Leishmaniasis in India resulting from infection of the hemoflagellate protozoan parasite Leishmania donovani manifests in two different forms, visceral leishmaniasis (VL; also known as kala-azar) and its dermatologic sequel post–kala-azar dermal leishmaniasis (PKDL; discussed in ref. 1 and references therein). PKDL was first described by Brahmachari in 1922 in cured VL patients with eruptions and plaques in the skin, it was confirmed by demonstration of Leishman–Donovan bodies (LD) in slit skin smears, and it was termed dermal leishmanoid (discussed in ref. 1 and references therein). Later, the disease was renamed PKDL, because eruptions follow the visceral form, commonly called kala-azar. PKDL manifests in a variety of clinical forms ranging from hypopigmented macules to infiltrated plaques and nodules. Diagnosing PKDL has always been a challenge, because its geographical pocket is also endemic for leprosy, a disease that closely mimics PKDL. A previous history of VL is often sought for making a diagnosis but can be misleading at times, because a history of VL was found in 87.5% of patients in a recent study with PKDL.2
Because PKDL is the proposed reservoir, especially during the interepidemic periods of VL, diagnosing PKDL is of paramount importance to prevent further epidemics (discussed in ref. 1 and references therein). In more recent years, several diagnostic approaches have been developed ranging from serological tests and immunohistochemistry to polymerase chain reaction (PCR).3 Among the serological tests, the immunochromatographic strip test using recombinant kinesin 39 (rK39) is considered as a rapid, convenient, and useful test for diagnosis of Indian leishmaniasis.4 The K39 epitope is highly conserved in the visceralizing species of Leishmania and was used to develop a diagnostic test for VL and PKDL.5,6 In cases of VL, the rK39 nitrocellulose-based dipstick test showed high sensitivity and specificity4 and therefore, has gained substantial popularity for its ease of use, especially in the field setting. For detection of polymorphic PKDL (comprising both macular and papulo-nodular skin lesions), the sensitivity of the rK39 strip test is 95.6%, and for macular PKDL, the sensitivity is 86.3%.6 This report deals with three cases where relying on the rK39 strip test led to misdiagnosis and subsequent therapeutic delay. The study was approved by the Institutional Ethical Committee, and peripheral blood or skin biopsy was collected after obtaining informed consent from the parent/guardian of the minors.
The American Committee on Clinical Tropical Medicine and Travelers' Health (ACCTMTH) assisted with publication expenses.
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