Efficacy and safety of single-dose liposomal amphotericin B in patients with visceral leishmaniasis in Bangladesh: a real-life experience

Follow-up assessment of visceral leishmaniasis treated patients and the impact of COVID-19 on control services in Nepal

BACKGROUND

Follow-up assessment of visceral leishmaniasis (VL) treated cases is important to monitor the long term effectiveness of treatment regimens. The main objective of this study was to identify the gaps and challenges in the follow-up of treated VL cases, to monitor treatment outcome and to assess the impact of COVID-19 on VL elimination services and activities.

METHODS

Clinicians treating VL patients, district focal persons for VL, and patients treated for VL in seven high endemic districts in Nepal during 2019-2022 were interviewed to collect data on challenges in the follow-up of VL treated patients as per national strategy.

RESULTS

Follow up status was poor in two districts with the largest number of reported cases. The majority of cases were children under 10 years of age (44.2%). Among 104 VL treated cases interviewed, 60.6% mentioned that clinicians had called them for follow-up but only 37.5% had complied. Among 112 VL treated cases followed up, 8 (7.14%) had relapse and 2 (1.8%) had PKDL. Among 66 cases who had VL during the COVID-19 lock down period, 32 (48.5%) were diagnosed within 1 week; however, 10 (15.1%) were diagnosed only after 4 weeks or more. During the COVID-19 pandemic, there was no active search for VL because of budget constraints and lack of diagnostic tests, and no insecticide spraying was done.

CONCLUSION

Relapses and PKDL are challenges for VL elimination and a matter of concern. Successful implementation of the national strategy for follow up of treated VL cases requires addressing elements related to patients (awareness, transport, communication) clinicians (compliance) and organization of service delivery (local health worker training and deployment). COVID-19 did not have much impact on VL diagnosis and treatment; however, public health programmes including active case detection and insecticide spraying for vector control were severely reduced.

Limitations of current chemotherapy and future of nanoformulation-based AmB delivery for visceral leishmaniasis-An updated review

Visceral leishmaniasis (VL) is the most lethal of all leishmaniasis diseasesand the second most common parasiticdisease after malaria and,still, categorized as a neglected tropical disease (NTD). According to the latest WHO study, >20 Leishmania species spread 0.7-1.0 million new cases of leishmaniasis each year. VL is caused by the genus, Leishmania donovani (LD), which affects between 50,000 and 90,000 people worldwide each year. Lack of new drug development, increasing drug resistance, toxicity and high cost even with the first line of treatmentof Amphotericin B (AmB), demands new formulation for treatment of VLFurther the lack of a vaccine, allowedthe researchers to develop nanofomulation-based AmB for improved delivery. The limitation of AmB is its kidney and liver toxicity which forced the development of costly liposomal AmB (AmBisome) nanoformulation. Success of AmBisome have inspired and attracted a wide range of AmB nanoformulations ranging from polymeric, solid lipid, liposomal/micellar, metallic, macrophage receptor-targetednanoparticles (NP) and even with sophisticated carbon/quantum dot-based AmBnano delivery systems. Notably, NP-based AmB delivery has shown increased efficacy due to increased uptake, on-target delivery and synergistic impact of NP and AmB. In this review, we have discussed the different forms of leishmaniasis disease and their current treatment options with limitations. The discovery, mechanism of action of AmB, clinical status of AmB and improvement with AmBisome over fungizone (AmB-deoxycholate)for VL treatment was further discussed. At last, the development of various AmB nanoformulation was discussed along with its adavantages over traditional chemotherapy-based delivery.

Amphotericin B resistance in Leishmania mexicana: Alterations to sterol metabolism and oxidative stress response

Amphotericin B is increasingly used in treatment of leishmaniasis. Here, fourteen independent lines of Leishmania mexicana and one L. infantum line were selected for resistance to either amphotericin B or the related polyene antimicrobial, nystatin. Sterol profiling revealed that, in each resistant line, the predominant wild-type sterol, ergosta-5,7,24-trienol, was replaced by other sterol intermediates. Broadly, two different profiles emerged among the resistant lines. Whole genome sequencing then showed that these distinct profiles were due either to mutations in the sterol methyl transferase (C24SMT) gene locus or the sterol C5 desaturase (C5DS) gene. In three lines an additional deletion of the miltefosine transporter gene was found. Differences in sensitivity to amphotericin B were apparent, depending on whether cells were grown in HOMEM, supplemented with foetal bovine serum, or a serum free defined medium (DM). Metabolomic analysis after exposure to AmB showed that a large increase in glucose flux via the pentose phosphate pathway preceded cell death in cells sustained in HOMEM but not DM, indicating the oxidative stress was more significantly induced under HOMEM conditions. Several of the lines were tested for their ability to infect macrophages and replicate as amastigote forms, alongside their ability to establish infections in mice. While several AmB resistant lines showed reduced virulence, at least two lines displayed heightened virulence in mice whilst retaining their resistance phenotype, emphasising the risks of resistance emerging to this critical drug.

Visceral Leishmaniasis: Epidemiology, Diagnosis, and Treatment Regimens in Different Geographical Areas with a Focus on Pediatrics

Visceral Leishmaniasis (VL) is a vector-borne disease caused by an intracellular protozoa of the genus Leishmania that can be lethal if not treated. VL is caused by Leishmania donovani in Asia and in Eastern Africa, where the pathogens’ reservoir is represented by humans, and by Leishmania infantum in Latin America and in the Mediterranean area, where VL is a zoonotic disease and dog is the main reservoir. A part of the infected individuals become symptomatic, with irregular fever, splenomegaly, anemia or pancytopenia, and weakness, whereas others are asymptomatic. VL treatment has made progress in the last decades with the use of new drugs such as liposomal amphotericin B, and with new therapeutic regimens including monotherapy or a combination of drugs, aiming at shorter treatment duration and avoiding the development of resistance. However, the same treatment protocol may not be effective all over the world, due to differences in the infecting Leishmania species, so depending on the geographical area. This narrative review presents a comprehensive description of the clinical picture of VL, especially in children, the diagnostic approach, and some insight into the most used pharmacological therapies available worldwide.