Remarks on criterion of nerve function alteration as a sign of relapse in leprosy patients during surveillance or postsurveillance periods
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To The Editor:
Nerve function alteration in leprosy patients during surveillance or postsurveillance periods is generally considered as a sign of relapse of the disease. This clinical sign, easily applicable in field work, may not be a sensitive operational indicator in a leprosy control program. Our remarks are based on the histopathological examination of 150 sural or radiocutaneous nerve biopsies from patients who had completed multidrug therapy but subsequently started to complain of new numbness or paresis. These patients have been referred to the hospital with the diagnosis of relapse after being released from treatment. The time interval between the date of release and the onset of the complaints varies from 6 months to 3 years.
In 72% of the cases, the histopathological finding was intra- and perineural fibrosis with no sign of active disease. We assume that the alteration in nerve function for these patients is related to an ongoing scarring phenomenon but not to an active inflammatory reaction caused by a reinfection or relapse (i.e., bacilli starting to multiply again). One objection may be raised against this hypothesis, namely, that the examined sural and radiocutaneous nerves are not mirroring the peripheral nervous system. However, we would like to stress that the scarring process is most likely the major mechanism involved in the alteration of nerve function for the majority of the patients after completion of chemotherapy. We understand the difficulty in discriminating between active and inactive cases and, under such circumstances, it is logical to give the benefit of retreatment to the patients. However, the problem is important in leprosy control programs, since the method of detection of relapse based on alteration in nerve function may distort the assessment of relapse rates which provides a crucial operational indicator of the ultimate value of the therapeutic regimens in use.
- Dr. Yohannes Negesse
Dr. Tivadar L. Miko
AHRI-ALERT
P.O. Box 1005
Addis Ababa, Ethiopia