Risk factors of visceral leishmaniasis: a case control study in north-western Ethiopia

Prevalence of asymptomatic Leishmania donovani infection and associated factors in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Visceral leishmaniasis is endemic in Ethiopia and caused by Leishmania donovani. Although the disease manifests with significant clinical variability, a substantial number of individuals are asymptomatic. These individuals can serve as reservoirs, complicating control efforts. However, comprehensive data on asymptomatic L. donovani infections in Ethiopia are lacking, highlighting the need for a systematic review and meta-analysis to consolidate evidence and understand the distribution and determinants of this infection.

METHODS

PRISMA guidelines followed and registered with PROSPERO (CRD42024531454). Systematically searched electronic databases and grey literature sources up to April 13, 2024. Original research articles in English considered. Statistical analyses performed using STATA version 16. Publication bias evaluated using funnel plots and Egger's regression tests. Pooled estimate of asymptomatic L. donovani infection derived using a random effects model. Study heterogeneity assessed using Chi-square (χ²)-based Q test (p < 0.1) and I² subgroup analysis and meta-regression conducted with significance set at p < 0.05.

RESULT

A total of 1,288 articles were identified, with 11 studies met inclusion criteria. These studies, published between 2012 and 2024, reported data from 17 districts across six regions. Sample sizes ranged from 185 to 1,682, with a total of 7,288. Six types of laboratory testing methods were employed. Prevalence of asymptomatic L. donovani infection per individual study ranged from 0.9 to 15.8%, while district-level prevalence varied from 0 to 31.1%. The overall pooled estimate of asymptomatic L. donovani infection in Ethiopia was 9.0% (95% CI: 6.0-11.0%). The pooled estimate in the Amhara region was 9.0% (95% CI: 8.0-11.0%), compared to 7.0% (95% CI: 3.0-12.0%) in other regions. Living in a household with domestic animals (OR: 2.54; 95% CI: 1.43-3.64) and being male (OR: 2.22; 95% CI: 1.21-3.23) were significantly associated with higher asymptomatic L. donovani infection.

CONCLUSION

A considerable number of asymptomatic L. donovani infections were reported in Ethiopia. Close contact with domestic animals and being male were identified as significant risk factors. Regular screening of people living in close contact with animals. This will minimize role of man as reservoir host of asymptomatic L. donovani infection VL and hence aid in disease control and management.

Serological and molecular analysis of Leishmania infection in a recent outbreak of visceral leishmaniasis in South Omo Zone, Ethiopia

BACKGROUND

Ethiopia has a high burden of visceral leishmaniasis. Recently, there was a significant increase in cases in the South Omo Zone. This study aims to assess the prevalence of Leishmania donovani infection and its associated factors.

METHODS

A household-based cross-sectional study was carried out in January 2023 in the South Omo Zone in Ethiopia. Dried blood spot samples were collected from 382 randomly selected study participants. Direct agglutination test (DAT) and kinetoplast DNA real-time PCR tests were performed to detect L. donovani infection. Participants' sociodemographic, clinical and risk factors for L. donovani infection data were collected using questionnaires. Bivariate and multivariate logistic regressions were used to analyze the data. Febrile cases were checked for malaria with a multiplex PCR assay.

RESULTS

Overall prevalence of L. donovani infection among the sampled population was 32.5% (n=124), of which 41.1% (n=51) was detected by PCR, 33.9% (n=42) by DAT and 25.0% (n=31) by both tests. The majority of the positives were from the Logira (28.2%; n=35) and Dilbayne (29.0%; n=36) villages. Participants residing in Logira (adjusted OR [AOR]: 5.80; 95% CI 1.85 to 18.15) and Dilbayne (AOR: 3.38; 95% CI 1.15 to 9.96) villages and owning cows (AOR: 2.31; 95% CI 1.03 to 5.15) showed an association with Leishmania infection. Plasmodium falciparum was detected in 3.4% (n=2) of 59 febrile participants.

CONCLUSIONS

The prevalence of L. donovani infection in the South Omo Zone is high. Further research on the role of cows in the transmission cycle is needed to design the best strategy to control Leishmania infection in the South Omo Zone. Such interventions should focus on the Logira and Dilbayne villages, where most of the infections were identified.

Demographic and Clinical Features of Visceral Leishmaniasis in Chad: A Prospective Cross-Sectional Survey

Visceral leishmaniasis (VL), caused by the protozoan Leishmania donovani complex, is endemic in many parts of the world. Little known in Chad, VL has been recently documented from previously nonendemic areas. We report an epidemiological investigation of VL in the Léré district hospital in southwestern Chad. After informed consent, 40 VL patients were enrolled in the study. Diagnosis made using the formalin serological test was confirmed by polymerase chain reaction on blood samples. Clinical parameters were obtained from the physician or nurse caregiver, and from patients. Of a total of 40 serology positive patients, L. donovani DNA was found in 33 (82.5%), with 55% being male patients. The most affected age groups were 15-29 (47.5%) and 0-14 (32.5%) years. Fever, weight loss, and pallor were frequent symptoms. Notably, splenomegaly and hepatomegaly were uncommon clinical signs. Common comorbidities included malaria (25%) and hepatitis B (15%), followed by gastric ulcer (10%) and tuberculosis (7.5%). These comorbidities were concurrent with VL and were diagnosed microscopically in blood and serum for malaria and tuberculosis, respectively, and by the rapid diagnostic test using serum for hepatitis B and gastric ulcer. Thirty-five percent of cases were treated with meglumine antimoniate, and three patients (7.5%), all with comorbidities, died. Sixty percent of patients lived close to the main town. Our data demonstrate that VL is endemic in the health district of Léré. Improving health education regarding L. donovani infection in endemic areas of Chad and providing training of health workers on early detection and management of VL are needed to help save lives.

Determinants of Visceral Leishmaniasis in Addis Zemen Health Center, Northwest Ethiopia

Background: Visceral leishmaniasis (VL) is one of the public health issues in some areas of Ethiopia, and over 3.2 million people are at risk with an estimated 4000 new cases occurring each year in the country. This study was conducted to determine the prevalence of VL and its associated risk factors in Addis Zemen Health Center, Northwest Ethiopia. Methods: Data were collected from Addis Zemen Health Center and meteorological office in Addis Ababa from 2012 to 2016. Univariate and multivariate analyses were conducted to identify the determinants of VL. According to the result obtained from the retrospective data analysis, a total of 4100 suspected VL patients diagnosed by rk39 in Addis Zemen Health Center from Libokemkem and nearby districts. Results: The overall prevalence of VL among study participants were 30% (1230/4100). Of this, the prevalence of VL among male and female study participants was 86.8% and 13.2%, respectively. The proportion of sex infected by VL was 3.26 times higher in male than female (AOR = 3.26, 95% CI: 2.42-4.40). The risk of acquiring VL in those people living in rural area was 62% more likely than those residing in urban (AOR = 1.62, 95% CI: 1.29-2.04). People that were traveled to the endemic area of VL were 18.44 times more likely to be affected than the people who have not traveled once (AOR = : 18.44, 95% CI: 14.49-23.47). Age, sex, residence, season, travel history to endemic areas, and mean monthly precipitation were found to be statistically significant for VL at 5% significance level. Conclusion and Recommendation: The prevalence of VL in the present study was high with the highest prevalence in the rural areas. Therefore, there is a need of the immediate establishment of sound control and prevention program in rural areas.

Prevalence of human visceral leishmaniasis and its risk factors in Eastern Africa: a systematic review and meta-analysis

Introduction

Visceral Leishmaniasis, also known as kala-azar, is a potentially fatal, neglected tropical disease caused by the protozoan parasite Leishmania and transmitted through infected sandflies. It is one of the major global public health problems and contributors to economic crisis among people. Though different studies investigated human visceral leishmaniasis in Eastern Africa, the findings were inconsistent and inconclusive enough, and there is no representative data on this devastating public health concern. Therefore, this systematic review and meta-analysis aimed to determine the pooled prevalence and risk factors associated with human visceral leishmaniasis in Eastern Africa.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA 2020) guidelines were followed for this study. Databases such as PubMed/MEDLINE, CINAHL, LIVIVO, African Journals Online, African Index Medicus (AIM), HINARI, Science Direct, Web of Science, Cochrane Library, Google Scholar, Semantic Scholar, and Google were used to retrieve all the relevant articles. The search was carried out from 23 May 2024 to 17 July 2024. Data were analyzed using STATA 17 software to determine the pooled prevalence of human visceral leishmaniasis with a 95% confidence interval using a random-effects model.

Result

In this meta-analysis, thirty-nine articles with 40,367 study participants were included. The overall pooled prevalence of human visceral leishmaniasis in Eastern Africa was 26.16% [95%; CI: 19.96, 32.36%; I2 = 99.67%; p = 0.00]. Gender, age, family size, presence of termite hill/mound, presence of cattle/domestic animals, outdoor sleeping, presence of VL infected family member/s, and presence of water source/pathway near home were the risk factors significantly associated with human visceral leishmaniasis.

Conclusion

The recorded pooled prevalence of human visceral leishmaniasis in Eastern Africa underscores the urgent need for comprehensive intervention strategies. This includes rigorous health education for residents, covering the disease's cause, transmission, vector breeding sites, and prevention mechanisms.

Environmental Risk Factors for Visceral Leishmaniasis: An Analysis of Housing Types and Behavioral Factors in Baringo County, Kenya

Visceral leishmaniasis (VL) is endemic in Baringo County, Kenya, and contributes significantly to the burden of disease in the region. Housing structures and other environmental risk factors contribute to transmission dynamics, but these have not been specifically studied in Baringo. The aim of this study was to increase understanding of VL transmission in the region through determining relationships between VL infection, housing, and other environmental factors. Data collection occurred from February 1 to May 31, 2023 at Chemolingot Sub-County Hospital and patients' homesteads via questionnaires of primary VL patients being treated and VL follow-up patients who were still residing in the same house as when the infection occurred. Factors assessed were housing structures, proximity to vector breeding and resting sites, and prevention and control measure practices. A baseline assessment of housing types was conducted through direct ethnographic observation and used in the analysis. Forty-one patients were included in the study. A χ2 analysis and Fisher's test were used to determine association between VL infection and housing materials, where VL patient housing data were compared with the regional baseline assessment. Significant associations with VL infection were found between mud and stick walls (P <0.001); mud walls (P <0.001); mud, stick, and grass combination walls (P = 0.02); and stick and grass walls (P <0.001). Behavior comparison showed that most VL-protective behaviors were practiced by follow-up patients after infection. Results showed an increased need for VL prevention focusing on environmental factors.

A case-control study on risk factors for visceral leishmaniasis in West Pokot County, Kenya

BACKGROUND

Visceral leishmaniasis (VL) is a severe parasitic disease transmitted by phlebotomine sandflies. VL is endemic in West Pokot County, Kenya, where effective strategies to interrupt transmission are impeded by the limited understanding of VL risk factors. Therefore, this case-control study aimed to explore environmental, behavioural and household determinants of VL in West Pokot.

METHODS

From November 2022 to January 2023, a structured questionnaire was administered to 36 symptomatic primary VL cases attending Kacheliba Sub-County Hospital in West Pokot and to 50 healthy controls from local villages. The VL status of all participants was confirmed using an rK39 rapid diagnostic test. Associations between questioned determinants and VL were investigated by means of age-corrected univariate logistic regression analysis.

RESULTS

Significant associations were found between VL and housing characteristics, such as window presence and floor type. VL cases more frequently reported the presence of cattle, dogs and sheep in their house yards. VL was also associated with cutting down trees in the house yard and house proximity to several Acacia tree species. Furthermore, outdoor activities, including travelling outside the residence for more than 2 weeks, activities near termite mounds, and forest activities during the rainy season, increased the risk of VL.

CONCLUSIONS

This work reports a number of previously undescribed risk factors for VL in the understudied West Pokot focus. The results suggest VL transmission occurs both peri-domestically at night and outdoors during the day, particularly when sandfly resting sites are disturbed. Our findings warrant further research into sandfly ecology and potential zoonotic parasite reservoirs in West Pokot.

Sero-Prevalence of Visceral Leishmaniasis and Associated Risk Factors among Febrile Patients Attending Metema Hospital, West Gondar Zone, North West Ethiopia

INTRODUCTION

In Ethiopia, visceral leishmaniasis (VL) is a public health concern that has been spreading to new endemic foci in recent years. An estimated 3.2 million people are at risk of infection, with 3700-7400 new cases yearly. Thus, the study aimed to determine the prevalence of VL and associated risk factors among febrile patients attending Metema Hospital, North West Ethiopia.

METHODS

A hospital-based cross-sectional study was conducted on 404 febrile patients attending Metema Hospital from February 2021 to June 2021. The test for VL was done using an immune-chromatographic test (RK39) according to the manufacturer's instructions (InBios International Inc., USA). An interviewer-administered, pretested questionnaire was used to collect data on risk factors associated with VL. Logistic regression and Chi-square assessed the association between VL and the associated risk factors.

REULTS

The overall prevalence of visceral leishmaniasis was 18.8% (76/404), with a higher prevalence of VL in males, in the age category between 21 and 30, in study participants who completed elementary school, and in those who earned less than 500 birr monthly compared to their counterparts. Houses with thatched roofs (adjusted odd ratio (AOR) = 17.648, 95CI = 6.549,47.563), houses with mud walls (AOR = 2.538, 95% CI = 1.187-5.411), cattle ownership (AOR = 3.173, 95% CI = 1.286-7.826), dog ownership (AOR = 2,533, 95% CI = 1.256-5.111), presence of Acacia trees near houses (AOR = 1.975, 95% CI:1.004-3.886), presence of Balanites tree (AOR = 3.015, 95% CI = 1.610-5.992), and outdoor sleeping (AOR = 2.259, 95% CI: 1.107-14.607) were the predictors of VL in the present study.

CONCLUSIONS

In the study area, VL is still very common. Thus, preventing and controlling infection in the area is largely dependent on raising community awareness of VL prevention and control measures and implementing the necessary interventions on the determinants that have been identified.

Leishmaniases in Ethiopia: a scoping review protocol to determine the scope of research and remaining gaps

INTRODUCTION

The leishmaniases are among the group of neglected tropical diseases that cause significant morbidity and mortality each year. Currently, the East Africa region has the highest visceral leishmaniasis burden in the world. Ethiopia is one of the East African countries that reports both visceral and cutaneous forms of the disease. As part of the Nairobi Declaration, Ethiopia showed commitment to the elimination of visceral leishmaniasis by 2030. In this endeavour, it is important to understand the scope of research conducted on leishmaniases in the country and identify where the research gaps exist. Determining the research landscape is vital in the plan towards leishmaniases control and elimination. It will help to reference conducted research, determine if systematic reviews are warranted and help prioritise future research directions.

METHODS AND ANALYSIS

This protocol was developed with reference to the JBI Scoping Review Methodology Group's guidance on conducting scoping reviews and the PRISMA-ScR reporting guidelines for scoping reviews. The following databases will be searched: PubMed, Embase via Embase.com, Web of Science Core Collection, Cochrane CENTRAL, Global Index Medicus, ClinicalTrials.gov, the Pan African Clinical Trials Registry and PROSPERO. Locally published literature that may not be indexed in the above-mentioned systems will be identified through team members familiar with the setting. Each record will be dually and blindly reviewed in an abstract-title screen and full-text screen using inclusion-exclusion criteria. Included articles must contain an in-depth discussion of leishmaniasis in Ethiopia. Data extracted will consist of study themes, study types, and categories and subcategories each defined in the developed codebook, in addition to type of leishmania, year of publication, funding source and the number of citations. Results will be reported with summary statistics.

ETHICS AND DISSEMINATION

Individual consenting and ethical approvals are not applicable. We plan to disseminate our findings to the appropriate stakeholders.

Social Demographic Characteristics Associated with Visceral Leishmaniasis in West Pokot, Kenya

Visceral leishmaniasis is a tropical disease with a significant global public health burden. This study aimed to determine the social demographic characteristics associated with visceral leishmaniasis in West Pokot of Kenya. A mixed-methods research design was adopted where household questionnaires and key informant interviews were administered. Quantitative data was analyzed using SPSS version 22, and qualitative data were analyzed to establish patterns for interpretation. Male children aged 10 years or younger were the most infected by Leishmania donovani in the community. The hospital record indicated that 60% of previously treated visceral leishmaniasis patients were severely malnourished during admission. Risk factors associated with the disease included low formal education (adjusted odds ratio [aOR] = 4.39; 95% CI = 1.66-11.59; P <0.05), peasant farming (aOR = 8.49; 95% CI = 2.77-26.00; P <0.05), and dog ownership (aOR = 4.86; 95% CI = 1.87-12.60; P <0.05). Social demographic risk factors for visceral leishmaniasis remain a major public health concern in West Pokot.

Sero-prevalence of visceral leishmaniasis and its associated factors among asymptomatic individuals visiting Denan health center, southeastern Ethiopia

BACKGROUND

In the Somali region of Ethiopia, visceral leishmaniasis (VL) is a public health concern. However, VL epidemiology and sand fly vectors have not been well studied in various areas of the regional state, including Denan district. Therefore, this study was conducted to determine the sero-prevalence, associated factors, and distribution of sand fly vectors of VL in Denan district, south-eastern Ethiopia.

METHODS

A facility-based cross-sectional study was conducted from April to September 2021 among VL patients with classic signs and symptoms visiting Denan Health Center in south-eastern Ethiopia. Using a convenience sampling method, 187 blood samples were collected from individuals who visited Denan Health Center during the study period. Blood samples were subjected to Direct Agglutination Test for the detection of antibodies to VL. A pre-tested structured questionnaire was also used to gather information on risk factors and other characteristics of knowledge and attitude assessment. Sand flies were also collected from indoor, peri-domestic, mixed forest, and termite mounds using light and sticky traps to determine the fauna and abundance.

RESULTS

The overall sero-prevalence rate was 9.63% (18/187). The sero-prevalence was significantly associated with outdoor sleeping (OR = 2.82), the presence of damp floors (OR = 7.76), and sleeping outdoor near animals (OR = 3.22). Around 53.48% of the study participants had previously heard about VL. Study participants practiced different VL control methods, including bed nets (42%), insecticide spraying (32%), smoking plant parts (14%), and environmental cleaning (8%). In total, 823 sand fly specimens, comprising 12 species in two genera (Phlebotomus and Sergentomyia), were trapped and identified. The most abundant species was Sergentomyia clydei (50.18%), followed by Phlebotomus orientalis (11.42%). Also, a higher proportion of P. orientalis was found in termite mounds (65.43%), followed by mixed forest (37.8%) and peri-domestic (20.83%) habitats.

CONCLUSION

The study demonstrated a 9.63% sero-positivity of VL and a remarkable gap in knowledge, attitude, and practices towards VL. P. orientalis was also detected, which could be a probable vector in this area. Thus, public education should be prioritized to improve the community's awareness of VL and its public health impact. In addition, detailed epidemiological and entomological studies are recommended.

Establishment of an indicator framework for the transmission risk of the mountain-type zoonotic visceral leishmaniasis based on the Delphi-entropy weight method

BACKGROUND

Visceral leishmaniasis (VL) is one of the most important neglected tropical diseases. Although VL was controlled in several regions of China during the last century, the mountain-type zoonotic visceral leishmaniasis (MT-ZVL) has reemerged in the hilly areas of China in recent decades. The purpose of this study was to construct an indicator framework for assessing the risk of the MT-ZVL in China, and to provide guidance for preventing disease.

METHODS

Based on a literature review and expert interview, a 3-level indicator framework was initially established in November 2021, and 28 experts were selected to perform two rounds of consultation using the Delphi method. The comprehensive weight of the tertiary indicators was determined by the Delphi and the entropy weight methods.

RESULTS

Two rounds of Delphi consultation were conducted. Four primary indicators, 11 secondary indicators, and 35 tertiary indicators were identified. The Delphi-entropy weight method was performed to calculate the comprehensive weight of the tertiary indicators. The normalized weights of the primary indicators were 0.268, 0.261, 0.242, and 0.229, respectively, for biological factors, interventions, environmental factors, and social factors. The normalized weights of the top four secondary indicators were 0.122, 0.120, 0.098, and 0.096, respectively, for climatic features, geographical features, sandflies, and dogs. Among the tertiary indicators, the top four normalized comprehensive weights were the population density of sandflies (0.076), topography (0.057), the population density of dogs, including tethering (0.056), and use of bed nets or other protective measures (0.056).

CONCLUSIONS

An indicator framework of transmission risk assessment for MT-ZVL was established using the Delphi-entropy weight method. The framework provides a practical tool to evaluate transmission risk in endemic areas.

Seroprevalence of visceral leishmaniasis and its associated factors among asymptomatic pastoral community of Dire District, Borena zone, Oromia Region, Ethiopia

Visceral leishmaniasis (VL) is a vector-borne protozoan neglected tropical disease. In some parts of Ethiopia, it is a public health problem and its main causative agent is the Leishmania donovani complex. The objective of the study was to determine the seroprevalence of VL and factors associated among the asymptomatic pastoral community of Dire District, Borena Zone, Oromia Region, Ethiopia. A community-based study was conducted among 432 pastoralist communities from June to July 2021. A systematic random sampling method was used to select households. Pretested structured questionnaires and face-to-face interviews were used to collect data. A single finger-prick blood sample was collected and tested for Leishmania donovani complex using an immune-chromatographic test (rk39-ICT). A logistic regression model was used to assess factors associated with VL infection and a p-value of < 0.05 was considered statistically significant. A total of 432 study participants were included (their mean age was 26.69) and 218 (50.5%) were females. The overall seroprevalence of VL was 33/432(7.6%) (95%CI: 5.32-15.60). Sero-prevalence was significantly associated with high family size (>5) (adjusted odds ratios (AOR) = 5.134; 95% CI: 2.032-9.748), sleeping or/and staying under acacia tree (AOR = 2.984; 95%CI = 1.074-8.288), presence of cracked house walls (AOR = 1.801; 95%CI: 1.026-4.926), presence of termite hills (AOR = 1.938; 95%CL: 1.002-7.050), availability of water points (AOR = 3.893; 95%CI: 1.034-7.426) and presence of domestic animals (AOR = 2.124; 95% CI: 2.341-5.108). It is recommended that community awareness on the transmission and prevention methods of Leishmania donovani complex and taking appropriate interventions on the identified factors play a greater role to prevent and control infection in the area. Further investigation is also needed to characterize the pathogens and risk factors and tackle the problem.

Epidemiological and clinical characteristics of cutaneous leishmaniasis among patients attending at Tefera Hailu Memorial Hospital, Sekota, Northeast Ethiopia: A five-year trend analysis (2016-2020)

Objective

This study was designed to determine the epidemiological and clinical characteristics of cutaneous leishmaniasis among patients attending at Tefera Hailu Memorial Hospital, Sekota, Northeast Ethiopia over the last 5 years.

Methods

A 5-year retrospective study was conducted at Tefera Hailu Memorial Hospital, Northeast Ethiopia. Data were summarized and analysed using Microsoft Excel and SPSS 26 version software, respectively. To present the data and evaluate the patterns in cutaneous leishmaniasis cases across the 5 years, months, and seasons, descriptive statistics were utilized. In multivariable logistic regression analysis of determinants in relation to cutaneous leishmaniasis positivity, p-value less than 0.05 was considered as statistically significant.

Result

The overall positivity rate of cutaneous leishmaniasis was 31.1% (452 out of 1455) over the last 5 years at Tefera Hailu Memorial Hospital. The result showed a fluctuating yet declining trend in cutaneous leishmaniasis infections. The highest number of cases was registered in 2016, while the lowest was in 2020. Males and the age group of 15-49 years, accounted 78.5% and 79.9% of the patients, respectively, were the hardest hit by cutaneous leishmaniasis in the area. Similarly, the highest number of cases was observed in Dehana district (268). From all registered confirmed cases, 54 (10.7%) were previously treated cases. Moreover, the majority of cases, 423 (93.6%) were localized cutaneous leishmaniasis and most of the lesions were on the face.

Conclusion

Although the results indicate a fluctuating yet declining trend, the positivity rate of confirmed cutaneous leishmaniasis cases in the area remains alarming and indicates a major public health burden. Therefore, efforts are required to reduce the disease burden through continuous monitoring and evaluation of control measures in the study area.

Climate Change and Environmental Influence on Prevalence of Visceral Leishmaniasis in West Pokot County, Kenya

Kala-azar is a parasitic disease caused by Leishmania species transmitted by sand fly. In Kenya, kala-azar is endemic in thirty subcounties spread over in eleven counties in the arid zones. Climate change-influenced seasonal weather variability and environmental alterations remain important determinants of many vector-borne diseases. The present study focused on climate change and environmental influence on kala-azar in West Pokot. A descriptive cross-sectional and retrospective research design was adapted. Study area was purposively selected. Locations were randomly selected, and households were systematically selected. Three hundred sixty-three household questionnaires, eleven key informant interviews, and five focus group discussions were undertaken. Secondary data were obtained from Kacheliba subcounty hospital records. Statistical Package for the Social Sciences version 24 was used to analyze quantitative data while qualitative data were analyzed to establish connection for interpretation. Kala-azar cases have been on the rise on aggregate and surge towards the end of dry season and just after the rains. Significant environmental factors included the presence of seasonal rain water pathways and rock piles around houses (AOR = 4.7; 95% CI = (2.3-9.6), p < 0.05), presence of acacia trees in and around homesteads (AOR = 8.5; 95% CI = (2.5-28.6), p < 0.05), presence of anthills around the homesteads (AOR = 5.2; 95% CI = (1.2-23.4), p < 0.05), and presence of animal shed within compound (AOR = 2.8; 95% CI = (0.96-8), p < 0.05). Climate change-induced seasonal weather variability, increased temperature and reduced precipitation as well as environmental alterations influence kala-azar occurrence in West Pokot. Community sensitization on disease prevalence, clearing of vector predilection sites, and improving community environmental risk perception are imperative to promote prevention.

Housing Risk Factors of Four Tropical Neglected Diseases: A Brief Review of the Recent Literature

Alongside peace, education, food, income, a stable ecosystem, sustainable resources and social justice, shelter is a prerequisite for health. According to international human rights law, everyone is entitled to an adequate standard of living, which includes adequate housing. Adequate housing, including access to water and sanitation, plays a critical role in the prevention and management of neglected tropical diseases, which affect over 1 billion people worldwide. Inadequate housing conditions represent a risk factor for many of them, e.g., Chagas disease that affects 6–8 million people worldwide, visceral leishmaniasis that kills 20,000–30,000 people/year, lymphatic filariasis which threatens 859 million people worldwide or dengue that has increased 8–10 fold over the last two decades. Vector control strategies for the above-mentioned diseases have shown their effectiveness and should include systematic and repetitive in-house spraying and individual protection (e.g., impregnated nets), as well as better-quality construction material and techniques and better sanitation infrastructures and practices. Access to adequate housing is a basic human right. The violation of the right to adequate housing may affect the enjoyment of other human rights. Access to adequate housing can strengthen (and facilitate access to) other basic human rights, such as the rights to work, health, security, and education.

Understanding the risk perception of visceral leishmaniasis exposure and the acceptability of sandfly protection measures among migrant workers in the lowlands of Northwest Ethiopia: a health belief model perspective

Background

Visceral leishmaniasis (VL) is the leading cause of health concerns among Ethiopian migrant workers. Understanding risk perception and health-protective behavior are significant challenges in the prevention and eradication of the disease. As a result, studies are required to assess these important epidemiological factors, which will provide guidance on how to assist migrant workers in taking preventive measures against VL.

Method

We conducted qualitative research among migrant workers on seasonal agricultural farms in Northwest Ethiopia between June and November 2019 to assess their perception of the risk of contracting VL and their willingness to use protective measures against the disease. Seventeen focus group discussions and 16 key informant interviews were conducted to study migrant workers’ risk perception in relation to sandfly bite exposure and use of sandfly control measures. For analysis, all interviews were recorded, transcribed, and translated. ATLASti was used to perform qualitative content analysis on the data.

Result

Migrant workers are fearful of VL because of previous exposure and the disease’s prevalence in the area. They believe, however, that VL is a minor illness that is easily treated. While Insecticide Treated Nets (ITNs) are widely accepted as a protective measure, there are still reservations about using them due to the seasonality of the transmission, difficulties in hanging them on farm areas, and a preference for alternative traditional practices. Regardless of perceived self-efficacy, the central cues were the message delivered by the health workers and an increase in sandfly bite irritation. Based on the findings, three levels of intervention modalities are suggested: 1) increasing pre-arrival awareness through outdoor media (posters, stickers, billboards), 2) encouraging proper use of protective measures upon arrival at farm camps, and 3) informing departing workers on disease recognition and best practices for health-seeking continuous use of protective measures at home.

Conclusion

This finding suggests that VL prevention interventions should focus on individuals’ perceptions in order to promote consistent use of protective measures. The findings are highly useful in planning effective interventions against VL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13406-3.

Neglected tropical zoonotic diseases in Tigray region, northern Ethiopia: Spatial distribution and trend analysis of rabies, tuberculosis, schistosomiasis, and visceral leishmaniasis in humans

Neglected tropical zoonotic diseases (NTZDs) continue to affect the health and livelihoods of humans particularly the poor and marginalized populations in developing countries. Mapping the distribution and burden of these diseases will support making an informed decision. A retrospective study was conducted to map the spatial distribution and analyse trend of NTZDs in Tigray region, Northern Ethiopia. A health management information system (HMIS) data between 2012/13 and 2016/17 was obtained from Tigray National Regional State Health Bureau. The Quantum-GIS software was used to map the spatial distribution and burden of selected NTZDs at zonal level. Only four of the NTZDs namely rabies, tuberculosis (TB), schistosomiasis and visceral leishmaniasis (VL) from the records of HMIS data were considered. A high incidence rate (IR) at least for one of the NTZDs was reported in males above 15 years old. In the 5-year period, of the 60,099 reported NTZD cases, 30.3% (18,220), 26.6% (16,005), 23.3% (14,001), 14.4% (8,661), and 5.3% (3,212) were, respectively, schistosomiasis, extra-pulmonary TB, rabies, pulmonary TB, and visceral leishmaniasis. The year-wise analysis showed an irregular trend for the NTZDs where both the decreasing and increasing trends didn't show statistically significant variation. However, the overall regional number of TB cases showed a decreasing trend, where the decrease for extra-pulmonary TB (1.8 cases per 100,000 population) was higher than pulmonary TB (0.5 cases per 100,000 population). Similarly, the annual number of rabies and VL cases showed a decreasing trend. On the other hand, the number of schistosomiasis cases showed an increasing trend (8.2 cases per 100,000 population). The annual average number of TB (171 cases per 100,000 population), schistosomiasis (354 cases per 100,000 population), and VL (63 cases per 100,000 population) cases were much higher in Western zone compared to the rest of the zones. The incidence rate of rabies was higher in Mekelle and Southeastern (100 cases per 100,000 population) and Northwestern (97 cases per 100,000 population) zones. Intervention strategies applied in the region should take into account the zonal distribution and burden of NTZDs.

Are backyard characteristics relevant factors for the occurrence of human visceral leishmaniasis in Central-Western Brazil?

BACKGROUND

This retrospective case-control study aimed to investigate the factors associated with the occurrence of human visceral leishmaniasis (VL) in the municipality of Rondonópolis, which is a highly endemic area for VL in Central-Western Brazil.

METHODS

All VL cases reported in Rondonópolis from 2011 to 2016 were included. For each case, two neighborhood- and age-matched controls with the absence of past and present history of VL and negative rk39-based immunochromatographic test, were recruited. Data were retrospectively collected through interviews that assessed socioeconomic aspects, housing features, backyard characteristics, presence of animals and daily habits. A multivariate conditional logistic regression analysis was used to identify factors associated with human VL.

RESULTS

During the study period, 81 VL cases were reported in Rondonópolis, of which 37 (45.7%) were included in this study. Seventy controls were also included. The variables associated with VL occurrence were the outdoor location of a bathroom and/or kitchen separated from the rest of the house (OR 7.8; 95% CI 2.1 to 29.5), the presence of a vegetable garden (OR 5.3; 95% CI 1.3 to 21.2) and the presence of decaying fruits (OR 10.7; 95% CI 2.0 to 52.1) in the backyard.

CONCLUSIONS

Our findings suggest an association between backyard characteristics and VL. This may be useful in guiding preventive and control measures against zoonotic VL worldwide.

Vulnerabilities to and the Socioeconomic and Psychosocial Impacts of the Leishmaniases: A Review

The leishmaniases are a group of four vector-borne neglected tropical diseases (NTDs) with 1.6 billion people in some 100 countries at risk. They occur in certain eco-epidemiological foci that reflect manipulation by human activities, such as migration, urbanization and deforestation, of which poverty, conflict and climate change are key drivers. Given their synergistic impacts, risk factors and the vulnerabilities of poor populations and the launch of a new 2030 roadmap for NTDs in the context of the global sustainability agenda, it is warranted to update the state of knowledge of the leishmaniases and their effects. Using existing literature, we review socioeconomic and psychosocial impacts of leishmaniasis within a framework of risk factors and vulnerabilities to help inform policy interventions. Studies show that poverty is an overarching primary risk factor. Low-income status fosters inadequate housing, malnutrition and lack of sanitation, which create and exacerbate complexities in access to care and treatment outcomes as well as education and awareness. The co-occurrence of the leishmaniases with malnutrition and HIV infection further complicate diagnosis and treatment, leading to poor diagnostic outcomes and therapeutic response. Even with free treatment, households may suffer catastrophic health expenditure from direct and indirect medical costs, which compounds existing financial strain in low-income communities for households and healthcare systems. The dermatological presentations of the leishmaniases may result in long-term severe disfigurement, leading to stigmatization, reduced quality of life, discrimination and mental health issues. A substantial amount of recent literature points to the vulnerability pathways and burden of leishmaniasis on women, in particular, who disproportionately suffer from these impacts. These emerging foci demonstrate a need for continued international efforts to address key risk factors and population vulnerabilities if leishmaniasis control, and ultimately elimination, is to be achieved by 2030.

A trend prevalence of visceral Leishmaniasis in West Armachiho District, Amhara Region, Northwest Ethiopia

Background

Visceral leishmaniasis (VL) is a disease caused by an obligate intracellular protozoan parasite that affects animals and humans. An estimated 3.2 million people are at risk of VL, and 3700–7400 cases occur annually in Ethiopia. The highest numbers of VL cases have been previously reported from the North Western parts of the country, especially in West Armachiho District. The aim of this study was to determine the trend prevalence of VL at the study area.

Methods

Health center based retrospective data were collected to determine the trend prevalence of VL among patients who had blood examination from January 2010 to August 2015. The blood samples were collected by finger pricking and the infections were confirmed by using rK₃₉ antibody test.

Result

Of the 9299 VL suspected cases, 1948 (21%) were positive for rK₃₉ antibody test. Of these, 1757 (90.2%) were primary kala-azar cases, 167 (8.6%) were relapse and the remaining 24 (1.2%) were post kala-azar dermal leishmaniasis cases.

Conclusions

The prevalence of VL is still high in the study area. Therefore, early case detection, diagnosis, treatment, and timely analysis are essential.

Prevalence and Risk Factors of Human Leishmaniasis in Ethiopia: A Systematic Review and Meta-Analysis

Introduction

Tropical diseases are public health problems affecting hundreds of millions of people globally. However, the development of adequate, affordable, and accessible treatments is mostly neglected, resulting in significant morbidity and mortality that could otherwise be averted. Leishmaniasis is one of the neglected tropical diseases caused by the obligate intracellular protozoan Leishmania parasite and transmitted by the bite of infected phlebotomine sandflies. No systematic review and meta-analysis has been done to identify the prevalence and risk factors of leishmaniasis to the authors’ knowledge. Therefore, the objective was to determine the prevalence and risk factors of human leishmaniasis in Ethiopia.

Methods

Eleven studies conducted in all regions of Ethiopia, which were fully accessible, written in any language, and original articles done on prevalence and risk factors of leishmaniasis, were included. STATA™ version 11.1 was used for statistical analysis. Chi-square, I², and p values were assessed to check heterogeneity. A random effects model with heterogeneity taken from an inverse-variance model was employed to estimate the pooled effect. Subgroup meta-analysis was computed to reduce random variations among each article’s point prevalence, and Egger and funnel plots were used to check for publication bias.

Results

The highest proportion of human leishmaniasis was reported from a study done in Amhara region (39.1%), and the lowest was reported from a survey done in Tigray (2.3%). The overall pooled prevalence of leishmaniasis was 9.13% (95% CI 5–13.27). Subgroup analysis by region revealed moderate heterogeneity (I² = 51.8%) in studies conducted in the Southern Nations Nationalities and Peoples Region (SNNPR). The presence of hyraxes and being male were associated with an increased risk of human leishmaniasis.

Conclusion

The prevalence of leishmaniasis in Ethiopia remains high (9.13%), with significant risk factors being male and the presence of hyraxes within a 300-m radius of the sleeping area.

Studies of host preferences of wild-caught Phlebotomus orientalis and Ph. papatasi vectors of leishmaniasis in Sudan

Introduction

Understanding the feeding behavior and host choice of sand flies provides valuable information on vector-host relationships and elucidates the epidemiological patterns of leishmaniasis transmission. Blood meal analysis studies are essential for estimating the efficiency of pathogen transmission, assessing the relative human disease risk, and assist in identifying the other potential hosts of leishmaniasis. In Sudan and most of East Africa, there are large remaining gaps in knowledge regarding the feeding habits of phlebotomine vectors. The study aimed to identify the blood meal sources and, therefore, the host preferences of the principal vectors Phlebotomus orientalis and Ph. papatasi in leishmaniasis endemic areas of eastern and central Sudan.

Materials and methods

Sand flies were collected from two endemic villages in eastern and central Sudan using CDC light traps and sticky traps. The phlebotomine sand flies were morphologically and then molecularly identified. The source of blood meal of the engorged females was determined using a multiplex PCR methodology and specific primers of cytochrome b gene of mitochondrial DNA for human, goat, cow, and dog. The detection of the Leishmania parasite was done using PCR.

Results

The total number of collected female phlebotomine sand flies was 180. Morphological identification revealed the abundance of Ph. orientalis 103 (57.2%), Ph. papatasi 42 (23.3%), Ph. bergeroti 31 (17.2%), Ph. rodhaini 2 (1.1%) and Ph. duboscqi 2 (1.1%) in the study sites. Out of the 180 collected, 31 (17%) were blood-fed flies. Three species were blood-fed and molecularly identified: Ph. papatasi (N = 7, 22.6%), Ph. bergeroti (N = 9, 26%), and Ph. orientalis (N = 15, 48.4%). Blood meal analysis revealed human DNA in two Ph. orientalis (6.4%), hence, the anthropophilic index was 13.3%.

Conclusions

Multiplex PCR protocol described here allowed the identification of blood meal sources of many vertebrate species simultaneously. The results indicate that wild-caught Ph. orientalis are anthropophilic in the study areas. Further studies on larger blood-fed sample size are required to validate the potential applications of this technique in designing, monitoring and evaluating control programs, particularly in investigating the potential non-human hosts of leishmaniasis.

Impact of Education on Knowledge and Practice of Kala Azar Preventive Measures among Seasonal and Migrant Agricultural Workers in Northwest Ethiopia

Kala azar occurs among seasonal and migrant agricultural workers in northwest Ethiopia and accounts for almost 60% of the disease burden in the country. We conducted a quantitative study on the level of knowledge and practice of this vulnerable group in relation to kala azar transmission and acceptability of its vector control tools. A total of 403 workers were randomly selected from eight farms using a purposive sampling technique. Knowledge and practice scores were calculated based on 12 and 9 core questions, respectively. Binary logistic regression was used to identify factors associated with knowledge and practice. A large gap in knowledge of the disease and the vector was evident with 61.8%, 24.6%, and 13.6% of the workers having poor, moderate, and good levels of knowledge scores, respectively. Similarly, 95% of the seasonal workers reported poor level of use of protective measures against the bite of the sand fly vector. Good level of knowledge about kala azar and its sand fly vector was statistically associated with formal education (adjusted odds ratio [AOR] = 2.11; 95% CI = 1.17, 3.80; P < 0.05) and previous exposure to health education (AOR = 4.72; 95% CI = 1.99, 11.16; P < 0.001). Despite poor current knowledge and practice, a large proportion of the study participants showed interest in using vector control tools if made available, with 78% of the seasonal and migrant workers expressing some willingness to pay for different measures that can protect against sand fly bites. Therefore, we strongly recommend that comprehensive health education and vector control programs should be provided to these workers.

Environmental and socioeconomic risk factors associated with visceral and cutaneous leishmaniasis: a systematic review

We performed a systematic review of the literature published since 1900 about leishmaniasis a neglected vector-borne disease, focused on environmental and social risk factors for visceral (VL) and cutaneous leishmaniasis (CL) to better understand their impact on the incidence of disease. The search terms were "leishmaniasis" AND "risk factors" using Google Scholar, PudMed, and Scielo. We reviewed 177 articles, 95 studies for VL, 75 for CL, and 7 on both forms. We identified 14 categories of risk factors which were divided into three groups: socioeconomic (7), environmental (5), and climate (2) variables. Socioeconomic factors were also associated with disease incidence in vulnerable human populations of arid and tropical developing regions. Environmental and climate factors showed significant associations with the incidence of VL and CL in all the studies that considered them. Proximity to natural vegetation remnants increased disease risk in both the New and Old World while the climate conditions favorable for disease transmission differed among regions. We propose a common conceptual framework for both clinical forms that highlights networks of interaction among risk factors. In both clinical forms, the interplay of these factors played a major role in disease incidence. Although there are similarities in environmental and socioeconomic conditions that mediate the transmission cycle of tropical, arid, and Mediterranean regions, the behavior of vector and reservoirs in each region is different. Special attention should be given to the possibility of vector adaptation to urban environments in developing countries where populations with low socioeconomic status are particularly vulnerable to the disease.

Knowledge, attitude and practices of the resident community about visceral leishmaniasis in West Armachiho district, Northwest Ethiopia

Visceral leishmaniasis (VL) or kala-azar is a tropical disease, which is caused by an obligate intracellular parasite of the genus Leishmania. It is transmitted by the bite of an infected phlebotomine sand fly. The disease is endemic in northwest part of Ethiopia particularly in areas bordering Sudan. Assessing the knowledge, attitude and practices (KAP) of the community is helpful to design and implement appropriate control and prevention strategies. A cross-sectional study was conducted to assess the KAP of the resident community on VL in West Armachiho district, northwest Ethiopia. Data were collected by using pretested and well-structured questionnaire. Two villages (Abderafi and Abrehajira) were selected randomly. Households engaged in the study were selected by systematic random sampling method and then finally, simple random sampling was used to engage a maximum of two individuals per household. A total of 422 participants were engaged in the study. Almost all participants heard about VL. The source of information was mainly from friends (80.8%). The highest proportion (88.2%) of participants thought that persistent enlargement of liver and spleen (enlargement of the abdomen) was the main symptom of VL. Of all participants, only 52.1% knew sand fly as the vector of the disease. The overall assessment of participants indicated that 21.1% were knowledgeable, 53.6% had positive attitudes and 14.9% had optimal practices on VL. In conclusion, the survey indicated that participants had better attitude about VL. However, there were a large gap in knowledge and practices. The misunderstanding and incorrect practices may remain serious concerns in the control and prevention of the disease. It is recommended that health education program should be strengthened to increase peoples' awareness and improve their practices on VL in the district and further studies are strongly suggested for better understanding of the dynamics of the disease in the area.

Housing Characteristics and Leishmaniasis: A Systematic Review

Leishmaniasis is a major neglected tropical disease associated with high rates of disability and death. This disease is associated with poverty, which can be reflected in housing quality, especially in rural areas. This systematic review found that mud walls with cracks and holes, damp, and dark houses were risk factors for transmission of leishmaniasis. These characteristics create favorable conditions for sand fly breeding and resting as sand flies prefer humidity, warmth, and protection from sunlight during the day. Housing interventions might be a promising research area with a special focus on education as individual and collective protection for the effective control of leishmaniasis.

A molecular analysis of sand fly blood meals in a visceral leishmaniasis endemic region of northwestern Ethiopia reveals a complex host-vector system

Background

Visceral leishmaniasis (VL, or “kala-azar”) is a major cause of disability and death, especially in East Africa. Its vectors, sand flies (Diptera: Psychodidae: Phlebotominae), are poorly controlled and guarded against in these regions, owing in part to a lack of understanding about their feeding behavior.

Methods

A total of 746 freshly fed female sand flies were collected in five population centers in Kafta Humera (northwestern Ethiopia), where VL is endemic. Flies were collected from habitats that ranged from inside houses to open fields, using light traps and sticky traps. Sources of sand fly blood meals were identified using enzyme-linked immunosorbent assays (ELISA) and DNA amplification with reverse-line blot analysis (PCR-RLB); 632 specimens were screened using ELISA, 408 of which had identifiable blood meals, and 114 were screened using PCR-RLB, 53 of which yielded identifications. Fly species determinations were based on morphology, and those specimens subjected to PCR-RLB were also screened for Leishmania parasites using conventional PCR to amplify the nuclear marker ITS1 (internal transcribed spacer 1) with Leishmania-specific primers.

Results

More than three-fourths of all sand flies collected were Phlebotomus orientalis, and the remaining portion was comprised of nine other species. Nearly two-thirds of P. orientalis specimens were collected at village peripheries. The most common blood source for all flies was donkey (33.9% of all identifications), followed by cow (24.2%), human (17.6%), dog (11.8%), and goat or sheep (8.6%); mixtures of blood meals from different sources were found in 28.2% of all flies screened. Unidentified blood meals, presumably from wildlife, not domestic animals, were significantly higher in farm fields. Leishmania parasites were not detected in any of the 114 flies screened, not surprising given an expected infection rate of 1–5 out of 1,000. Meals that included a mixture of human and cow blood were significantly more frequent relative to all cow meals than human blood meals were to non-cow meals, suggesting a zoopotentiative interaction between cows and humans in this system.

Conclusions

Habitat and host preferences of sand fly vectors in Kafta Humera confirmed the finding of previous reports that the main vector in the region, Phlebotomus orientalis, is a highly opportunistic feeder that prefers large animals and is most commonly found at village peripheries. These results were similar to those of a previous study conducted in a nearby region (Tahtay Adiabo), except for the role of cattle on the prevalence of human blood meals. Preliminary examinations of blood meal data from different settings point to the need for additional surveys and field experiments to understand the role of livestock on biting risks.

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.

Epidemiology of visceral leishmaniasis in Shebelle Zone of Somali Region, eastern Ethiopia

Background

Visceral leishmaniasis (VL), a vector-borne disease caused by species of the L.donovani complex, has (re)-emerged in Ethiopia during the last two decades and is currently of increasing public health concern. However, very little is known about VL epidemiology in the Somali Region of Ethiopia. The aim of this study was to provide detailed epidemiological information on seroprevalence, associated factors and incriminated vectors of VL in Shebelle Zone and Ethiopian Somali Region in general.

Methods

A cross-sectional epidemiological study was conducted between March and May 2016 in Gode and Adadle districts of Shebelle Zone, Ethiopian Somali Region. Two-stage semi-random sampling was applied for selecting study participants for the field survey. The study included structured questionnaire interviews, serological assays (rK39-immunochromatographic test), ELISA and entomological surveys.

Results

From a total of 361 participants, 57 (15.8%) were seropositive for VL including 46 (12.7%) rK39 positive and 11 (3.0%) positive by both rK39 and ELISA. VL seroprevalence was higher (P < 0.001) in Adadle (31.1%) compared to Gode (12.7%) district. The VL seroprevalence rate was higher in females than in males [rK39 (17.2 vs 14.0%) and ELISA (3.4 vs 2.5%)]. Children under the 15 years of age were the most highly affected group [rK39 (20.4%) and ELISA (4.4%)]. Increased VL risk was associated with presence of termite hills, study district, outdoor sleeping, Acacia trees and domestic animals [odds ratio (95% confidence interval): 12.58 (5.911–26.763), 5.40 (2.90–10.07), 5.31 (2.283–12.364), 2.37 (1.1190–4.728) and 0.199 (0.097–0.410), respectively]. The entomological survey identified 74 Phlebotomus [P. (Larroussius) orientalis (52/74), P. (Anaphlebotomus) rodhaini (14/74), P. (Paraphlebotomus) sergenti (8/74)] and 11 Sergentomyia sand flies. The average frequency of P. orientalis (3.06 ± 0.66) collected by all traps per night was higher than that of other species. The average frequency of total and specific (P. orientalis) female sand flies was higher in Adadle (1.89 ± 0.423 vs 1.11 ± 0.309) than in Gode (0.62 ± 0.324 vs 0.38 ± 0.183) district. The highest mean numbers of total (8 ± 1.5) and P. orientalis (6 ± 0.913) sand flies were collected in termite hills.

Conclusions

The present findings revealed potential new VL-transmission foci in the study districts. Therefore, the need for parasitological and molecular characterization of the parasite in humans and vector sand flies is of paramount importance to confirm transmission.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3452-5) contains supplementary material, which is available to authorized users.

Seroprevalence of Asymptomatic Leishmania donovani among Laborers and Associated Risk Factors in Agricultural Camps of West Armachiho District, Northwest Ethiopia: A Cross-Sectional Study

Background

Visceral leishmaniasis (VL, also called kala-azar) is a public health problem in Ethiopia, especially in sesame and sorghum growing areas. Compared to other populations, labor migrants are the most exposed. Knowing the seroprevalence of Leishmania donovani and associated risk factors is essential to design appropriate control measures. The main aim of this study was to assess the seroprevalence of asymptomatic L. donovani among laborers and associated risk factors in agricultural camps of West Armachiho district, Northwest Ethiopia. Therefore, this study was conducted to know the seroprevalence and associated risk factors of L. donovani infection.

Method

A cross-sectional study was conducted among 185 laborers from October to December 2017. A simple random sampling technique was used to select study participants from selected agricultural camps. After obtaining written informed consent, data were collected using a structured pretested Amharic version questionnaire using the interview technique. A single finger prick blood sample was collected from the study participants and the blood samples were subjected to the serological diagnostic method using the rk39 kit. The multivariable logistic regression model was used to identify risk factors associated with L. donovani infection.

Result

Among 185 participants examined using rk39, 14 (7.6%) were seroreactive for L. donovani. Leishmania donovani infection had a statistically significant association with sleeping under Balanites trees (AOR: 4.36, 95%CI: 1.186-16.06), presence of domestic animals near sleeping place (AOR: 4.68, 95% CI: 1.25-17.56), and lack of knowledge about VL transmission (AOR: 3.79, 95% CI: 1.07-13.47).

Conclusion

Seroprevalence of asymptomatic L. donovani among laborers in agricultural camps of West Armachiho was low. Prevention measures and health education about risk factors that expose to L. donovani infection for the laborers are essential to prevent the spread of the disease.

Zoonotic impact and epidemiological changes of leishmaniasis in Ethiopia

Leishmaniasis is one of the growing public health challenges in Ethiopia and estimated over 7,000 and 50,000 new cases of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) per year, respectively. The aim of the review is to address zoonotic impact and epidemiological changes of leishmaniasis in Ethiopia. VL is caused by L. donovani and it is endemic in many parts of the country with one third of the country’s landmass is highly suitable for VL. CL is principally caused by L. aethiopica. CL is endemic and widespread in the highland of Ethiopia. Northern lowland foci are Humera and Metema plains in the Tigray and Amhara regional states constitute the main VL endemic areas in the country, contributing over 60% of the total burden. The southern foci are the south-western savannah, and the south-eastern semi-arid lowlands which account for approximately 20 % of the total VL burden in Ethiopia. Leishmaniasis is a serious zoonotic disease in Ethiopia with more reservoir hosts maintaining the disease. Dogs and hyraxes are the main reservoir hosts for visceral and cutaneous leishmaniasis in the country, respectively. Epidemiological changes of leishmaniasis may relate to environmental changes and expansion of mega projects such as irrigations and sugar cane factories, knowledge and socio-economic factors, development of new settlements, migration of peoples and HIV/AIDS co-infection. Expansions of mega projects such as sugar factories and irrigations are suitable for reproduction of stray dogs, rodents, wild canids and vectors. VL is one of the major challenges to prevent and control in the endemic areas of the country. Therefore, new research should be imperative, especially in the mega projects to design strategic control and prevention methods.

Incidence and Trends of Leishmaniasis and Its Risk Factors in Humera, Western Tigray

INTRODUCTION

Leishmaniasis is a neglected vector borne disease, which constitutes a major public health concern in several tropical and subtropical countries. An estimated 4500 to 4000 new cases of visceral leishmaniasis (VL) occur per year and over 3.2 million people are at risk of infection in the country. In Humera, VL epidemics are associated with migration of workers from nonendemic highlands into the visceral leishmaniasis endemic extensive farmlands. Therefore, the objective of this study is to estimate the incidence and the risk factors of leishmaniasis in Humera, Western Tigray.

METHODS

A retrospective study was conducted using the hospital admission database on all patients admitted who have been suspected of having leishmaniasis infection and tested for rK39-based immune chromatographic test (ICT) at Kahsay Abera Hospital in Humera town from January 2012 to December 2017. Potential risk factors for leishmaniasis infection in human were collected from the hospital, which included categorical variables: age, sex, origin of place, clinical forms of leishmaniasis, mortality rates, and the occurrence of infections according to format of hospital.

RESULTS

A total of 26511 hospital discharged patients with diagnosis of leishmaniasis were identified, out of which 2232 (8.42%) human leishmaniasis cases were registered and of them 71 were dead from January 2012 to December 2017. Mortality rates of leishmaniasis were 18 (3.3%) in 2012, 16 (3.1%) in 2013, 15 (2.4%) in 2014, 8 (3.3%) in 2015, 9 (4.1%) in 2016, and 5 (5.4%) in 2017. Univariate analysis of the infection rate of leishmaniasis was based on the potential risk factors and found higher male infection rates than female (P <0.05) in all the study years. Origin of place was also significantly associated (P< 0.05) where labor migrants from highland to agricultural fields had higher infection rates than those who permanently lived in and around Humera. Trends in season of occurrence revealed that weeding and harvesting time (July-December) had higher incidence of leishmaniasis than dry time (January-June).

CONCLUSION

Male labor migrants from the highlands older than 15 years of age were at the highest risks of leishmaniasis during weeding and harvest season. Therefore, awareness creation on the risks of sleeping outdoors and the impact of using of bed nets is imperative especially for labor migrants during weeding and harvesting season.

Serological investigation of visceral Leishmania infection in human and its associated risk factors in Welkait District, Western Tigray, Ethiopia

Visceral leishmaniasis (VL) is major neglected public health problem in terms of geographical spread and incidence in Ethiopia. Magnitude, public health impact and dynamics of VL were not well studied in Welkait District, Western Tigray, though the area is known for VL. Hence, this study aimed to determine sero-prevalence of human VL and associated risk factors in Welkait as new foci. A cross sectional study design was employed in this study. Two stage stratified random sampling method was used to select study participants. Hence, a total of 329 human study participants were included for serological survey using ITleish and leishmanin skin tests. Semi structured questionnaire was also used to identify VL associated risk factors. Univariate and multivariate logistic regression statistical methods were used to determine the degree of association. The overall sero-prevalence of human VL in the study area was found to be 8.81%. Statistical significant difference in the prevalence of the disease was found among Sub-districts, sex, re-settlement, sleeping outdoor and dog ownership (P < 0.05). Participants who resettled from their original place were found 2 times (AOR = 2.143; 95% CI = 1.02, 14.20) more vulnerable to VL infection. Those who had an experience of sleeping outdoor were found almost 4 times (AOR = 4.29; 95% CI = 1.58, 11.69) more likely to be at risk of acquiring VL infection than those sleep indoor. Furthermore, individuals who owned dogs were 3 times more prone to the VL infection than their counterparts (AOR = 3.37; 95% CI = 1.29, 8.76). Alarming sero-positivity of human VL was recorded from new foci. Hence, it is recommended to improve the VL health services in the study area. The investigation also invites further study on VL dynamics in the study area.

Leishmaniasis in Sri Lanka: spatial distribution and seasonal variations from 2009 to 2016

BACKGROUND

Leishmaniasis is listed as one of the eight neglected tropical diseases by the World Health Organization and the number of cases in endemic areas has seen a sharp rise in the past decade. More alarmingly, reports have shown that leishmaniasis is spreading to non-endemic areas of the world due to co-infection with HIV. In Sri Lanka, leishmaniasis is considered as a notifiable disease from 2008 and has seen a rising trend of incidence since then. This is the first study describing the burden, seasonal variation and spatial distribution of leishmaniasis in Sri Lanka since the disease has been included as a notifiable disease.

METHODS

Data on health statistics from 2009 to 2016 were obtained from published databases maintained by the Epidemiology Unit of the Ministry of Health in Sri Lanka. Climatic data for Sri Lanka were obtained from the Department of Meteorology and the populations in administrative districts were obtained from the Department of Census and Statistics, Sri Lanka. Descriptive spatiotemporal analysis, correlation between leishmaniasis incidence and climatic variables were analyzed using SPSS statistical software.

RESULTS

The total number of people reported with leishmaniasis during the study period was 8487. Cutaneous leishmaniasis is the prominent form in Sri Lanka while few visceral and muco-cutaneous cases were reported. Although leishmaniasis patients were identified from all 25 districts in the island, almost 90% of the total caseload was reported from Anuradhapura, Hambantota, Polonnaruwa, Kurunegala and Matara districts. The highest number of patients was reported from the Anuradhapura district and the highest incidence per 100,000 persons was reported from the Hambantota district. The disease has a seasonal trend, a peak of leishmaniasis occur in July to September in the north-central region and in October to December in the southern region. Maximum temperature, humidity and wind speed are significantly associated climatic variables with leishmaniasis in endemic regions.

CONCLUSIONS

Leishmaniasis is an emerging public health problem in north-central and southern Sri Lanka. Public awareness programs for the prevention and control of the disease in endemic regions are essential to reduce the incidence of leishmaniasis.

Diversity and altitudinal distribution of phlebotomine sand flies (Diptera: Psychodidae) in visceral leishmaniasis endemic areas of northwest Ethiopia

BACKGROUND

The Leishmaniases are caused by the protozoan parasites of the genus Leishmania and are transmitted to humans by the bite of infected female phlebotomine sand flies. Both visceral and cutaneous leishmaniases are widely distributed in different parts of Ethiopia. The aim of this study was to determine the diversity and altitudinal distribution of phlebotomine sand flies from Kafta Humera to Gondar town in northwest Ethiopia.

METHODS

Seven localities were selected with distinct altitudinal variations between 550m above sea level (m a.s.l) and 2300m a.s.l. In each locality, sand flies were collected using standard CDC light traps and sticky traps during the active sand fly season from December 2012 to May 2013. Shannon-Weiner species diversity index and Jaccard's coefficient were used to estimate species diversity and similarity between altitudes and localities, respectively.

RESULTS

A total of 89,044 sand flies (41,798 males and 47, 246 females) were collected from the seven localities/towns throughout the study period. Twenty-two species belonging to 11 species in the genus Phlebotomus and 11 species in the genus Sergentomyia were documented. Of these, Sergentomyia clydei (25.87%), S. schwetzi (25.21%), S. africana (24.65%), S. bedfordi (8.89%), Phlebotomus orientalis (6.43%), and S. antennata (4.8%) were the most prevalent species. The remaining 10 Phlebotomus species and six Sergentomyia were less frequent catches. In CDC light trap and sticky trap, higher species diversity and richness for both male and female sand flies was observed at low altitude ranging from 550 to 699m a.s.l in Adebay village in Kafta Humera district whereas low species richness and high evenness of both sexes were also observed in an altitude 1950-2300m a.s.l.

CONCLUSION

The results revealed that the presence of leishmaniasis vectors such as P. orientalis, P. longipes, P. papatasi, and P. duboscqi in different altitudes in northwest Ethiopia. P. orientalis a vector of L. donovani, occurred between altitude 500-1100m a.s.l, the area could be at high risk of VL. P. longipes a vector of L. aethiopica, was recorded in the highland area in Tikil-Dingay and Gondar town, implicating the possibility of CL transmission. Hence, further investigation into vector competence in relation to leishmaniasis (VL and CL) in the region is very vital.

Preliminary study on investigation of zoonotic visceral leishmaniasis in endemic foci of Ethiopia by detecting Leishmania infections in rodents

OBJECTIVE

To investigate the zoonotic visceral leishmaniasis (ZVL) by identification of the most probable reservoir hosts using parasite isolation and analysis of a possible transmission dynamics of the disease in extra-domestic agricultural fields and rural villages.

METHODS

Rodents were collected from selected study sites in kala-azar endemic areas based on information for localities of kala-azar cases for screening of Leishmania infections using parasitological, serological and polymerase chain reaction (PCR) from March, 2013 to January, 2014. Ketamine (Clorketam Veterinary) was used to anaesthesize the rodents according the prescribed dosage (average 2 mg/kg for intra-venous route). The blood obtained using sterile needle was dropped into sterile filter paper and allowed to air dry before sealing in plastic bags. The tissues from liver, spleen and skin were macerated in Locke's solution before transferring them into NNN medium. Blood and touch smears of liver, spleen, skin and bone marrow were prepared for fixing using methanol and staining by Giemsa stain for microscopy. These tissues were also used for DNA extractions and PCR amplification of Leishmania infection.

RESULTS

A total of 335 rodents (13 species) were analyzed by sampling internal organs. The infection rate by PCR was 11.1% (6/54) for Arvicanthis nilothicus compared to 17.6% (3/17) and 12.5% (2/16) for Acomys cahirinus and Tarera (G) robustus respectively. Almost all the infections were found from bone marrow samples (8/48 or 16.7%) compared with 1/91 (1.1%) liver, 2/87 (2.2%) spleen and 0/87 (0%) skin. In all study sites with past human VL cases, rodents and proved vectors shared similar habitats.

CONCLUSIONS

Leishmania donovani might circulate among different species of rodents in kala-azar endemic lowlands and valleys of Ethiopia by Phlebotomus orientalis and Phlebotomus martini. Detailed studies to substantiate the preliminary data on the possible role of these rodents are urgently needed.

Correlation of Rk39-Specific Antibodies and Thyroid Function in Patients with Visceral Leishmaniasis

OBJECTIVE

This study aimed to determine whether anti-rK39 antibodies were diagnostic markers for visceral leishmaniasis (kala-azar) and to evaluate the correlation between age and gender in disease occurrence in Iraqi patients. In addition, it aimed to evaluate the correlation between thyroid hormones, i.e., thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) and anti-rK39 antibodies.

MATERIALS AND METHODS

Immunochromatographic technique used for anti-rK39 antibodies detection. Enzyme-linked immunosorbent assay was used for determining the serum TSH, T3, and T4 levels.

RESULTS

One hundred thirty-eight patients with visceral leishmaniasis were included. The mean age was 27.65±11.60 years. Sixty-one patients (44.2%) were males, and their mean age was 29.65±11.10 years. The mean age of females was 26.12±11.89 years. Anti-rK39 antibodies were detected in 11.59% of patients. Anti-rK39 antibodies were equally detected (5.8%) in both genders without a significant difference (p=0.212) or correlation between gender and anti-rK39 antibodies (p=0.623). There was neither a significant difference (p>0.05) nor correlation between gender; age groups according to gender and anti-rK39 antibodies (p>0.05). Both males and females who were positive for anti-rK39 antibodies had normal TSH, T3, and T4 levels. Only one patient who was positive for anti-rK39 antibodies had an elevated T4 level (>12 μg/dL). Neither a significant difference nor correlation was reported among genders; anti-rK39 antibody positivity (p>0.05); and TSH, T3, and T4 levels.

CONCLUSION

Anti-rK39 antibodies, a daignostic marker for visceral leishmaniasis have no correlation with patients age and gender. Serum TSH and T3 levels were not affected by visceral leishmaniasis. Visceral leishmaniasis causes the increase in serum T4 levels. Thyroid involvement appears to be uncommon in patients who present with visceral leishmaniasis.

Habitat preference and seasonal dynamics of Phlebotomus orientalis in urban and semi-urban areas of kala-azar endemic district of Kafta Humera, northwest Ethiopia

Visceral leishmaniasis is a significant public health problem in northwest Ethiopia, particularly in Kafta Humera district. The study was designed to determine the species composition and population dynamics of sand flies in five villages representing urban and semi-urban areas of Kafta Humera district namely, Setit Humera, Mykadra, Rawyan, Bereket and Adebay. Sand flies were collected for two to three nights monthly from May 2011 to April 2012 using CDC light-traps and sticky traps. Traps were placed in villages, at periphery of villages and farm fields. Sticky traps were also used for sampling indoor active sand flies. In total, 13,097 sand fly specimens of eight Phlebotomus species and 91,949 Sergentomyia specimens were collected. Among the Phlebotomus, P. orientalis was the predominant species (58.1%) followed by P. papatasi (29.6%), P. lesleyae (5.6%), P. bergeroti (3.8%), P. duboscqi (2.1%), P. alexandri (0.4%), P. heischi (0.2%) and P. rodhaini (0.2%). Significantly, higher number of P. orientalis was caught in Adebay village and the least in Setit Humera town. Seasonal abundance of P. orientalis increased during the dry season (January-May) and dropped drastically in the wet season (late June-September). Significant positive correlation was found between monthly abundance of P. orientalis and the monthly average air and surface soil temperature, while a negative correlation was found with monthly average rainfall and relative humidity. Higher number of P. orientalis was collected outdoors, especially in the farm fields followed by periphery of villages. Thus, various observations strongly suggested P. orientalis to be the principal vector in the study areas, where farm lands and periphery of villages were identified as the most risky habitats, whereas the indoors were the least ones. Appropriate control methods should be designed and implemented according to the knowledge of P. orientalis habitat preferences and seasonal dynamics in the district.

Prevalence of Leishmania tropica in school boys of khyber agency, FATA near Pak-Afghan border

In Pakistan leishmaniasis occurs periodically throughout the year and various out breaks are reported frequently. In continuation of our research on this neglected disease, the aim of present study is to explore: (1) the prevalence of cutaneous leishmaniasis in school boys; (2) Leishmania species identification in order to epidemiology and dynamics of the disease; (3) Identification of risk factors for Leishmaniasis especially for CL. The data was collected in August 2014 The experimental strategy involved a questionnaire for data collection and along with clinical diagnosis of 134 out of 9368 students for incidence of Leishmania spp. in 7 square kilometres area in the schoolboys at Tehsil Landi Kotal, District Khyber Agency, FATA Pakistan. The parasitological and molecular diagnosis of clinically suspected cutaneous leishmaniasis cases were performed using microscopical examination of Giemsa-stained smears of lesion exudates and minicircle kDNA semi nested PCR, respectively. Microscopy (x=1000) positive cases were 84/134 (62.6%) and 50/134 (37.4%) slides did not showed any presence of amastigotes of Leishmania spp. The samples were amplified using kDNA semi nested PCR and confirmed the presence of L. Tropica (Ac.no KT 985473). PCR positive cases were 97/134 (72.4%) and 37(27.6%) were negative. The prevalence of L. tropica in school boys was 1.4% (134/9368) in the total population studied (n=9368). The parasite prevalence might be greater as only male students were considered in the study due to ethical and social issues and limitations.

A review of visceral leishmaniasis during the conflict in South Sudan and the consequences for East African countries

Background

Visceral leishmaniasis (VL), caused predominantly by Leishmania donovani and transmitted by both Phlebotomus orientalis and Phlebotomus martini, is highly endemic in East Africa where approximately 30 thousands VL cases are reported annually. The largest numbers of cases are found in Sudan - where Phlebotomus orientalis proliferate in Acacia forests especially on Sudan’s eastern border with Ethiopia, followed by South Sudan, Ethiopia, Somalia, Kenya and Uganda. Long-standing civil war and unrest is a dominant determinant of VL in East African countries. Here we attempt to identify the correlation between VL epidemics and civil unrest.

Objective and methodology

In this review, literature published between 1955 and 2016 have been gathered from MSF, UNICEF, OCHA, UNHCR, PubMed and Google Scholar to analyse the correlation between conflict and human suffering from VL, which is especially apparent in South Sudan.

Findings

Waves of forced migration as a consequence of civil wars between 1983 and 2005 have resulted in massive and lethal epidemics in southern Sudan. Following a comprehensive peace agreement, but especially with increased allocation of resources for disease treatment and prevention in 2011, cases of VL declined reaching the lowest levels after South Sudan declared independence. However, in the latest epidemic that began in 2014 after the onset of a civil war in South Sudan, more than 1.5 million displaced refugees have migrated internally to states highly endemic for VL, while 800,000 have fled to neighboring countries.

Conclusion

We find a strong relationship between civil unrest and VL epidemics which tend to occur among immunologically naïve migrants entering VL-endemic areas and when Leishmania-infected individuals migrate to new areas and establish additional foci of disease. Further complicating factors in East Africa’s VL epidemics include severe lack of access to diagnosis and treatment, HIV/AIDS co-infection, food insecurity and malnutrition. Moreover, cases of post-kala-azar dermal leishmaniasis (PKDL) can serve as important reservoirs of anthroponotic Leishmania parasites.

Cyclodextrin complexes for treatment improvement in infectious diseases

Infectious diseases are a heterogeneous group of maladies that represent a serious burden to healthcare systems worldwide. Most of the available antimicrobial drugs display poor biopharmaceutical properties that compromise their effectiveness. Cyclodextrins (CDs) are cyclic oligosaccharides of glucopyranose formed by a variable number of repeating units that combine a hydrophilic surface with a hydrophobic cavity. The production of drug/CD complexes has become one of the most extensively investigated technology approaches to improve the stability, solubility, dissolution rate and bioavailability of drugs. The present work overviews the applications of CDs for the formulation of anti-infective agents along with the most relevant administration routes. Finally, an update on the complexes with CDs available on the market to treat infectious diseases is presented.

Risk factors, representations and practices associated with emerging urban human visceral leishmaniasis in Posadas, Argentina

INTRODUCTION

Visceral leishmaniasis is an often overlooked disease with high lethality rates about which there is need of additional local studies to inform the design of effective control strategies. The urbanization of its transmission has already been verified in America, with domestic dogs being the primary reservoirs and vectors of the disease. Socio-economic conditions, demographics and practices of domestic groups typically present in urban settings may play a specific role in the transmission of the infection, which is still poorly understood. 

OBJECTIVE

To analyze the sociodemographic characteristics, risk factors and overall practices concerning prevention and coping strategies of visceral leishmaniasis, in both human beings and canines. 

MATERIALS AND METHODS

This study utilized a cross-sectional case-control design. Cases were defined as a domestic group where the Public Health Ministry had at least one record of a member with human visceral leishmaniasis. Control cases were defined as a domestic group without a clinical record of the disease. The populations were characterized demographically and socially using primary information sources. Measures of household quality and a ranking of knowledge and attitudes towards visceral leishmaniasis were constructed, and practices associated with the presence, and the risk for canine visceral leishmaniasis were described. 

RESULTS

Low household quality (p≤0.001), a member of the domestic group out of the household after 6:00 pm (OR=4.4; 95% CI: 1.69-12.18), the uncontrolled racial breeding of dogs (OR=15.7; 95% CI: 3.91-63.2), and the presence of infected dogs infected in the household (OR=120.3; 95% CI: 18.51-728.3) were variables positively associated with the risk of infection. 

CONCLUSION

We observed certain social risk factors, primarily low household quality and overcrowding, associated with structural poverty that could increase human-vector contact probability. The most important risk factor for human visceral leishmaniasis was the possession of infected dogs in the household.

One Health Approach Prospect for Integrated Control and Elimination of Visceral Leishmaniasis in Ethiopia: A Narrative Review Article

BACKGROUND

Leishmaniasis is an obligate intercellular protozoon that affects animals and human. It has zoonosis and/or anthroponosis transmission. Human and veterinary medicine, environmental science and wildlife conservation specialists have many commonalities in case of visceral leishmaniasis. Still the above disciplines respond against leishmaniasis in a separate way. The aim of this review is to indicate inter- and intra- sectoral collaboration for planning future control strategies.

METHODS

literatures written on visceral leishmaniasis and one health approach were systematically reviewed from the year 1969 to 2014 from Pub Med, Scopus, Medline and Google scholar sources.

RESULT

Such a one health approach would enhance biomedical progress; improve medical and veterinary serves, entomological control and wildlife conservation for Visceral Leishmaniasis especially in endemic areas.

CONCLUSION

Inter- and intra - sectoral collaboration in the leishmaniasis control is limited in Ethiopia. Therefore, incorporating one health approach or integrated inter- and intra - sectoral collaboration for visceral leishmaniasis control is an effective control strategy in endemic areas.

Determinants of Visceral Leishmaniasis: A Case-Control Study in Gedaref State, Sudan

BACKGROUND

Improving knowledge on local determinants of visceral leishmaniasis (VL) is crucial to guide the development of relevant control strategies. This study aimed to identify individual and household level determinants of primary VL in 24 highly endemic villages of Tabarak Allah hospital's catchment area, Gedaref State, Sudan.

METHODS

From September 2012 to July 2013, in an unmatched case-control design, 198 patients with primary VL were compared to 801 controls free of VL symptoms and with a negative VL rapid test. Using random spatial sampling, controls were selected with a distribution of age, sex and village of residence proportionate to the distribution of the target population. Data were collected using a structured questionnaire.

RESULTS

Children and men were at higher risk of VL. Reporting VL patient(s) in the household in the previous year was the strongest VL risk factor. In a multivariate analysis, VL risk increased with household size, sleep location (outside the yard, not in the farm), evening outdoor activities in the rainy season (playing, watching TV, radio listening), use of ground nut oil as animal repellent and of smoke of Acacia seyal as indoor repellent, presence of dogs in the yard at night, Acacia nilotica in the yard's immediate surroundings and of a forest at eye range. VL risk appeared to decrease with the use of drinking water sources other than the village water tank, a buffer distance from the adjacent house yard, and with the presence of animals other than dogs in the yard at night. In contrast with previous studies, housing factors, mosquito-net use, black cotton soil, ethnicity, socioeconomic index, presence of Balanites aegyptica and Azadirachta indica in the yard were not independent VL determinants.

DISCUSSION AND CONCLUSION

Although these results do not provide evidence of causality, they provide useful suggestions for guiding further intervention studies on VL preventive measures.

Mathematical analysis of a model for AVL-HIV co-endemicity

A model for the transmission dynamics of Anthroponotic Visceral Leishmaniasis (AVL) and human immunodeficiency virus (HIV) in a population is developed and used to assess the impact of the spread of each disease on the overall transmission dynamics. As for other vector-borne disease models, the AVL component of the model undergoes backward bifurcation when the associated reproduction number of the AVL-only sub-model (denoted by RL) is less than unity. Uncertainty and sensitivity analyzes of the model, using data relevant to the dynamics of the two diseases in Ethiopia, show that the top three parameters that drive the AVL infection (with respect to the associated response function, RL) are the average number of times a sandfly bites humans per unit time (σV), carrying capacity of vectors (KV) and transmission probability from infected humans to susceptible sandflies (β2). The distribution of RL is RL∈[0.06,3.94] with a mean of RL=1.08. Furthermore, the top three parameters that affect HIV dynamics (with respect to the response function RH) are the transmission rate of HIV (βH), HIV-induced death rate (δH), and the modification parameter for the increase in infectiousness of AIDS individuals in comparison to HIV infected without clinical symptoms of AIDS (ωH). The distribution of RH is RH∈[0.88,2.79] with a mean of RH=1.46. The dominant parameters that affect the dynamics of the full VL-HIV model (with respect to the associated reproduction number, RLH, as the response function) are the transmission rate of HIV (βH), the average number of times a sandfly bites humans per unit time (σV), and HIV-induced death rate (δH) (the distribution of RLH is RLH∈[0.88,3.94] with a mean of RLH=1.64). Numerical simulations of the model show that the two diseases co-exist (with AVL dominating, but not driving HIV to extinction) whenever the reproduction number of each disease exceeds unity. It is shown that AVL can invade a population at HIV-endemic state if a certain threshold quantity, known as invasion reproduction number, exceeds unity.

Eco-epidemiology of visceral leishmaniasis in Ethiopia

Visceral leishmaniasis (VL, Kala-azar) is one of the growing public health challenges in Ethiopia with over 3.2 million people at risk and estimated up to 4000 new cases per year. Historically, VL was known as the diseases of the lowlanders; in the lower and upper Kola agro-ecological zones of Ethiopia. The 2005–07 out breaks in highlands of Libo Kemkem and Fogera, in the Woina Degas, that affected thousands and claimed the life of hundreds misdiagnosed as drug resistance malaria marked that VL is no more the problem of the lowlanders. The Kola (lower and upper) and the Woina Dega are the most productive agroecological zones, supporting both the ongoing and planned expansions of large or small scale agriculture and/or agriculture based industries. Thus, the (re)emergence of VL is not only a public health and social problem but also have a direct implication on the country’s economy and further development. Thus is high time for its control and/or elimination. Yet, the available data seem incomplete to plan for a cost-effective and efficient VL control strategy: there is a need to update data on vector behaviour in specific ecosystems and the roles of domestic animals need to be ascertained. The effectiveness and social acceptability of available vector control tools need be evaluated. There is a need for identifying animal reservoir(s), or establish the absence of zoonosis in Ethiopia. The planning of prevention of (re)emergence and spread of VL to areas adjacent to endemic foci need be supported with information from spatio-temporal mapping. In affected communities, available data showed that their knowledge about VL is generally very low. Thus, well designed studies to identify risk factors, as well as better tools for social mobilization with the understanding of their knowledge, aptitude and practice towards VL are necessary.