Visceral leishmaniasis control: a public health perspective

Current Development of Nano-Drug Delivery to Target Macrophages

Macrophages are the most important innate immune cells that participate in various inflammation-related diseases. Therefore, macrophage-related pathological processes are essential targets in the diagnosis and treatment of diseases. Since nanoparticles (NPs) can be preferentially taken up by macrophages, NPs have attracted most attention for specific macrophage-targeting. In this review, the interactions between NPs and the immune system are introduced to help understand the pharmacokinetics and biodistribution of NPs in immune cells. The current design and strategy of NPs modification for specific macrophage-targeting are investigated and summarized.

Epidemiological features and spatial-temporal distribution of visceral leishmaniasis in mainland China: a population-based surveillance study from 2004 to 2019

BACKGROUND

Although visceral leishmaniasis (VL) was largely brought under control in most regions of China during the previous century, VL cases have rebounded in western and central China in recent decades. The aim of this study was to investigate the epidemiological features and spatial-temporal distribution of VL in mainland China from 2004 to 2019.

METHODS

Incidence and mortality data for VL during the period 2004-2019 were collected from the Public Health Sciences Data Center of China and annual national epidemic reports of VL, whose data source was the National Diseases Reporting Information System. Joinpoint regression analysis was performed to explore the trends of VL. Spatial autocorrelation and spatial-temporal clustering analysis were conducted to identify the distribution and risk areas of VL transmission.

RESULTS

A total of 4877 VL cases were reported in mainland China during 2004-2019, with mean annual incidence of 0.0228/100,000. VL incidence showed a decreasing trend in general during our study period (annual percentage change [APC] = -4.2564, 95% confidence interval [CI]: -8.0856 to -0.2677). Among mainly endemic provinces, VL was initially heavily epidemic in Gansu, Sichuan, and especially Xinjiang, but subsequently decreased considerably. In contrast, Shaanxi and Shanxi witnessed significantly increasing trends, especially in 2017-2019. The first-level spatial-temporal aggregation area covered two endemic provinces in northwestern China, including Gansu and Xinjiang, with the gathering time from 2004 to 2011 (relative risk [RR] = 13.91, log-likelihood ratio [LLR] = 3308.87, P < 0.001). The secondary aggregation area was detected in Shanxi province of central China, with the gathering time of 2019 (RR = 1.61, LLR = 4.88, P = 0.041). The epidemic peak of October to November disappeared in 2018-2019, leaving only one peak in March to May.

CONCLUSIONS

Our findings suggest that VL is still an important endemic infectious disease in China. Epidemic trends in different provinces changed significantly and spatial-temporal aggregation areas shifted from northwestern to central China during our study period. Mitigation strategies, including large-scale screening, insecticide spraying, and health education encouraging behavioral change, in combination with other integrated approaches, are needed to decrease transmission risk in areas at risk, especially in Shanxi, Shaanxi, and Gansu provinces.

Epidemiology of Leishmania Carriers in Tan Chang County, Gansu Province, China

Background

Leishmaniasis is a regional infectious disease caused by the bite of Leishmania-carrying sandflies. The clinical symptoms include prolonged fever, spleen enlargement, anemia, emaciation, leukopenia, and increased serum globulin levels. If not appropriately treated, patients may die of complications caused by leishmaniasis within 1-2 years after the onset of the illness. Therefore, further investigation of the mechanisms of infection by this pathogen is required. Here, an epidemiological study of Leishmania carriers was conducted. The potential mechanism of infection through domestic animals as carriers of the parasite was investigated to identify potential reservoir hosts for Leishmania.

Methods

The rK-39 strip test was performed on blood samples from previously infected patients. Blood samples were collected from the patients and their families. The blood, liver, spleen, and diaphragm muscle samples were collected from livestock. To perform nested polymerase chain reaction (PCR), DNA was extracted and the internal transcribed spacer sequence was used. The amplified products were then subjected to restriction fragment length polymorphism and phylogenetic analyses.

Results

Among previously infected patients, 40% (12/30) showed positive results in the rK-39 strip test. The nested PCR positive rates for previously infected patients/relatives and livestock samples were 86% (77/90) and 80% (8/10), respectively. Moreover, the phylogenetic analysis showed that the pathogen was Leishmania infantum. Dogs, patients, and domesticated animals carrying Leishmania were found to be a potential source of infection for leishmaniasis.

Conclusions

The results of this study provide a basis for developing disease prevention and control strategies for leishmaniasis.

Immunotherapy in treatment of leishmaniasis

Leishmaniasis caused by various species of protozoan transmitted by sand fly vectors occurs as a spectrum of clinical features including cutaneous, mucocutaneous and visceral forms. It is a geographically distributed parasitic disease and a major public health problem in the world. The clinical syndromes are highly variable depending on the parasite species, host genetics, vectors and environment. To date, there is no effective vaccine and traditional treatments are toxic, expensive with long administration duration and many adverse side effects and/or drug resistance. Instead of treatments based on chemotherapy, certain strategies aim to recover leishmaniasis and reduce the parasitic burden. Immunotherapy has focused on the induction of effective immune response to rapidly control the disease. Recent studies have indicated that a single dose of a suitable therapeutic vaccine induces a quick and lasting recovery in patients. Immunotherapy reduces the toxicity of drug and the emergence of resistance dramatically. It could be an effective addition to chemotherapy with a safe and potent drug compared with monotherapy, resulting in a prophylactic and therapeutic cure of leishmaniasis. This review has focused on treatment of leishmaniasis with particular emphasis on immunotherapy as an alternative to conventional drug treatment.

Pediatric visceral leishmaniasis: a retrospective study to propose the diagnostic tests algorithm in southern Iran

Leishmania infantum is the most common cause of visceral leishmaniasis (VL) in Iran, where mainly the patients are children under the age of 5 years. Timely, less invasive, and accurate diagnosis and proper treatment of the disease are necessary. This retrospective study aimed to search for a less invasive but robust algorithm on VL diagnostic tests in children. Four hundred and fifteen patients with clinical suspicion of VL, 50 healthy children from VL endemic areas, 46 healthy individuals from non-endemic VL areas, and 47 non-VL diseases were tested using three diagnostic tests: indirect immunofluorescent antibody test (IFAT), rK39-rapid diagnostic test (rK39-RDT), and quantitative PCR (qPCR). One hundred and two suspected VL cases were positive in at least one test and were cured after receiving appropriate treatment. Of these 102 VL patients, 94 were positive in qPCR, 84 in IFAT, and 79 in rK39-RDT. None of the tests detected all the patients, but overall, qPCR is capable of detecting more VL patients than serological tests, i.e., 92.2%, compared to IFAT, 82.4%, and rK39, 77.5%. There was only a significant difference between the sensitivity of qPCR and rK39-RDT (p = 0.024). The specificity was 100% for qPCR and IFAT (≥128) and 98.6% for rK39-RDT. qPCR alone is capable of detecting most of the VL-suspected children. Serological tests like IFAT and rk39-RDT are recommended to increase the overall sensitivity of detection in patients with a negative molecular test. Combining qPCR with a serological test (IFAT or rK39-RDT) can help diagnose 98% of VL. In laboratories without molecular facilities, we recommend testing with the combination of rK39-RDT and IFAT yielding a combined sensitivity of 93.1% equivalent to that of qPCR in our study.

Visceral leishmaniasis in northwest China from 2004 to 2018: a spatio-temporal analysis

BACKGROUND

Although visceral leishmaniasis (VL), a disease caused by parasites, is controlled in most provinces in China, it is still a serious public health problem and remains fundamentally uncontrolled in some northwest provinces and autonomous regions. The objective of this study is to explore the spatial and temporal characteristics of VL in Sichuan Province, Gansu Province and Xinjiang Uygur Autonomous Region in China from 2004 to 2018 and to identify the risk areas for VL transmission.

METHODS

Spatiotemporal models were applied to explore the spatio-temporal distribution characteristics of VL and the association between VL and meteorological factors in western China from 2004 to 2018. Geographic information of patients from the National Diseases Reporting Information System operated by the Chinese Center for Disease Control and Prevention was defined according to the address code from the surveillance data.

RESULTS

During our study period, nearly 90% of cases occurred in some counties in three western regions (Sichuan Province, Gansu Province and Xinjiang Uygur Autonomous Region), and a significant spatial clustering pattern was observed. With our spatiotemporal model, the transmission risk, autoregressive risk and epidemic risk of these counties during our study period were also well predicted. The number of VL cases in three regions of western China concentrated on a few of counties. VL in Kashi Prefecture, Xinjiang Uygur Autonomous Region is still serious prevalent, and integrated control measures must be taken in different endemic areas.

CONCLUSIONS

The number of VL cases in three regions of western China concentrated on a few of counties. VL in Kashi Prefecture, Xinjiang Uygur Autonomous Region is still serious prevalent, and integrated control measures must be taken in different endemic areas. Our findings will strengthen the VL control programme in China.

The potential impact of human visceral leishmaniasis vaccines on population incidence

Human visceral leishmaniasis (VL) vaccines are currently under development and there is a need to understand their potential impact on population wide VL incidence. We implement four characteristics from different human VL vaccine candidates into two published VL transmission model variants to estimate the potential impact of these vaccine characteristics on population-wide anthroponotic VL incidence on the Indian subcontinent (ISC). The vaccines that are simulated in this study 1) reduce the infectiousness of infected individuals towards sand flies, 2) reduce risk of developing symptoms after infection, 3) reduce the risk of developing post-kala-azar dermal leishmaniasis (PKDL), or 4) lead to the development of transient immunity. We also compare and combine a vaccine strategy with current interventions to identify their potential role in elimination of VL as a public health problem. We show that the first two simulated vaccine characteristics can greatly reduce VL incidence. For these vaccines, an approximate 60% vaccine efficacy would lead to achieving the ISC elimination target (<1 VL case per 10,000 population per year) within 10 years’ time in a moderately endemic setting when vaccinating 100% of the population. Vaccinating VL cases to prevent the development of PKDL is a promising tool to sustain the low incidence elimination target after regular interventions are halted. Vaccines triggering the development of transient immunity protecting against infection lead to the biggest reduction in VL incidence, but booster doses are required to achieve perduring impact. Even though vaccines are not yet available for implementation, their development should be pursued as their potential impact on transmission can be substantial, both in decreasing incidence at the population level as well as in sustaining the ISC elimination target when other interventions are halted.

Vaccines for human visceral leishmaniasis (VL) are currently under development. In this study, we simulate VL transmission dynamics using mathematical models to explore the potential impact of vaccines on population-wide incidence. We show that some vaccines have high potential to reduce VL incidence, namely those that reduce the infectiousness of infected individuals to sand flies and those that reduce the chance of developing symptoms once infected. The effect of vaccines that lead to protection from infection is potentially the greatest, but depending on the duration of immunity, individuals would require booster doses to guarantee lifelong impact. Vaccines that prevent the development of post-kala-azar dermal leishmaniasis are a promising tool to sustain low VL incidence and prevent recrudescence of infection when regular interventions are halted. Our results strongly support the continued development of VL vaccines, as their potential impact on population incidence can be substantial.

In Vitro and in Vivo Activity of mTOR Kinase and PI3K Inhibitors Against Leishmania donovani and Trypanosoma brucei

Kinetoplastid parasites, including Leishmania and Trypanosoma spp., are life threatening pathogens with a worldwide distribution. Next-generation therapeutics for treatment are needed as current treatments have limitations, such as toxicity and drug resistance. In this study, we examined the activities of established mammalian target of rapamycin (mTOR)/phosphoinositide 3-kinase (PI3K) inhibitors against these tropical diseases. High-throughput screening of a library of 1742 bioactive compounds against intracellular L. donovani was performed, and seven mTOR/PI3K inhibitors were identified. Dose-dilution assays revealed that these inhibitors had half maximal effective concentration (EC₅₀₎ values ranging from 0.14 to 13.44 μM for L. donovani amastigotes and from 0.00005 to 8.16 μM for T. brucei. The results of a visceral leishmaniasis mouse model indicated that treatment with Torin2, dactolisib, or NVP-BGT226 resulted in reductions of 35%, 53%, and 54%, respectively, in the numbers of liver parasites. In an acute T. brucei mouse model using NVP-BGT226 parasite numbers were reduced to under the limits of detection by five consecutive days of treatment. Multiple sequence and structural alignment results indicated high similarities between mTOR and kinetoplastid TORs; the inhibitors are predicted to bind in a similar manner. Taken together, these results indicated that the TOR pathways of parasites have potential for the discovery of novel targets and new potent inhibitors.

Biogenic metal nanoparticles as a potential class of antileishmanial agents: mechanisms and molecular targets

Leishmaniasis, a category 1 disease, has remained neglected for decades, and therefore, has developed into a severe health problem worldwide. Unfortunately, the available antileishmanial drugs are limited, and the parasites have shown an inevitable resistance toward most of these drugs. All these factors pose a barrier to control the parasite at present. Hence, new strategies are needed to develop more effective and less toxic nanomedicines that could treat and manage the Leishmania parasite. One of these effective strategies is to construct nanometals with biologically active molecules that could possess dynamic antileishmanial activities with desirable biocompatibility. In this review paper, antileishmanial potencies of different metal nanoparticles, with particular emphasis on biogenic metal nanoparticles from 2011 to 2019, are summarized. The mechanisms by which metal-based nanomedicines kill Leishmania are also discussed.

Leishmania donovani Growth Inhibitors from Pathogen Box Compounds of Medicine for Malaria Venture

INTRODUCTION

Leishmaniasis is a collective term used to describe various pathological conditions caused by an obligate intracellular protozoan of the genus Leishmania. It is one of the neglected diseases and has been given minimal attention by drug discovery and development stakeholders to narrow the safety and efficacy gaps of the drugs currently used to treat leishmaniasis. The challenge is further exacerbated by the emergence of drug resistance by the parasites.

METHODS

Aiming to look for potential anti-leishmanial hits and leads, we screened Medicines for Malaria Venture (MMV) Pathogen Box compounds against clinically isolated Leishmania donovani strain. In this medium-throughput primary screening assay, the compounds were screened against promastigotes, and then against amastigote stages.

RESULTS

From the total 400 compounds screened, 35 compounds showed >50% inhibitory activity on promastigotes in the initial screen (1 μM). Out of these compounds, nine showed >70% inhibition, with median inhibitory concentration (IC50) ranging from 12 to 491 nM using the anti-promastigote assay, and from 53 to 704 nM using the intracellular amastigote assay. Identified compounds demonstrated acceptable safety profiles on THP-1 cell lines and sheep red blood cells, and had appropriate physicochemical properties suitable for further drug development. Two compounds (MMV690102 and MMV688262) were identified as leads. The anti-tubercular agent MMV688262 (delamanid) showed a synergistic effect with amphotericin B, indicating the prospect of using this compound for combination therapy.

CONCLUSION

The current study indicates the presence of additional hits which may hold promise as starting points for anti-leishmanial drug discovery and in-depth structure-activity relationship studies.

Awareness of residents about kala-azar and its related practices in two endemic areas of Bangladesh

Kala-azar, a worldwide disease, is caused by the parasitic protozoan species of genus Leishmania and transmitted by species of sandflies. Awareness of the population about the disease is essential to run a successful control-strategies program. This cross-sectional study was conducted to assess the awareness of residents about it and related practices in two highly-endemic areas of Bangladesh. In total, 511 household respondents were selected conveniently from two unions (Kushmail and Kanihari) under two sub-districts (Trishal and Fulbaria) of Mymensingh district. Interviewer-administered questionnaires were used for assessing the awareness of the respondents about kala-azar and their practices. Knowledge scores were categorized as poor (<mean -1SD), average (mean ±1SD), good (>mean +1SD). Statistical tests were considered significant at p value of ≤5% (≤0.05). Chi-squared and Student's t-tests were performed for statistical analysis. The mean knowledge score of the respondents of Kanihari union regarding kala-azar was significantly higher than that of the respondents of Kushmail union (mean ±SD, 4.30 ±0.86 versus 4.12 ±0.75, p = 0.002). Of the respondents, 11% and 20% had good (>5.04), 77% and 72% had average (3.43-5.04), 12% and 8% had poor (<3.43) (GAP) knowledge on kala-azar in Kushmail union and Kanihari union respectively. However, the mean knowledge score of the respondents of Kanihari union relating sandfly was significantly lower compared to that of the respondents of Kushmail union (mean ±SD, 2.49 ±0.79 versus 2.65 ±0.85, p = 0.03). Of them, 22% and 19% had good (>3.39), 67% and 64% had average (3.39-1.75), and 11% and 17% had poor (<1.75) knowledge on sandfly in Kushmail union and Kanihari union respectively. More than 70% of the respondents from Kushmail and Kanihari mentioned only injection as the preferred treatment of kala-azar. Eighty-seven percent and 88% of the respondents in the two unions had chosen upazilla health complex for the treatment of their kala-azar. About 50% of the respondents in Kushmail and Kanihari liked to use coil or mat as a preventive measure to avoid sandfly bites. The findings of this study indicate the importance of awareness and related practices of the community people in two endemic areas that will help implement the kala-azar-elimination program successfully in Bangladesh.

Epidemiological survey of sheep as potential hosts for Leishmania in China

Background

Leishmania parasites cause visceral leishmaniasis (VL), an important infectious disease that is endemic to large parts of the world and often leads to epidemics. Sand flies are the primary transmission vector for the parasite in endemic regions. We hypothesized that sheep might serve as an overlooked reservoir for Leishmania transmission to humans due to the asymptomatic nature of infection in many species. As a preliminary test of this hypothesis, the aim of the present study was to investigate sheep in an area of China that is endemic for the desert sub-type of zoonotic VL and establish if they are potential carriers of Leishmania.

Results

Sheep tissue samples were collected from abattoirs in VL endemic areas of Jiashi County, China during the non-transmission season. rK39 immunochromatographic tests were performed to detect the presence of the parasite in blood samples. In addition, DNA was extracted from the blood, and used for detection of the Leishmania-specific internal transcribed spacer-1 (ITS-1) genomic region using a nested polymerase chain reaction (PCR) approach. PCR products were further analyzed to identify restriction fragment-length polymorphism patterns and representative sequences of each pattern were selected for phylogenetic analysis. The rK-39 and nested PCR data indicated positive detection rates for Leishmania in sheep of 26.32 and 54.39%, respectively. The phylogenetic analysis revealed that all of the samples belonged to the species L. infantum and were closely related to strains isolated from human infections in the same area.

Conclusions

Sheep could be a potential host for Leishmania in VL endemic areas in China and may be an overlooked reservoir of human VL transmission in this region. To further confirm livestock as a potential host, further verification is required using a sand fly biting experiment.

Visceral leishmaniasis elimination targets in India, strategies for preventing resurgence

INTRODUCTION

Visceral leishmaniasis (VL) is a fatal parasitic disease caused by a parasite belonging to the Leishmania donovani complex and transmitted by infected female Phlebotomous argentipes sand flies. The VL elimination strategy in the Indian subcontinent (ISC), which has a current goal of reducing the incidence of VL to below 1/10,000 of population by the year 2020, consists of rapid detection and treatment of VL to reduce the number of human reservoirs as well as vector control using indoor residual spraying (IRS). However, as the incidence of VL declines toward the elimination goal, greater targeting of control methods will be required to ensure appropriate early action to prevent the resurgence of VL. Area covered: We discuss the current progress and challenges in the VL elimination program and strategies to be employed to ensure sustained elimination of VL. Expert commentary: The VL elimination initiative has saved many human lives; however, for VL elimination to become a reality in a sustained way, an intense effort is needed, as substantial numbers of endemic subdistricts (primary health centers (PHCs) blocks level) are yet to reach the elimination target. In addition to effective epidemiological surveillance, appropriate diagnostic and treatment services for VL at PHCs will be needed to ensure long-term sustainability and prevent reemergence of VL.

Leishmanicidal activity of α-bisabolol from Tunisian chamomile essential oil

According to the World Health Organization, leishmaniasis is considered as a major neglected tropical disease causing an enormous impact on global public health. Available treatments were complicated due to the high resistance, toxicity, and high cost. Therefore, the search for novel sources of anti-leishmania agents is an urgent need. In the present study, an in vitro evaluation of the leishmanicidal activity of the essential oil of Tunisian chamomile (Matricaria recutita L.) was carried out. Chamomile essential oil exhibits a good activity on promastigotes forms of L. amazonensis and L. infantum with a low inhibitory concentration at 50% (IC₅₀) (10.8 ± 1.4 and 10.4 ± 0.6 μg/mL, respectively). Bio-guided fractionation was developed and led to the identification of (-)-α-bisabolol as the most active molecule with low IC₅₀ (16.0 ± 1.2 and 9.5 ± 0.1 μg/mL for L. amazonensis and L. infantum, respectively). This isolated sesquiterpene alcohol was studied for its activity on amastigotes forms (IC₅₀ = 5.9 ± 1.2 and 4.8 ± 1.3 μg/mL, respectively) and its cytotoxicity (selectivity indexes (SI) were 5.4 and 6.6, respectively). The obtained results showed that (-)-α-bisabolol was able to activate a programmed cell death process in the promastigote stage of the parasite. It causes phosphatidylserine externalization and membrane damage. Moreover, it decreases the mitochondrial membrane potential and total ATP levels. These results highlight the potential use of (-)-α-bisabolol against both L. amazonensis and L. infantum, and further studies should be undertaken to establish it as novel leishmanicidal therapeutic agents.

Assessing Knowledge, Attitudes, and Preventive Practices Related to Kala-A: A Study of Rural Madhepura, Bihar, India

To assess the knowledge, attitude, and preventive practices related to kala-azar in Madhepura district of Bihar, a community-based cross-sectional study was carried out in November 2014. A total of 353 households were interviewed from 24 villages of four blocks of Madhepura district. Data were collected using structured interview schedule. For knowledge, attitude, and preventive practice indexes, scores were assigned to individual questions based on the accuracy of responses. Univariate and binary logistic regressions were applied for the analysis. Eighty-four percent households had heard of kala-azar disease, but only 15.9% could recognize that sand flies were responsible for transmitting the disease. Overall, only 43.9% had fair knowledge on kala-azar disease (e.g., mode of transmission, signs and symptoms, and the outcome if left untreated) and the vector (breeding place, season, and biting time). Almost 48.6% had a favorable attitude toward treatability and management of kala-azar and 37.7% practiced proper mechanism to prevent and control kala-azar. Occupation emerged as a significant predictor for all three indexes. Other important predictors for the attitude index were literacy, household type, households ever had a kala-azar case, and knowledge index. Despite 61.8% of the households ever reported to have a member diagnosed with kala-azar, the overall knowledge of the disease and vector, attitude, and practices about prevention and control of kala-azar was found to be lagging. Therefore, our investigation suggests that further strengthening of comprehensive knowledge about kala-azar and preventive practices is needed.

Antileishmanial Mechanism of Diamidines Involves Targeting Kinetoplasts

Leishmaniasis is a disease caused by pathogenic Leishmania parasites; current treatments are toxic and expensive, and drug resistance has emerged. While pentamidine, a diamidine-type compound, is one of the treatments, its antileishmanial mechanism of action has not been investigated in depth. Here we tested several diamidines, including pentamidine and its analog DB75, against Leishmania donovani and elucidated their antileishmanial mechanisms. We identified three promising new antileishmanial diamidine compounds with 50% effective concentrations (EC₅₀s) of 3.2, 3.4, and 4.5 μM, while pentamidine and DB75 exhibited EC₅₀s of 1.46 and 20 μM, respectively. The most potent antileishmanial inhibitor, compound 1, showed strong DNA binding properties, with a shift in the melting temperature (ΔT_m) of 24.2°C, whereas pentamidine had a ΔT_m value of 2.1°C, and DB75 had a ΔT_m value of 7.7°C. Additionally, DB75 localized in L. donovani kinetoplast DNA (kDNA) and mitochondria but not in nuclear DNA (nDNA). For 2 new diamidines, strong localization signals were observed in kDNA at 1 μM, and at higher concentrations, the signals also appeared in nuclei. All tested diamidines showed selective and dose-dependent inhibition of kDNA, but not nDNA, replication, likely by inhibiting L. donovani topoisomerase IB. Overall, these results suggest that diamidine antileishmanial compounds exert activity by accumulating toward and blocking replication of parasite kDNA.

Worldwide risk factors in leishmaniasis

Recently, vector-borne parasitic diseases such as leishmaniasis have been emerged or re-emerged in many geographical areas and resulted in global health and economic concerns that involve humans, domestic animals and wild life. The ecology and epidemiology of leishmaniasis are affected by the between host, reservoir and vector (human, animal and sandfly) and the environment. Important drivers for the emergence and spread of leishmaniasis include environmental factors such as alterations in temperature and water storage, irrigation habits, deforestation, climate changes, immunosuppression by HIV or organ transplant, development of drug resistance, increase traveling to endemic regions and dog importation. War, poor socio-economic status and low level household are also major contributors to the spread of this disease. Health education via the public media and training should be implemented by international organizations and governmental agencies in collaboration with research institutions. Fully protection during transmission season, using bednets and insecticides and reservoirs' control should be also mentioned in the planning. Based on the findings of the recent studies and high prevalence of leishmaniasis, it is concluded that serious public health monitoring should be considered.

Assessment of the sensitivity and specificity of serological (IFAT) and molecular (direct-PCR) techniques for diagnosis of leishmaniasis in lagomorphs using a Bayesian approach

Leishmaniasis, caused by Leishmania infantum, is a vector‐borne zoonotic disease that is endemic to the Mediterranean basin. The potential of rabbits and hares to serve as competent reservoirs for the disease has recently been demonstrated, although assessment of the importance of their role on disease dynamics is hampered by the absence of quantitative knowledge on the accuracy of diagnostic techniques in these species. A Bayesian latent‐class model was used here to estimate the sensitivity and specificity of the Immuno‐fluorescence antibody test (IFAT) in serum and a Leishmania‐nested PCR (Ln‐PCR) in skin for samples collected from 217 rabbits and 70 hares from two different populations in the region of Madrid, Spain. A two‐population model, assuming conditional independence between test results and incorporating prior information on the performance of the tests in other animal species obtained from the literature, was used. Two alternative cut‐off values were assumed for the interpretation of the IFAT results: 1/50 for conservative and 1/25 for sensitive interpretation. Results suggest that sensitivity and specificity of the IFAT were around 70–80%, whereas the Ln‐PCR was highly specific (96%) but had a limited sensitivity (28.9% applying the conservative interpretation and 21.3% with the sensitive one). Prevalence was higher in the rabbit population (50.5% and 72.6%, for the conservative and sensitive interpretation, respectively) than in hares (6.7% and 13.2%). Our results demonstrate that the IFAT may be a useful screening tool for diagnosis of leishmaniasis in rabbits and hares. These results will help to design and implement surveillance programmes in wild species, with the ultimate objective of early detecting and preventing incursions of the disease into domestic and human populations.

Apoptotic protein profile in Leishmania donovani after treatment with hexaazatrinaphthylenes derivatives

Two hexaazatrinaphthylene derivatives, DGV-B and DGV-C previously known to induce an apoptotic-like process in Leishmania donovani parasites were used in this study. For this purpose, two different human protein commercial arrays were used to determine the proteomic profile of the treated parasites compared to non-treated ones. One of the commercial arrays is able to detect the relative expression of 35 human apoptosis-related proteins and the other one is able to identify 9 different human kinases. The obtained results showed that the two tested molecules were able to activate a programmed cell death process by different pathways in the promastigote stage of the parasite. The present study reports the potential application of two commercialised human apoptotic arrays to evaluate the action mechanism of active compounds at least against Leishmania donovani. The obtained data would be useful to establish the putative activated apoptosis pathways in the treated parasites and to further support the use of hexaazatrinaphthylene derivatives for the treatment of leishmaniasis in the near future. Nevertheless, further molecular studies should be developed in order to design and evaluate specific apoptotic arrays for Leishmania genus.

Visceral leishmaniasis: Revisiting current treatments and approaches for future discoveries

The current treatments for visceral leishmaniasis are old and toxic with limited routes of administration. The emergence of drug-resistant Leishmania threatens the efficacy of the existing reservoir of antileishmanials, leading to an urgent need to develop new treatments. It is particularly important to review and understand how the current treatments act against Leishmania in order to identify valid drug targets or essential pathways for next-generation antileishmanials. It is equally important to adapt newly emerging biotechnologies to facilitate the current research on the development of novel antileishmanials in an efficient fashion. This review covers the basic background of the current visceral leishmaniasis treatments with an emphasis on the modes of action. It briefly discusses the role of the immune system in aiding the chemotherapy of leishmaniasis, describes potential new antileishmanial drug targets and pathways, and introduces recent progress on the utilization of high-throughput phenotypic screening assays to identify novel antileishmanial compounds.

Development of loop-mediated isothermal amplification (LAMP) for simple detection of Leishmania infection

Background

Leishmaniasis is a neglected tropical disease that is caused by an obligate intracellular protozoan of the genus Leishmania. Recently, an increasing number of autochthonous leishmaniasis cases caused by L. martiniquensis and the novel species L. siamensis have been described in Thailand, rendering an accurate diagnosis of this disease critical. However, only a few laboratories are capable of diagnosing leishmaniasis in Thailand. To expand leishmaniasis diagnostic capabilities, we developed a simple colorimetric loop-mediated isothermal amplification (LAMP) technique for the direct detection of Leishmania DNA.

Methods

LAMP was performed for 75 min using four primers targeting the conserved region of the18S ribosomal RNA gene, and the DNA indicator used was malachite green (MG). To simulate crude samples, cultured promastigotes of L. siamensis were mixed with blood or saliva. Also, clinical samples (blood, saliva, and tissue biopsies) were obtained from patients with cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL). All samples were boiled for 10 min and introduced directly into the LAMP reaction mixture without DNA purification.

Results

The use of MG resulted in an unambiguous differentiation of positive and negative controls. For L. siamensis, the detection limit was 10³ parasites/mL or 2.5 parasites/tube. Saliva, tissue biopsies, and whole blood were indicative of active Leishmania infection, and their direct usages did not adversely affect the detection limit. In addition, this LAMP assay could detect DNA from multiple Leishmania species other than L. siamensis and L. martiniquensis, including L. aethiopica, L. braziliensis, L. donovani and L. tropica.

Conclusions

The simplicity and sensitivity of LAMP in detecting active Leishmania infection could enable the rapid diagnosis of leishmaniasis, thereby facilitating the survey and control of leishmaniasis in Thailand. However, our limited number of samples warranted a further validation with a larger cohort of patients before this assay could be deployed.

Development of an Immunochromatographic Test for Diagnosis of Visceral Leishmaniasis Based on Detection of a Circulating Antigen

Background

Visceral leishmaniasis (VL) is a life-threatening disease caused by protozoan parasites of the Leishmania donovani complex. Early case detection followed by adequate treatment is essential to the control of VL. However, the available diagnostic tests are either invasive and require considerable expertise (parasitological demonstration of the parasite in tissue smears) or unable to distinguish between past and active infection (serological methods). Therefore, we aimed to develop a lateral flow assay in the form of an immunochromatographic test (ICT) device based on the detection of a circulating Leishmania antigen using monoclonal antibodies (mAbs).

Methodology/Principal Findings

mAbs were produced by fusion of murine myeloma cells with splenocytes isolated from a mouse immunized with L. donovani soluble crude antigen. Out of 12 cloned hybridoma cell lines, two secreted mAbs recognizing the same leishmanial protein. These mAbs were used to produce an ICT as a sandwich assay for the detection of circulating antigen in serum and blood samples. The ICT was evaluated with 213 serum samples from VL patients living in VL endemic areas in China, and with 156 serum samples from patients with other diseases as well as 78 serum samples from healthy donors. Sensitivity, specificity and diagnostic efficiency of the new ICT was 95.8%, 98.7% and 97.3%, respectively. Compared with a commercially available antibody detecting ICT, our antigen-based ICT performed slightly better.

Conclusion/Significance

The newly developed ICT is an easy to use and more accurate diagnostic tool which fulfils the performance and operational characteristics required for VL case detection under field and laboratory conditions. As our ICT detects a circulating antigen, it will also be useful in monitoring treatment success and diagnosing VL in immunocompromised patients.

Visceral leishmaniasis is a neglected disease caused by different species of protozoan parasites of the genus Leishmania. The disease is endemic in 61 countries, and in many of them it poses a serious public health issue. As visceral leishmaniasis is fatal if left untreated, early diagnosis is essential for treatment and control of the disease. Current available diagnostic tests are either difficult to carry out under field conditions or insufficiently accurate. In this study we developed a new diagnostic test which detects a circulation parasite-derived antigen in serum or blood samples of patients with visceral leishmaniasis. We found that our test performed better than most other tests based on the detection of parasite-specific antibodies. In addition, as our test is a device for the detection of an acute infection, it will be useful to validate treatment and in the diagnosis of the disease in patients with deficient antibody production (as in AIDS patients).

Synergistic enhancement of parasiticidal activity of amphotericin B using copaiba oil in nanoemulsified carrier for oral delivery: an approach for non-toxic chemotherapy

BACKGROUND AND PURPOSE

The aim of this study was to devise a nanoemulsified carrier system (CopNEC) to improve the oral delivery of amphotericin B (AmB) by increasing its oral bioavailability and synergistically enhance its antileishmanial activity with copaiba oil (Cop).

EXPERIMENTAL APPROACH

The AmB encapsulated NEC (CopNEC-AmB) comprised of Cop, d-α-tocopheryl polyethylene glycol 1000 succinate and phosphatidylcholine was prepared by high-pressure homogenization method. Stability study of CopNEC-AmB was carried out in simulated gastric fluid and simulated intestinal fluid. The CopNEC-AmB and plain AmB were compared as regards their in vitro antileishmanial activity, pharmacokinetics, organ distribution and toxicity.

KEY RESULTS

The optimal CopNEC-AmB had a small globule size, low polydispersity index, high ζ potential and encapsulation efficiency. The high resolution transmission electron microscopy illustrated spherical particle geometry with homogeny in their sizes. The optimal CopNEC-AmB was found to be stable in gastrointestinal fluids showing insignificant changes in globule size and encapsulation efficiency. The AUC0-48 value of CopNEC-AmB in rats was significantly improved showing 7.2-fold higher oral bioavailability than free drug. The in vitro antileishmanial activity of CopNEC-AmB was significantly higher than that of the free drug as Cop synergistically enhanced the antileishmanial effect of AmB by causing drastic changes in the morphology of Leishmania parasite and rupturing its plasma membrane. The CopNEC-AmB showed significantly less haemolytic toxicity and cytotoxicity and did not change the histopathology of kidney tissues as compared with AmB alone.

CONCLUSIONS AND IMPLICATIONS

This prototype CopNEC formulation showed improved bioavailability and had a non-toxic synergistic effect on the antileishmanial activity of AmB.

In vitro activities of hexaazatrinaphthylenes against Leishmania spp

The in vitro activity of a novel group of compounds, hexaazatrinaphthylene derivatives, against two species of Leishmania is described in this study. These compounds showed a significant dose-dependent inhibition effect on the proliferation of the parasites, with 50% inhibitory concentrations (IC(50)s) ranging from 1.23 to 25.05 μM against the promastigote stage and 0.5 to 0.7 μM against intracellular amastigotes. Also, a cytotoxicity assay was carried out to in order to evaluate the possible toxic effects of these compounds. Moreover, different assays were performed to determine the type of cell death induced after incubation with these compounds. The obtained results highlight the potential use of hexaazatrinaphthylene derivatives against Leishmania species, and further studies should be undertaken to establish them as novel leishmanicidal therapeutic agents.

Immune regulation during chronic visceral leishmaniasis

Visceral leishmaniasis is a chronic parasitic disease associated with severe immune dysfunction. Treatment options are limited to relatively toxic drugs, and there is no vaccine for humans available. Hence, there is an urgent need to better understand immune responses following infection with Leishmania species by studying animal models of disease and clinical samples from patients. Here, we review recent discoveries in these areas and highlight shortcomings in our knowledge that need to be addressed if better treatment options are to be developed and effective vaccines designed.

Rapid tests for the diagnosis of visceral leishmaniasis in patients with suspected disease

BACKGROUND

The diagnosis of visceral leishmaniasis (VL) in patients with fever and a large spleen relies on showing Leishmania parasites in tissue samples and on serological tests. Parasitological techniques are invasive, require sophisticated laboratories, consume time, or lack accuracy. Recently, rapid diagnostic tests that are easy to perform have become available.

OBJECTIVES

To determine the diagnostic accuracy of rapid tests for diagnosing VL in patients with suspected disease presenting at health services in endemic areas.

SEARCH METHODS

We searched MEDLINE, EMBASE, LILACS, CIDG SR, CENTRAL, SCI-expanded, Medion, Arif, CCT, and the WHO trials register on 3 December 2013, without applying language or date limits.

SELECTION CRITERIA

This review includes original, phase III, diagnostic accuracy studies of rapid tests in patients clinically suspected to have VL. As reference standards, we accepted: (1) direct smear or culture of spleen aspirate; (2) composite reference standard based on one or more of the following: parasitology, serology, or response to treatment; and (3) latent class analysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed quality of included studies using the QUADAS-2 tool. Discrepancies were resolved by a third author. We carried out a meta-analysis to estimate sensitivity and specificity of rapid tests, using a bivariate normal model with a complementary log-log link function. We analysed each index test separately. As possible sources of heterogeneity, we explored: geographical area, commercial brand of index test, type of reference standard, disease prevalence, study size, and risk of bias (QUADAS-2). We also undertook a sensitivity analysis to assess the influence of imperfect reference standards.

MAIN RESULTS

Twenty-four studies containing information about five index tests (rK39 immunochromatographic test (ICT), KAtex latex agglutination test in urine, FAST agglutination test, rK26 ICT, and rKE16 ICT) recruiting 4271 participants (2605 with VL) were included. We carried out a meta-analysis for the rK39 ICT (including 18 studies; 3622 participants) and the latex agglutination test (six studies; 1374 participants). The results showed considerable heterogeneity. For the rK39 ICT, the overall sensitivity was 91.9% (95% confidence interval (95% CI) 84.8 to 96.5) and the specificity 92.4% (95% CI 85.6 to 96.8). The sensitivity was lower in East Africa (85.3%; 95% CI 74.5 to 93.2) than in the Indian subcontinent (97.0%; 95% CI 90.0 to 99.5). For the latex agglutination test, overall sensitivity was 63.6% (95% CI 40.9 to 85.6) and specificity 92.9% (95% CI 76.7 to 99.2).

AUTHORS' CONCLUSIONS

The rK39 ICT shows high sensitivity and specificity for the diagnosis of visceral leishmaniasis in patients with febrile splenomegaly and no previous history of the disease, but the sensitivity is notably lower in east Africa than in the Indian subcontinent. Other rapid tests lack accuracy, validation, or both.

Trend analysis of visceral leishmaniasis at Addis Zemen health center, Northwest Ethiopia

BACKGROUND

Visceral leishmaniasis (VL) is a systemic disease caused by the Leishmania donovani complex. It is one of the fatal diseases if left untreated. In Ethiopia, there are many VL endemic foci. The aim of this study was to determine the trends of VL in the study area.

METHODOLOGY

A retrospective study was conducted at Addis Zemen health center from September 2005 to August 2011. Data were collected from laboratory registration book and entered and analyzed by using SPSS version 20 software and P value of ≤0.05 was considered statistically significant.

RESULT

A total of 7161 VL suspected cases were reported in the study area. The overall prevalence of VL was 2801 (39.1%). Of the 2801 VL positive cases, the highest annual prevalence, 988 (46.8%), was reported in 2005 but the trend gradually decreases. Majority of the VL confirmed cases were in the age groups of 5-14 years and males were more affected.

CONCLUSION

The prevalence of VL in the study area was high in early 2005 but, gradually, the trend has been decreased and it becomes one of VL endemic foci in Ethiopia.

Evidence of Leishmania infantum infection in rabbits (Oryctolagus cuniculus) in a natural area in Madrid, Spain

Leishmaniasis is one of the most important neglected zoonosis and remains endemic in at least 88 developing countries in the world. In addition, anthropogenic environmental changes in urban areas are leading to its emergency world wide. Zoonotic leishmaniasis control might only be achieved by an integrated approach targeting both the human host and the animal reservoirs, which in certain sylvatic cycles are yet to be identified. Recently, hares have been pointed out as competent reservoirs of Leishmania infantum in Spain, but the role of other lagomorphs has not been clarified. Here, 69 rabbits (Oryctolagus cuniculus) from a natural area in Madrid in which a high density was present were analyzed using indirect (immunofluorescence antibody test, IFAT) and direct (PCR, culture) techniques. Fifty-seven (82.6%) of the animals were positive to at least one technique, with IFAT yielding the highest proportion of positive samples. L. infantum was isolated in 13% animals demonstrating the occurrence of infection in this setting. Our results suggest that rabbits could play a role of competent reservoir of L. infantum and demonstrate that the prevalence of infection is high in the analyzed area.

Detection of anti-Leishmania infantum antibodies in sylvatic lagomorphs from an epidemic area of Madrid using the indirect immunofluorescence antibody test

An outbreak of human leishmaniasis was confirmed in the southwest of the province of Madrid, Spain, between July 2009 and December 2012. Incidence of Leishmania infection in dogs was unchanged in this period, prompting a search for alternative sylvatic infection reservoirs. We evaluated exposure to Leishmania in serum samples from animals in the area with an indirect immunofluorescence test (IFAT). Using promastigotes from six culture passages and a 1/25 threshold titer, we found anti-Leishmania infantum seroreactivity in 9.3% of cats (4 of 43), 45.7% of rabbits (16/35) and 74.1% of hares (63/85). Use of promastigotes from >10 in vitro passages resulted in a notably IFAT lower titer, suggesting antigenic changes during extended culture. Postmortem inspection of seropositive animals showed no clinical signs of infection. The results clearly suggest that asymptomatic hares were the main reservoir in the outbreak, and corroborate IFAT as a sensitive serological surveillance method to detect such cryptic Leishmania infections.

Diagnosis of visceral leishmaniasis: the sensitivities and specificities of traditional methods and a nested PCR assay

In the present study, 67 patients suspected to be cases of visceral leishmaniasis (VL) were each checked for leishmanial infection by the microscopical evaluation of various biological specimens, in-vitro culture, serology and an assay based on nested PCR. Most (35) of the subjects were immunocompetent (IC) but 32 were immunodeficient (ID) as the result of HIV infection (18 cases), treatment to prevent transplanted organs being rejected (six) or haematological malignancies (eight). Forty-one (61.2%) of the subjects (19 IC subjects, 12 HIV-positive patients, four transplant patients and six patients with malignancies) were considered true cases of VL. For the IC subjects, only the production and microscopical examination of leucocytoconcentrates and cultures of Buffy coats gave sensitivities of <80%, the results of the other methods showing higher sensitivities and almost perfect agreement with the 'gold-standard' diagnoses. For the ID subjects, however, only the serological tests and the PCR gave reasonable sensitivities (of >80%). For the initial diagnosis of leishmaniasis in ID patients, IFAT and western blots may be useful, as, among the present ID patients, they gave sensitivities (of 80.9% and 88.2%, respectively) that were almost as high as that for the PCR, and specificities of 100%. In the diagnosis of VL in either IC or ID patients, the assay based on a nested PCR appeared to be particularly reliable, with sensitivities of 88.9% and 95.2%, respectively, and a specificity of 100% in both groups of patients. The testing of bone-marrow aspirates by PCR revealed very few VL cases who were not found positive when samples of their peripheral blood were checked in the same assay. For both IC and ID subjects therefore, the use of the PCR-based method to test samples of peripheral blood (which can be collected much more easily than bone-marrow aspirates and with much less pain for the subject) is recommended.

Strategies for the design of orally bioavailable antileishmanial treatments

Leishmaniasis is one of the six major tropical diseases targeted by the World Health Organization. The most serious, life-threatening form is visceral leishmaniasis (VL). No vaccine is yet available for human use and chemotherapy is the main mean of dealing with this disease. This review focuses on the development of drug delivery systems (DDS) for treatment of leishmaniasis. After an overview of the significance of leishmaniasis in 2013, current chemotherapy and its limitations are considered, leading to possible strategies to improve the treatment of VL: new drugs, combinations of existing drugs and DDS, particularly for oral administration. Nanostructured biomaterials such as lipid-based or polymeric nanoparticles have unique physicochemical properties, ultra-small and controllable size, large surface area to mass ratio and the possibility of surface modification which can be used to advantage for the oral administration of antileishmanial drugs. They can improve the rate of dissolution of poorly water-soluble drugs, increase intestinal residence time by bioadhesion and, especially when lipid additives are used, influence the route and efficiency of absorption. These recent advances in this very active field should lead to better management of this serious disease.

Endemic characteristics of infantile visceral leishmaniasis in the People's Republic of China

Background

Visceral leishmaniasis (VL) was once a severe parasitic disease in China. Thanks to the great efforts of integrated control, VL was eliminated in most epidemic areas, except for certain western provinces (autonomous region) at the end of 1950s. From then on, VL gained less attention and has seemed to spread, especially in the last 15 years. Infants are the most important population threatened by VL. However, there have been few studies on the endemic characteristics of infantile VL in China.

Methods

Infantile VL cases were collected from the online National Infectious Diseases Reporting System (NIDRS). Statistical description and inference was used to reveal the endemic characteristics in gender, age group, time and regionalism. Spatial analysis was carried out to explore the high risk area for infantile VL in China.

Results

A total of 1093 infantile VL cases were reported from 2006 to 2012. There was no statistically significant difference in gender over time. The minimum, maximum and mean age of these cases was 1.1, 35.9 and 13.8 months, respectively. Among them 86.92% were under 2 years of age, and there was a statistically significant difference among age groups over time. An incidence peak appeared in 2008-2009, most cases were distributed in the months September to December, and there was a tail-raising effect in the coming two months of the next year. More than 98% of cases were reported in Xinjiang Uygur Autonomous Region, Gansu Province and Sichuan Province, accounting for 61.02%, 32.75% and 4.57%, respectively. A total of 56 counties reported infantile VL cases, with the cumulative incidence ranging from 0.02 to 24.57%. There were two main zones of high endemicity for infantile VL in China. The monthly incidence clearly coincides with the number of towns where infantile VL cases were reported. Three fatalities were reported during the study period, the case fatality rate was 2.75‰.

Conclusions

The endemic situation of infantile VL is serious, and there are several active foci of infantile VL prevalence in China. VL has emerged as a severe threat to infants of endemic regions in China.

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.

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.

Copaiba Oil: An Alternative to Development of New Drugs against Leishmaniasis

Leishmaniasis is a neglected disease that is increasing globally at an alarming rate. Glucantime has been the therapy of choice for more than 50 years. A recent study reported the antileishmanial activity of copaiba oil against Leishmania amazonensis. These results led us to investigate morphological and ultrastructural changes in L. amazonensis treated with copaiba oil, using electron microscopy and flow cytometry to assess specific organelles as targets for copaiba oil. In the promastigote and axenic amastigote forms, this copaiba oil caused notable morphological and ultrastructural changes, including extensive mitochondrial damage and denaturation of the plasma membrane. Copaiba oil treatment also induced a decrease in Rh123 fluorescence, suggesting interference with the mitochondrial membrane potential and loss of cell viability with an increase in plasma membrane permeability, as observed by flow cytometry after staining with propidium iodide. In conclusion, copaiba oil could be exploited for the development of new antileishmanial drugs.

Recent advances in leishmaniasis treatment

About 1.5 million new cases of cutaneous leishmaniasis and 500,000 new cases of visceral leishmaniasis occur each year around the world. For over half a century, the clinical forms of the disease have been treated almost exclusively with pentavalent antimonial compounds. In this review, we describe the arsenal available for treating Leishmania infections, as well as recent advances from research on plants and synthetic compounds as source drugs for treating the disease. We also review some new drug-delivery systems for the development of novel chemotherapeutics. We observe that the pharmaceutical industry should employ its modern technologies, which could lead to better use of plants and their extracts, as well as to the development of synthetic and semi-synthetic compounds. New studies have highlighted some biopharmaceutical technologies in the design of the delivery strategy, such as nanoparticles, liposomes, cochleates, and non-specific lipid transfer proteins. These observations serve as a basis to indicate novel routes for the development and design of effective anti-Leishmania drugs.

Lay perceptions of kala-azar, mosquitoes and bed nets in Bihar, India

OBJECTIVE

To describe the lay perception of kala-azar (KA) in an endemic area of Muzaffarpur District, Bihar, India: local names, symptoms, affected persons, perceived severity and modes of transmission, as well as perceived mosquito nuisance, modes of protection and use of bed nets.

METHODS

We held 16 focus group discussions (FGD) in eight remote villages with altogether 157 participants in March 2008. Separate FGDs were held according to gender, socio-economic status (SES) and with key informants.

RESULTS

Kala-azar is most commonly named pilahi. Poor people were said to be the most affected. Knowledge about symptoms was satisfactory. Fever and prolonged fever were the most stated symptoms. KA was perceived as a life-threatening disease with a heavy economic burden. Mosquito bites were perceived as the main mode of transmission but in lower socio-economic groups, non-vector-related explanations were also provided. The main modes of protection from mosquitoes mentioned were the use of fumes and bed nets. Season was the strongest factor influencing the use of bed nets and non-affordability for not owning them.

CONCLUSIONS

Although the sand fly is not recognised as the vector, the relatively good awareness of disease transmission by mosquitoes and the nuisance caused by their high density might be an entry point for adopting preventive measures to protect from mosquito bite and thereby indirectly preventing from KA. Educational campaigns targeted to the poorer segments of society are needed to enhance knowledge about KA, its mode of transmission, risks of getting infected and to increase bed net use.

Management of visceral leishmaniasis in rural primary health care services in Bihar, India

OBJECTIVE

In 2005 a visceral leishmaniasis (VL) elimination initiative was launched on the Indian subcontinent, with early diagnosis based on a rapid diagnostic test and treatment with the oral drug miltefosine as its main strategy. Several recent studies have signaled underreporting of VL cases in the region. Information on treatment outcomes is scanty. Our aim was to document VL case management by the primary health care services in India.

METHODS

We took a random sample of all VL patients registered in rural primary health care (PHC) facilities of Muzaffarpur district, Bihar, India during 2008. Patients were traced at home for an interview and their records were reviewed. We recorded patient and doctor delay, treatment regimens, treatment outcomes and costs incurred by patients.

RESULTS

We could review records of all 150 patients sampled and interview 139 patients or their guardian. Most patients (81%) had first presented to unqualified practitioners; median delay before reaching the appropriate primary healthcare facility was 40 days (IQR 31-59 days). Existing networks of village health workers were under-used. 48% of VL patients were treated with antimonials; 40% of those needed a second treatment course. Median direct expenditure by patients was 4000 rupees per episode (IQR 2695-5563 rupees), equivalent to almost 2 months of household income.

CONCLUSION

In 2008 still critical flaws remained in VL case management in the primary health care services in Bihar: obsolete use of antimonials with high failure rates and long patient delay. To meet the target of the VL elimination, more active case detection strategies are needed, and village health worker networks could be more involved. Costs to patients remain an obstacle to early case finding.

Diagnosis of visceral leishmaniasis

Leishmaniasis is a vector-borne disease with up to 350 million people at risk of infection worldwide. Among its different clinical manifestations, visceral is the most severe form. Since clinical features of visceral leishmaniasis (VL) mimic several other common diseases, accurate diagnosis is crucial as the treatment is associated with significant toxicity. Invasive and risky techniques involving demonstration of the parasites in stained preparations from splenic and bone marrow aspirate is still the gold standard for VL diagnosis. Serological tests using rK39 in ELISA or rapid immunochromatographic format, Direct Agglutination Test (DAT), immunoblotting have issues related to a significant proportion of asymptomatic individuals being positive with these tests and their inability to diagnose relapses as these remain positive for several months to years after cure. PCR is the most common molecular technique successfully used for diagnosis and differentiation of species. Through this review we focus extensively on the comparative utilities of the various diagnostic tools currently available for VL, describing in depth their advantages and disadvantages, addressing the recent advances attained in the field. A simple, rapid, non invasive, accurate and cost effective marker of active VL, which can be used in field conditions, is necessary to improve diagnosis of VL.

Upregulated expression of B-cell antigen family tandem repeat proteins by Leishmania amastigotes

Proteins with tandem repeat (TR) domains have been found in various protozoan parasites, and they are often targets of B-cell responses. Through systematic analyses of whole proteomes, we recently demonstrated that two trypanosomatid parasites, Leishmania infantum and Trypanosoma cruzi, are rich in antigenic proteins with large TR domains. However, the reason that these proteins are antigenic was unclear. Here, by performing molecular, immunological, and bioinformatic characterizations of Leishmania TR proteins, we found two possible factors affecting the antigenicity of these proteins; one factor is their fundamental composition as TR proteins, and the other is regulation of their expression by parasites. Enzyme-linked immunosorbent assays (ELISAs) using recombinant proteins revealed that the copy number of the repeat affects the affinity of binding between antigens and antibodies, as expected based on thermodynamic binding kinetics. Other than containing TR domains, the TR proteins do not share characteristics, such as sequence similarity or biased cellular location predicted by the presence of a signal sequence(s) and/or a transmembrane domain(s). However, the TR proteome contained a higher percentage of proteins upregulated in amastigotes than the whole proteome, and upregulated expression of a TR protein seemed to affect its antigenicity. These results indicate that Leishmania parasites actively utilize the TR protein family for parasitism in mammalian hosts.

In vitro effects of Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens on Leishmania major promastigotes

Plant extracts from Warburgia ugandensis Sprague (Family: Canellaceae), Psiadia punctulata Vatke (Family: Compositae) and Chasmanthera dependens Hoschst (Family: Menispermaceae) were tested for activity on Leishmania major promastigotes (Strain IDU/KE/83 = NLB-144) and infected macrophages in vitro. Plants were collected from Baringo district, dried, extracted, weighed and tested for antileishmanial activity. Serial dilutions of the crude extracts were assayed for their activity against Leishmania major in cell free cultures and in infected macrophages in vitro. Inhibitory concentrations and levels of cytotoxicity were determined. Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens had an IC(50) of 1.114 mg/ml, 2.216 mg/ml and 4.648 mg/ml, respectively. The cytotoxicity of the drugs on BALB/c peritoneal macrophage cells was insignificant as compared to the highly toxic drug of choice Pentostam(®). The supernatants from control and Leishmania infected macrophages were analyzed for their nitrite contents by Griess reaction and nitrite absorbance measured at 540 nm. Warburgia ugandensis (stem bark water extract), Chasmanthera dependens (stem bark water extract) and Psiadia punctulata (stem bark methanol extract) produced 112.3%, 94% and 88.5% more nitric oxide than the untreated infected macrophages respectively. Plant crude extracts had significant (p<0.05) anti-leishmanial and immunomodulative effects but insignificant cytotoxic effects at 1mg/ml concentration. All experiments were performed in triplicate. Statistical analysis of the differences between mean values obtained from the experimental group compared to the controls was done by students't test. ANOVA was used to determine the differences between the various treatment groups. The analysis program Probit was used to determine IC(50)s.

Clinical risk factors for therapeutic failure in kala-azar patients treated with pentavalent antimonials in Nepal

Drug-related factors and parasite resistance have been implicated in the failure of pentavalent antimonials (Sb(v)) in the Indian subcontinent; however, little information is available on host-related factors. Parasitologically confirmed kala-azar patients, treatment naïve to Sb(v), were prospectively recruited at a referral hospital in Nepal and were treated under supervision with 30 doses of quality-assured sodium stibogluconate (SSG) 20mg/kg/day and followed for 12 months to assess cure. Analysis of risk factors for treatment failure was assessed in those receiving >or=25 doses and completing 12 months of follow-up. One hundred and ninety-eight cases were treated with SSG and the overall cure rate was 77.3% (153/198). Of the 181 cases who received >or=25 doses, 12-month follow-up data were obtained in 169, comprising 153 patients (90.5%) with definite cure and 16 (9.5%) treatment failures. In the final logistic regression model, increased failure to SSG was significantly associated with fever for >or=12 weeks [odds ratio (OR)=7.4], living in districts bordering the high SSG resistance zone in Bihar (OR=6.1), interruption of treatment (OR=4.3) and ambulatory treatment (OR=10.2). Early diagnosis and supervised treatment is of paramount importance to prevent treatment failures within the control programme.

Antileishmanial activity, pharmacokinetics and tissue distribution studies of mannose-grafted amphotericin B lipid nanospheres

Leishmania parasite resides mainly in the liver and the spleen and multiplies. Effective therapy of leishmaniasis could be achieved by delivering antileishmanial drugs to these sites. Present investigations were aimed at developing lipid nanospheres of amphotericin B (LN-A) anchored with mannose to achieve targeted delivery to the liver. Mannose is specifically involved in the recognition of parasite or appropriate ligands on the macrophage surface LN-A, and mannose-anchored lipid nanospheres (LN-A-MAN) were prepared by homogenization followed by ultrasonication method. Particle size and zeta potential were measured using Malvern Zetasizer. The average particle size after sterilization of LN-A and LN-A-MAN ranged from 193.4 +/- 1.1 to 775.8 +/- 9.1. Leishmaniasis was induced in BALB/c mice by injecting Leishmania donovani parasites intravenously. Infected mice were administered with a single dose (5 mg/kg body weight) of LN-A, LN-A-MAN, and Fungizone (marketed product).The efficacy of the formulations was evaluated by measuring the reduction in parasite burden. Fungizone reduced 82 and 69%, LN-A reduced 90 and 85%, LN-A-MAN reduced 95 and 94% of parasite burden in the liver and the spleen, respectively. LN-A and LN-A-MAN-treated mice did not show any elevation in serum glutamate pyruvate transaminase (SGPT), alkaline phosphatase (ALP), urea, and creatinine levels as compared with Fungizone. Pharmacokinetic parameters were estimated and the concentration of amphotericin B (AmB) in mice plasma declined biexponentially and AmB concentrations were significantly higher for LN-A- and LN-A-MAN than Fungizone-treated mice (P < 0.05). Tissue distribution patterns were studied in different tissues such as the liver, the spleen, the kidney, and the brain of BALB/c mice. LN-A-MAN was found to distribute more rapidly to the liver and the spleen explaining the reason for higher antileishmanial activity.