an ill-defined hypopigmented or erythematous macule or patch
a few well-demarcated, hypopigmented, or erythematous skin lesions with reduced sensation
multiple diffuse erythematous papules and nodules on arms and legs, sparing the torso
an infiltration of skin, progressing to thickened skin, possibly with reduced sensation o diffuse
infiltration of the skin and neuropathy (e.g., “glove and stocking”) (representing diffuse leprosy)
OR
The absence of skin lesions and thickening of a peripheral nerve trunk with pain or tenderness of the nerve
(representing primary neural leprosy).
Laboratory Criteria
Confirmatory Laboratory Evidence:
Detection of acid-fast bacilli in a nerve by the Fite-Faraco method,
OR
Detection of acid-fast bacilli in skin by the Fite-Faraco method, without growth of mycobacteria on
culture** (if done),
OR
Detection of M. leprae or M. lepromatosis in skin or a nerve by a nucleic acid detection test***.
Presumptive Laboratory Evidence:
N/A
Supportive Laboratory Evidence:
Detection of non-sarcoid non-caseating granuloma with peripheral nerve involvement, without growth of
mycobacteria on culture** (if done)
* Note: The categorical labels used here to stratify laboratory
evidence are intended to support the standardization of case classifications for public health surveillance.
The categorical labels should not be used to interpret the utility or validity of any laboratory test
methodology.
** If acid-fast bacilli are detected in skin only, mycobacterial
culture negativity is highly recommended to rule out infection with mycobacteria other than those in the M.
leprae complex. To rule out M. haemophilum, hemin or iron-citrate containing medium would be needed. To rule
out M. xenopi or M. marinum, incubation at 42 and 30 degrees centigrade, respectively, would be needed.
*** Note that a negative nucleic acid test on a tissue specimen does
not rule out Mycobacterium leprae or Mycobacterium lepromatosis as the cause of illness.
Epidemiologic Linkage Criteria
Prolonged close contact with an untreated person with new or recurring leprosy,
OR
Residency or repeated travel in a region with higher endemicity (prevalence >1 case per 10,000 population or
new case detection rate ≥ 50 per million population per year) for leprosy,
OR
Prolonged or frequent, direct contact† with armadillos, especially nine-banded armadillos, or soil in the
environment in which they live.
† Prolonged or frequent direct contact refers to activities
such as raising, maintaining, butchering, hunting, field dressing, or consuming armadillos. It does not
refer to brief, cursory, or sporadic touching such as might occur with a visitor to a petting zoo.
Case Classifications
Confirmed:
Meets clinical criteria AND confirmatory laboratory evidence.
Probable:
Meets clinical criteria for primary neural leprosy AND meets epidemiologic linkage criteria.
Suspect:
Meets clinical criteria for a clinically compatible illness with skin lesions AND meets epidemiologic
linkage criteria, OR
Meets clinical criteria for a clinically compatible illness with skin lesions AND meets supportive
laboratory evidence.
Criteria to Distinguish a New Case of Leprosy from Reports or Notifications which Should Not be Enumerated as a
New Case for Surveillance
For surveillance purposes, a new case of leprosy should be enumerated by public health based on the following
criteria:
A person should be enumerated as a case if not previously enumerated as a case,
OR
A person was previously enumerated as a case, followed by adequate treatment with current, standard,
multidrug therapeutic regimen and newly meets the criteria for a confirmed or probable case,
OR
A person was previously enumerated as a case, but genetic sequencing results are distinctly different in a
new positive specimen from a previous positive specimen,
OR
A person was previously enumerated as a case, but the M. leprae complex species identified (e.g.,
M. leprae vs. M. lepromatosis) in a new positive specimen is different than identified in a
previous specimen in the same person.