Classification Since 1998, the World Health Organization (WHO) has recommended that the initiation of multiple drug therapy may be based on the number of skin lesions present without a formal quantification of bacterial load. The classification is paucibacillary if the patient is not experiencing a leprosy reaction and has five or fewer skin lesions, implying a diminutive bacterial load. If the patient has six or more skin lesions, the classification is multibacillary, implying a high bacterial load. Table 1 presents recommended US treatment regimens for patients with
paucibacillary and
multibacillary disease. Although the WHO classification facilitates treatment, it is less effective in providing information regarding the potential for a leprosy reaction.
9,10 The Ridley-Jopling system provides an insightful clinical classification based on the patient's immunologic response to the infection. It also permits a prediction of which patients could experience a leprosy reaction (see Table 2).
Tuberculoid leprosy denotes an adequate immune response to
M leprae;
lepromatous leprosy denotes aninadequate response. Interpolated between the tuberculoid and the lepromatous classifications are
borderline tuberculoid,
borderline borderline, and
borderline lepromatous. Interpolated classifications are arranged according to declining immunologic response to the infection, beginning with borderline tuberculoid and ending with borderline lepromatous. Declining immunologic response manifests clinically with an increase in the number of lesions, nodularity of individual lesions, and bacterial load. A tendency for disease progression towards the lepromatous classification is observed in patients whose initial classifications represent a diminished immune response to the infection. Indeterminate leprosy is a transitory state that may terminate with resolution of infection or progress into one of the other categories of the Ridley-Jopling classification system, depending on immune response.
3,11Leprosy reactions There are two major types of leprosy reaction, which is an immunologic change represented by clinical signs and symptoms that may occur during the course of leprosy.
3,7 More than 25% of patients with borderline and lepromatous leprosy may experience a leprosy reaction during the course of their disease.
8 Those with tuberculoid leprosy do not experience either type of reaction. Leprosy reactions may be triggered by multiple drug therapy for the infection, other infections, other medications, vaccinations, pregnancy, and physical and mental stress.
7 Antimicrobial treatment should not be stopped in the presence of either reaction.
3 
Type 1 reactions result from the interaction of T lymphocytes with antigens derived from disintegrating M leprae and occur only in patients with borderline disease.
7 Of course, the closer the disease is to the lepromatous classification, the greater the bacterial load and the greater the potential antigen load. Type 1 reactions are marked by edema, increased erythema, and potential ulceration of existing skin lesions. Nerve damage, however, is the major concern. Clinically, nerves may increase in size and become tender. Neuritis can occur without symptoms but still damage the nerve. Type 1 reactions are typically managed with 40 to 60 mg of oral prednisone daily, which is slowly tapered once the reaction has been controlled. Mild reactions without neurologic changes may be treated with bed rest and aspirin or NSAIDs.
3,9 Type 2 reactions, also called
erythema nodosum leprosum, occur in patients with borderline lepromatous and
lepromatous disease. They may manifest with fever, arthralgias, myalgias, and anorexia—unlike type 1 reactions, which produce no systemic signs. Erythematous, tender nodules appear in large numbers, typically on the extensor surfaces of the extremities.
Conjunctivitis, neuritis, keratitis, iritis, synovitis, nephritis, hepatosplenomegaly, orchitis, and lymphadenopathy may also occur. The reaction may last from a few days to years.
3 Type 2 reactions without neuritis may be managed with thalidomide; however, neuritis requires systemic corticosteroids.
8 The frequency of this reaction type has been reduced to 5% or less since clofazimine was added to the treatment regimen.
9 Histology Clinically involved tissue from a patient with tuberculoid leprosy will contain no acid-fast bacilli. Conversely, that from a patient with lepromatous leprosy will demonstrate an abundance of acid-fast bacilli. Foamy histiocytes are characteristic of lepromatous leprosy.
11 Treatment Leprosy treatment is quite effective; the WHO has reported failure rates of around 1%. If treatment failure occurs in a patient with multibacillary disease, the patient should be retreated with the same drug regimen because of the low prevalence of drug resistance. When paucibacillary disease does not respond to treatment, however, the retreatment should be using the regimen for multibacillary disease.
8 Patients treated for paucibacillary disease should be seen every 6 months for 5 years; those treated for multibacillary disease should be reevaluated every 6 months for 10 years.
9 Regarding the time frame for potential risk of transmitting infection following treatment initiation, a patient may be considered noninfectious within 2 days of initiating treatment with rifampin.
8
Outcome The patient in this case received a diagnosis of lepromatous leprosy, which was treated as multibacillary with multidrug therapy. He improved significantly and has yet to experience a leprosy reaction.
JAAPA
Acknowledgements The author thanks Michael Kent, MD, Susan Rowland, MD, Ronald Washburn, MD, Tushar Vachharajani, MD, and Naveen Atray, MD, for their assistance with this manuscript.
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