A new focus of cutaneous leishmaniasis in Himachal Pradesh (India)

Introduction

In India, indigenous cases of cutaneous leishmaniasis (CL), anthroponotic (ACL) as well as zoonotic (ZCL), are mainly confined to hot dry north western region and are endemic in the western Thar desert of Rajasthan[1]. Few cases of CL acquired in Saudi Arabia or indigenously have been observed in the states of Kerala[2],[3] Assam[4] and Haryana[5]. CL is transmitted by sandfly, Phlebotomus, of which more than 600 species have been identified. In India, P papatasii is the most common vector for CL. Epidemics of CL have been associated with deforestation, road construction or any other activity in which humans intrude in the habitat of the vector.[6]

CL was not known to occur in Himachal Pradesh before 1988. However, from late eighties onwards 38 new cases of this disease have been detected in the Department of Dermatology. We present here the clinical and epidemiological observations on this recently introduced disease in the region with aim of documenting the new focus.

Materials and Methods

During the period 1988-2001, thirty--eight new patients of CL were diagnosed among the patients attending Dermatology outpatient Department of Indira Gandhi Medical College, Shimla, Himachal Pradesh (India). Of these, 26 patients were from various places of Kinnaur district while other 12 were from adjoining areas of bordering districts. All these areas are situated along the river Satluj [Figure - 1]. The climate in the region of Kinnaur District is mildly warm and dry during summers, and temperate during winters with snow cover for almost 4-6 months of the year. Rain fall is minimal through out the year. The terrain of Kinnaur is dry, sandy with loose rocks and altitude ranges from 1830 to 2900 meters. The climate of other areas is moderately warm with altitude between 900 to 1000 meters. None of our patients had ever gone out of the state in the preceding 3 years. Three patients belonging to other distant places of the state had stayed for a period of 3-6 months in this region a year before the onset of their lesions.

The diagnosis of CL was mainly based on the clinical criteria proposed by Kubba and AI -Gindan,[7] demonstration of Leishman Donovan (LD) bodies in Geimsa stained direct tissue smears and histopathology. For each of these patients, detailed information was collected on age, sex, residence, and clinical features of lesions and their visits outside the district or state especially to the endemic areas, in the preceding 3 years. Both, tissue smears and histopathology were performed in 34 patients. In two patients each, either tissue smear or histopathology reports were not available hence they are not included in the final results.

They were treated with 1- 5 ml. of sodium antimony gluconate injected intralesionally till blanching of lesion; an alternate day schedule for three days of Tallab et al[8]. Larger dose was used for bigger or multiple lesions. The patients were followed up for cure. The parameters for clinical cure were disappearance of induration and resolution of the lesions.

Results

The age of patients ranged from two to 75 years. (average 22.05 years) and included 18 males and 20 females. Two of these patients were lost to follow up before the treatment could be started. The recorded duration of lesions varied from one month to two years (average 6.44 months).Twenty eight patients had single lesion involving face, neck or upper extremities. In other 10 patients the number of lesions varied from two to four. Face was afflicted in 33 patients and the lesions were confined mainly to cheeks, lips, forehead and bridge or tip of the nose. In one case each, they were on neck, upper arm and forearm. Two patients had single lesion each over dorsum of hands. The lesions were mostly nodulo-ulcerative plaques. Four patients had involvement of labial mucous membrane. The mucosal involvement seemed to be contiguous extension of cutaneous lesions.

Tissue smears for LD bodies were positive in 21 of 34 (61.7%) patients smear positivity was higher from the lesions of ( 6 months duration, wet lesions and those on mucocutaneous junctions.

In biopsy sections, all the 34 patients showed epitheloid cell granuloma interspersed with Langhans giant cells. Although 21 of these 34 patients were positive for LD bodies in tissue smears but 11 did not show LD bodies on histopathology and in 10 patients LD bodies were seen both in tissue smears as well as in histopathology.

Three intralesional injections of sodium antimony gluconate given on alternate days produced consistently reliable response in all patients and no major side effects were noted. There was no major difference in response to treatment in patients with or without mucosal lesions.

Discussion

Cutaneous leishmaniasis was not known to occur in Himachal Pradesh before 1988. The fad that all these 38 patients detected between 1988-2001 had contracted the disease indigenously is suggestive of a local vector and reservoir. This recent occurrence of the disease seems to be due to migrant labour population form Rajasthan, an ACL endemic area, stationed in the region for various hydroelectric projects. The disturbance of natural habitat of the vector due to various construction activities may be another possible reason of this new focus of infection. Adaptation of the vector as well as the parasite to strange, often bizarre habitats and hosts is well known, for instance, in India, the anthroponotic transmission with no intermediate host has been observed.[6]

The presence of lesions over face and hands (exposed parts) in all our patients conforms to the established clinical picture of the disease. Moreover, due to extremely cold climate in these areas, most of the body is heavily covered leaving face and hands the most accessible parts to the vector.

Various morphological forms of CL have been described,[9] of which nodulo-ulcerative form; classically known as ′oriental sore′ is the most common. All our patients had this characteristic clinical morphology. Mucosal lesions are rarely caused by L. tropica and occur usually on or around muco cutaneous junctions such as lips or nostrils.[10] The mechanism of mucous membrane involvement remains obscure. It may occur by haematic or lymphatic dissemination and rarely by contiguous spread. In our series, mucosal involvement seen in four patients is perhaps due to contiguous spread.

Demonstration of parasite in direct smears remains the easiest and the most specific method of diagnosis. The smears are positive in 50-70% of the cases, depending on the age of lesions; younger lesions being more likely to yield the parasite.[7] Tissue smear positivity was 61.7% in our series and majority of the lesions were 2-4 months of duration.

Histopathological examination is diagnostic only when the parasite is found. As a rule the organisms are scarce and difficult to identify in sections stained with H & E stain.[6] In our study, the presence of epitheloid cell granulomas and the absence of demonstrable LD bodies in biopsies of 24 patients, compares well with the group V of Ridleys classification[11] of pathology of cutaneous leishmaniasis. The presence of LD bodies in tissue smears and failure to demonstrate them in histopathology sections remains unexplained. Bahamdam et al[12] made similar observations in their 3 of 21 patients and postulated that probably leishmania organisms appear larger in touch smears and are scanty in histopathology due to repeated processing of biopsy specimens with dehydrating solutions.

Non-availability of facilities for Novy-MacNeal-Nicolle (NNN) culture medium and Leishmanin test at most of the centres especially in non-endemic areas is a limiting factor for species identification and follow up of therapy.

Pentavalent antimony compounds with their efficacy and consistency of results still remain the drug of choice for CL. However, the doses required in their systemic use often result in side effects and toxicity. Intralesional infiltration of sodium antimonygluconate, as suggested byTallab et al,[8] has been consistently effective in our patients without any side effect.

Occurrence of a number of cases, its transmission to migrants, in Kinnaur district of Himachal Pradesh, implies that the disease has become indigenous to the area. Although, migrant labour from Rajasthan is also working in other parts of this state, but why the disease has got limited to a particular pocket needs to be explored. Possibly, the availability of a local vector and/or disturbance of its natural habitat due to various construction activities may be responsible for the disease to have become endemic in this new area. There is no data available on the existence of P.papatassi, the vector for CL in India, at this altitude. The present study has highlighted only a new focus of cutaneous leishmaniasis in this area, which will be of considerable public health interest. Further epidemiological studies are warranted to establish the identity of the vector and strain of the leishmania involved.