Risk Factors of Leishmania Infection among HIV-Infected Patients in Trang Province, Southern Thailand: A Study on Three Prevalent Species

Leishmania Infection among HIV-Infected Patients in a Southern Province of Thailand: A Cross-Sectional Study

Leishmaniasis, a neglected tropical disease, imposes a notable health burden, especially on immunocompromised individuals such as HIV patients. Recognizing its prevalence and risk factors in specific populations is vital for effective prevention. This study in Satun Province, southern Thailand, aimed to ascertain leishmaniasis prevalence and identify associated risks among HIV-infected patients. A cross-sectional study was conducted among 650 HIV-infected individuals at a tertiary care hospital. Data on demographic characteristics, clinical parameters, and potential risk factors were collected. Individual plasma, buffy coat, and saliva samples were collected. Leishmania infection was determined using the direct agglutination test and nested polymerase chain reaction (nPCR) of nPCR-buffy coat and nPCR-saliva. The association between risk factors and Leishmania infection was assessed with logistic regression analysis. The prevalence of Leishmania infection was 8.61% (56/650). Species was identified among 20 HIV-infected patients as follows: Leishmania orientalis (n = 14), Leishmania martiniquensis (n = 4), and Leishmania donovani complex (n = 2). The factors associated with Leishmania infection included age (adjusted odds ratio [OR] = 1.03), intravenous drug use (adjusted OR = 2.39), CD4 cell count <500 cells/mm3 (adjusted OR = 2.40), and a viral load ≥50 copies/mL (adjusted OR = 5.16). The prevalence of Leishmania infection among HIV-infected patients in Satun Province was considerable. These findings underscore the need for integrated care and targeted interventions to address this infection and improve public health outcomes. Further research and collaborative efforts are warranted to develop effective prevention and control strategies for Leishmania infection in the HIV-infected Thai population.

Development of nucleic acid lateral flow immunoassay for duplex detection of Leishmania martiniquensis and Leishmania orientalis in asymptomatic patients with HIV

Leishmaniasis, a neglected tropical disease caused by parasitic protozoa of the Leishmania genus, remains a global health concern with significant morbidity and mortality. In Thailand, the rising incidence of autochthonous leishmaniasis cases involving Leishmania (Mundinia) martiniquensis and novel Leishmania (Mundinia) orientalis underscores the critical need for accurate diagnosis and effective control strategies. This study presents a sensitive and specific nucleic acid lateral flow immunoassay (NALFIA) that integrates a duplex PCR assay with a lateral flow device (LFD) strip format. Targeting the internal transcribed spacer 1 (ITS1) region, known for its unique combination of conserved and variable sequences, this assay employs primers labeled with biotin, digoxigenin, and fluorescein isothiocyanate (FITC) markers, enabling precise species identification and differentiation of these two Leishmania species. Remarkably, the assay achieves a sensitivity that surpasses agarose gel electrophoresis, detecting as few as 10-2 parasite/μL for L. martiniquensis and 10-4 parasite/μL for L. orientalis. Notably, the assay exhibited reliable specificity, revealing no cross-amplification with other major viscerotropic Leishmania species or reference organisms. Evaluation using 62 clinical samples further confirms the effectiveness of the PCR-LFD assay, with a sensitivity of 100% for L. martiniquensis and 83.3% for L. orientalis, and an excellent agreement (κ value = 0.948) with nested PCR. This integrated assay represents a promising advancement in diagnostic tools, offering rapid and accurate results that can significantly contribute to effective disease management and control. Given the increasing relevance of these Leishmania species in current public health scenarios, this assay serves as a valuable tool for both diagnostic and research applications.

In vitro drug susceptibility using a parasite-rescue and transformation assay of Leishmania (Mundinia) martiniquensis and Leishmania (Mundinia) orientalis amastigotes against antileishmanial drugs

Leishmaniasis is an emerging infectious disease in Thailand, with Leishmania martiniquensis and Leishmania orientalis identified as the primary causative agents among immunocompetent and immunocompromised individuals. Variations in drug susceptibility among different Leishmania species have been reported in different regions. Therefore, drug susceptibility assays are essential to assess the effectiveness of antileishmanial drugs used or potentially used in the affected areas. This study investigated the in vitro drug sensitivity of L. martiniquensis and L. orientalis, along with two reference species causing VL, namely L. donovani and L. infantum, against six antileishmanial drugs. Using a parasite-rescue and transformation assay, the results demonstrated that the IC50 values of amphotericin B (AmB), miltefosine (MIL), and sodium stibogluconate (Sb(III)) against all Leishmania species tested were within the sensitive range of each drug. On the contrary, the IC50 values of artemisinin (ART) and dihydroartemisinin (DHA), drugs primarily used for malaria treatment, were outside the sensitive range of the Leishmania species tested except L. infantum. This in vitro study highlights that AmB could effectively exhibit good sensitivity against the intracellular amastigotes of L. martiniquensis and L. orientalis. Also, MIL and Sb(III) could be considered alternative drugs for antileishmanial treatment in Thailand.

Prevalence of visceral leishmaniasis among people with HIV: a systematic review and meta-analysis

Leishmaniasis is a parasitic infection expressing different clinical phenotypes. Visceral leishmaniasis (VL) is considered an opportunistic infection among people with human immunodeficiency virus (HIV). The objective of this review was to identify published data on the prevalence of Leishmania spp. infection among PWH and to define particular determinants that affect critically the epidemiological characteristics of VL-HIV coinfection and, potentially, its burden on public health. Two independent reviewers conducted a systematic literature search until June 30, 2022. Meta-analyses were conducted using random-effects models to calculate the summary prevalence and respective 95% confidence intervals (CI) of leishmaniasis among PWH. Meta-regression analysis was performed to investigate the impact of putative effect modifiers, such as the mean CD4 cell count, on the major findings. Thirty-four studies were eligible, yielding a summary prevalence of 6% (95%CI, 4-11%) for leishmaniasis (n = 1583) among PWH (n = 85,076). Higher prevalence rates were noted in Asia (17%, 95%CI, 9-30%) and America (9%, 95%CI, 5-17%) than in Europe (4%, 95%CI, 2-8%). Prevalence rates were significantly mediated by the age, sex, and CD4 cell count of participants. Heterogeneity remained significant in all meta-analyses (p < 0.0001). In the majority of included studies, people were coinfected with HIV and Leishmania species associated with VL, as opposed to those associated with cutaneous leishmaniasis. No sign of publication bias was shown (p = 0.06). Our summary of published studies on leishmaniasis among PWH is important to provide prevalence estimates and define potential underlying factors that could guide researchers to generate and further explore specific etiologic hypotheses.

Nutritional Modulation of the Immune Response Mediated by Nucleotides in Canine Leishmaniosis

Leishmaniasis is an emerging, uncontrolled, and neglected zoonotic disease. Climate change is contributing to its ongoing global expansion. The dog is the main reservoir; hence the importance of implementing effective treatment, prevention, and control measures in this animal species to protect public health. However, although the standard treatment for canine leishmaniosis (CanL) is effective, it does not provide full parasitological clearance, and side effects and drug resistance have been described. The host's immune system plays a key role in the establishment and evolution of leishmaniasis. Dietary nucleotides modulate the immune response and, given their reported efficacy and safety in sick and clinically healthy Leishmania-infected dogs and because they represent a sustainable option with no associated side effects or resistance, they could be included within the prevention, treatment, and control strategies for leishmaniasis. This article briefly summarizes the scientific literature on CanL management, including unresolved issues, and reviews the scientific evidence on immunomodulatory effects of dietary nucleotides in different animal species. It also proposes a CanL management algorithm, including nucleotides. It is concluded that nutritional modulation of the immune response with nucleotides can contribute to better management of leishmaniasis following a One Health approach, especially in the COVID-19 era.

Prevalence and associated risk factors of Leishmania infection among immunocompetent hosts, a community-based study in Chiang Rai, Thailand

Background

Leishmaniasis is an emerging infectious disease reported in the north and south of Thailand of which patients with HIV/AIDS are a high risk group for acquiring the infection. A lack of information regarding prevalence, and the risk association of Leishmania infection among asymptomatic immunocompetent hosts needs further investigation. Information on potential vectors and animal reservoirs in the affected areas is also important to control disease transmission.

Methods

An outbreak investigation and a cross-sectional study were conducted following one index case of cutaneous leishmaniasis (CL) caused by L. martiniquensis in an immunocompetent male patient reported in August 2015, Chiang Rai Province, Thailand. From September to November 2015, a total of 392 participants at two study areas who were related to the index case, 130 students at a semi-boarding vocational school and 262 hill tribe villagers in the patient’s hometown, were recruited in this study. The nested internal transcribed spacer 1-PCR (ITS1-PCR) was performed to detect Leishmania DNA in buffy coat, and nucleotide sequencing was used to identify species. Antibody screening in plasma was performed using the Direct Agglutination Test (DAT), and associated risk factors were analyzed using a standardized questionnaire. Captured sandflies within the study areas were identified and detected for Leishmania DNA using nested ITS1-PCR. Moreover, the animal reservoirs in the study areas were also explored for Leishmania infection.

Results

Of 392 participants, 28 (7.1%) were positive for Leishmania infection of which 1 (4.8%) was L. martiniquensis, 12 (57.1%) were L. orientalis and 8 (38.1%) were Leishmania spp. Of 28, 15 (53.6%) were DAT positive. None showed any symptoms of CL or visceral leishmaniasis. Risk factors were associated with being female (adjusted odds ratio, AOR 2.52, 95%CI 1.01–6.26), increasing age (AOR 1.05, 95%CI 1.02–1.08), having an animal enclosure in a housing area (AOR 3.04, 95%CI 1.13–8.22), being exposed to termite mounds (AOR 3.74, 95%CI 1.11–12.58) and having domestic animals in a housing area (AOR 7.11, 95%CI 2.08–24.37). At the semi-boarding vocational school, six Sergentomyia gemmea samples were PCR positive for DNA of L. orientalis and one S. gemmea was PCR positive for DNA of L. donovani/L. infantum. Additionally, one Phlebotomus stantoni was PCR positive for DNA of L. martiniquensis, and one black rat (Rattus rattus) was PCR positive for DNA of L. martiniquensis.

Conclusion

This information could be useful for monitoring Leishmania infection among immunocompetent hosts in affected areas and also setting up strategies for prevention and control. A follow-up study of asymptomatic individuals with seropositive results as well as those with positive PCR results is recommended.

This is the first community-based study investigating the prevalence and associated risk factors of Leishmania infection among immunocompetent individuals, demonstrating the situation of Leishmania infection in endemic areas of Thailand. An outbreak investigation and a cross-sectional study were conducted following one index case of cutaneous leishmaniasis (CL) caused by L. martiniquensis in an immunocompetent male patient reported in August 2015, Chiang Rai Province, Thailand. Of 392 participants, 28 (7.1%) were positive for Leishmania infection of which 1 (4.8%) was L. martiniquensis, 12 (57.1%) were L. orientalis and 8 (38.1%) were Leishmania spp. The factors associated with Leishmania infection included being female, increasing age, having an animal enclosure in a housing area, being exposed to termite mounds and having domestic animals in a housing area. This information revealed the first burden and risk factors of Leishmania infection among immunocompetent individuals in Thailand and highlighted the urgent need for effective interventions to prevent and control the disease in high risk populations in endemic areas.