scholarly journals Rapid shifts in the age-specific burden of malaria following successful control interventions in four regions of Uganda

2020 ◽  
Author(s):  
Simon P. Kigozi ◽  
Ruth N. Kigozi ◽  
Adrienne Epstein ◽  
Arthur Mpimbaza ◽  
Asadu Sserwanga ◽  
...  
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Indoor Residual Spraying ◽  
Malaria Prevention ◽  
Older Individuals ◽  
Multinomial Regression ◽  
Transmission Reduction ◽  
Successful Control ◽  
And Control ◽  
The Impact

Abstract Background: Malaria control using long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) has been associated with reduced transmission throughout Africa. However, the impact of transmission reduction on the age distribution of malaria cases remains unclear.Methods: Over a 10-year period (January, 2009 to July, 2018), outpatient surveillance data from four health facilities in Uganda were used to estimate the impact of control interventions on temporal changes in the age distribution of malaria cases using multinomial regression. Interventions included mass distribution of LLINs at all sites and IRS at two sites.Results: Overall, 896,550 patient visits were included in the study; 211,632 aged <5 years, 171,166 aged 5-15 years, and 513,752 >15 years. Over time, the age distribution of patients not suspected of malaria and those malaria negative either declined or remained the same across all sites. In contrast, the age distribution of suspected and confirmed malaria cases increased across all four sites. In the two LLINs-only sites, the proportion of malaria cases in <5 years decreased from 31% to 16% and 35% to 25%, respectively. In the two sites receiving LLINs plus IRS, these proportions decreased from 58% to 30% and 64% to 47%, respectively. Similarly, in the LLINs-only sites, the proportion of malaria cases >15 years increased from 40% to 61% and 29% to 39%, respectively. In the sites receiving LLINs plus IRS, these proportions increased from 19% to 44% and 18% to 31%, respectively.Conclusions: These findings demonstrate a shift in the burden of malaria from younger to older individuals following implementation of successful control interventions, which has important implications for malaria prevention, surveillance, case management and control strategies.

scholarly journals Rapid shifts in the age-specific burden of malaria following successful control interventions in four regions of Uganda

2020 ◽  
Author(s):  
Simon P. Kigozi ◽  
Ruth N. Kigozi ◽  
Adrienne Epstein ◽  
Arthur Mpimbaza ◽  
Asadu Sserwanga ◽  
...  
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Indoor Residual Spraying ◽  
Malaria Prevention ◽  
Older Individuals ◽  
Multinomial Regression ◽  
Transmission Reduction ◽  
Successful Control ◽  
And Control ◽  
The Impact

Abstract Background: Malaria control using long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) has been associated with reduced transmission throughout Africa. However, the impact of transmission reduction on the age distribution of malaria cases remains unclear. Methods: Over a 10-year period (January, 2009 to July, 2018), outpatient surveillance data from four health facilities in Uganda were used to estimate the impact of control interventions on temporal changes in the age distribution of malaria cases using multinomial regression. Interventions included mass distribution of LLINs at all sites and IRS at two sites. Results: Overall, 896,550 patient visits were included in the study; 211,632 aged <5 years, 171,166 aged 5-15 years, and 513,752 >15 years. Over time, the age distribution of patients not suspected of malaria and those malaria negative either declined or remained the same across all sites. In contrast, the age distribution of suspected and confirmed malaria cases increased across all four sites. In the two LLINs-only sites, the proportion of malaria cases in <5 years decreased from 31% to 16% and 35% to 25%, respectively. In the two sites receiving LLINs plus IRS, these proportions decreased from 58% to 30% and 64% to 47%, respectively. Similarly, in the LLINs-only sites, the proportion of malaria cases >15 years increased from 40% to 61% and 29% to 39%, respectively. In the sites receiving LLINs plus IRS, these proportions increased from 19% to 44% and 18% to 31%, respectively. Discussion: These findings demonstrate a shift in the burden of malaria from younger to older individuals following implementation of successful control interventions, which has important implications for malaria prevention, surveillance, case management and control strategies.

scholarly journals Rapid shifts in the age-specific burden of malaria following successful control interventions in four regions of Uganda

2019 ◽  
Author(s):  
Simon P. Kigozi ◽  
Ruth N. Kigozi ◽  
Adrienne Epstein ◽  
Arthur Mpimbaza ◽  
Asadu Sserwanga ◽  
...  
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Indoor Residual Spraying ◽  
Malaria Prevention ◽  
Older Individuals ◽  
Multinomial Regression ◽  
Transmission Reduction ◽  
Successful Control ◽  
And Control ◽  
The Impact

Abstract Background: Malaria control using long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) has been associated with reduced transmission throughout Africa. However, the impact of transmission reduction on the age distribution of malaria cases remains unclear. Methods: Over a 10-year period (January, 2009 to July, 2018), outpatient surveillance data from four health facilities in Uganda were used to estimate the impact of control interventions on temporal changes in the age distribution of malaria cases using multinomial regression. Interventions included mass distribution of LLINs at all sites and IRS at two sites. Results: Overall, 896,550 patient visits were included in the study; 211,632 aged <5 years, 171,166 aged 5-15 years, and 513,752 >15 years. Over time, the age distribution of patients not suspected of malaria and those malaria negative either declined or remained the same across all sites. In contrast, the age distribution of suspected and confirmed malaria cases increased across all four sites for. In the two LLINs-only sites, the proportion of malaria cases in <5 years decreased from 31% to 16% and 35% to 25%, respectively. In the two sites receiving LLINs plus IRS, these proportions decreased from 58% to 30% and 64% to 47%, respectively. Similarly, in the LLINs-only sites, the proportion of malaria cases >15 years of age increased from 40% to 61% and 29% to 39%, respectively. In the sites receiving LLINs plus IRS, these proportions increased from 19% to 44% and 18% to 31%, respectively. Discussion: These findings demonstrate a shift in the burden of malaria from younger to older individuals following implementation of successful control interventions, which has important implications for malaria prevention, surveillance, case management and control strategies.

scholarly journals Assessing the impact of low-technology emanators alongside long-lasting insecticidal nets to control malaria

2020 ◽  
Vol 376 (1818) ◽  
pp. 20190817 ◽  
Author(s):  
Joel Hellewell ◽  
Ellie Sherrard-Smith ◽  
Sheila Ogoma ◽  
Thomas S. Churcher
Keyword(s):  
Disease Transmission ◽  
Pyrethroid Resistance ◽  
Control Strategies ◽  
Indoor Residual Spraying ◽  
Additional Benefit ◽  
Sub Saharan Africa ◽  
Outdoor Biting ◽  
Mosquito Mortality ◽  
The Impact ◽  
Long Lasting Insecticidal Nets

Malaria control in sub-Saharan Africa relies on the widespread use of long-lasting insecticidal nets (LLINs) or the indoor residual spraying of insecticide. Disease transmission may be maintained even when these indoor interventions are universally used as some mosquitoes will bite in the early morning and evening when people are outside. As countries seek to eliminate malaria, they can target outdoor biting using new vector control tools such as spatial repellent emanators, which emit airborne insecticide to form a protective area around the user. Field data are used to incorporate a low-technology emanator into a mathematical model of malaria transmission to predict its public health impact across a range of scenarios. Targeting outdoor biting by repeatedly distributing emanators alongside LLINs increases the chance of elimination, but the additional benefit depends on the level of anthropophagy in the local mosquito population, emanator effectiveness and the pre-intervention proportion of mosquitoes biting outdoors. High proportions of pyrethroid-resistant mosquitoes diminish LLIN impact because of reduced mosquito mortality. When mosquitoes are highly anthropophagic, this reduced mortality leads to more outdoor biting and a reduced additional benefit of emanators, even if emanators are assumed to retain their effectiveness in the presence of pyrethroid resistance. Different target product profiles are examined, which show the extra epidemiological benefits of spatial repellents that induce mosquito mortality. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases’.

Introduction to pertussis transmission and epidemiological dynamics

Pertussis ◽  
2018 ◽  
pp. 6-25
Author(s):  
Pejman Rohani ◽  
Samuel V. Scarpino
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Population Level ◽  
Vaccine Uptake ◽  
Effective Control ◽  
Transmission Potential ◽  
Epidemic Period ◽  
The Impact ◽  
Pertussis Epidemiology

Resolving the long-term, population-level consequences of changes in pertussis epidemiology, arising from bacterial evolution, shifts in vaccine-induced immunity, or changes in surveillance, are key challenges for devising effective control strategies. This chapter reviews some of the key features of pertussis epidemiology, together with the underlying epidemiological principles that set the context for their interpretation. These include the relationship between the age distribution of cases and pertussis transmission potential, the impact of vaccine uptake on incidence, periodicity and age incidence, as well as spatially explicit recurrent pertussis epidemics and associated extinction frequency. This review highlights some of the predictable and consistent aspects of pertussis epidemiology (e.g. the systematic increase in the inter-epidemic period with the introduction of whole-cell vaccines) and a number of important heterogeneities, including variations in contemporary patterns of incidence and geographic spread.

Assessing the Impact of Temperature Change on the Effectiveness of Insecticide-Treated Nets

2011 ◽  
Vol 3 (3) ◽  
pp. 35-48 ◽  
Author(s):  
Gregory J. Davis
Keyword(s):  
Control Strategies ◽  
Global Climate ◽  
Financial Burden ◽  
Insecticide Treated Nets ◽  
Policy Makers ◽  
Agent Based ◽  
Mosquito Abundance ◽  
Vector Borne ◽  
And Control ◽  
The Impact

Malaria is a vector-borne illness affecting millions of lives annually and imposes a heavy financial burden felt worldwide. Moreover, there is growing concern that global climate change, in particular, rising temperature, will increase this burden. As such, policy makers are in need of tools capable of informing them about the potential strengths and weaknesses of intervention and control strategies. A previously developed agent-based model of the Anopheles gambiae mosquito is extended, one of the primary vectors of malaria, to investigate how changes in temperature influence the dynamics of malaria transmission and the effectiveness of a common malaria intervention: insecticide-treated nets (ITNs). Results from the simulations suggest two important findings. Consistent with previous studies, an increase in mosquito abundance as temperature increases is observed. However, the increase in mosquito abundance reduces the effectiveness of ITNs at a given coverage level. The implications and limitations of these findings are discussed.

scholarly journals Mathematical modelling and phylodynamics for the study of dog rabies dynamics and control: A scoping review

2021 ◽  
Vol 15 (5) ◽  
pp. e0009449
Author(s):  
Maylis Layan ◽  
Simon Dellicour ◽  
Guy Baele ◽  
Simon Cauchemez ◽  
Hervé Bourhy
Keyword(s):  
Mathematical Modelling ◽  
Mathematical Models ◽  
Scoping Review ◽  
Control Strategies ◽  
Domestic Dog ◽  
Interdisciplinary Approaches ◽  
Dynamics And Control ◽  
And Control ◽  
The Impact

Background Rabies is a fatal yet vaccine-preventable disease. In the last two decades, domestic dog populations have been shown to constitute the predominant reservoir of rabies in developing countries, causing 99% of human rabies cases. Despite substantial control efforts, dog rabies is still widely endemic and is spreading across previously rabies-free areas. Developing a detailed understanding of dog rabies dynamics and the impact of vaccination is essential to optimize existing control strategies and developing new ones. In this scoping review, we aimed at disentangling the respective contributions of mathematical models and phylodynamic approaches to advancing the understanding of rabies dynamics and control in domestic dog populations. We also addressed the methodological limitations of both approaches and the remaining issues related to studying rabies spread and how this could be applied to rabies control. Methodology/principal findings We reviewed how mathematical modelling of disease dynamics and phylodynamics have been developed and used to characterize dog rabies dynamics and control. Through a detailed search of the PubMed, Web of Science, and Scopus databases, we identified a total of n = 59 relevant studies using mathematical models (n = 30), phylodynamic inference (n = 22) and interdisciplinary approaches (n = 7). We found that despite often relying on scarce rabies epidemiological data, mathematical models investigated multiple aspects of rabies dynamics and control. These models confirmed the overwhelming efficacy of massive dog vaccination campaigns in all settings and unraveled the role of dog population structure and frequent introductions in dog rabies maintenance. Phylodynamic approaches successfully disentangled the evolutionary and environmental determinants of rabies dispersal and consistently reported support for the role of reintroduction events and human-mediated transportation over long distances in the maintenance of rabies in endemic areas. Potential biases in data collection still need to be properly accounted for in most of these analyses. Finally, interdisciplinary studies were determined to provide the most comprehensive assessments through hypothesis generation and testing. They also represent new avenues, especially concerning the reconstruction of local transmission chains or clusters through data integration. Conclusions/significance Despite advances in rabies knowledge, substantial uncertainty remains regarding the mechanisms of local spread, the role of wildlife in dog rabies maintenance, and the impact of community behavior on the efficacy of control strategies including vaccination of dogs. Future integrative approaches that use phylodynamic analyses and mechanistic models within a single framework could take full advantage of not only viral sequences but also additional epidemiological information as well as dog ecology data to refine our understanding of rabies spread and control. This would represent a significant improvement on past studies and a promising opportunity for canine rabies research in the frame of the One Health concept that aims to achieve better public health outcomes through cross-sector collaboration.

scholarly journals Trends in malaria cases and stratification of malaria incidence in the malaria elimination setting, Harari Region, Eastern Ethiopia

2020 ◽  
Author(s):  
Endashaw Esayas ◽  
Asefa Tufa ◽  
Fekadu Massebo ◽  
Abdulhamid Ahemed ◽  
Ibssa Ibrahim ◽  
...  
Keyword(s):  
Malaria Elimination ◽  
Prevention And Control ◽  
Malaria Incidence ◽  
Control Strategies ◽  
Epidemiological Data ◽  
Malaria Prevention ◽  
Scaling Up ◽  
Malaria Risk ◽  
Eastern Ethiopia ◽  
And Control

Abstract Abstract Background: Ethiopia has shown a notable progress in reducing the burden of malaria over the last two decades. Based on the progress, the country shifted from control to elimination of malaria. This study was conducted to analyse trends in malaria cases and stratification of malaria incidence in the malaria elimination setting in eastern Ethiopia. Methods: A retrospective malaria data recorded from 2013 to 2019 were reviewed from Harari Region, eastern Ethiopia. In addition, three years malaria data were used to assess the sub-district ( kebele ) level stratification of malaria incidence. Results: A total of 44,882 (46.9%) malaria cases were detected from 95,629 malaria-suspected outpatient diagnosed in Harari Region from 2013 to 2019. Of these, 41,046 were confirmed malaria cases (microscopically and rapid diagnostic test) while 3,836 were reported as clinical cases. In the region, malaria trend was fluctuating year to year, the high peak was reported in 2016 but malaria cases showed decreasing trend in number of malaria cases from 2017 to 2019. Plasmodium falciparum , P. vivax and mixed infections were accounted for 69.2%, 30.6% and 0.2% of the cases, respectively. The malaria risk appears to be heterogeneous and varies between districts, higher number of malaria cases were recorded in Jenella, Erer and Amir Nur districts, and about 80% of the cases were from these districts. According to the latest (2019) sub-district ( kebele ) level epidemiological data of malaria stratification, 8.3% of the sub-districts in the Harari region reported no malaria and a majority (61.1%) of sub-districts reported fewer than five cases per thousand population. Furthermore, there were no high malaria strata in the Region. The highest peak of malaria cases in the Region was reported from September to November followed by from April to May. Conclusions: In the Harari Region, the retrospective malaria data showed a significant declining trend. Thus, if this achievement is sustained and scaling-up of the existing malaria prevention and control strategies by focusing on those populations living in the higher malaria transmission districts and sub-districts, planning of malaria elimination from the study area might be feasible. Key words: Elimination, Harari region, Ethiopia, Incidence, Malaria, Sub-district, Stratification

scholarly journals Multiple insecticide resistance target sites in adult field strains of An. gambiae s.l. from southeast Senegal.

2020 ◽  
Author(s):  
El hadji Diouf ◽  
El hadji Amadou Niang ◽  
Badara Samb ◽  
Cheikh Tidiane Diagne ◽  
Mbaye Diouf ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Control Strategies ◽  
Mosquito Species ◽  
Indoor Residual Spraying ◽  
Malaria Prevention ◽  
Mortality Rates ◽  
Malaria Vectors ◽  
Public Health Issue ◽  
Genetic Mutations ◽  
African Countries

Abstract Background: Malaria prevention strategies are based on the use of long-lasting insecticide-treated mosquito nets (LLINs), indoor residual spraying of insecticides (IRS) and seasonal malaria chemoprevention (SMC). The combination of these strategies with artemisinin-based combination therapy (ACTs) has led to a significant reduction in malaria cases. However, malaria remains a major public health issue in most sub-Saharan African countries. Indeed, the resistance of vectors to most WHO-approved insecticides could jeopardize vector-control strategies. This study examines insecticide resistance and associated genetic mutations among malaria vectors in southeast Senegal. Methods: The study was conducted in October and November 2014 in two sites in southeast Senegal. An. gambiae s.l. populations were sampled from Kedougou (Kedougou district) and Wassadou-Badi (Tambacounda district) and were evaluated for insecticide resistance according to WHO susceptibility tests. Specimens were 3 to 5-day-old adults raised from collected larvae. Eleven insecticides belonging to the four known classes of insecticides were assessed. Mosquito species were identified and mutations associated with insecticide resistance (ace-1, rdl (A296S or A296G), Vgsc-1014F and Vgsc-1014S) were determined. Results: A total of 3,742 An. gambiae s.l. were exposed to insecticides (2,439 from Kedougou and 1,303 from Wassadou-Badi). In both sites, mosquitoes showed high levels of resistance to all the five pyrethroids tested (mortality rates ranged from 42.8 to 81.4% in Kedougou and 52.4 to 86.4% in Wassadou-Badi) as well as to dieldrin (67.8 and 83%) and DDT (12.7 and 55%). The mosquitoes were susceptible to pirimiphos-methyl (mortality rate 100%) and malathion (mortality rates 100% and 99% in Kedougou and Wassadou-Badi respectively). An. gambiae s.l. populations from Kedougou were also resistant to bendiocarb and fenitrothion. Of the 745 An. gambiae s.l. genotyped An. gambiae s.s. (71.6%) was the predominant species, followed by An. arabiensis (21.7%), An. coluzzii (6.3%) and hybrids (An. gambiae s.s./An. coluzzii; 0.4%). The Vgsc-1014F mutation was widely distributed and is predominant in An. gambiae s.s. and An. coluzzii in comparison to An. arabiensis. Vgsc-1014S was present in An. gambiae s.l. populations in Wassadou but not in Kedougou. The ace-1 and rdl mutations were more frequent in An. gambiae s.s. compared to An. arabiensis whereas they were detected weakly in An. coluzzii populations.Conclusions: The present study demonstrates the resistance of malaria vectors to pyrethroids and organo chlorines in southeast Senegal as well as the presence of genetic mutations associated with this resistance in An. gambiae s.l. No Vgsc-1014S mutation was detected in An. gambiae s.s. population in Kedougou. These findings are key for monitoring and managing the resistance of vectors to insecticides in this region.

scholarly journals Evaluating the Effectiveness of Vaccines Using a Regression Discontinuity Design

2019 ◽  
Vol 188 (6) ◽  
pp. 987-990
Author(s):  
Nicole E Basta ◽  
M Elizabeth Halloran
Keyword(s):  
Randomized Clinical Trials ◽  
Regression Discontinuity ◽  
Control Strategies ◽  
Regression Discontinuity Design ◽  
Vaccination Programs ◽  
Wide Range ◽  
Quasi Experimental ◽  
Psychology Literature ◽  
And Control ◽  
The Impact

Abstract The regression discontinuity design (RDD), first proposed in the educational psychology literature and popularized in econometrics in the 1960s, has only recently been applied to epidemiologic research. A critical aim of infectious disease epidemiologists and global health researchers is to evaluate disease prevention and control strategies, including the impact of vaccines and vaccination programs. RDDs have very rarely been used in this context. This quasi-experimental approach using observational data is designed to quantify the effect of an intervention when eligibility for the intervention is based on a defined cutoff such as age or grade in school, making it ideally suited to estimating vaccine effects given that many vaccination programs and mass-vaccination campaigns define eligibility in this way. Here, we describe key features of RDDs in general, then specific scenarios, with examples, to illustrate that RDDs are an important tool for advancing our understanding of vaccine effects. We argue that epidemiologic researchers should consider RDDs when evaluating interventions designed to prevent and control diseases. This approach can address a wide range of research questions, especially those for which randomized clinical trials would present major challenges or be infeasible. Finally, we propose specific ways in which RDDs could advance future vaccine research.

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