Is Western Ghats An Endemic Region for Cutaneous Leishmaniasis?

Sir,

Leishmaniasis is a group of diseases caused by the protozoan parasites belonging to more than 20 species of Leishmania. Visceral leishmaniasis (VL), the more serious form of the disease, is more common in India than cutaneous leishmaniasis (CL). CL is reported mainly from the northwestern region of India (Rajasthan and Punjab) bordering Pakistan[1,2] and in some smaller pockets of Himachal Pradesh.[3] Sporadic cases of indigenous CL have been reported from Kerala.[4,5] Here, we report another case of indigenous CL from Thrissur district in Kerala state.

A 50-year-old farmer residing on the foothills of the Western Ghats in Thrissur district, who had never traveled outside the state, presented for an asymptomatic, slowly growing erythematous plaque of size 2.5 cm × 1.5 cm on the front of the neck for the past 2 years [Figure 1a]. It became eroded and crusted in the center 3 months ago. On evaluation, he had 10 more discrete, skin-colored or pinkish papules of size 0.2–0.4 cm on the face, neck, and back of the trunk, which had appeared during the preceding 3 months [Figure 1b and c]. The sensations were normal. There was no peripheral nerve thickening, mucosal lesions, or lymphadenopathy. Systemic examination was normal.

Figure 1.

(a) Asymptomatic erythematous plaque of size 2.5 cm × 1.5 cm on the front of the neck. (b) Skin-colored papule on the forehead. (c) Erythematous papules on the forehead and scalp

Hemogram, renal function tests, liver function tests, and urine analysis were normal. Serological tests for Human immunodeficiency virus, Hepatitis B, Hepatitis C were negative. Ultrasonograms of the abdomen and pelvis were normal. Slit skin smear was negative for acid lepra bacilli. Tissue smear, treated with Giemsa stain (40X) showed plenty of Leishman-Donovan bodies, the amastigote forms of Leishmania [Figure 2].

Figure 2.

Tissue smear stained with Giemsa stain showing amastigotes of Leishmania, also known as Leishman-Donovan bodies, in and around the macrophages (100X)

Histopathological examination from a papule showed mixed inflammatory infiltrate with parasitized macrophages and non-caseating granulomas in the dermis (H and E; 10X) [Figure 3a]. Oval basophilic structures with double dot appearance were seen inside the macrophages and extracellularly (H and E; 100X) [Figure 3b]. Polymerase chain reaction (PCR) from the scrapings of lesional skin showed positivity for kinetoplast DNA of Leishmania; rk39 rapid test of the serum to diagnose active VL was negative. Though we tried to identify the species by PCR, it was not successful as the parasitic load was low.

Figure 3.

(a) Histopathology of the lesion showing epidermis and dermis. The epidermis is unremarkable. The dermis is showing mixed inflammatory infiltrate with parasitized macrophages and non-caseating granulomas (H and E, 100X). (b) On magnification, oval basophilic structures with a double dot appearance were seen in the macrophages, both in the intracellular and extracellular parts (H and E, 1000X)

The skin lesions were treated by cryotherapy with liquid nitrogen. Three sessions of the spray freezing method were used for smaller lesions and five sessions for the larger ones. All the lesions subsided within a few weeks and there was only negligible scarring. No new lesions or systemic involvement were observed during the follow-up period of 1 year.

In 1988, Unnithan et al.[5] from Trivandrum reported two patients with CL who had recently returned from Middle East countries. In 1990, Muhammed et al.[6] reported the first indigenous cases of CL from Kerala in the Nilambur of Malappuram district. These patients had localized type of CL. Bora et al.[7] (1996) did a survey of the Nilambur region and reported the prevalence of CL to be 2.7% among the 406 villagers surveyed. In 1995, Criton et al.[8] reported a case of CL on the lip. Criton et al.[9] reported two indigenous cases of CL out of six cases from different parts of central Kerala in 1997.[9] One of the cases in their series had features of diffuse CL and the other had a mucosal lesion.

In 2009, Simi S M, et al.[10] reported an endemic focus of CL in two tribal settlements in Thiruvananthapuram district. Twelve of them had active lesions and six had healed lesions. The vector identified was Phlebotomus argentipes, which is considered as a vector of Leishmania donovani. But they could not isolate the species. In 2015, Kumar et al.[4] identified the organism in the same tribal belt as L. donovani. This was the first confirmed report of L. donovani being the cause of CL in South India. Localized CL caused by L. donovani has also been reported from Himachal Pradesh.[3]

Different clinical presentations like localized, diffuse, and mucosal lesions among indigenous cases reported from Kerala could indicate the presence of more than one species of Leishmania in this region. A few indigenous cases of VL caused by L. donovani too have been reported from regions close to the Western Ghats in Kerala.[11,12]

Most cases of indigenous CL in Kerala, including ours, have been in patients who live at or near the Western Ghats. As the Western Ghats span across the other states like Karnataka, Goa, and Maharashtra, an extensive epidemiological survey of this region would be warranted. It would be interesting to know if the species identified from this region s similar to those reported from the rest of the country.

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Conflicts of interest

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