LEPROSY

Last updated: 06 September 2004

1. Reason for surveillance

• To monitor the epidemiology of leprosy in NSW so as to inform the development of better prevention strategies.

2. Case definition

A confirmed case requires

• Laboratory definitive evidence, and

• Clinical evidence.

Laboratory definitive evidence

• Demonstration of characteristic acid fast bacilli in split skin smears and biopsies prepared from the ear lobe or other relevant sites, or

• Histopathological report from skin or nerve biopsy compatible with leprosy (Hansen's disease) examined by an anatomical pathologist or specialist microbiologist experienced in leprosy diagnosis.

Clinical evidence

• Compatible nerve conduction studies,

• Peripheral nerve enlargement, or

• Loss of neurological function not attributable to trauma or other disease process, or

• Hypopigmented or reddish skin lesions with definite loss of sensation.

Note: International reporting to WHO is based on the WHO working definition:

A person showing one or more of the following features, and who as yet has to complete a full course of treatment:

• Hypopigmented or reddish skin lesions with definite loss of sensation

• Involvement of the peripheral nerves, as demonstrated by definite thickening with loss of sensation

• Skin smear positive for acid-fast bacilli definition.

The difference should be noted to the WHO when reported.

Epidemiological evidence
Not applicable

3. Notification criteria and procedure

Leprosy is to be notified by:

• Medical practitioners and hospital CEOs on diagnosis (ideal reporting by routine mail)

• Laboratories on microbiological diagnosis (ideal reporting by routine mail).

Only confirmed cases should be entered onto NDD.

4. The disease

Infectious agent
The bacillus Mycobacterium leprae.

Mode of transmisison
The exact mechanism of transmission is unclear. Leprosy is probably transmitted by droplet infection and direct contact with discharges from respiratory mucous membranes of infected persons. Household and prolonged, close contact appear to be important in transmission. In children <1 year old, transmission is presumed to be transplacental.

Timeline
The typical incubation period is 9 months to 20 years, the average is probably 4 years for tuberculoid leprosy and 8 years for lepromatous leprosy.

Leprosy loses its infectiousness after treatment with appropriate antibiotics.

Clinical manifestations
The usual clinical presentation varies between the two polar forms, lepromatous and tuberculoid leprosy.

In lepromatous leprosy, nodules, papules, macules and diffuse infiltrations are bilaterally symmetrical and usually numerous and extensive. The nasal mucosa may be involved, and iritis and keratitis can occur.

In tuberculoid leprosy skin lesions are single or few, sharply demarcated, anaesthetic or hyperaesthetic and bilaterally asymmetrical; peripheral nerve involvement tends to be severe.

5. Managing single notifications

Response time
Investigation
Within 3 working days of notification begin follow-up investigation.

Data entry
Within 5 working days of notification enter on NDD confirmed cases only.

The World Health Organization requires the following data:
1. Classification of the case. Options are:
    a) Single-lesion paucibacillary leprosy (SLPB). This includes:
       - Only one skin lesion (i)
       - No nerve trunk involvement (ii)

    b) Paucibacillary leprosy (PB) this includes:
       - 2 to 5 skin lesions (i), that are asymmetrically distributed, and definite loss of sensation
       - Only one nerve trunk damaged (ii)

    c) Multibacillary leprosy (MB)
       - More than 5 skin lesions (i), distributed more symmetrically, and a loss of sensation
       - Many nerve trunks damaged (ii)

2. Whether the case is new or a relapsed case previously treated with multidrug therapy.

3. Whether the case had a grade 2 disability at first presentation. A grade 2 disability in leprosy is visible deformity or damage (including ulceration, shortening, disorganisation, stiffness, loss of part) to hands or feet and/or severe visual impairment (visual activity less than 6/60) or lagopthalmus or iridocyelitis or corneal opacity.

Notes:
(i) Skin lesions include macules (flat lesions), papules (raised lesions) and nodules.
(ii) Resulting in loss of sensation or weakness of muscles supplied by the affected nerve.

Enter these data on NDD under "Clinical Notes".

Response procedure
The response to a notification will normally be carried out in collaboration with a specialist physician and if necessary, the local chest clinic staff. 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

• Review case and contact management

• Identify the likely source of infection

Case management
Investigation and treatment
Medication should be administered under the supervision of a specialist physician. Chest Clinic staff can assist if necessary. Combination chemotherapy is usually indicated, such as monthly rifampicin and clofazimine plus daily dapsone and clofazimine until skin smears are negative. However, refer to Therapeutic Guidelines: Antibiotic for resources on patient management.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. In particular, emphasis should be placed on foot care and prevention of injury.

Exposure investigation
None routinely

Isolation and restriction
An infectious case may be restricted if behaving in a way that is endangering, or is likely to endanger the health of the public (Public Health Act 1991, Section 23).

No restriction is placed on attendance at work or school if the case is regarded as non-infectious.

Environmental evaluation
None

Contact management
Identification of contacts
A person who has been in close regular contact with an infected person over a prolonged period.

Treatment
Contacts should be referred to a specialist medical practitioner for investigation and treatment. BCG vaccination is recommended for neonates born to cases.

Education
Advise contacts (or parents/guardians) of the mode of transmission and the low risk of infection.

Isolation and restriction
None