Leprosy (Hansen’s disease): symptoms, diagnosis and treatment in the UK

Leprosy is caused by the bacterium Mycobacterium leprae, and more rarely Mycobacterium lepromatosis. UKHSA notes that it mainly affects the cooler parts of the body: the skin, the lining of the airways, the eyes and the peripheral nerves, which carry sensation and movement signals to the hands, feet and face.

The WHO explains that the disease is believed to spread by inhaling droplets from the nose and mouth of an untreated person after prolonged close contact. Most people exposed do not develop the disease. UKHSA says most people who are infected are thought not to develop clinical disease, though the proportion is not known.

The way the illness appears depends on the immune response. UKHSA describes a spectrum from tuberculoid disease, with few well-defined skin lesions, to lepromatous disease, in which many bacteria multiply and the skin is widely affected. For treatment purposes it is divided into paucibacillary disease (one to five skin lesions) and multibacillary disease (six or more).

The WHO says the disease usually appears as skin lesions with a different colour to the surrounding skin, paler or reddish, which may be flat, raised or nodular, single or multiple, with definite loss of sensation. It also affects peripheral nerves.

UKHSA describes what clinicians look for in someone who has lived in or travelled to an area where leprosy is common:

• A chronic, non-itchy patch of skin that does not look like any known condition or has not responded to treatment.

• Reduced sensitivity to light touch, pain or temperature within a paler patch; complete numbness in a lesion makes leprosy the leading diagnosis.

• Widespread skin changes, or persistent bumps or nodules, in lepromatous disease.

• Signs of damage to nerve trunks, such as the ulnar, median, common peroneal or posterior tibial nerves, with pain in a nerve or thickened nerves.

• An ulcer on the sole of the foot.

See a GP if you have a numb patch of skin that is not going away, especially if you have lived in or spent time in a country where leprosy occurs. UKHSA notes that people often present many years after arriving in Britain, so the diagnosis may not be considered, and that common misdiagnoses include diabetic neuropathy, other nerve problems and skin conditions such as sarcoidosis.

Tell the clinician where you have lived and when. UKHSA says that if you are already known to have leprosy and develop signs of a reaction, such as new tender skin lesions, fever, nerve pain or sudden weakness, you should contact the leprosy specialist immediately to be seen within 24 hours, because rapid treatment prevents nerve damage.

UKHSA says the diagnosis depends on clinical signs plus the finding of acid-fast bacilli on microscopy and/or appropriate histology, and that it should be confirmed in every case. Slit-skin smears are taken by a Consultant Advisor in Leprosy or their delegate and sent to reference laboratories, and a skin biopsy goes for specialist histology. There is no reliable blood test, and PCR for Mycobacterium leprae is not routinely available in the UK.

The WHO bases the diagnosis on at least one cardinal sign: definite loss of sensation in a pale or reddish skin patch, a thickened peripheral nerve with loss of sensation or weakness, or bacilli on a slit-skin smear.

In England, doctors must notify new cases to the local authority in confidence; UKHSA says notification does not lead to isolation, detainment or deportation and is intended to ensure specialist management and appropriate follow-up of close contacts.

Treatment is with multidrug therapy (MDT). The WHO says the regimen of dapsone, rifampicin and clofazimine kills the bacterium and cures the patient, with 6 months of treatment for paucibacillary and 12 months for multibacillary disease. In the UK, UKHSA says the regimen is chosen by combining the classification, skin smear results and biopsy findings, and that rifampicin and clofazimine are given monthly under observation with daily clofazimine and dapsone self-administered, in a blister pack.

UKHSA notes that clofazimine causes skin pigmentation and dryness, that improvement is often visible within 7 to 14 days, and that within a few days of starting treatment virtually all bacilli are dead and the patient may be considered no longer infectious.

UKHSA explains that immune-mediated reactions can occur before, during or after treatment, in almost a third of people with multibacillary disease. They do not mean the treatment is failing. Type 1 reactions cause redness and swelling of skin lesions and/or acute nerve inflammation; type 2 reactions (erythema nodosum leprosum) cause crops of tender skin lesions with fever, malaise, nerve or bone pain.

Between 30 and 60 per cent of patients have nerve damage at diagnosis, according to UKHSA, and new damage is more likely to improve with corticosteroids if it is caught early, so nerve function is checked regularly. People with numb hands or feet are taught to protect them, wear well-fitting shoes with suitable insoles, and have regular podiatry; physiotherapy, splints and reconstructive surgery may help established deformity.

People with lepromatous disease are at risk of an inflammation inside the eye that can be painless, so UKHSA advises regular eye examinations by an ophthalmologist. Close household contacts are examined, and children and young adults under 16 who are household contacts should be offered BCG if they have not had it.

Because leprosy is so uncommon in the UK, care is concentrated in a small number of national referral centres with consultant advisors in leprosy, and a GP or hospital doctor refers a suspected case there. UKHSA says most newly diagnosed people can be treated as outpatients without danger to themselves or others, and no special infection control precautions are needed in hospital.

UKHSA asks doctors in any setting to refer suspected or confirmed cases to one of the national leprosy centres and to notify them in confidence, so a private doctor who suspects leprosy would be expected to use the same specialist route. UKHSA also notes that patients may need advice or help with social problems, housing and employment as well as encouragement to complete treatment.