scholarly journals Inferring transmission trees to guide targeting of interventions against visceral leishmaniasis and post-kala-azar dermal leishmaniasis

2020 ◽  
Author(s):  
Lloyd A. C. Chapman ◽  
Simon E. F. Spencer ◽  
Timothy M. Pollington ◽  
Chris P. Jewell ◽  
Dinesh Mondal ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Epidemiological Data ◽  
Disease Spread ◽  
Estimation Methods ◽  
Duration Of Symptoms ◽  
Individual Level ◽  
Targeted Interventions ◽  
Space And Time ◽  
Kala Azar ◽  
Spatiotemporal Transmission

Understanding of spatiotemporal transmission of infectious diseases has improved significantly in recent years. Advances in Bayesian inference methods for individual-level geo-located epidemiological data have enabled reconstruction of transmission trees and quantification of disease spread in space and time, while accounting for uncertainty in missing data. However, these methods have rarely been applied to endemic diseases or ones in which asymptomatic infection plays a role, for which novel estimation methods are required. Here, we develop such methods to analyse longitudinal incidence data on visceral leishmaniasis (VL), and its sequela, post-kala-azar dermal leishmaniasis (PKDL), in a highly endemic community in Bangladesh. Incorporating recent data on infectiousness of VL and PKDL, we show that while VL cases drive transmission when incidence is high, the contribution of PKDL increases significantly as VL incidence declines (reaching 55% in this setting). Transmission is highly focal: >85% of mean distances from inferred infectors to their secondary VL cases were <300m, and estimated average times from infector onset to secondary case infection were <4 months for 90% of VL infectors, but up to 2.75yrs for PKDL infectors. Estimated numbers of secondary VL cases per VL and PKDL case varied from 0-6 and were strongly correlated with the infector’s duration of symptoms. Counterfactual simulations suggest that prevention of PKDL could have reduced VL incidence by up to a quarter. These results highlight the need for prompt detection and treatment of PKDL to achieve VL elimination in the Indian subcontinent and provide quantitative estimates to guide spatiotemporally-targeted interventions against VL.Significance StatementAlthough methods for analysing individual-level geo-located disease data have existed for some time, they have rarely been used to analyse endemic human diseases. Here we apply such methods to nearly a decade’s worth of uniquely detailed epidemiological data on incidence of the deadly vector-borne disease visceral leishmaniasis (VL) and its secondary condition, post-kala-azar dermal leishmaniasis (PKDL), to quantify the spread of infection around cases in space and time by inferring who infected whom, and estimate the relative contribution of different infection states to transmission. Our findings highlight the key role long diagnosis delays and PKDL play in maintaining VL transmission. This detailed characterisation of the spatiotemporal transmission of VL will help inform targeting of interventions around VL and PKDL cases.

scholarly journals Inferring transmission trees to guide targeting of interventions against visceral leishmaniasis and post–kala-azar dermal leishmaniasis

2020 ◽  
Vol 117 (41) ◽  
pp. 25742-25750
Author(s):  
Lloyd A. C. Chapman ◽  
Simon E. F. Spencer ◽  
Timothy M. Pollington ◽  
Chris P. Jewell ◽  
Dinesh Mondal ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Indian Subcontinent ◽  
Epidemiological Data ◽  
Asymptomatic Infection ◽  
Disease Spread ◽  
Estimation Methods ◽  
Secondary Case ◽  
Duration Of Symptoms ◽  
Targeted Interventions ◽  
Kala Azar

Understanding of spatiotemporal transmission of infectious diseases has improved significantly in recent years. Advances in Bayesian inference methods for individual-level geo-located epidemiological data have enabled reconstruction of transmission trees and quantification of disease spread in space and time, while accounting for uncertainty in missing data. However, these methods have rarely been applied to endemic diseases or ones in which asymptomatic infection plays a role, for which additional estimation methods are required. Here, we develop such methods to analyze longitudinal incidence data on visceral leishmaniasis (VL) and its sequela, post–kala-azar dermal leishmaniasis (PKDL), in a highly endemic community in Bangladesh. Incorporating recent data on VL and PKDL infectiousness, we show that while VL cases drive transmission when incidence is high, the contribution of PKDL increases significantly as VL incidence declines (reaching 55% in this setting). Transmission is highly focal: 85% of mean distances from inferred infectors to their secondary VL cases were <300 m, and estimated average times from infector onset to secondary case infection were <4 mo for 88% of VL infectors, but up to 2.9 y for PKDL infectors. Estimated numbers of secondary cases per VL and PKDL case varied from 0 to 6 and were strongly correlated with the infector’s duration of symptoms. Counterfactual simulations suggest that prevention of PKDL could have reduced overall VL incidence by up to 25%. These results highlight the need for prompt detection and treatment of PKDL to achieve VL elimination in the Indian subcontinent and provide quantitative estimates to guide spatiotemporally targeted interventions against VL.

Factors associated with human visceral leishmaniasis cases during urban epidemics in Brazil: a systematic review

Parasitology ◽  
2021 ◽  
pp. 1-9
Author(s):  
Cleya da Silva Santana Cruz ◽  
David Soeiro Barbosa ◽  
Vinícius Cunha Oliveira ◽  
Diogo Tavares Cardoso ◽  
Nathália Sernizon Guimarães ◽  
...  
Keyword(s):  
Systematic Review ◽  
Visceral Leishmaniasis ◽  
Urban Areas ◽  
Grey Literature ◽  
Cochrane Library ◽  
Positive Correlation ◽  
Individual Level ◽  
Factors Associated ◽  
The North ◽  
Unified Health System

Abstract Visceral leishmaniasis (VL) is endemic in 70 countries and has been reported in 12 countries of Latin America, with over 90% of the cases reported in Brazil, where epidemics have occurred since 1980. The objective of this review is to describe the factors associated with the occurrence of VL epidemics in humans in urban areas. A systematic review was conducted according to the PRISMA-P guidelines. The databases PubMed (by Medline), Cochrane Library, Embase, Amed, LILACS and grey literature [Google Scholar and handsearch of the database of the Information System for Notifiable Diseases (SINAN) of Brazil's Unified Health System] were used. The protocol was registered under PROSPERO (CRD42019128998). Climatic, environmental factors and indicators of urban social structure were described as influencing the outbreaks in the North and Northeast regions. Gender and age characteristics were related to a greater chance of developing VL in the Central-West, Northeast and Southeast regions. Vector indicators showed a positive correlation with the incidence of VL in studies in the Northeast region. In the Southeast and Northeast regions, studies revealed the presence of dogs with positive correlation with VL. Knowledge gaps remain regarding the contribution to the increase in the risk factors described in ecological approaches, as no analysis was performed at the individual level, and it is still necessary to discuss the influence of other associated elements in epidemic episodes in the spread of VL.

Auxological perspectives on ‘growth’ in DOHaD

2015 ◽  
Vol 6 (5) ◽  
pp. 390-398 ◽  
Author(s):  
M. Lampl ◽  
A. Mummert ◽  
M. Schoen
Keyword(s):  
Disease Risk ◽  
Environmental Influences ◽  
Functional Anatomy ◽  
Biological Clocks ◽  
Maternal Condition ◽  
Future Health ◽  
Individual Level ◽  
Targeted Interventions ◽  
Specificity And Sensitivity ◽  
Multiple Variables

David Barker established growth as a seminal link between early development and later health attainment and disease risk. This was nothing less than a paradigm shift in health and medicine, turning the focus of disease causality away from contemporary environmental influences to earliest growth as a time when functional anatomy and physiology sets in place critical structures and function for a lifetime.Barker’s prodigious work investigated time- and place-specific interactions between maternal condition and exogenous environmental influences, focusing on how growth unfolds across development to function as a mechanistic link to ensuing health. Subsequent applications do not always attend to the specificity and sensitivity issues included in his original work, and commonly overlook the long-standing methods and knowledge base of auxology. Methodological areas in need of refinement include enhanced precision in how growth is represented and assessed. For example, multiple variables have been used as a referent for ‘growth,’ which is problematic because different body dimensions grow by different biological clocks with unique functional physiologies. In addition, categorical clinical variables obscure the spectrum of variability in growth experienced at the individual level. Finally, size alone is a limited measure as it does not capture how individuals change across age, or actually grow.The ground-breaking notion that prenatal influences are important for future health gave rise to robust interest in studying the fetus. Identifying the many pathways by which size is realized permits targeted interventions addressing meaningful mechanistic links between growth and disease risk to promote health across the lifespan.

scholarly journals Post-Kala-Azar Dermal Leishmaniasis Without Previous History of Visceral Leishmaniasis

2016 ◽  
Vol 95 (6) ◽  
pp. 1383-1385 ◽  
Author(s):  
Golam Hasnain ◽  
Dinesh Mondal ◽  
Shakhawat Hossain ◽  
Shinjiro Hamano ◽  
Prakash Ghosh ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Previous History ◽  
Kala Azar ◽  
History Of

scholarly journals The correlation between socioeconomic factors and COVID-19 among immigrants in Norway: a register-based study

2021 ◽  
pp. 140349482110158
Author(s):  
Marte Kjøllesdal ◽  
Katrine Skyrud ◽  
Abdi Gele ◽  
Trude Arnesen ◽  
Hilde Kløvstad ◽  
...  
Keyword(s):  
Socioeconomic Factors ◽  
Low Income ◽  
Emergency Preparedness ◽  
Epidemiological Data ◽  
Group Level ◽  
Socioeconomic Indicators ◽  
Targeted Interventions ◽  
Low Income Families ◽  
Crowded Housing

Aim: Immigrants in Norway have higher COVID-19 notification and hospitalisation rates than Norwegian-born individuals. The knowledge about the role of socioeconomic factors to explain these differences is limited. We investigate the relationship between socioeconomic indicators at group level and epidemiological data for all notified cases of COVID-19 and related hospitalisations among the 23 largest immigrant groups in Norway. Methods: We used data on all notified COVID-19 cases in Norway up to 15 November 2020, and associated hospitalisations, from the Norwegian Surveillance System for Communicable Diseases and the emergency preparedness register at the Norwegian Institute of Public Health. We report notified COVID-19 cases and associated hospitalisation rates per 100,000 and their correlation to income, education, unemployment, crowded housing and years of residency at the group level. Results: Crowded housing and low income at a group level were correlated with rates of both notified cases of COVID-19 (Pearson`s correlation coefficient 0.77 and 0.52) and related hospitalisations (0.72, 0.50). In addition, low educational level and unemployment were correlated with a high number of notified cases. Conclusions: Immigrant groups living in disadvantaged socioeconomic positions are important to target with preventive measures for COVID-19. This must include targeted interventions for low-income families living in overcrowded households.

scholarly journals How effective is dog culling in controlling zoonotic visceral leishmaniasis? a critical evaluation of the science, politics and ethics behind this public health policy

2011 ◽  
Vol 44 (2) ◽  
pp. 232-242 ◽  
Author(s):  
Carlos Henrique Nery Costa
Keyword(s):  
Visceral Leishmaniasis ◽  
Control Measure ◽  
Scientific Evidence ◽  
Critical Evaluation ◽  
Scientific Data ◽  
Ethical Considerations ◽  
Brazilian Government ◽  
Kala Azar ◽  
Scientific Results

INTRODUCTION: Zoonotic kala-azar, a lethal disease caused by protozoa of the genus Leishmania is considered out of control in parts of the world, particularly in Brazil, where transmission has spread to cities throughout most of the territory and mortality presents an increasing trend. Although a highly debatable measure, the Brazilian government regularly culls seropositive dogs to control the disease. Since control is failing, critical analysis concerning the actions focused on the canine reservoir was conducted. METHODS: In a review of the literature, a historical perspective focusing mainly on comparisons between the successful Chinese and Soviet strategies and the Brazilian approach is presented. In addition, analyses of the principal studies regarding the role of dogs as risk factors to humans and of the main intervention studies regarding the efficacy of the dog killing strategy were undertaken. Brazilian political reaction to a recently published systematic review that concluded that the dog culling program lacked efficiency and its effect on public policy were also reviewed. RESULTS: No firm evidence of the risk conferred by the presence of dogs to humans was verified; on the contrary, a lack of scientific support for the policy of killing dogs was confirmed. A bias for distorting scientific data towards maintaining the policy of culling animals was observed. CONCLUSIONS: Since there is no evidence that dog culling diminishes visceral leishmaniasis transmission, it should be abandoned as a control measure. Ethical considerations have been raised regarding distorting scientific results and the killing of animals despite minimal or absent scientific evidence

scholarly journals EXPANSION OF VISCERAL LEISHMANIASIS IN THE STATE OF RIO DE JANEIRO, BRAZIL: REPORT OF THE FIRST AUTOCHTHONOUS CASE IN THE MUNICIPALITY OF VOLTA REDONDA AND THE DIFFICULTY OF DIAGNOSIS

2014 ◽  
Vol 56 (3) ◽  
pp. 271-274 ◽  
Author(s):  
Luiz Henrique Conde Sangenis ◽  
Sebastião Roberto de Almeida Lima ◽  
Cíntia Xavier de Mello ◽  
Daniela Trindade Cardoso ◽  
Jurema Nunes Mello ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Symptom Onset ◽  
Urban Areas ◽  
Correct Diagnosis ◽  
Great Difficulty ◽  
The State ◽  
Differential Diagnoses ◽  
The North ◽  
Kala Azar ◽  
Epidemiological Changes

Visceral Leishmaniasis has been showing remarkable epidemiological changes in recent decades, with marked expansion and an emergence of cases in urban areas of the North, Southeast and Midwest regions of Brazil. The Kala-azar cases reported here, despite being very characteristic, presented a great difficulty of diagnosis, because the disease is not endemic in Volta Redonda. The child underwent two hospitalizations in different hospitals, but got the correct diagnosis only after 11 months of symptom onset. In this report we discuss the main differential diagnoses and call attention to the suspected symptoms of visceral leishmaniasis in patients with prolonged fever, hepatosplenomegaly and pancytopenia, even in areas not traditionally endemic for the disease.

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