Estimation of under-reporting of visceral leishmaniasis cases in Bihar, India

Deciphering the intricate dynamics of inflammasome regulation in visceral and post-kala-azar dermal leishmaniasis: A meta-analysis of consistencies

Post Kala-azar dermal leishmaniasis (PKDL) arises as a significant dermal sequel following Visceral leishmaniasis (VL) caused by protozoan parasite Leishmania donovani (LD). PKDL acts as a significant constrain for VL elimination serving as a crucial reservoir for LD. PKDL patients exhibit depigmented macular and papular lesions on their skin, which results in social discrimination due to loss of natural skin color. Inflammatory reactions, prevalent in both VL and PKDL, potentially lead to tissue damage in areas harboring the parasite. Disruption of the immune-inflammasomal network not only facilitates LD persistence but also leads to the skin hypopigmentation seen in PKDL, impacting social well-being. Activation of inflammasomal markers like STAT1, NLRP1, NLRP3, AIM2, CASP11, and NLRP12 have been identified as a common host-defense mechanism across various Leishmania infections. Conversely, Leishmania modulates inflammasome activation to sustain its presence within the host. Nevertheless, in specific instances of Leishmania infection, inflammasome activation can worsen disease pathology by promoting parasite proliferation and persistence. This study encompasses recent transcriptomic analyses conducted between 2016 and 2023 on human and murine subjects afflicted with VL/PKDL, elucidating significant alterations in inflammasomal markers in both conditions. It offers a comprehensive understanding how these markers contribute in disease progression, drawing upon available literature for logical analysis. Furthermore, our analysis identifies validated miRNA network that could potentially disrupt this crucial immune-inflammasomal network, thereby offering a plausible explanation on how secreted LD-factors could enable membrane-bound LD, isolated from the host cytoplasm, to modulate cytoplasmic inflammasomal markers. Insights from this study could guide the development of host-directed therapeutics to impede transmission and address hypopigmentation, thereby mitigating the social stigma associated with PKDL.

Arsenic exposure to mouse visceral leishmaniasis model through their drinking water linked to the disease exacerbation via modulation in host protective immunity: a preclinical study

A large body of evidence has shown a direct link between arsenic exposure and drug resistance to Leishmania parasites against antimonial preparations in visceral leishmaniasis (VL) hyper-endemic regions, especially in India and its sub-continent. However, the implicated roles of arsenic on the VL host, pathophysiological changes, and immune function have not yet been clarified, particularly at the reported concentration of arsenic in the VL hyper-endemic area of Bihar, India. Herein, we exposed the mouse VL model to arsenic (0.5 mg/L to 2 mg/L) through their drinking water and analyzed its effect on T cells proliferation, Th1/Th2-mediators, MAPK signaling cascade, and parasite load in preclinical models. Coherently, the parasite count in Giemsa stained spleen imprint has been investigated and found significant positive associations with levels of arsenic exposure. The liver and kidney function tests (AST, ALT, ALP, BUN, Creatinine, Urea, etc.) are apparent to hepatonephric toxicity in arsenic exposed VL mice compared to unexposed. This observation appears to be consistent with the up-regulated expression of immune regulatory Th2 mediators (IL-4, IL-10, TGF-β) and down-regulated expression of Th1 mediators (IL-12, IFN-γ, TNF-α) with a suppressed leishmanicidal function of macrophage (ROS, NO, iNOS). We also established that arsenic exposure modulated the host ERK-1/2 and p38 MAPK signaling cascade, limited T lymphocyte proliferation, and a lower IgG2a/IgG1 ratio to favor the Leishmania parasite survival inside the host. This study suggests that the contorted Th1-subtype and exacerbated Th2-subtype immune responses are involved in the increased susceptibility and pathogenesis of Leishmania parasite among subjects/individuals regularly exposed to arsenic.

Impetiginous Cutaneous Leishmaniasis after COVID-19 Infection in a Patient with Poor Cardiac Profile: A Case Report and Literature Review

Cutaneous leishmaniasis incidence has been rising in the past couple of decades. Standard therapy often includes antileishmanial drugs; however, due to their low safety and toxicity threshold, alternative treatments are being investigated. The association between COVID-19 and cutaneous leishmaniasis remains unclear and exploring this connection may offer crucial insights into the pathophysiology of and treatment strategies for infected patients. In this article, we describe a case of a male patient with a history of cardiac and other comorbidities who presented with cutaneous leishmaniasis in the form of impetigo-like skin lesions after being infected with COVID-19. Due to the patient's poor cardiac profile, sodium stibogluconate was not used and an alternative therapeutic approach was employed. The patient was treated with oral terbinafine, cryotherapy on specific lesions, and a course of cephalexin. Following the course of treatment and subsequent follow-up, the patient exhibited complete resolution and healing of the lesions with scarring, and no active lesions or recurrence were observed. This case highlights the potential for alternative treatment strategies for cutaneous leishmaniasis in patients with comorbidities and emphasizes the importance of further research to better understand the link between COVID-19 and cutaneous leishmaniasis.

Estimating the global demand curve for a leishmaniasis vaccine: A generalisable approach based on global burden of disease estimates

Background

A pressing need exists to develop vaccines for neglected diseases, including leishmaniasis. However, the development of new vaccines is dependent on their value to two key players–vaccine developers and manufacturers who need to have confidence in the global demand in order to commit to research and production; and governments (or other international funders) who need to signal demand based on the potential public health benefits of the vaccine in their local context, as well as its affordability. A detailed global epidemiological analysis is rarely available before a vaccine enters a market due to lack of resources as well as insufficient global data necessary for such an analysis. Our study seeks to bridge this information gap by providing a generalisable approach to estimating the commercial and public health value of a vaccine in development relying primarily on publicly available Global Burden of Disease (GBD) data. This simplified approach is easily replicable and can be used to guide discussions and investments into vaccines and other health technologies where evidence constraints exist. The approach is demonstrated through the estimation of the demand curve for a future leishmaniasis vaccine.

Methodology/Principal findings

We project the ability to pay over the period 2030–2040 for a vaccine preventing cutaneous and visceral leishmaniasis (CL / VL), using an illustrative set of countries which account for most of the global disease burden. First, based on previous work on vaccine demand projections in these countries and CL / VL GBD-reported incidence rates, we project the potential long-term impact of the vaccine on disability-adjusted life years (DALYs) averted as a result of reduced incidence. Then, we apply an economic framework to our estimates to determine vaccine affordability based on the abilities to pay of governments and global funders, leading to estimates of the demand and market size. Based on our estimates, the maximum ability-to-pay of a leishmaniasis vaccine (per course, including delivery costs), given the current estimates of incidence and population at risk, is higher than $5 for 25–30% of the countries considered, with the average value-based maximum price, weighted by quantity demanded, being $5.7–6 [$0.3 - $34.5], and total demand of over 560 million courses.

Conclusion/Significance

Our results demonstrate that both the quantity of vaccines estimated to be required by the countries considered as well as their ability-to-pay could make a vaccine for leishmaniasis commercially attractive to potential manufacturers. The methodology used can be equally applied to other technology developments targeting health in developing countries.

Overcoming roadblocks in the development of vaccines for leishmaniasis

INTRODUCTION

The leishmaniases represent a group of parasitic diseases caused by infection with one of several species of Leishmania parasites. Disease presentation varies because of differences in parasite and host genetics and may be influenced by additional factors such as host nutritional status or co-infection. Studies in experimental models of Leishmania infection, vaccination of companion animals and human epidemiological data suggest that many forms of leishmaniasis could be prevented by vaccination, but no vaccines are currently available for human use.

AREAS COVERED

We describe some of the existing roadblocks to the development and implementation of an effective leishmaniasis vaccine, based on a review of recent literature found on PubMed, BioRxiv and MedRxiv. In addition to discussing scientific unknowns that hinder vaccine candidate identification and selection, we explore gaps in knowledge regarding the commercial and public health value propositions underpinning vaccine development and provide a route map for future research and advocacy.

EXPERT OPINION

Despite significant progress, leishmaniasis vaccine development remains hindered by significant gaps in understanding that span the vaccine development pipeline. Increased coordination and adoption of a more holistic view to vaccine development will be required to ensure more rapid progress in the years ahead.

Improved kala-azar case management through implementation of health facility-based sentinel sites surveillance system in Bihar, India

Background

Visceral leishmaniasis (VL), also known as kala-azar (KA), is a neglected vector-borne disease, targeted for elimination, but several affected blocks of Bihar are posing challenges with the high incidence of cases, and moreover, the disease is spreading in newer areas. High-quality kala-azar surveillance in India, always pose great concern. The complete and accurate patient level data is critical for the current kala-azar management information system (KMIS). On the other side, no accurate data on the burden of post kala-azar dermal leishmaniasis (PKDL) and co-infections are available under the current surveillance system, which might emerge as a serious concern. Additionally, in low case scenario, sentinel surveillance may be useful in addressing post-elimination activities and sustaining kala-azar (KA) elimination. Health facility-based sentinel site surveillance system has been proposed, first time to do a proper accounting of KA, PKDL and co-infection morbidity, mortality, diagnosis, case management, hotspot identification and monitoring the impact of elimination interventions.

Methodology/principal findings

Kala-azar sentinel site surveillance was established and activated in thirteen health facilities of Bihar, India, using stratified sampling technique during 2011 to 2014. Data were collected through specially designed performa from all patients attending the outpatient departments of sentinel sites. Among 20968 symptomatic cases attended sentinel sites, 2996 cases of KA and 53 cases of PKDL were registered from 889 endemic villages. Symptomatic cases meant a person with fever of more than 15 days, weight loss, fatigue, anemia, and substantial swelling of the liver and spleen (enlargement of spleen and liver).The proportion of new and old cases was 86.1% and 13.9% respectively. A statistically significant difference was observed for reduction in KA incidence from 4.13/10000 in 2011 to 1.75/10000 in 2014 (p<0.001). There were significant increase (0.08, 0.10 per 10 000 population) in the incidences of PKDL and co-infection respectively in the year 2014 as compared to that of 2011 (0.03, 0.06 per 10 000 population). The proportion of HIV-VL co-infection was significantly higher (1.6%; p<0.05) as compared to other co-infections. Proportions of male in all age groups were higher and found statistically significant (Chi-square test = 7.6; P = 0.026). Utilization of laboratory services was greatly improved. Friedman test showed statistically significant difference between response of different anti kala-azar drugs (F = 25.0, P = 0.004).The initial and final cure rate of AmBisome was found excellent (100%). The results of the signed rank sum test showed significant symmetry of unresponsiveness rate (P = 0.03). Similarly, relapse rate of sodium antimony gluconate (SAG) was also found significantly higher as compared to other drugs (95%CI 0.2165 to 19.7035; P = 0.03). A statistically significant difference was found (p<0.001) between villages having 1–2 cases (74%) and villages with 3–5 cases (15%). Significantly higher proportion (95%) of cases were captured by existing Govt. surveillance system (KMIS) (p<0.001), as compared to private providers (5%).

Conclusions/significance

Establishment of a sentinel site based kala-azar surveillance system in Bihar, India effectively detected the rising trend of PKDL and co-infections and captured complete and accurate patient level data. Further, this system may provide a model for improving laboratory services, KA, PKDL and co-infection case management in other health facilities of Bihar without further referral. Program managers may use these results for evaluating program’s effectiveness. It may provide an example for changing the practices of health care workers in Bihar and set a benchmark of high quality surveillance data in a resource limited setting. However, the generalizability of this sentinel surveillance finding to other context remains a major limitation of this study. The justifications for this; the sentinel sites were made in the traditionally high endemic PHC’s. The other conditions were Program commitment for diagnostic (rk-39) and the first line anti kala-azar drug i.e. miltefosine throughout the study period in the sentinel sites. In addition, there were clause of fulfillment of readiness criteria at each sentinel site (already described in the line no 171 to 180 at page no-8, 181–189 at page no-9 and 192–212 at page no-10). Rigorous efforts were taken to improve all the sentinel sites to meet the readiness criteria and research activities started only after meeting readiness criteria at the site. Therefore sentinel site surveillance described under the present study cannot be integrated into other set up (medium and low endemic areas). However, it can be integrated into highly endemic areas with program commitment and fulfillment of readiness criteria.

Visceral leishmaniasis is a neglected vector-borne disease, and one of the major public health problems of Bihar. The disease has been targeted for elimination by 2020. Bihar still posing challenge i.e. incidence is much high in a number of affected blocks, and even the disease is spreading in newer areas. None availability of an accurate data on the burden of post kala-azar dermal leishmaniasis (PKDL) and co-infections under the current surveillance system may emerge as a serious concern. Therefore, health facility-based sentinel site surveillance system has been attempted for the first time in Bihar for proper accounting of KA, PKDL and co-infection morbidity, mortality, diagnosis, case management, hotspot identification and monitoring the impact of elimination interventions. A system for capturing regional transmission is essential that can target focal areas of infection to monitor progress towards kala-azar elimination. Kala-azar sentinel site surveillance was established and activated in thirteen health facilities of Bihar during 2011 to 2014. The results showed a significant increase in PKDL and co-infection in 2014 when compared to 2011. Findings further revealed that utilization of laboratory services and case management were greatly improved, as majority of patients with KA, PKDL & co-infections were managed by the sentinel sites itself. The final cure rate of AmBisome was found excellent (100%). These observations may be useful to provide the basis for the design, refinement and resource allocation of the kala-azar control program. This system may also be useful in measuring impact of elimination interventions, their effectiveness and finally help in improving program management. It may further be used as an example for changing the practices of health care workers in Bihar and a lesson how to achieve high quality surveillance data in a resource limited setting. Standardization of sentinel site surveillance in terms of improved procedure, training, logistics, etc may further increase the effectiveness of this system. It may possibly be used as a cost-effective approach for capturing real-time kala-azar data under national kala-azar elimination programme.

Development and Evaluation of Active Case Detection Methods to Support Visceral Leishmaniasis Elimination in India

As India moves toward the elimination of visceral leishmaniasis (VL) as a public health problem, comprehensive timely case detection has become increasingly important, in order to reduce the period of infectivity and control outbreaks. During the 2000s, localized research studies suggested that a large percentage of VL cases were never reported in government data. However, assessments conducted from 2013 to 2015 indicated that 85% or more of confirmed cases were eventually captured and reported in surveillance data, albeit with significant delays before diagnosis. Based on methods developed during these assessments, the CARE India team evolved new strategies for active case detection (ACD), applicable at large scale while being sufficiently effective in reducing time to diagnosis. Active case searches are triggered by the report of a confirmed VL case, and comprise two major search mechanisms: 1) case identification based on the index case's knowledge of other known VL cases and searches in nearby houses (snowballing); and 2) sustained contact over time with a range of private providers, both formal and informal. Simultaneously, house-to-house searches were conducted in 142 villages of 47 blocks during this period. We analyzed data from 5030 VL patients reported in Bihar from January 2018 through July 2019. Of these 3033 were detected passively and 1997 via ACD (15 (0.8%) via house-to-house and 1982 (99.2%) by light touch ACD methods). We constructed multinomial logistic regression models comparing time intervals to diagnosis (30-59, 60-89 and ≥90 days with <30 days as the referent). ACD and younger age were associated with shorter time to diagnosis, while male sex and HIV infection were associated with longer illness durations. The advantage of ACD over PCD was more marked for longer illness durations: the adjusted odds ratios for having illness durations of 30-59, 60-89 and >=90 days compared to the referent of <30 days for ACD vs PCD were 0.88, 0.56 and 0.42 respectively. These ACD strategies not only reduce time to diagnosis, and thus risk of transmission, but also ensure that there is a double check on the proportion of cases actually getting captured. Such a process can supplement passive case detection efforts that must go on, possibly perpetually, even after elimination as a public health problem is achieved.

Optimizing Village-Level Targeting of Active Case Detection to Support Visceral Leishmaniasis Elimination in India

Background

India has made major progress in improving control of visceral leishmaniasis (VL) in recent years, in part through shortening the time infectious patients remain untreated. Active case detection decreases the time from VL onset to diagnosis and treatment, but requires substantial human resources. Targeting approaches are therefore essential to feasibility.

Methods

We analyzed data from the Kala-azar Management Information System (KAMIS), using village-level VL cases over specific time intervals to predict risk in subsequent years. We also graphed the time between cases in villages and examined how these patterns track with village-level risk of additional cases across the range of cumulative village case-loads. Finally, we assessed the trade-off between ACD effort and yield.

Results

In 2013, only 9.3% of all villages reported VL cases; this proportion shrank to 3.9% in 2019. Newly affected villages as a percentage of all affected villages decreased from 54.3% in 2014 to 23.5% in 2019, as more surveillance data accumulated and overall VL incidence declined. The risk of additional cases in a village increased with increasing cumulative incidence, reaching approximately 90% in villages with 12 cases and 100% in villages with 45 cases, but the vast majority of villages had small cumulative case numbers. The time-to-next-case decreased with increasing case-load. Using a 3-year window (2016-2018), a threshold of seven VL cases at the village level selects 329 villages and yields 23% of cases reported in 2019, while a threshold of three cases selects 1,241 villages and yields 46% of cases reported in 2019. Using a 6-year window increases both effort and yield.

Conclusion

Decisions on targeting must consider the trade-off between number of villages targeted and yield and will depend upon the operational efficiencies of existing programs and the feasibility of specific ACD approaches. The maintenance of a sensitive, comprehensive VL surveillance system will be crucial to preventing future VL resurgence.

Towards a Sustainable Vector-Control Strategy in the Post Kala-Azar Elimination Era

Visceral leishmaniasis (VL) is a potentially deadly parasitic disease. In the Indian sub-continent, VL is caused by Leishmania donovani and transmitted via the bite of an infected Phlebotomus argentipes female sand fly, the only competent vector species in the region. The highest disease burden is in the northern part of the Indian sub-continent, especially in the state of Bihar. India, Bangladesh, and Nepal embarked on an initiative, coordinated by World Health Organization, to eliminate VL as a public health problem by the year 2020. The main goal is to reduce VL incidence below one case per 10,000 people through early case-detection, prompt diagnosis and treatment, and reduction of transmission using vector control measures. Indoor residual spraying, a major pillar of the elimination program, is the only vector control strategy used by the government of India. Though India is close to its VL elimination target, important aspects of vector bionomics and sand fly transmission dynamics are yet to be determined. To achieve sustained elimination and to prevent a resurgence of VL, knowledge gaps in vector biology and behavior, and the constraints they may pose to current vector control methods, need to be addressed. Herein, we discuss the successes and failures of previous and current vector-control strategies implemented to combat kala-azar in Bihar, India, and identify gaps in our understanding of vector transmission towards development of innovative tools to ensure sustained vector control in the post-elimination period.

Impact of Changes in Detection Effort on Control of Visceral Leishmaniasis in the Indian Subcontinent

Background

Control of visceral leishmaniasis (VL) on the Indian subcontinent relies on prompt detection and treatment of symptomatic cases. Detection efforts influence the observed VL incidence and how well it reflects the underlying true incidence. As control targets are defined in terms of observed cases, there is an urgent need to understand how changes in detection delay and population coverage of improved detection affect VL control.

Methods

Using a mathematical model for transmission and control of VL, we predict the impact of reduced detection delays and/or increased population coverage of the detection programs on observed and true VL incidence and mortality.

Results

Improved case detection, either by higher coverage or reduced detection delay, causes an initial rise in observed VL incidence before a reduction. Relaxation of improved detection may lead to an apparent temporary (1 year) reduction in VL incidence, but comes with a high risk of resurging infection levels. Duration of symptoms in detected cases shows an unequivocal association with detection effort.

Conclusions

VL incidence on its own is not a reliable indicator of the performance of case detection programs. Duration of symptoms in detected cases can be used as an additional marker of the performance of case detection programs.

Xenodiagnosis to address key questions in visceral leishmaniasis control and elimination

Visceral leishmaniasis (VL) remains an important public health issue worldwide causing substantial morbidity and mortality. The Indian subcontinent accounted for up to 90% of the global VL burden in the past but made significant progress during recent years and is now moving towards elimination. However, to achieve and sustain elimination of VL, knowledge gaps on infection reservoirs and transmission need to be addressed urgently. Xenodiagnosis is the most direct way for testing the infectiousness of hosts to the vectors and can be used to investigate the dynamics and epidemiology of Leishmania donovani transmission. There are, however, several logistic and ethical issues with xenodiagnosis that need to be addressed before its application on human subjects. In the current Review, we discuss the critical knowledge gaps in VL transmission and the role of xenodiagnosis in disease transmission dynamics along with its technical challenges. Establishment of state of the art xenodiagnosis facilities is essential for the generation of much needed evidence in the VL elimination initiative.

Differential Regulation of miRNA Profiles of Human Cells Experimentally Infected by Leishmania donovani Isolated From Indian Visceral Leishmaniasis and Post-Kala-Azar Dermal Leishmaniasis

MicroRNAs are small ribonucleic acid that act as an important regulator of gene expression at the molecular level. However, there is no comparative data on the regulation of microRNAs (miRNAs) in visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL). In this current study, we compared the expression miRNA profile in host cells (GTHP), with VL strain (GVL) and PKDL strain-infected host cell (GPKDL). Normalized read count comparison between different conditions revealed that the miRNAs are indeed differentially expressed. In GPKDL with respect to GVL and GTHP, a total of 798 and 879 miRNAs were identified, out of which 349 and 518 are known miRNAs, respectively. Comparative analysis of changes in miRNA expression suggested that the involvement of differentially expressed miRNAs in various biological processes like PI3K pathway activation, cell cycle regulation, immunomodulation, apoptosis inhibition, different cytokine production, T-cell phenotypic transitions calcium regulation, and so on. A pathway enrichment study using in silico predicted gene targets of differentially expressed miRNAs showed evidence of potentially universal immune signaling pathway effects. Whereas cytokine-cytokine receptor interaction, phagocytosis, and transforming growth factor beta (TGF-β) signaling pathways were more highly enriched using targets of miRNAs upregulated in GPKDL. These findings could contribute to a better understanding of PKDL pathogenesis. Furthermore, the identified miRNAs could also be used as biomarkers in diagnosis, prognosis, and therapeutics of PKDL infection control.

Cutaneous leishmaniasis: A neglected disfiguring disease for women

Leishmaniasis is one of eight neglected tropical diseases currently endemic in 102 countries/areas around the world. In recent years, cutaneous leishmaniasis (CL) has been increasingly observed among migrants, travelers, ecotourists, and military personnel. Because of its great capacity to mimic other dermatoses, CL is one of the great imitators and can mislead practitioners, which can result in untreated lesions that cause scars. CL is a disfiguring disease, especially for women, and often leaves scars on visible body sites, causing psychological, social, and economic problems. CS is a challenge, especially in nonendemic regions, such as Australia, because experience with diagnosis and management of the disease is limited.

Eliminating visceral leishmaniasis in South Asia: the road ahead

Suman Rijal and colleagues highlight lessons from a regional collaboration to eliminate visceral leishmaniasis and identify priorities for the post-elimination plan

Barriers of Visceral Leishmaniasis reporting and surveillance in Nepal: comparison of governmental VL-program districts with non-program districts

OBJECTIVES

At the time when Nepal is on the verge of reaching the maintenance phase of the Visceral Leishmaniasis (VL) elimination program, the country is facing new challenges. The disease has expanded to 61 of the country's 75 districts including previously non-endemic areas where there is no control or patient management program in place. This study aimed to assess which elements of the surveillance and reporting systems need strengthening to identify cases at an early stage, prevent further transmission and ensure sustained VL elimination.

METHODS

In a cross-sectional mixed-method study, we collected data from two study populations in VL program and non-program districts. From February to May 2016, structured interviews were conducted with 40 VL patients, and 14 in-depth and semi-structured interviews were conducted with health managers.

RESULTS

The median total delay from onset of symptoms to successful reporting to the Ministry of Health was 68.5 days in the VL-program and 83 days in non-program districts. The difference in patient's delay from the onset of symptoms to seeking health care was 3 days in VL-program and 20 days in non-program districts. The diagnostic delay (38.5 days and 36 days, respectively), treatment delay (1 vs. 1 days) and reporting delay (45 vs. 36 days) were similar in program and non-program districts. The diagnostic delay increased three-fold from 2012, while treatment and reporting delay remained unchanged. The main barriers to surveillance were: (i) lack of access and awareness in non-program districts; (ii) growing private sector not included in and not participating to referral, treatment and reporting; (iii) lack of cooperation and coordination among stakeholders for training and deployment of interventions; (iv) insufficient validation, outreach and process optimisation of the reporting system.

CONCLUSIONS

Corrective measures are needed to maintain the achievements of the VL elimination campaign and prevent resurgence of the disease in Nepal. A clear patient referral structure, reinforcement of report notification and validation and direct relay of data by local hospitals and the private sector to the district health offices are needed to ensure prompt treatment and timely and reliable information to facilitate a responsive system of interventions.

Age trends in asymptomatic and symptomatic Leishmania donovani infection in the Indian subcontinent: A review and analysis of data from diagnostic and epidemiological studies

BACKGROUND

Age patterns in asymptomatic and symptomatic infection with Leishmania donovani, the causative agent of visceral leishmaniasis (VL) in the Indian subcontinent (ISC), are currently poorly understood. Age-stratified serology and infection incidence have been used to assess transmission levels of other diseases, which suggests that they may also be of use for monitoring and targeting control programmes to achieve elimination of VL and should be included in VL transmission dynamic models. We therefore analysed available age-stratified data on both disease incidence and prevalence of immune markers with the aim of collating the currently available data, estimating rates of infection, and informing modelling and future data collection.

METHODOLOGY/PRINCIPAL FINDINGS

A systematic literature search yielded 13 infection prevalence and 7 VL incidence studies meeting the inclusion criteria. Statistical tests were performed to identify trends by age, and according to diagnostic cut-off. Simple reversible catalytic models with age-independent and age-dependent infection rates were fitted to the prevalence data to estimate infection and reversion rates, and to test different hypotheses about the origin of variation in these rates. Most of the studies showed an increase in infection prevalence with age: from ≲10% seroprevalence (<20% Leishmanin skin test (LST) positivity) for 0-10-year-olds to >10% seroprevalence (>20% LST-positivity) for 30-40-year-olds, but overall prevalence varied considerably between studies. VL incidence was lower amongst 0-5-year-olds than older age groups in most studies; most showing a peak in incidence between ages 5 and 20. The age-independent catalytic model provided the best overall fit to the infection prevalence data, but the estimated rates for the less parsimonious age-dependent model were much closer to estimates from longitudinal studies, suggesting that infection rates may increase with age.

CONCLUSIONS/SIGNIFICANCE

Age patterns in asymptomatic infection prevalence and VL incidence in the ISC vary considerably with geographical location and time period. The increase in infection prevalence with age and peaked age-VL-incidence distribution may be due to lower exposure to infectious sandfly bites in young children, but also suggest that acquired immunity to the parasite increases with age. However, poor standardisation of serological tests makes it difficult to compare data from different studies and draw firm conclusions about drivers of variation in observed age patterns.

Trends in spatio-temporal dynamics of visceral leishmaniasis cases in a highly-endemic focus of Bihar, India: an investigation based on GIS tools

Background

Visceral leishmaniasis (VL) in Bihar State (India) continues to be endemic, despite the existence of effective treatment and a vector control program to control disease morbidity. A clear understanding of spatio-temporal distribution of VL may improve surveillance and control implementation. This study explored the trends in spatio-temporal dynamics of VL endemicity at a meso-scale level in Vaishali District, based on geographical information systems (GIS) tools and spatial statistical analysis.

Methods

A GIS database was used to integrate the VL case data from the study area between 2009 and 2014. All cases were spatially linked at a meso-scale level. Geospatial techniques, such as GIS-layer overlaying and mapping, were employed to visualize and detect the spatio-temporal patterns of a VL endemic outbreak across the district. The spatial statistic Moran’s I Index (Moran’s I) was used to simultaneously evaluate spatial-correlation between endemic villages and the spatial distribution patterns based on both the village location and the case incidence rate (CIR). Descriptive statistics such as mean, standard error, confidence intervals and percentages were used to summarize the VL case data.

Results

There were 624 endemic villages with 2719 (average 906 cases/year) VL cases during 2012–2014. The Moran’s I revealed a cluster pattern (P < 0.05) of CIR distribution at the meso-scale level. On average, 68 villages were newly-endemic each year. Of which 93.1% of villages’ endemicity were found to have occurred on the peripheries of the previous year endemic villages. The mean CIR of the endemic villages that were peripheral to the following year newly-endemic villages, compared to all endemic villages of the same year, was higher (P < 0.05).

Conclusion

The results show that the VL endemicity of new villages tends to occur on the periphery of villages endemic in the previous year. High-CIR plays a major role in the spatial dispersion of the VL cases between non-endemic and endemic villages. This information can help achieve VL elimination throughout the Indian subcontinent by improving vector control design and implementation in highly-endemic district.

Visceral leishmaniasis cyclical trends in Bihar, India - implications for the elimination programme

Background: Visceral leishmaniasis (VL) is a vector-borne disease of public health importance in India, with the highest burden of disease in the states of Bihar, Jharkhand, West Bengal and Uttar Pradesh. The disease is currently targeted for elimination (annual incidence to less than one per 10,000 population) using indoor residual spraying, active case detection and treatment. Historically the disease trend in India has been regarded as cyclical with case resurgence characteristically occurring every 15 years.  Understanding this pattern is essential if the VL elimination gains are to be sustained. To better understand the cyclical trends, annual climatic indicators including rainfall, temperature and humidity over time were compared with annual VL case incidence data. 

Methods: Annual climate data (rainfall, average and maximum temperature and specific humidity) from 1956-2004 were used to identify potential factors influencing VL incidence.  Months relevant to the VL life-cycle were identified and defined (Monsoon, Sand-fly Peak, Pre-Sand-fly Peak and Annual) for analysis. The Kruskall-Wallis test was used to determine significant difference between categorical rainfall and VL incidence, whilst univariate negative binomial regression models were used to determine predictors of disease incidence.

Results: The negative binomial regression model showed statistically significant associations (p <0.05) for VL incidence and maximum temperature, and average temperature, when considering annual and pre-sand fly peak time periods. No other associations between humidity, rainfall or temperature and VL incidence were detected (all values p >0.05). 

Conclusion: The VL programme in Bihar has made significant progress in adopting best practices for improved treatment and vector control, with the aim to achieve VL elimination.  However, open access granular programme data for indoor residual spray activities and case detection is required to fully understand the role of climate in disease transmission and potential resurgence.

A decade bibliometric analysis of global research on leishmaniasis in Web of Science database

BACKGROUND

Leishmaniasis is an extremely relevant tropical disease, with global distribution. It still remains a main public health concern in low-income countries, and it is necessary to support more research on this common disease. Thus, a bibliometric analysis of the global scientific production on leishmaniasis was carried out.

METHODS

All the articles registered in Web of Science with the subject of leishmaniasis between 2006 and 2015 were analysed, using Pajek and VOS viewer as tools.

RESULTS

13,658 records in the field of leishmaniasis were indexed in the Web of Science database for this ten-year study period (2006-2015). This shows that studies on leishmaniasis have been growing, from 1071 in 2006 to 1537 in 2015. "Sundar S" is the most active researcher in the field of leishmaniasis, compiling and participating in 232 Articles. Brazil ranks first in scientific production, by performing 3315 studies on leishmaniasis. The United States, United Kingdom and Australia had the most collaboration in performing the studies of leishmaniasis with each other. In addition, PLOS NEGLECTED TROPICAL DISEASES published the most articles, with 483.

CONCLUSION

Our data shows an increase in the number of publications in the field of leishmaniasis. In addition, Brazil, USA, and India lead scientific production on leishmaniasis research.

Bionomics of Phlebotomus argentipes in villages in Bihar, India with insights into efficacy of IRS-based control measures

Background

Visceral leishmaniasis (VL) is a deadly vector-borne disease. Approximately 90% of Indian VL cases occur in Bihar, where the sand fly, Phlebotomus argentipes, is the principal vector. Sand fly control in Bihar consists of indoor residual spraying (IRS), the practice of spraying the inner walls of village dwellings with insecticides. Prior researchers have evaluated success of IRS-control by estimating vector abundance in village houses, but the number of sampling periods (n = 2–3) were minimal, and outdoor-resting P. argentipes were neglected. We describe a large-scale field study, performed in 24 villages within two Bihari districts, during which P. argentipes were collected biweekly over 47-weeks, in cattle enclosures, houses, and outdoors in peri-domestic vegetation. The objectives of this study were to provide updated P. argentipes ecological field data, and determine if program-initiated IRS-treatment had led to noticeable differences in vector abundance.

Principal findings

P. argentipes (n = 126,901) relative abundance was greatest during the summer months (June-August) when minimum temperatures were highest. P. argentipes were most frequently collected from cattle enclosures (~46% total; ~56% blood fed). Many sand flies were found to have taken blood from multiple sources, with ~81% having blood fed on humans and ~60% blood feeding on bovines. Nonparametric statistical tests were determined most appropriate for evaluating IRS-treatment. Differences in P. argentipes abundance in houses, cattle enclosures and vegetation were detected between IRS-treated and untreated villages in only ~9% of evaluation periods occurring during the peak period of human-vector exposure (June-August) and in ~8% of the total observations. No significant differences were detected between the numbers of P. argentipes collected in vegetation close to the experimental villages.

Conclusion

The results of this study provide updated data regarding P. argentipes seasonal abundance, spatial distribution, and host preferances, and suggest vector abundance has not significantly declined in IRS-treated villages. We suggest that IRS be supplemented with vector control strategies targeting exophagic, exophilic P. argentipes, and that disease surveillance be accompanied by rigorous vector population monitoring.

Visceral leishmaniasis is a disease caused by a deadly vector-borne parasite (Leishmania donovani) transmitted to man by phlebotomine sand flies. Indoor residual spraying (IRS), performed within village dwellings, is the primary means of sand fly control performed in Bihar, India and more explicit methods of evaluating the success of control are warranted. A field-based study was conducted to collect ecological sand fly data for use in evaluating the effectiveness of IRS in reducing relative sand fly abundance. Results indicate that sand flies blood feed primarily on humans and cattle and are most frequently found within cattle enclosures. Results further suggest IRS-treatment has a limited impact on vector density. Our approach incorporates detailed evaluation of sand fly spatial distribution (cattle enclosures, houses, vegetation), seasonal fluctuations in abundance, host blood meal preferences within Bihari villages, and dates of IRS performed within treated villages. Hence, this study provides an explicit means of monitoring vector populations and evaluating control measures in Bihar.

Variations in visceral leishmaniasis burden, mortality and the pathway to care within Bihar, India

BACKGROUND

Visceral leishmaniasis (VL) has been targeted by the WHO for elimination as a public health problem (< 1 case/10,000 people/year) in the Indian sub-continent (ISC) by 2020. Bihar State in India, which accounts for the majority of cases in the ISC, remains a major target for this elimination effort. However, there is considerable spatial, temporal and sub-population variation in occurrence of the disease and the pathway to care, which is largely unexplored and a threat to achieving the target.

METHODS

Data from 6081 suspected VL patients who reported being clinically diagnosed during 2012-2013 across eight districts in Bihar were analysed. Graphical comparisons and Chi-square tests were used to determine differences in the burden of identified cases by season, district, age and sex. Log-linear regression models were fitted to onset (of symptoms)-to-diagnosis and onset-to-treatment waiting times to estimate their associations with age, sex, district and various socio-economic factors (SEFs). Logistic regression models were used to identify factors associated with mortality.

RESULTS

Comparisons of VL caseloads suggested an annual cycle peaking in January-March. A 17-fold variation in the burden of identified cases across districts and under-representation of young children (0-5 years) relative to age-specific populations in Bihar were observed. Women accounted for a significantly lower proportion of the reported cases than men (41 vs 59%, P < 0.0001). Age, district of residence, house wall materials, caste, treatment cost, travelling for diagnosis and the number of treatments for symptoms before diagnosis were identified as correlates of waiting times. Mortality was associated with age, district of residence, onset-to-treatment waiting time, treatment duration, cattle ownership and cost of diagnosis.

CONCLUSIONS

The distribution of VL in Bihar is highly heterogeneous, and reported caseloads and associated mortality vary significantly across different districts, posing different challenges to the elimination campaign. Socio-economic factors are important correlates of these differences, suggesting that elimination will require tailoring to population and sub-population circumstances.

The genome of Leishmania adleri from a mammalian host highlights chromosome fission in Sauroleishmania

Control of pathogens arising from humans, livestock and wild animals can be enhanced by genome-based investigation. Phylogenetically classifying and optimal construction of these genomes using short sequence reads are key to this process. We examined the mammal-infecting unicellular parasite Leishmania adleri belonging to the lizard-infecting Sauroleishmania subgenus. L. adleri has been associated with cutaneous disease in humans, but can be asymptomatic in wild animals. We sequenced, assembled and investigated the L. adleri genome isolated from an asymptomatic Ethiopian rodent (MARV/ET/75/HO174) and verified it as L. adleri by comparison with other Sauroleishmania species. Chromosome-level scaffolding was achieved by combining reference-guided with de novo assembly followed by extensive improvement steps to produce a final draft genome with contiguity comparable with other references. L. tarentolae and L. major genome annotation was transferred and these gene models were manually verified and improved. This first high-quality draft Leishmania adleri reference genome is also the first Sauroleishmania genome from a non-reptilian host. Comparison of the L. adleri HO174 genome with those of L. tarentolae Parrot-TarII and lizard-infecting L. adleri RLAT/KE/1957/SKINK-7 showed extensive gene amplifications, pervasive aneuploidy, and fission of chromosomes 30 and 36. There was little genetic differentiation between L. adleri extracted from mammals and reptiles, highlighting challenges for leishmaniasis surveillance.

Visceral Leishmaniasis in Southeastern Iran: A Narrative Review

BACKGROUND

Visceral leishmaniasis (VL) has strong links with poverty, substantial medical and veterinary impacts. This review aimed to focus in studies published during 1994-2016 on VL in southeastern Iran.

METHODS

The present review is based on expert knowledge and historical studies published during the past 23 yr (1994-2016) on VL in southeastern Iran. In addition, related literature found in PubMed by using the keywords such as visceral leishmaniasis, kala-azar, and Leishmania infantum are included.

RESULTS

Overall, 118 children aged 4.2 yr were detected as infected with human VL (HVL). The majority of the cases were from Orzoieh district (37.1%) in southwest of Kerman Province, followed by Sirjan (15.7%), Jiroft (14.8%), Kahnuj (9.3%) and to lesser extent from other areas. The male to female ratio was 1.7. The three most frequent clinical features were represented by fever (100.0%), anemia (95.0%) and splenomegaly (91.5%). Altogether, 42.0% of the VL cases developed secondary bacterial infections, the overall case-fatality rate was 3.4%, and majorities (88.0%) of the VL patients were undernourished. Overall, 733 dogs and wild canines were examined by different techniques with various seroprevalence ranges.

CONCLUSION

In southeastern Iran, VL is endemic in Orzoieh district in Kerman Province. While the dogs are implicated as the main domestic reservoir of VL, wide range of wild canines can serve as a secondary potential reservoir host.

Epidemiologic Correlates of Mortality among Symptomatic Visceral Leishmaniasis Cases: Findings from Situation Assessment in High Endemic Foci in India

Background

Visceral leishmaniasis (VL) is highly prevalent in the Indian state of Bihar and, without proper diagnosis and treatment, is associated with high fatality. However, lack of efficient reporting mechanism had been an impediment in estimating the burden of mortality and its antecedents among symptomatic VL cases. The objectives of the current study were to generate a reliable estimate of symptomatic VL caseload and mortality in Bihar, as well as to identify the epidemiologic and health infrastructure-related predictors of VL mortality.

Methodology and Principal Findings

Using an elaborate index case tracing method, we attempted to locate all symptomatic VL patients in eight districts of Bihar. Interviews and medical-record-reviews were conducted with cases (or next-of-kin for the dead) meeting the eligibility criteria. The information collected during the interviews included socio-demographic characteristics, onset of disease symptoms, place of diagnosis, pre- and post-diagnosis treatment history, type and duration of drugs received. In total, we analyzed data on 4925 VL patients—59% were male and 68% were less than 30 years old. There were 158 (3.2%) deaths and the incidence rate of mortality was 3.2/100 person-years. In the adjusted Cox-proportional-hazards analysis, treatment at public facility [Adjusted Hazard Ratio (AHR) = 0.61; 95% CI = 0.43–0.86], shorter (≤30 days) diagnostic delay [AHR = 0.62, 95% CI = 0.43–0.92], and treatment completion [AHR = 0.03, 95% CI = 0.02–0.05] emerged as significant negative predictors of mortality.

Conclusion

Mortality reduction efforts in Bihar should focus on improving access to early diagnosis, quality treatment and treatment-adherence measures, with special emphasis on marginalized communities.

More than 70% cases of visceral leishmaniasis (VL), a parasitic disease transmitted by sand flies, in India are reported from Bihar, a resource-poor state. In absence of early diagnosis and treatment, the fatality is very high among symptomatic VL cases. However, community-based data on VL mortality is limited in Bihar. Also, little information on the factors associated with mortality among symptomatic VL patients is available from this Indian state. Evidences regarding mortality parameters can prove immensely helpful in designing specific interventions targeted at reduction of such mortality. In the current study, we created a registry of symptomatic VL cases in eight districts of Bihar to estimate the burden of VL mortality and the socio-demographic factors associated with it. The mortality rate among the symptomatic VL patients was found to be fairly high. Shorter interval between onset of symptoms and diagnosis, and completing course of treatment were associated with increased survival. We recommend improving access to early diagnosis and treatment services, especially among the marginalized communities, as a key measure to reduce mortality among symptomatic VL patients in Bihar.

Snowball Vs. House-to-House Technique for Measuring Annual Incidence of Kala-azar in the Higher Endemic Blocks of Bihar, India: A Comparison

Background

Visceral Leishmaniasis, commonly known as kala-azar, is widely prevalent in Bihar. The National Kala-azar Control Program has applied house-to-house survey approach several times for estimating Kala-azar incidence in the past. However, this approach includes huge logistics and operational cost, as occurrence of kala-azar is clustered in nature. The present study aims to compare efficiency, cost and feasibility of snowball sampling approach to house-to-house survey approach in capturing kala-azar cases in two endemic districts of Bihar, India.

Methodology/Principal findings

A community based cross-sectional study was conducted in two highly endemic Primary Health Centre (PHC) areas, each from two endemic districts of Bihar, India. Snowball technique (used to locate potential subjects with help of key informants where subjects are hard to locate) and house-to-house survey technique were applied to detect all the new cases of Kala-azar during a defined reference period of one year i.e. June, 2010 to May, 2011. The study covered a total of 105,035 households with 537,153 populations. Out of total 561 cases and 17 deaths probably due to kala-azar, identified by the study, snowball sampling approach captured only 221 cases and 13 deaths, whereas 489 cases and 17 deaths were detected by house-to-house survey approach. Higher value of McNemar’s χ² statistics (64; p<0.0001) for house-to-house survey approach than snowball sampling and relative difference (>1) indicates that most of the kala-azar cases missed by snowball sampling were captured by house-to-house approach with 13% of omission.

Conclusion/Significance

Snowball sampling was not found sensitive enough as it captured only about 50% of VL cases. However, it captured about 77% of the deaths probably due to kala-azar and was found more cost-effective than house-to-house approach. Standardization of snowball approach with improved procedure, training and logistics may enhance the sensitivity of snowball sampling and its application in national Kala-azar elimination programme as cost-effective approach for estimation of kala-azar burden.

Visceral Leishmaniasis, commonly known as kala-azar, is one of the major health concerns for Bihar state in India. Time to time estimation of kala-azar incidence plays a pivotal role in defining and evaluating control strategies under National Kala-azar Elimination programme. The house-to-house survey approach, adopted several times for estimation of kala-azar incidence, requires huge logistics and operational cost as occurrence of kala-azar is clustered in nature. Snowball sampling approach is used to locate potential subjects with help of key informants where subjects are hard to locate. This is the first ever comparative study to assess efficacy, cost and feasibility of snowball sampling approach to house-to-house survey in capturing kala-azar cases. Snowball sampling was found cost-effective, but not sensitive enough as it captured about 50% of kala-azar cases. It captured deaths possibly due to kala-azar more efficiently (77%). However, standardization of snowball approach with improved procedure, training, logistics, etc. may enhance the sensitivity of snowball sampling and its application in national Kala-azar elimination programme as cost-effective approach for estimation of kala-azar burden.

Transmission Dynamics of Visceral Leishmaniasis in the Indian Subcontinent - A Systematic Literature Review

Background

As Bangladesh, India and Nepal progress towards visceral leishmaniasis (VL) elimination, it is important to understand the role of asymptomatic Leishmania infection (ALI), VL treatment relapse and post kala-azar dermal leishmaniasis (PKDL) in transmission.

Methodology/ Principal Finding

We reviewed evidence systematically on ALI, relapse and PKDL. We searched multiple databases to include studies on burden, risk factors, biomarkers, natural history, and infectiveness of ALI, PKDL and relapse. After screening 292 papers, 98 were included covering the years 1942 through 2016. ALI, PKDL and relapse studies lacked a reference standard and appropriate biomarker. The prevalence of ALI was 4–17-fold that of VL. The risk of ALI was higher in VL case contacts. Most infections remained asymptomatic or resolved spontaneously. The proportion of ALI that progressed to VL disease within a year was 1.5–23%, and was higher amongst those with high antibody titres. The natural history of PKDL showed variability; 3.8–28.6% had no past history of VL treatment. The infectiveness of PKDL was 32–53%. The risk of VL relapse was higher with HIV co-infection. Modelling studies predicted a range of scenarios. One model predicted VL elimination was unlikely in the long term with early diagnosis. Another model estimated that ALI contributed to 82% of the overall transmission, VL to 10% and PKDL to 8%. Another model predicted that VL cases were the main driver for transmission. Different models predicted VL elimination if the sandfly density was reduced by 67% by killing the sandfly or by 79% by reducing their breeding sites, or with 4–6y of optimal IRS or 10y of sub-optimal IRS and only in low endemic setting.

Conclusion/ Significance

There is a need for xenodiagnostic and longitudinal studies to understand the potential of ALI and PKDL as reservoirs of infection.

The role of asymptomatic Leishmania infection (ALI), PKDL and VL relapse in transmission is unclear as VL elimination is achieved in the Indian subcontinent. ALI, PKDL and relapse studies lacked a reference standard and appropriate biomarker. ALI was 4–17-fold more prevalent than VL. The risk of ALI was higher in VL case contacts. Most infections remained asymptomatic or resolved spontaneously. The natural history of PKDL showed variability. Twenty nine percent had no past history of VL treatment. The risk of VL relapse was higher with HIV co-infection. Modelling studies predicted different effects. Early diagnosis was unlikely to eliminate VL in the long term. ALI was predicted to contribute to 82% of the overall transmission, VL to 10% and PKDL to 8%. Another model predicted that VL cases were the main driver for transmission. VL elimination was predicted if the sandfly density was reduced by 67% by killing the sandfly or by 79% by reducing their breeding sites, or with 4–6y of optimal IRS or 10y of sub-optimal IRS and only in low endemic setting. There is a need for more studies to fully understand the potential of ALI and PKDL as reservoirs of infection.

Social and Economic Burden of Human Leishmaniasis

Leishmaniasis continues to pose a major public health problem worldwide. With new epidemics occurring in endemic areas and the spread of the disease to previously free areas because of migration, tourism, and military activities, there is a great need for the development of an effective vaccine. Leishmaniasis is a disease of the poor, occurring mostly in remote rural villages with poor housing and little or no access to modern health-care facilities. In endemic areas, diagnosis of any form of leishmaniasis puts a huge financial strain on an already meagre financial resource at both the individual and community levels. Most often families need to sell their assets (land and livestock) or take loans from informal financial outfits with heavy interest rates to pay for the diagnosis and treatment of leishmaniasis. Here, we discuss the disease with special emphasis on its socioeconomic impact on the affected individual and community. In addition, we highlight the reasons why continued research aimed at developing an effective Leishmania vaccine is necessary.

Quantification of the natural history of visceral leishmaniasis and consequences for control

Background

Visceral leishmaniasis has been targeted for elimination as a public health problem (less than 1 case per 10,000 people per year) in the Indian sub-continent by 2017. However, there is still a high degree of uncertainty about the natural history of the disease, in particular about the duration of asymptomatic infection and the proportion of asymptomatically infected individuals that develop clinical visceral leishmaniasis. Quantifying these aspects of the disease is key for guiding efforts to eliminate visceral leishmaniasis and maintaining elimination once it is reached.

Methods

Data from a detailed epidemiological study in Bangladesh in 2002–2004 was analysed to estimate key epidemiological parameters. The role of diagnostics in determining the probability and rate of progression to clinical disease was estimated by fitting Cox proportional hazards models. A multi-state Markov model of the natural history of visceral leishmaniasis was fitted to the data to estimate the asymptomatic infection period and the proportion of asymptomatic individuals going on to develop clinical symptoms.

Results

At the time of the study, individuals were taking several months to be diagnosed with visceral leishmaniasis, leading to many opportunities for ongoing transmission. The probability of progression to clinical disease was strongly associated with initial seropositivity and even more strongly with seroconversion, with most clinical symptoms developing within a year. The estimated average durations of asymptomatic infection and symptomatic infection for our model of the natural history are 147 days (95 % CI 130–166) and 140 days (95 % CI 123–160), respectively, and are significantly longer than previously reported estimates. We estimate from the data that 14.7 % (95 % CI 12.6-20.0 %) of asymptomatic individuals develop clinical symptoms—a greater proportion than previously estimated.

Conclusions

Extended periods of asymptomatic infection could be important for visceral leishmaniasis transmission, but this depends critically on the relative infectivity of asymptomatic and symptomatic individuals to sandflies. These estimates could be informed by similar analysis of other datasets. Our results highlight the importance of reducing times from onset of symptoms to diagnosis and treatment to reduce opportunities for transmission.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1136-3) contains supplementary material, which is available to authorized users.

DDT-based indoor residual spraying suboptimal for visceral leishmaniasis elimination in India

Indoor residual spraying (IRS) is used to control visceral leishmaniasis (VL) in India, but it is poorly quality assured. Quality assurance was performed in eight VL endemic districts in Bihar State, India, in 2014. Residual dichlorodiphenyltrichloroethane (DDT) was sampled from walls using Bostik tape discs, and DDT concentrations [grams of active ingredient per square meter (g ai/m(2))] were determined using HPLC. Pre-IRS surveys were performed in three districts, and post-IRS surveys were performed in eight districts. A 20% threshold above and below the target spray of 1.0 g ai/m(2) was defined as "in range." The entomological assessments were made in four districts in IRS and non-IRS villages. Vector densities were measured: pre-IRS and 1 and 3 mo post-IRS. Insecticide susceptibility to 4% DDT and 0.05% deltamethrin WHO-impregnated papers was determined with wild-caught sand flies. The majority (329 of 360, 91.3%) of pre-IRS samples had residual DDT concentrations of <0.1 g ai/m(2). The mean residual concentration of DDT post-IRS was 0.37 g ai/m(2); 84.9% of walls were undersprayed, 7.4% were sprayed in range, and 7.6% were oversprayed. The abundance of sand flies in IRS and non-IRS villages was significantly different at 1 mo post-IRS only. Sand flies were highly resistant to DDT but susceptible to deltamethrin. The Stockholm Convention, ratified by India in 2006, calls for the complete phasing out of DDT as soon as practical, with limited use in the interim where no viable IRS alternatives exist. Given the poor quality of the DDT-based IRS, ready availability of pyrethroids, and susceptibility profile of Indian sand flies, the continued use of DDT in this IRS program is questionable.

Performance of kala-azar surveillance in Gaffargaon subdistrict of Mymensingh, Bangladesh

Introduction

Elimination of kala-azar is planned for South Asia requiring good surveillance along with other strategies. We assessed surveillance in Gaffargaon upazila (a subdistrict of 13 unions) of Mymensingh district, Bangladesh highly endemic for kala-azar.

Methods

In 4703 randomly sampled households, within nine randomly sampled villages, drawn from three randomly sampled unions, we actively searched for kala-azar cases that had occurred between January 2010 and December 2011. We then searched for medical records of these cases in the patient registers of Gaffargaon upazila health complex (UHC). We investigated factors associated with the medical recording by interviewing the cases and their families. We also did a general observation of UHC recording systems and interviewed health staff responsible for the monthly reports of kala-azar cases.

Results

Our active case finding detected 58 cases, but 29 were not recorded in the Gaffargaon UHC. Thus, only 50% (95% CI: 37%–63%) of kala-azar cases were reported via the government passive surveillance system. Interviews with health staff based in the study UHC revealed the heavy reporting burden for multiple diseases, variation in staff experience, high demands on the staff time and considerable complexity in the recording system. After adjusting for kala-azar treatment drug, recording was found more likely for those aged 18 years or more, males, receiving supply and administration of drug at the UHC, and more recent treatment.

Discussion

Fifty percent of kala-azar cases occurring in one highly endemic area of Bangladesh were recorded in registers that were the source for monthly reports to the national surveillance system. Recording was influenced by patient, treatment, staff and system factors. Our findings have policy implications for the national surveillance system. Future studies involving larger samples and including interviews with health authorities at more central level and surveillance experts at the national level will generate more precise and representative evidence on the performance of kala-azar surveillance in Bangladesh.

Visceral leishmaniasis, a parasitic disease transmitted by sandflies, is known as kala-azar in South Asia, and has been targeted for elimination in that region. The aim is to reduce its incidence to a low level so that it is no longer a public health problem. Elimination strategies include good surveillance for occurrence of the disease. We assessed surveillance in Gaffargaon subdistrict of Mymensingh district in Bangladesh where occurrence of kala-azar is high. We randomly sampled 4703 households and searched for kala-azar cases that had occurred between January 2010 and December 2011. We then searched for medical records of these cases in the patient registers of Gaffargaon upazila or subdistrict health complex (UHC). We interviewed cases, their families and health staff responsible for the monthly reports of kala-azar. We also observed the UHC recording system. We detected 58 cases, but 29 (50%) were not recorded in the Gaffargaon UHC. Problems include the heavy reporting burden for multiple diseases, variation in staff experience, high demands on the staff time and complexity in the recording system. Recording was more likely for adults, males, those given drugs at the UHC, and more recent treatment. Our findings have implications for kala-azar surveillance.

Recombinant NAD-dependent SIR-2 protein of Leishmania donovani: immunobiochemical characterization as a potential vaccine against visceral leishmaniasis

Background

The development of a vaccine conferring long-lasting immunity remains a challenge against visceral leishmaniasis (VL). Immunoproteomic characterization of Leishmania donovani proteins led to the identification of a novel protein NAD+-dependent Silent Information regulatory-2 (SIR2 family or sirtuin) protein (LdSir2RP) as one of the potent immunostimulatory proteins. Proteins of the SIR2 family are characterized by a conserved catalytic domain that exerts unique NAD-dependent deacetylase activity. In the present study, an immunobiochemical characterization of LdSir2RP and further evaluation of its immunogenicity and prophylactic potential was done to assess for its possible involvement as a vaccine candidate against leishmaniasis.

Methodology/Principal Findings

LdSir2RP was successfully cloned, expressed and purified. The gene was present as a monomeric protein of ~45 kDa and further established by the crosslinking experiment. rLdSir2RP shown cytosolic localization in L. donovani and demonstrating NAD+-dependent deacetylase activity. Bioinformatic analysis also confirmed that LdSir2RP protein has NAD binding domain. The rLdSir2RP was further assessed for its cellular response by lymphoproliferative assay and cytokine ELISA in cured Leishmania patients and hamsters (Mesocricetus auratus) in comparison to soluble Leishmania antigen and it was observed to stimulate the production of IFN-γ, IL-12 and TNF-α significantly but not the IL-4 and IL-10. The naïve hamsters when vaccinated with rLdSir2RP alongwith BCG resisted the L. donovani challenge to the tune of ~75% and generated strong IL-12 and IFN-γ mediated Th1 type immune response thereof. The efficacy was further supported by remarkable increase in IgG2 antibody level which is indicative of Th1 type of protective response. Further, with a possible implication in vaccine design against VL, identification of potential T-cell epitopes of rLdSir2RP was done using computational approach.

Conclusion/Significance

The immunobiochemical characterization strongly suggest the potential of rLdSir2RP as vaccine candidate against VL and supports the concept of its being effective T-cell stimulatory antigen.

Visceral Leishmaniasis (VL) is the most fatal form of leishmaniasis disease in Indian subcontinent. Through proteomic approaches, NAD-dependent Silent information regulator-2 was identified as one of the potent immunostimulatory proteins. Herein, it was first reported the cloning, expression, purification and immunobiochemical characterization of a NAD+-dependent protein from Leishmania donovani. The gene encodes a monomeric protein (LdSir2RP) of approximately 45 kDa and showed NAD+-dependent deacetylase activity. LdSir2RP was immunodetected in whole cell lysate of L. donovani and further it immunolocalized in cytoplasm of the Leishmania parasite. Recombinant protein rLdSir2RP shown immunogenicity in PBMCs of cured Leishmania patients and hamsters (Mesocricetus auratus). rLdSir2RP stimulated the production of IFN-γ, IL-12 and TNF-α but not IL-4 and IL-10. This was further supported by remarkable increase in IgG2 antibody level.

It was further demonstrated that rLdSir2RP was able to provide considerable protection to hamsters against L. donovani challenge. These results supported by the increased iNOS mRNA transcript and the specific Th1-type cytokines—IFN-γ, IL-12 and TNF-α and down-regulation of IL-4, IL-10 and TGF-β. Hence, it is inferred that rLdSir2RP confer significant protection against experimental VL and considered as potential vaccine targets against visceral leishmaniasis.

Leishmaniasis in the middle East: incidence and epidemiology

Leishmaniasis is a major health problem worldwide, with several countries reporting cases of leishmaniasis resulting in loss of human life or a lifelong stigma because of bodily scars. The Middle East is endemic for cutaneous leishmaniasis, with countries like Syria reporting very high incidence of the disease. Despite several countries establishing national control programs for containing the sandfly vector and treatment of infection, the disease continues to spread. In addition to the endemicity of the region for leishmaniasis, the Middle East has seen a great deal of human migration either for earning of livelihood or due to political upheaval in the region. These factors contribute to the spread and proliferation of the causative species Leishmania and its sandfly host. This review discusses the current epidemiological scenario in Iraq, Syria, Saudi Arabia, and Jordan, emphasizing the number of cases reported, vector species, Leishmania species, and treatment available. The data is primarily from WHO reports for each country and current and old literature.

Asymptomatic Leishmania infections in northern India: a threat for the elimination programme?

Visceral leishmaniasis (VL) continues to embody as a mammoth public health problem and hurdle to the socioeconomic development of Bihar, India. Interestingly, all leishmanial infections do not lead to overt clinical disease and may stay asymptomatic for a period of time. Asymptomatic cases of VL are considered as probable potential reservoirs of VL, and thus can play a major role in transmission of the disease in highly endemic areas of Bihar, India. They outnumber the exact disease burden in endemic areas of this region, thus jeopardizing the goal of the elimination program that is due by 2015. This article discusses the potential risk factors, epidemiological markers of transmission and requirement of highly sensitive diagnostic tools for efficient recognition of the high risk groups of conversion to symptomatic for proper designing of strategies for implementation of the control programs.

Nucleosomal histone proteins of L. donovani: a combination of recombinant H2A, H2B, H3 and H4 proteins were highly immunogenic and offered optimum prophylactic efficacy against Leishmania challenge in hamsters

The present study includes cloning and expression of recombinant Leishmania donovani histone proteins (rLdH2B, rLdH3, rLdH2A and rLdH4), assessment of their immunogenicity in Leishmania infected cured patients/endemic contacts as well as in cured hamsters and finally evaluation of their prophylactic efficacy in hamsters against L. donovani challenge. All recombinant proteins were expressed and purified from the heterologous bacterial host system. Leishmania infected cured patients/endemic contacts as well as cured hamsters exhibited significantly higher proliferative responses to individual recombinant histones and their pooled combination (rLdH2B+rLdH3+rLdH2A+rLdH4) than those of L.donovani infected hosts. The L.donovani soluble antigens (SLD) stimulated PBMCs of cured/exposed and Leishmania patients to produce a mixed Thl/Th2-type cytokine profile, whereas rLdH2B, rLdH3, rLdH2A, rLdH4 and pooled combination (rLdH2-4) stimulated the production of Th1 cytokines IFN-γ, IL-12 and TNF-α but not Th2 cytokines IL-4 or IL-10. The immunogenicity of these histone proteins along with their combination was also checked in cured hamsters where they stimulated higher lymphoproliferation and Nitric oxide production in lymphocytes of cured hamsters than that of infected controls. Moreover, significantly increased IgG2 response, an indicative of cell mediated immunity, was observed in cured hamsters against these individual proteins and their combination as compared to infected hamsters. Further, it was demonstrated that rLdH2B, rLdH3, rLdH2A and rLdH4 and pooled combination were able to provide considerable protection for hamsters against L. donovani challenge. The efficacy was supported by the increased inducible Nitric Oxide Synthase (iNOS) mRNA transcripts and Th1-type cytokines--IFN-γ, IL-12 and TNF-α and down-regulation of IL-4, IL-10 and TGF-β. Hence, it is inferred that pooled rLdH2-4 elicits Thl-type of immune responses exclusively and confer considerable protection against experimental Visceral Leishmaniasis.

Five-year field results and long-term effectiveness of 20 mg/kg liposomal amphotericin B (Ambisome) for visceral leishmaniasis in Bihar, India

Background

Visceral Leishmaniasis (VL; also known as Kala-azar) is an ultimately fatal disease endemic in Bihar. A 2007 observational cohort study in Bihar of 251 patients with VL treated with 20 mg/Kg intravenous liposomal amphotericin B (Ambisome) demonstrated a 98% cure rate at 6-months. Between July 2007 and August 2012, Médecins Sans Frontières (MSF) and the Rajendra Memorial Research Institute (RMRI) implemented a VL treatment project in Bihar, India—an area highly endemic for Leishmania donovani—using this regimen as first-line treatment.

Methods and Principal Findings

Intravenous Ambisome 20 mg/kg was administered in four doses of 5 mg/kg over 4–10 days, depending on the severity of disease. Initial clinical cure at discharge was defined as improved symptoms, cessation of fever, and recession of spleen enlargement. This observational retrospective cohort study describes 8749 patients with laboratory-confirmed primary VL treated over a 5-year period: 1396 at primary healthcare centers, 7189 at hospital, and 164 at treatment camps. Initial clinical cure was achieved in 99.3% of patients (8692/8749); 0.3% of patients (26/8749) defaulted from treatment and 0.4% (31/8749) died. Overall, 1.8% of patients (161/8749) were co-infected with HIV and 0.6% (51/8749) with tuberculosis. Treatment was discontinued because of severe allergic reactions in 0.1% of patients (7/8749). Overall, 27 patients (0.3%) were readmitted with post Kala-azar dermal leishmaniasis (PKDL). Risk factors for late presentation included female sex, age >15 years and being from a scheduled caste.

In 2012, a long-term efficacy survey in the same area of Bihar determined relapse rates of VL after 5 years' intervention with Ambisome. Of 984 immunocompetent patients discharged between September 2010 and December 2011, 827 (84.0%) were traced in order to determine their long-term outcomes. Of these, 20 patients (2.4%) had relapsed or received further treatment for VL. Of those completing 6, 12, and 15 month follow-up, 0.3% (2/767), 3.7% (14/383), and 2.4% (4/164), respectively, had relapsed. The mean ±SD time-to-relapse was 9.6±3.0 months.

Significance

This is the largest cohort of VL patients treated with 20 mg/kg Ambisome worldwide. The drug has high initial and long-term efficacy, and a low rate of adverse reactions when administered under field conditions in Bihar, India. Although challenging, its use as first line treatment in rural settings in Bihar is safe and feasible.

Visceral leishmaniasis (VL), also known as Kala-azar, is a protozoan parasitic disease transmitted by phlebotomine sandflies. After malaria, VL accounts for the second-highest burden of parasitic diseases worldwide. India has half of all the VL patients worldwide, of which up to 90% are in Bihar state. Between 2007–2012, Médecins Sans Frontières (MSF) together with the Rajendra Memorial Research Institute (RMRI) supported existing health structures in Vaishali district, Bihar, by treating 8749 VL patients with intravenous liposomal amphotericin B (Ambisome) 20 mg/kg. Initial cure rate was high, with low default and mortality rates. We describe the demographic and clinical characteristics of this large patient group, including risk factors for late presentation. Ambisome can be given in short courses and is safer, better tolerated, and more effective than existing VL treatments. The MSF-supported program treated nearly 1400 ambulatory patients in rural primary healthcare centers, using existing government facilities and non-incentivized staff, demonstrating that a resource-limited healthcare system in a rural setting can meet the cold chain and human resource standards required to administer Ambisome safely. We also describe a long-term follow-up survey showing a continuing low VL relapse rate after 5 years of routine use of Ambisome. More relapses occurred after 6-month follow-up; suggesting a 12-month follow-up in future VL studies may be more appropriate.

Socioeconomic inequalities in non-communicable diseases prevalence in India: disparities between self-reported diagnoses and standardized measures

BACKGROUND

Whether non-communicable diseases (NCDs) are diseases of poverty or affluence in low-and-middle income countries has been vigorously debated. Most analyses of NCDs have used self-reported data, which is biased by differential access to healthcare services between groups of different socioeconomic status (SES). We sought to compare self-reported diagnoses versus standardised measures of NCD prevalence across SES groups in India.

METHODS

We calculated age-adjusted prevalence rates of common NCDs from the Study on Global Ageing and Adult Health, a nationally representative cross-sectional survey. We compared self-reported diagnoses to standardized measures of disease for five NCDs. We calculated wealth-related and education-related disparities in NCD prevalence by calculating concentration index (C), which ranges from -1 to +1 (concentration of disease among lower and higher SES groups, respectively).

FINDINGS

NCD prevalence was higher (range 5.2 to 19.1%) for standardised measures than self-reported diagnoses (range 3.1 to 9.4%). Several NCDs were particularly concentrated among higher SES groups according to self-reported diagnoses (Csrd) but were concentrated either among lower SES groups or showed no strong socioeconomic gradient using standardized measures (Csm): age-standardised wealth-related C: angina Csrd 0.02 vs. Csm -0.17; asthma and lung diseases Csrd -0.05 vs. Csm -0.04 (age-standardised education-related Csrd 0.04 vs. Csm -0.05); vision problems Csrd 0.07 vs. Csm -0.05; depression Csrd 0.07 vs. Csm -0.13. Indicating similar trends of standardized measures detecting more cases among low SES, concentration of hypertension declined among higher SES (Csrd 0.19 vs. Csm 0.03).

CONCLUSIONS

The socio-economic patterning of NCD prevalence differs markedly when assessed by standardized criteria versus self-reported diagnoses. NCDs in India are not necessarily diseases of affluence but also of poverty, indicating likely under-diagnosis and under-reporting of diseases among the poor. Standardized measures should be used, wherever feasible, to estimate the true prevalence of NCDs.

The household costs of visceral leishmaniasis care in south-eastern Nepal

Background and objectives

Visceral leishmaniasis (VL) is an important public health problem in south-eastern Nepal affecting very poor rural communities. Since 2005, Nepal is involved in a regional initiative to eliminate VL. This study assessed the economic impact of VL on households and examined whether the intensified VL control efforts induced by the government resulted in a decrease in household costs.

Methods

Between August and September 2010, a household survey was conducted among 168 patients that had been treated for VL within 12 months prior to the survey in five districts in south-eastern Nepal. We collected data on health-seeking behaviour, direct and indirect costs and coping strategies.

Results

The median total cost of one episode of VL was US$ 165 or 11% of annual household income. The median delay between the onset of symptoms and presentation to a qualified provider was 25 days. Once the patient presented to a qualified provider, the delay to correct diagnosis was minimal (median 3 days). Direct and indirect costs (income losses) represented 47% and 53% of total costs respectively. Households used multiple strategies to cope with the cost of illness, mainly mobilizing cash/savings (71%) or taking a loan (56%).

Conclusions

The provision of free VL diagnosis and drugs by the Nepalese control programme has been an important policy measure to reduce the cost of VL to households. But despite the free VL drugs, the economic burden is still important for households. More effort should be put into reducing indirect costs, in particular the length of treatment, and preventing the transmission of VL through vector control.

Visceral leishmaniasis (VL) is a parasitic disease and is fatal if untreated. VL mainly affects poor populations in rural areas and has important socio-economic consequences to the household because of high expenditures to access treatment and coping strategies to cover the costs of care. Since 2005, the government of Nepal has been engaged in a regional collaborative effort to eliminate VL from the Indian subcontinent. In this study we examined the economic burden of VL from the perspective of the household after the intensified implementation of VL control activities. Our findings indicate that the economic burden of VL as a percent of household income has decreased compared to studies conducted prior to the implementation of the VL elimination initiative in Nepal. In particular, the free provision of diagnosis and drugs at public health facilities has been an important policy measure. However, the economic impact of VL is still considerable and efforts are needed to further reduce the burden of VL to affected households or prevent the transmission of VL.

Identification and functional characterization of Leishmania donovani secretory peroxidase: delineating its role in NRAMP1 regulation

Leishmania silently evades host immune system and establish in the hostile environment of host macrophage phagolysosomes. For differentiation, growth and division parasite acquires divalent cations especially iron from the host nutritive pool. Natural resistance associated with macrophage protein1 (NRAMP1), a cation transporter that effluxes out divalent cations specifically iron from phagosomal milieu to the cytosol, to create ions deprived status for pathogenic microorganisms. The mechanisms of NRAMP1 regulation are largely unknown in leishmanial infections. In the present study, we identified a secretory Leishmania donovani peroxidase (Prx) that showed peroxidoxin like peroxidase activity and significantly reduced H₂O₂, O₂.⁻ and NO levels in LPS activated macrophages. Further, we also observed down regulated Nramp1 expression and concomitantly declined labile iron pool in activated macrophages treated with identified peroxidase. Prx also decreased levels of TNF-α, IFN-γ and IL-12 in LPS activated macrophages. These observations indicate a bifunctional protective role of secretory Prx; first it reduces redox activation of macrophages, and secondly it allows iron access to Leishmania by down regulating NRAMP1 expression.

Leishmaniasis worldwide and global estimates of its incidence

As part of a World Health Organization-led effort to update the empirical evidence base for the leishmaniases, national experts provided leishmaniasis case data for the last 5 years and information regarding treatment and control in their respective countries and a comprehensive literature review was conducted covering publications on leishmaniasis in 98 countries and three territories (see ‘Leishmaniasis Country Profiles Text S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50, S51, S52, S53, S54, S55, S56, S57, S58, S59, S60, S61, S62, S63, S64, S65, S66, S67, S68, S69, S70, S71, S72, S73, S74, S75, S76, S77, S78, S79, S80, S81, S82, S83, S84, S85, S86, S87, S88, S89, S90, S91, S92, S93, S94, S95, S96, S97, S98, S99, S100, S101’). Additional information was collated during meetings conducted at WHO regional level between 2007 and 2011. Two questionnaires regarding epidemiology and drug access were completed by experts and national program managers. Visceral and cutaneous leishmaniasis incidence ranges were estimated by country and epidemiological region based on reported incidence, underreporting rates if available, and the judgment of national and international experts. Based on these estimates, approximately 0.2 to 0.4 cases and 0.7 to 1.2 million VL and CL cases, respectively, occur each year. More than 90% of global VL cases occur in six countries: India, Bangladesh, Sudan, South Sudan, Ethiopia and Brazil. Cutaneous leishmaniasis is more widely distributed, with about one-third of cases occurring in each of three epidemiological regions, the Americas, the Mediterranean basin, and western Asia from the Middle East to Central Asia. The ten countries with the highest estimated case counts, Afghanistan, Algeria, Colombia, Brazil, Iran, Syria, Ethiopia, North Sudan, Costa Rica and Peru, together account for 70 to 75% of global estimated CL incidence. Mortality data were extremely sparse and generally represent hospital-based deaths only. Using an overall case-fatality rate of 10%, we reach a tentative estimate of 20,000 to 40,000 leishmaniasis deaths per year. Although the information is very poor in a number of countries, this is the first in-depth exercise to better estimate the real impact of leishmaniasis. These data should help to define control strategies and reinforce leishmaniasis advocacy.