scholarly journals Omitting age-dependent mosquito mortality in malaria models underestimates the effectiveness of insecticide-treated nets

2021 ◽  
Author(s):  
Melissa Alexis Iacovidou ◽  
Priscille Barreaux ◽  
Matthew B Thomas ◽  
Erin E Gorsich ◽  
Kat S Rock
Keyword(s):  
Mathematical Models ◽  
Mortality Rates ◽  
Vectorial Capacity ◽  
Insecticide Treated Nets ◽  
Mosquito Mortality ◽  
Age Dependent ◽  
Vector Borne ◽  
Mortality Function ◽  
The Impact ◽  
Age Independent

Mathematical models of vector-borne infections, including malaria, often assume age-independent mortality rates of vectors, despite evidence that many insects senesce. In this study we present survival data on insecticide-resistant Anopheles gambiae s.l. from field experiments in Côte d’Ivoire. We fit a constant mortality function and two age-dependent functions (logistic and Gompertz) to the data from mosquitoes exposed (treated) and not exposed (control) to insecticide-treated nets (ITNs), to establish biologically realistic survival functions. This enables us to explore the effects of insecticide exposure on mosquito mortality rates, and the extent to which insecticide resistance might impact the effectiveness of ITNs. We investigate this by calculating the expected number of infectious bites a mosquito will take in its lifetime, and by extension the vectorial capacity. Our results show that the predicted vectorial capacity is substantially lower in mosquitoes exposed to ITNs, despite the mosquitoes in the experiment being highly insecticide-resistant. The more realistic age-dependent functions provide a better fit to the experimental data compared to a constant mortality function and, hence, influence the predicted impact of ITNs on malaria transmission potential. In models with age-independent mortality, there is a reduction of 56.52% ( [[EQUATION]] 14.66) for the vectorial capacity under exposure compared to no exposure. However, the two age-dependent functions predicted a larger reduction due to exposure: for the logistic function the reduction is 74.38% ( [[EQUATION]] 9.93) and for the Gompertz 74.35% ( [[EQUATION]] 7.11), highlighting the impact of incorporating age in the mortality rates. These results further show that multiple exposures to ITNs had a considerable effect on the vectorial capacity. Overall, the study highlights the importance of including age dependency in mathematical models of vector-borne disease transmission and in fully understanding the impact of interventions.

How to model the impact of climate change on vector-borne diseases?

2021 ◽  
pp. 26-31
Author(s):  
Cyril Caminade
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Mathematical Models ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Risk ◽  
Vector Borne Diseases ◽  
Impact Of Climate Change ◽  
Vector Borne ◽  
The Impact

Abstract This expert opinion provides an overview of mathematical models that have been used to assess the impact of climate change on ticks and tick-borne diseases, ways forward in terms of improving models for the recent context and broad guidelines for conducting future climate change risk assessment.

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 Age-Independent Adult Mortality in a Long-Lived Herb

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 187 ◽  
Author(s):  
Edelfeldt ◽  
Lindell ◽  
Dahlgren
Keyword(s):  
General Pattern ◽  
Cost Of Reproduction ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Trade Offs ◽  
Age Dependent ◽  
Annual Mortality ◽  
Age Independent ◽  
Long Term Studies

Relative to mammals and birds, little is known about the mortality trajectories of perennial plants, as there are few long-term demographic studies following multiple yearly cohorts from birth to death. This is particularly important because if reproductively mature individuals show actuarial senescence, current estimations of life spans assuming constant survival would be incorrect. There is also a lack of studies documenting how life history trade-offs and disturbance influence the mortality trajectories of plants. We conducted Bayesian survival trajectory analyses (BaSTA) of a 33-year individual-based dataset of Pulsatilla vulgaris ssp. gotlandica. Mortality trajectories corresponded to “Type III” survivorship patterns, with rapidly decreasing annual mortality rates for young plants, but with constant mortality for reproductively mature individuals. We found trade-off effects resulting in a cost of growth for non-reproductive plants but no apparent cost of reproduction. Contrarily to our expectation, young plants that had previously shrunk in size had a lower mortality. However, accounting for trade-offs and disturbance only had minor effects on the mortality trajectories. We conclude that BaSTA is a useful tool for assessing mortality patterns in plants if only partial age information is available. Furthermore, if constant mortality is a general pattern in polycarpic plants, long-term studies may not be necessary to assess their age-dependent demography.

Abstract 18130: Quantitative Heart Measures Are More Predictive of 1-Year Mortality Than Weight-Based Donor-Recipient Matching in Heart Transplantation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ziad Taimeh ◽  
Khalil Murad ◽  
Monica Colvin ◽  
Sue Duval ◽  
Cindy Martin ◽  
...  
Keyword(s):  
Heart Transplantation ◽  
Mathematical Models ◽  
Mortality Rates ◽  
Cardiac Volume ◽  
Ethnic Study ◽  
End Diastolic Volume ◽  
Ventricular Mass ◽  
The Impact ◽  
Age And Sex ◽  
United Network

Introduction and hypothesis: Donor-recipient matching in heart transplantation (HT) is heavily dependent on weight. The limited pool of donor hearts mandates efforts to expand that pool without compromising outcomes. We evaluated the impact of matching based on quantitative heart measures (QHMs) on 1-year survival after HT. Methods: Data from the United Network for Organ Sharing (UNOS) registry was used to calculate QHMs of both donors and recipients of HT. QHM uses validated mathematical models derived from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort based on height, weight, age, and sex to estimate total ventricular mass (TVM), total ventricular end-diastolic volume (TVV), and total cardiac volume (TCV). The matching level of each donor-recipient pair was assessed for each QHM; matched ±25%, undersized and oversized. Association between matching level (by weight, and by each QHM) and 1-year mortality rates were then analyzed. Results: We identified a total of 37,265 donor-recipient pairs between 1987 and 2013. Matching by weight did not have any 1-year mortality (p=0.43) benefit. Under-sizing or over-sizing by TCV had significantly higher 1-year mortality (p<0.001). Over-sizing by either TVM or TVV had significantly higher 1-year mortality (p<0.001, p=0.024, respectively) (Table and Figure). Conclusions: In HT, donor-recipient matching by QHMs derived from height, weight, age, and sex may offer advantages for making decisions about organ suitability over a weight-based algorithm.

scholarly journals Accessing the syndemic of COVID-19 and malaria intervention in Africa

2020 ◽  
Author(s):  
Benyun Shi ◽  
Jinxin Zheng ◽  
Shang Xia ◽  
Shan Lin ◽  
Xinyi Wang ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Malaria Transmission ◽  
Vectorial Capacity ◽  
Insecticide Treated Nets ◽  
Transmission Potential ◽  
The Impact ◽  
Pharmaceutical Interventions ◽  
Epidemiological Parameters

Abstract Background: The pandemic of the coronavirus disease 2019 (COVID-19) has caused substantial disruptions to health services in the low and middle-income countries with a high burden of other diseases, such as malaria in sub-Saharan Africa. The aim of this study is to assess the impact of COVID-19 pandemic on malaria transmission potential in malaria-endemic countries in Africa. Methods: We present a data-driven method to quantify the extent to which the COVID-19 pandemic, as well as various non-pharmaceutical interventions (NPIs), could lead to the change of malaria transmission potential in 2020. First, we adopt a particle Markov Chain Monte Carlo method to estimate epidemiological parameters in each country by fitting the time series of the cumulative number of reported COVID-19 cases. Then, we simulate the epidemic dynamics of COVID-19 under two groups of NPIs: (i) contact restriction and social distancing, and (ii) early identification and isolation of cases. Based on the simulated epidemic curves, we quantify the impact of COVID-19 epidemic and NPIs on the distribution of insecticide-treated nets (ITNs). Finally, by treating the total number of ITNs available in each country in 2020, we evaluate the negative effects of COVID-19 pandemic on malaria transmission potential based on the notion of vectorial capacity. Results: In this paper, we conduct case studies in four malaria-endemic countries, Ethiopia, Nigeria, Tanzania, and Zambia, in Africa. The epidemiological parameters (i.e., the basic reproduction number R_0 and the duration of infection D_I) of COVID-19 in each country are estimated as follows: Ethiopia (R_0=1.57, D_I=5.32), Nigeria (R_0=2.18, D_I=6.58), Tanzania (R_0=2.47, D_I=6.01), and Zambia (R_0=2.12, D_I=6.96). Based on the estimated epidemiological parameters, the epidemic curves simulated under various NPIs indicated that the earlier the interventions are implemented, the better the epidemic is controlled. Moreover, the effect of combined NPIs is better than contact restriction and social distancing only. By treating the total number of ITNs available in each country in 2020 as a baseline, our results show that even with stringent NPIs, malaria transmission potential will remain higher than expected in the second half of 2020. Conclusions: By quantifying the impact of various NPI response to the COVID-19 pandemic on malaria transmission potential, this study provides a way to jointly address the syndemic between COVID-19 and malaria in malaria-endemic countries in Africa. The results suggest that the early intervention of COVID-19 can effectively reduce the scale of the epidemic and mitigate its impact on malaria transmission potential. Keywords : COVID-19 pandemic; Non-pharmaceutical interventions; Particle Markov chain Monte Carlo; Insecticide-treated nets; Vectorial capacity; Malaria transmission potential

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

2012 ◽  
pp. 241-255
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 Impact of Intervention Practices on Malaria Treatment Outcomes Among Patients in Bushenyi District, Uganda

2021 ◽  
Author(s):  
Josephat Nyabayo Maniga ◽  
David Kalenzi Atuhaire ◽  
Claire Mack Mugasa
Keyword(s):  
Treatment Outcomes ◽  
Indoor Residual Spraying ◽  
Cross Sectional Study ◽  
Malaria Treatment ◽  
Insecticide Treated Nets ◽  
Cross Sectional ◽  
Vector Borne ◽  
One Year ◽  
Study Participants ◽  
The Impact

Abstract BackgroundMalaria remains a major vector borne disease causing both mortalities and morbidities in the world. Uganda as a country has currently scaled out major campaigns to reduce and eliminate the disease using different interventions. However, there is no clear data on the impact of such interventions on malaria treatment outcomes. Therefore, this study was aimed at assessing the impact of malaria intervention practices on Artemether- Lumefantrine (AL) treatment outcomes among the residents of Bushenyi district, Uganda, a high intensity malaria transmission area.MethodsThis was a descriptive cross-sectional study carried out among 184 study participants for a period of one year (August 2017 to August 2018) in four selected health centers in Bushenyi district, Uganda. The investigative methods used included a researcher administered questionnaire, laboratory and clinical evaluations of participants. Data analysis was done by using statistical package for social sciences (SPSS version 10 windows) for descriptive statistics. ResultsStatistically significant factors for treatment outcome at p ≤0.05 were; practicing indoor residual spraying (IRS) at home (𝑃 = 0.001; CI), source of prescription (𝑃 = 0.018; CI), finishing dosage (𝑃 = 0.006; CI), frequency of malaria infection (𝑃 = 0.028; CI), Frequency of antimalaria usage (𝑃 = 0.042; CI) and sleeping under insecticide treated nets (ITNs) (𝑃 = 0.039; CI) respectively. ConclusionsIRS and ITNs were found to be the major intervention practice of malaria reduction after treatment with ACTs.

The Scientific Basis for the Prevention of Zooanthroponoze Vector-Borne Diseases Spread by Parasitic Arthropods of the Center of the East European Plain

2020 ◽  
Vol 14 (1) ◽  
pp. 81-88
Author(s):  
Fedor I. Vasilevich ◽  
Anna M. Nikanorova
Keyword(s):  
Mathematical Models ◽  
Culex Pipiens ◽  
Preventive Measures ◽  
Mosquito Species ◽  
Natural Habitat ◽  
Piperonyl Butoxide ◽  
East European Plain ◽  
Vector Borne Diseases ◽  
Vector Borne ◽  
Kaluga Region

The purpose of the research is development of preventive measures against zooanthroponoze vector-borne diseases spread by parasitic arthropods in the Kaluga Region. Materials and methods. The subject of the research was Ixodidae, mosquitoes, and small mammals inhabiting the Kaluga Region. The census of parasitic arthropods was carried out on the territory of all districts of the Kaluga Region and the city of Kaluga. Open natural habitat and human settlements were investigated. Weather conditions from 2013 to 2018 were also taken into account. For the purposes of the study, we used standard methods for capturing and counting arthropods and mouse-like rodents. In order to obtain mathematical models of small mammal populations, a full factorial experiment was conducted using the collected statistical data. In-process testing of the drug based on s-fenvalerate and piperonyl butoxide were carried out under the conditions of the agricultural collective farm “Niva” of the Kozelsky District, the Kaluga Region, and LLC “Angus Center of Genetics” of the Babyninsky District, the Kaluga Region. Results and discussion. In the Kaluga Region, two species of ixodic ticks are found, namely, Ixodes ricinus and Dermacentor reticulatus, which have two activity peaks. Mosquito may have 3-4 generations in a year in the Kaluga region. The most common mosquito species in the Kaluga Region are Aedes communis, Ae. (Och.) togoi and Ae. (Och.) diantaeus, Culex pipiens Culex Linnaeus, 1758 (Diptera, Culicidae) (Culex pipiens): Cx. pipiens f. pipiens L. (non-autogenic form) and Cx. p. f. molestus Fors. (autogenic form), which interbreed, and reproductively isolated in the Region. The developed mathematical models make it possible to quantify the risks of outbreaks of zooanthroponoze vector-borne diseases without the cost of field research, and allow for rational, timely and effective preventive measures. Medications based on s-fenvalerate and piperonyl butoxide and based on cyfluthrin showed high insecto-acaricidal efficacy and safety.

scholarly journals Simultaneous Casualty Admissions—Do they Affect Treatment in the Receiving Trauma Center?

2021 ◽  
Author(s):  
Michel Paul Johan Teuben ◽  
Carsten Mand ◽  
Laura Moosdorf ◽  
Kai Sprengel ◽  
Alba Shehu ◽  
...  
Keyword(s):  
Injury Severity ◽  
Damage Control ◽  
Ct Scanning ◽  
Mortality Rates ◽  
Trauma Centers ◽  
Simultaneous Treatment ◽  
Diagnostic Pathway ◽  
Injured Patients ◽  
The Impact ◽  
Mean Time

Abstract Background Simultaneous trauma admissions expose medical professionals to increased workload. The impact of simultaneous trauma admissions on hospital allocation, therapy, and outcome is currently unclear. We hypothesized that multiple admission-scenarios impact the diagnostic pathway and outcome. Methods The TraumaRegister DGU® was utilized. Patients admitted between 2002–2015 with an ISS ≥ 9, treated with ATLS®- algorithms were included. Group ´IND´ included individual admissions, two individuals that were admitted within 60 min of each other were selected for group ´MULT´. Patients admitted within 10 min were considered as simultaneous (´SIM´) admissions. We compared patient and trauma characteristics, treatment, and outcomes between both groups. Results 132,382 admissions were included, and 4,462/3.4% MULTiple admissions were found. The SIM-group contained 1,686/1.3% patients. The overall median injury severity score was 17 and a mean age of 48 years was found. MULT patients were more frequently admitted to level-one trauma centers (68%) than individual trauma admissions were (58%, p < 0.001). Mean time to CT-scanning (24 vs. 26/28 min) was longer in MULT / SIM patients compared to individual admissions. No differences in utilization of damage control principles were seen. Moreover, mortality rates did not differ between the groups (13.1% in regular admissions and 11.4%/10,6% in MULT/SIM patients). Conclusion This study demonstrates that simultaneous treatment of injured patients is rare. Individuals treated in parallel with other patients were more often admitted to level-one trauma centers compared with individual patients. Although diagnostics take longer, treatment principles and mortality are equal in individual admissions and simultaneously admitted patients. More studies are required to optimize health care under these conditions.

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