# Therapeutic challenges in relapsing cutaneous and visceral leishmaniasis caused by Leishmania (Mundinia) martiniquensis in patients with advanced HIV disease from Southern Thailand

## TL;DR

This paper reports two cases of relapsing leishmaniasis in HIV patients in Thailand, highlighting treatment challenges and possible drug resistance.

## Contribution

The study provides new clinical and molecular insights into L. martiniquensis infections in immunocompromised patients in Thailand.

## Key findings

- L. martiniquensis caused relapsing cutaneous and visceral leishmaniasis in two HIV patients despite standard treatment.
- Parasite strains were isolated before and after relapse, suggesting possible drug resistance.
- Current treatment options in Thailand are limited and less effective compared to WHO-recommended therapies.

## Abstract

Autochthonous leishmaniasis has become increasingly recognized in Thailand, with Leishmania (Mundinia) martiniquensis identified as the predominant species, particularly among immunocompromised individuals. Infected immunosuppressed patients often present with complex clinical features, which can delay diagnosis and complicate treatment. Given the limited clinical data available and emerging reports of resistant infections, improved awareness, prompt diagnosis, and optimized management strategies are urgently needed to address this underrecognized pathogen in Thailand.

We report two patients with advanced HIV disease (AHD) from Songkhla Province, Southern Thailand, who developed chronic diffuse cutaneous leishmaniasis characterized by widespread non-ulcerative papulonodular lesions that progressed to visceral involvement. Histopathological examination of the skin nodules showed prominent dermal fibrosis with infiltration by macrophages heavily parasitized with kinetoplast-containing amastigotes, consistent with cutaneous leishmaniasis. Molecular analyses identified L. martiniquensis as the causative agent in both cases. The parasite strains (WHO codes: MHOM/TH/2022/CULE7.1 and MHOM/TH/2022/CULE7.2) were successfully isolated from the bone marrow and cutaneous biopsy of the second patient before treatment. Furthermore, the parasite was isolated again from a cutaneous biopsy of the same patient after relapse, designated MHOM/TH/2023/CULE8. Due to the high costs of liposomal amphotericin B and the unavailability of miltefosine in Thailand, contrary to the WHO guideline recommending these as first-line therapy, patients received intravenous amphotericin B deoxycholate (AmB-D) combined with oral itraconazole. Despite repeated treatment with AmB-D and itraconazole, both patients relapsed, and Case 1 died. This raises concerns about drug resistance.

These cases illustrate complex cutaneous manifestations and therapeutic challenges of relapsing diffuse cutaneous and visceral leishmaniasis caused by L. martiniquensis in patients with AHD from Southern Thailand. The persistence and relapse despite AmB-D therapy raise concerns about emerging drug-resistant strains and underscore the need for enhanced surveillance, parasite isolation, and optimized treatment strategies for this neglected pathogen. Moreover, this report expands the understanding of the cutaneous spectrum of L. martiniquensis in patients with AHD, emphasizing the importance of including leishmaniasis in the differential diagnosis of complex skin diseases among immunosuppressed individuals, particularly in endemic areas.