A review of Leishmaniasis in Eastern Africa

Medicinal plants with promising antileishmanial activity in Ethiopia: A systematic review and meta-analysis

INTRODUCTION

Toxicity and resistance to chemotherapy used to treat leishmaniasis are increasing. Research on natural plant compounds has revealed their antileishmanial effects on certain Leishmania organisms. This review aimed to estimate the pooled IC50 values of medicinal plants with promising antileishmanial activity in Ethiopia.

METHODS

A systematic literature search was conducted using Science Direct, PubMed, Cochrane Library, and Google Scholar to locate potential studies. Studies published in peer-reviewed journals and gray literature in university repositories before April 1, 2022, which included a full-length study reporting the half-maximal inhibitory concentration (IC50) of Ethiopian medicinal plants that were written in English were included. Conference proceedings, review articles, letters to the editor, and correspondence were excluded. The quality of the included studies was assessed using the GIVIMP critical appraisal tools. Heterogeneity between studies was verified using Cochrane Q test statistics and I2 test statistics, and the effects were checked using Egger statistical test at a level of significance. A random-effects model was used to estimate the pooled IC50 of the medicinal plants.

RESULTS

Six articles that were conducted in Ethiopia that fulfilled the inclusion criteria, with a total of 62 in vitro experiments, were reviewed. The aggregated mean IC50 for medicinal plants in Ethiopia was 16.80 (95% CI: 12.44, 21.16) and 13.81 (95% CI: 13.12, 14.50) µg/mL for antipromastigote and antiamastigote activity, respectively. Aqueous was the significant preparation with IC50 of 0.53 (0.34, 0.73) µg/mL against promastigote and 0.98 (0.20, 1.76) µg/mL against the amastigote stage.

DISCUSSION

This review indicated that the pooled mean of IC50 for Ethiopian medicinal plants against promastigotes and amastigotes was relatively low and showed better efficacy. This strongly suggests the need to focus on antipromastigote and antiamastigote medicinal plants in Ethiopia for the development of antileishmanial drugs. It is necessary to identify their active components, and their potential toxic effects can lead to the production of well-tolerated and safe drugs for leishmaniasis. The high heterogeneity is the limitation of this study.

REGISTRATION

The review has been registered at Prospero with identification number CRD42022343543.

Leishmaniasis Beyond East Africa

Climate change is having a substantial impact on our environment and ecosystems and has altered the way humans live, access, and utilize resources with increased risk of zoonotic infectious disease encounters. As global temperatures continue to increase, they impact on public health, migration, food security and land conflict, and as new environments become favorable, exposure to disease carrying vectors. Increased forests or natural habitat clearance for land repurposing, urbanization, road building, and water management are related to an increase in emerging vector borne parasitic diseases. The East African region remains one of the most impacted regions globally for leishmaniasis, a vector borne disease that impacts significantly on the health, wellbeing and livelihoods of affected communities and for which a lack of reporting and control interventions hinder progress toward elimination of this neglected tropical disease. As our world continues to transform, both politically and climatically, it is essential that measures are put in place to improve surveillance and disease management with implementation of control measures, including vector control, especially in low- and middle-income countries that are expected to be most impacted by changes in climate. Only through effective management, now, can we be sufficiently resilient to preventing the inevitable spread of vectors into suitable habitat and expansion of the geographical range of leishmaniasis. This review offers a current perspective on Leishmaniasis as an endemic disease in East Africa and examines the potential of the recent emergence of Leishmania infection in hitherto unaffected regions to become a public health concern if no disease management is achieved.

Skin maculae, chronic diarrhea, cachexia, and splenomegaly-Late presentation of the first autochthonous case of visceral leishmaniasis in Tanzania

A 20-year-old man from Simanjiro district in northern Tanzania presented with a 3-year history of splenomegaly, fatigue, cachexia, skin maculae, and recent onset of watery diarrhea at Kilimanjaro Christian Medical Centre (KCMC) in Northern Tanzania. Due to laboratory findings of pancytopenia, diagnostic workup included bone marrow aspiration cytology and biopsy. Although the rapid test (IT LEISH, rK39 RDT) was negative, blood smear showed amastigote forms of leishmaniasis in macrophages. Repeat bone marrow aspiration and PCR eventually confirmed visceral leishmaniasis (VL). The patient denied travel to known endemic areas of VL. Treatment was initiated with Amphotericin B, but the patient died on the fourth day of treatment from respiratory insufficiency. An autopsy revealed massive organ manifestations of VL. This is the first reported autochthonous case of VL in Tanzania. Clark and colleagues detected the vector Phlebotomus martini in Northern Tanzania in 2013, in a region bordering the district of our patient. The negative rapid test draws attention to the fact that sensitivity and specificity were found to be low in East African VL patients as displayed earlier by a Kenyan study. Therefore, tissue samples (spleen or bone marrow) remain necessary for diagnosis. The variety of symptoms in this presented case was remarkable, including the occurrence of post-kala-azar dermal leishmaniasis (PKDL) and VL at the same time. This has been described in East African VL cases before as well as the occurrence of chronic diarrhea. An elongated undiagnosed period likely led to a mixed clinical picture that included hepato-splenomegaly, PKDL, cachexia, and diarrhea.

Prevalence of human visceral leishmaniasis in Iran: A systematic review and meta-analysis

Leishmania infantum is the main cause of human visceral leishmaniasis (HVL; also known as kala-azar) in the Middle East and may be fatal if left untreated. This disease was first reported in 1949 in Iran. Despite marked improvements in hygiene and sanitation conditions, the disease is still endemic in some parts of Iran. It is difficult to determine the current prevalence of HVL in Iran due to the scarcity of comprehensive studies in this regard. In response to this gap, a systematic review and meta-analysis was conducted to gain better understanding of HVL epidemiology in the general population of Iran. English and Persian databases were searched for studies reporting the prevalence and risk factors associated with HVL in the Iranian people from January 1995 to December 2019. The reported data were selected according to inclusion and exclusion criteria. The pooled prevalence of HVL infection and its 95 % confidence intervals were calculated. Quality assessment, heterogeneity testing and publication bias assessment were also done. Literature search revealed 3634 studies, of which 35 studies met our eligibility criteria, with a total of 50,716 individuals. The meta-analysis was performed on 31 out of 35 included studies. The estimated pooled prevalence of HVL infection according to seropositivity was 2% (95 % CI: 1-2%) in the general population of Iran in which western and northern provinces had the lowest and the highest prevalence, 0.5 % (95 %CI, 0.2-0.7%) and 3% (95 %CI, 1-5 %), respectively. The seroprevalence of HVL among females (2%; 95 %CI, 1-2 %) was more than males (1%; 95 %CI, 1-2 %). The ≤10 and >10 years age groups had similar seroprevalence rates (1%, 95 %CI, 1-2 % versus 1%, 95 %CI, 0-1 %, respectively). There was no significant difference in terms of geographic area, age and sex. Of 31 studies included in the meta-analysis, the most common diagnostic test was the direct agglutination test (96.77 %). To the best of our knowledge, this is the first systematic review of the prevalence of HVL in Iran. The results showed a low seroprevalence of HVL infection. However, the lack of published reports of HVL in an area does not exclusively mean the absence of the disease or carrier. We therefore recommend further studies in this regard.

Rapid Clinical Management of Leishmaniasis in Emergency Department: A Case Report with Clinical Review of Recent Literature

Simple Summary

In this article, we have briefly described the various forms of leishmania infection occur in emergency settings as well as the principal differential diagnoses, and we propose a decision algorithm to facilitate its early recognition in the emergency department (ED). Regarding the last point, the costs and validity of the most common modern diagnostic technologies have been examined, with particular attention to their sensibility and specificity; particularly, rk39-based RTD has been examined. To reinforce the importance of a quick diagnosis performed in the emergency room, we introduce a rather paradigmatic case report of a 19-year-old patient presenting with suspected lymphoproliferative disease and subsequently addressed to the incorrect hospital ward. As often happens, signs and symptoms tended toward the diagnosis of a hematologic disease rather than an infectious one: therefore, it is crucial to include a variety of diagnostic possibilities when a patient presents with fever and associated lympho-adenomegaly with minor symptoms: Leishmaniasis always needs to be considered among them.

Abstract

Systemic or localized lympho-adenomegaly is a common cause of access to the emergency department (ED), and differential diagnosis is often complicated. The combination of anamnesis, physical examination, laboratory tests, and instrumental diagnosis are extremely important to orientate toward a rapid and correct therapy, even if a prompt discrimination of the etiology of this lymphadenomegaly is not often possible. Our aim with this review is to improve the management of a differential diagnosis between hematological and infective diseases as leishmaniasis in ED and suggest quick diagnostic techniques that might be useful for early identification. Together in the review, we describe a case report of a young man affected from visceral leishmaniasis who presented to our ED and was incorrectly addressed to the wrong ward for the study of his condition. Subsequently, we focus on the clinical presentation of visceral leishmaniasis and compare it to the most common differential diagnoses that are usually taken into account in the management of such patients.

Progress of Mucocutaneous Leishmaniasis to Drug Nonresponsive Diffuse Cutaneous Leishmaniasis in Ethiopia. A Case Report

Background

Leishmaniasis is one of the neglected tropical diseases, yet it is associated with high mortality and morbidity. It is caused by intracellular protozoan parasites of the genus Leishmania. Based on the infecting parasite species and host factors, leishmaniasis could be manifested as cutaneous (localized or diffuse), mucocutaneous or visceral clinical forms. In Ethiopia, L. aethiopica is well known to cause all forms of cutaneous leishmaniasis, the localized form being mostcommon.

Case Presentation

An adult patient from Yayu district, west Oromia region of Ethiopia presents with multiple skin lesions on his face, hands and mutilation of nose through both nostrils. Eight years before the present symptoms, he has developed spontaneously healed cutaneous ulcer on his face leaving a permanent scar. Physical examination revealed multiple nodular lesions on his hands, face and nose as well as swelling of the upper lip. Parasitological examination of ulcer lesion revealed presence of amastigotes, and the patient was diagnosed with mucocutaneous leishmaniasis. He was treated with sodium stibogluconate (20 mg/kg/day IM for 30 days) and clinically cured. After two years, he presented with clinical outcomes typical of diffuse cutaneous leishmaniasis. After confirmation by parasitological examination, he was put on sodium stibogluconate (20 mg/kg/day IM for 30 days) and paromomycin (15 mg/kg/day IM for 30 days) combination therapy. As he showed no progress, he was treated with prolonged sodium stibogluconate (20 mg/kg/day IM for 60 days) monotherapy. He was still nonresponsive and discharged uncured.

Conclusion

The present case is unusual in Ethiopia with relapse of mucocutaneous leishmaniasis progressing to diffuse form. The later form was nonresponsive for both mono and combination therapy, therefore, formulating new drugs or evaluating other anti-Leishmania drugs is required.

Leishmaniasis in Ethiopia: A systematic review and meta-analysis of prevalence in animals and humans

Leishmaniasis is a neglected tropical disease caused by obligate intracellular protozoa of the genus Leishmania. Ethiopia does not have an overall estimation of prevalence of leishmaniasis infection at a country level. The objective of this systematic review and meta-analysis was to summarize and pool estimates of studies that report the prevalence of leishmaniasis in Ethiopia. The literature search was conducted to identify all published studies reporting the prevalence of leishmaniasis with clearly designed inclusion and exclusion criteria. From all screened articles, 30 studies were eligible for final meta-analysis and systematic review. Because substantial heterogeneity was expected, random-effects meta-analyses were carried out using the total sample size and number of positives to estimate the prevalence of the disease at a country level. Between-study variability was high (τ² = 0.02; heterogeneity I² = 99.72% with Heterogeneity chi-square = 11985.41, a degree of freedom = 33 and P = 0.001). The overall random pooled prevalence of leishmaniasis was 19% (95% CI 14%-24%). Meta-regression analysis showed that diagnosis method used have contributed to the heterogeneity of studies. Molecular diagnosis has significantly lower prevalence than microscopic examination with a coefficient of -0.32, a p-value of 0.024, and CI (-0.6-0.05). The result of effect estimates against its standard error showed there was no publication bias with a P value of 0.084. This review indicated that there is still a higher prevalence of Leishmaniasis in the country. Reporting on risk factors like sex and age affected, species of Leishmania involved and many more other risk factors reviewing was not possible in this study due to lack of completeness in articles included. However, this report is an indication that the country needs nationally coordinated extensive prevention and control plan to reduce public health and socio-economic impact of the disease.

Ethnomedicines and anti-parasitic activities of Pakistani medicinal plants against Plasmodia and Leishmania parasites

BACKGROUND

Leishmaniasis and malaria are the two most common parasitic diseases and responsible for large number of deaths per year particularly in developing countries like Pakistan. Majority of Pakistan population rely on medicinal plants due to their low socio-economic status. The present review was designed to gather utmost fragmented published data on traditionally used medicinal plants against leishmaniasis and malaria in Pakistan and their scientific validation.

METHODS

Pub Med, Google Scholar, Web of Science, ISI Web of knowledge and Flora of Pakistan were searched for the collection of data on ethnomedicinal plants. Total 89 articles were reviewed for present study which was mostly published in English. We selected only those articles in which complete information was given regarding traditional uses of medicinal plants in Pakistan.

RESULTS

Total of 56 plants (malaria 33, leishmaniasis 23) was found to be used traditionally against reported parasites. Leaves were the most focused plant part both in traditional use and in in vitro screening against both parasites. Most extensively used plant families against Leishmaniasis and Malaria were Lamiaceae and Asteraceae respectively. Out of 56 documented plants only 15 plants (Plasmodia 4, Leishmania 11) were assessed in vitro against these parasites. Mostly crude and ethanolic plant extracts were checked against Leishmania and Plasmodia respectively and showed good inhibition zone. Four pure compounds like artemisinin, physalins and sitosterol extracted from different plants proved their efficacy against these parasites.

CONCLUSIONS

Present review provides the efficacy and reliability of ethnomedicinal practices and also invites the attention of chemists, pharmacologist and pharmacist to scientifically validate unexplored plants that could lead toward the development of novel anti-malarial and anti-leishmanial drugs.

Interactions of antileishmanial drugs with monolayers of lipids used in the development of amphotericin B-miltefosine-loaded nanocochleates

The emergence of strains of Leishmania resistant to existing drugs complicates the treatment of life-threatening visceral leishmaniasis. The development of new lipid formulation (nanocochleates), containing two active drugs: amphotericin B (AmB) and miltefosine (hexadecylphosphocholine, HePC), could increase effectiveness, decrease toxicity and reduce the risk of appearance of resistance. Nanocochleates are cigar-shaped structures of rolled negatively charged lipid bilayers bridged by calcium, prepared from dioleoylphosphatidylserine (DOPS) and cholesterol (Cho) and able to accommodate drugs. To determine the interaction, the orientation and the stability of the amphiphilic drugs in the lipid mixture and the optimal drugs/lipids ratio, the Langmuir film balance and BAM (Brewster angle microscopy) were used. The drugs were mixed with the lipids (DOPS or 9DOPS/1Cho) and spread at the air-water interface. A stability study showed that DOPS maintained HePC at the interface at low molar fraction of HePC; this effect became more marked in the presence of Cho. The fact that HePC can be stably associated with the monolayer at low molar fraction (below 10%) suggests that in the nanocochleates HePC is inserted between the lipid molecules rather than between the bilayers. Phase diagrams and BAM images showed that, even at low pressure, DOPS maintains AmB at low molar fraction (below 10%) in the "erect" rather than the horizontal form at the interface and that the presence of Cho reinforces this effect. These results allowed us to predict the organization and the orientation of these drugs in the nanocochleates and to determine the optimal drugs/lipids ratio.

Safety and skin delayed-type hypersensitivity response in vervet monkeys immunized with Leishmania donovani sonicate antigen delivered with adjuvants

In this study, we report on the safety and skin delayed-type hypersensitivity (DTH), responses of the Leishmania donovani whole cell sonicate antigen delivered in conjunction with alum-BCG (AlBCG), Montanide ISA 720 (MISA) or Monophosphoryl lipid A (MPLA) in groups of vervet monkeys. Following three intradermal injections of the inoculums on days 0, 28 and 42, safety and DTH responses were assessed. Preliminary tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) levels were also measured and these were compared with DTH. Only those animals immunized with alum-BCG reacted adversely to the inoculum by producing ulcerative erythematous skin indurations. Non-parametric analysis of variance followed by a post-test showed significantly higher DTH responses in the MISA+Ag group compared with other immunized groups (p < 0.001). The MPLA+Ag group indicated significantly lower DTH responses to the sonicate antigen compared with the AlBCG+Ag group. There was a significant correlation between the DTH and cytokine responses (p < 0.0001). Based on this study we conclude that Leishmania donovani sonicate antigen containing MISA 720 is safe and is associated with a strong DTH reaction following immunization.

In vitro Antiprotozoal Activity of Extracts of five Turkish Lamiaceae Species

The in vitro antiprotozoal activities of crude methanolic extracts from the aerial parts of five Lamiaceae plants ( Salvia tomentosa, S. sclarea, S. dichroantha, Nepeta nuda subsp. nuda and Marrubium astracanicum subsp. macrodon) were evaluated against four parasitic protozoa, i.e. Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and Plasmodium falciparum. The cytotoxic potentials of the extracts on L6 cells were also evaluated. Melarsoprol, benznidazole, miltefosine, chloroquine and podophyllotoxin were used as reference drugs. All crude MeOH extracts showed antiprotozoal potential against at least three parasites, so they were dispersed in water and partitioned against n-hexane and chloroform to yield three subextracts that were screened in the same test systems. The n-hexane extract of N. nuda was the most active against T. brucei rhodesiense while the CHCl3 extracts of S. tomentosa and S. dichroantha showed significant activity against L. donovani. All organic extracts displayed in vitro antimalarial and moderate trypanocidal activities against T. cruzi with the n-hexane extract of S. sclarea being the most active against the latter. The extracts displayed low or no cytotoxicity towards mammalian L6 cells.