobacterium bovis and Mycobacterium africanum cause disease in humans. Mode of transmission
Tuberculosis is transmitted by airborne droplets from cases of pulmonary or laryngeal disease produced by expiratory efforts such as coughing, singing or sneezing. Bovine tuberculosis may also be transmitted by ingestion of raw milk. Time line
The typical incubation period from infection to demonstrable primary lesion or significant tuberculin reaction is 4 to 12 weeks. The risk of infection is higher in people who have had close contact with a case of pulmonary or laryngeal tuberculosis as they may have inhaled expelled TB bacteria. Such people include: household contacts of cases, persons born in countries with a high prevalence of TB, and persons living in close proximity to others, eg in prisons, nursing homes or hostels. Infection can be detected by demonstration of a positive Tuberculin skin test. After infection with M.tuberculosis, most people will have no symptoms. Newly infected people have about a 10% chance of developing active tuberculosis in their lifetime; about half those who develop tuberculosis do so within 2 years of infection. The risk of progressing to disease is higher in persons who are: immunocompromised (eg, with HIV infection), neonates, injecting drug users, or homeless; or have diabetes, silicosis or previous gastric surgery. The degree of infectiousness is determined from clinical, radiological, bacteriological and nucleic acid detection findings, and categorised as follows: High infectiousness
- Sputum smear positive (bacteria of TB detected in sputum)
- Evidence of transmission to other contacts
Medium infectiousness
- Nucleic acid detection positive and smear negative
- Bronchial washing smear positive, no chest x-ray cavitation.
Low infectiousness
- Sputum culture and smear negative or smear positive and clinically unlikely to be TB disease
- Extra-pulmonary tuberculosis except where there is a discharging lesion.
Clinical presentation
Patients may present with a range of symptoms depending on the site of disease. Common symptoms include:
Because TB is an uncommon cause of these symptoms in Australia, the diagnosis is often not made on initial presentation.
5. Managing single notifications
Response time
Investigation
Within 1 working day of notification of a confirmed case, report the case to the local Area TB Coordinator by phone. Data entry
Within 3 working days of notification, enter confirmed cases onto NDD. Within 8 months of the initial notification, (and if necessary again at the end of treatment) in collaboration with the Chest Clinic managing the case, update NDD information relating to treatment and its outcome. Response procedure
Chest Clinics undertake contact screening and other relevant investigations, and forward details of the case to the PHU for entry onto NDD, using the Tuberculosis Investigation Form. Case management
Chest Clinic staff will interview the patient to obtain a list of contacts and to initiate appropriate public health action. All patients should receive directly observed therapy (DOT) throughout treatment to ensure compliance. DOT should be provided by chest clinic staff, except in special circumstances where an alternative health care worker or other trusted person trained by the chest clinic who is familiar with compliance issues agrees to observe the patient swallow all medications. Investigation and treatment
All isolates of Mycobacterium species should be referred to the Mycobacterium Reference Laboratory at ICPMR for confirmation and susceptibility testing. Hospitalisation of tuberculosis patients
Generally patients with tuberculosis should be admitted to hospital if:
- Essential investigations are required that can only be carried out on an in-patient basis
- There is a need to assess the patient's tolerance to medication
- The patient requires isolation to prevent further spread.
When to hospitalise
A longer time in hospital may be required if there is:
- Concern for continued infectivity due to severe disease with cavitation, or
- Previous medication failures, or
- Social situations that may lead to non-compliance and disease transmission.
When to discharge
Patients with tuberculosis may be discharged from hospital before confirmation of decreased infectivity (three negative sputum smears). Each case must be assessed for risk of disease transmission before discharge from hospital. Chest Clinic staff should counsel the patient about infection control at home and in the community. Care at home
Patients who are sputum smear positive who do not need hospital admission may be managed at home with counselling about the disease, its transmission and prevention (including advice to cover the mouth and nose when coughing or sneezing). Patients must be instructed to stay at home for at least two weeks after the commencement of anti-tuberculosis treatment. Multi-drug resistant tuberculosis (MDR TB) and other difficult to manage cases
All cases of MDR TB (i.e. persons with TB resistant to at least rifampicin and isoniazid) should be referred to the NSW Health MDR TB Expert Panel. The Panel will help the managing physicians and chest clinic develop a case management plan. In addition, clinicians can refer difficult to manage cases of active tuberculosis to the panel for peer review. Referral to the Panel can be made via the NSW Tuberculosis Program Manager. The Panel will generally include:
- The Area Tuberculosis Coordinator
- An infectious diseases physician
- A representative from the State TB Reference Laboratory (ICPMR)
- Other physicians expert in tuberculosis
- A public health practitioner
- Other relevant persons as defined by the chair of the panel.
Education
Cases should be counselled about the nature of the disease and its mode of transmission, the need to adhere to treatment, to cover their mouth and nose when coughing and sneezing, and if infectious, to avoid contact with any new persons. If treated at home, they must be instructed to remain there for ≥2 weeks after the commencement of anti-TB treatment or until they are assessed as not being infectious. Isolation and restriction
Hospitalised cases with suspected infectious TB must be managed in single rooms, ideally with negative pressure airflow. This is essential when drug resistant TB or extensive cavitatory disease is suspected. Such rooms should have a minimum of 6 total air changes per hour, including ≥2 outside air changes per hour, plus good air circulation within the room to dilute and/or remove TB bacilli from areas where HCWs, patients, and visitors may be exposed. If negative pressure rooms are unavailable the patient should be managed in a room with the door closed at all times. The patient and staff must be fully informed of the reasons for the door being closed. A P2 (N95) mask should be worn by:
- Infectious patients when leaving their rooms to walk in the hospital grounds or during transport
- All HCWs and others entering the room.
Children should be discouraged from visiting infectious cases. People with infectious TB must be isolated from immunocompromised persons, until sputum is negative for acid fast bacilli (AFB) or until no sputum is being produced. Immunocompromised staff members should not work on wards where there are cases of infectious TB. Standard precautions should be followed in the disposal of sharps, contaminated waste and linen and all body fluids. Soiled tissues should be isposed of in a sealed bag. Sputum must be collected in a disposable container, with a lid that can be secured. Laboratory specimens should be well sealed with no contamination of the outside of the container and transported immediately to the laboratory in a sealed bag. The case may be confined if behaving in a way that is endangering, or is likely to endanger the health of the public because the person is suffering from tuberculosis (Public Health Act 1991, Section 23). Consult with the NSW TB Program Manager and see Controlling TB in NSW. There are no restrictions on the movement of patients with non-respiratory disease, or those on treatment with negative sputum smears. Environmental evaluation
To assist in the identification of contacts at risk of infection, an environmental assessment shall be done. Factors to consider include:
Contact management
Contact tracing should be managed by the Chest Clinic according to NSW Health's Controlling TB in NSW, but the PHU should provide assistance where requested, and if screening of >25 contacts is proposed. The aims of contact tracing are to identify those infected by the case,
an the source of the case's infection. The estimated risk of transmission should guide the priority, rapidity and thoroughness of the contact investigation. The following steps should be undertaken:
- Categorise the case according to the likely degree of infectiousness (see section 4)
- Obtain a list of contacts and categorise the contacts according to their estimated risks
- Examine all high-risk contacts of pulmonary TB cases first
- Consider examination of medium risk (followed by low risk) contacts of pulmonary TB cases if there is evidence of transmission in high-risk contacts
- Consult with the NSW TB Program Manager, if:
- The case works in a hospital, school, day care, prison, any other institution or long term care facility,
- Screening may be indicated for >25 contacts, or
- There is doubt about the priority/ extent of contact screening required.
Identification of contacts
A list of close contacts, including names and addresses, should be compiled first. Contacts should be categorised into: High Risk
- Frequent, prolonged and close contact while the case was symptomatic (or if unclear of the clinical history, for 3 months before diagnosis).
This group includes:
- All people living in the same dwelling
- Relatives and friends who have frequent, prolonged and close contact
- Any others who have spent ≥8 hours with the case in a closed environment.
Medium risk
- Frequent but less intense contact.
This group may include:
- Relatives who frequently visit the case.
Low risk
- Includes other contacts at school (especially Primary Schools) or in the workplace or in clubs. However, obtaining details of low risk contacts is not necessary initially and need only be pursued if there is evidence of transmission in the high risk and medium risk groups.
Investigation and treatment
Relevant contacts should receive a Tuberculin Skin Test (TST). Contacts who are TST positive or symptomatic at any visit should have a chest x-ray, and be referred to a physician for assessment for treatment. Symptomatic contacts should have sputum collected for assessment. If the first screening occurs <12 weeks after last exposure to the infectious case, TST negative contacts should have a repeat TST 16 weeks after the last exposure. TST negative children < 5 years old who are high risk contacts of highly infectious cases should be referred to a physician and considered for preventive therapy until the 16 week TST is shown to be negative. Screening priorities
Examine all high-risk contacts of pulmonary TB cases first.
- High-risk contacts of highly infectious cases should be assessed within 7 days of notification for child contacts and 10 days for adult contacts.
- High-risk contacts of cases of medium or low infectiousness should be assessed within 21 days of notification of the case.
- Contacts of cases with negligible infectiousness need not be examined
- Only if there is evidence of transmission in the highrisk contacts group, should screening progress to the medium risk group
- Only if there is evidence of transmission in the medium risk group, should screening progress to the low risk group.
If ≥ 10 of the closest contacts have been tested and all are TST negative, testing of more remote contacts is usually unnecessary. If < 10 contacts have been tested, and all are TST negative, careful consideration should be given to the theoretical risk of infection before stopping the contact investigation. All contact tracing is carried out free of charge at NSW Chest Clinics. Education
Contacts should be counselled about the nature of the infection, its mode of transmission, and symptoms, and the need to adhere to the prescribed follow up plan and preventive therapy (if provided). Isolation and restriction
Contacts of cases are not restricted unless that contact is suspected to have infectious TB.
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