scholarly journals La Crosse virus spread within the mosquito population in Knox County, TN

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249811
Author(s):  
Cameron Cook ◽  
Annastashia Blesi ◽  
Samantha Brozak ◽  
Suzanne Lenhart ◽  
Hanna Reed ◽  
...  
Keyword(s):  
Control Strategies ◽  
Mosquito Population ◽  
Health Concern ◽  
La Crosse Virus ◽  
Knox County ◽  
Vector Population ◽  
Driven System ◽  
Local Vector ◽  
Mosquito Population Dynamics ◽  
Entomological Data

In Appalachia, La Crosse virus (LACV) is a leading pediatric arbovirus and public health concern for children under 16 years. LACV is transmitted via the bite of an infected Aedes mosquito. Thus, it is imperative to understand the dynamics of the local vector population in order to assess risk and transmission. Using entomological data collected from Knox County, Tennessee in 2013, we formulate an environmentally-driven system of ordinary differential equations to model mosquito population dynamics over a single season. Further, we include infected compartments to represent LACV transmission within the mosquito population. Findings suggest that the model, with dependence on degree days and accumulated precipitation, can closely describe field data. This model confirms the need to include these environmental variables when planning control strategies.

scholarly journals Inter-annual variability of the effects of intrinsic and extrinsic drivers affecting West Nile virus vector Culex pipiens population dynamics in northeastern Italy

2020 ◽  
Author(s):  
Diletta Fornasiero ◽  
Matteo Mazzuccato ◽  
Marco Barbujani ◽  
Fabrizio Montarsi ◽  
Gioia Capelli ◽  
...  
Keyword(s):  
Population Dynamics ◽  
West Nile Virus ◽  
Intraspecific Competition ◽  
Culex Pipiens ◽  
Climatic Variables ◽  
Mosquito Population ◽  
Health Concern ◽  
West Nile ◽  
Northeastern Italy ◽  
Mosquito Population Dynamics

Abstract Background: Vector-borne infectious diseases (VBDs) represent a major public health concern worldwide. Among VBDs, West Nile Virus (WNV) showed an increasingly wider spread in temperate regions of Europe, including Italy. During the last decade, WNV outbreaks have been recurrently reported in mosquitoes, horses, wild birds, and humans, showing great variability in the temporal and spatial distribution pattern. Due to the complexity of the environment-host-vector-pathogen interaction and the incomplete understanding of the epidemiological pattern of the disease, WNV occurrences can be hardly predictable. The analyses of ecological drivers responsible for the earlier WNV reactivation and transmission are pivotal; in particular, variations in the vector population dynamics may represent a key point of the recent success of WNV and, more in general, of the VBDs.Methods: We investigated the variations of Culex pipiens population abundance using environmental, climatic and trapping data obtained over nine years (2010 to 2018) through the WNV entomological surveillance program implemented in northeastern Italy. An Information Theoretic approach (IT-AIC c ) and model-averaging algorithms were implemented to examine the relationship between the seasonal mosquito growth rates and both intrinsic (e.g. intraspecific competition) and extrinsic (e.g. environmental and climatic variables) predictors, to identify the most significant combinations of variables outlining the Cx. pipiens population dynamics. Results: Population density (proxy for intraspecific competition) and length of daylight were the predominant factors regulating the mosquito population dynamics; however, also other drivers encompassing environmental and climatic variables had a significant impact, although sometimes counterintuitive and not univocal. The analyses of the single-year datasets, and the comparison with the results obtained from the overall model (all data available from 2010 to 2018), highlighted remarkable differences in coefficients magnitude, sign, and significance. These outcomes indicate that different combinations of factors might have distinctive, and sometimes divergent, effects on mosquito population dynamics. Conclusions: A more realistic acquaintance of the intrinsic and extrinsic mechanism of mosquito population fluctuations in relation to continuous changes in environmental and climatic conditions is paramount to properly reinforce VBDs risk-based surveillance activities, to plan targeted density control measures and to implement effective early detection programs.

scholarly journals Effects of Spatial Heterogeneity on Transmission Potential in Vectorial-Contact Networks: A Comparison of Three Aedes aegypti Control Strategies

2017 ◽  
Author(s):  
Héctor M. Sánchez C. ◽  
John M. Marshall ◽  
Sean L. Wu ◽  
Edgar E. Vallejo
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Mosquito Control ◽  
Control Strategies ◽  
Human Movement ◽  
Mosquito Population ◽  
Human Populations ◽  
Lethal Gene ◽  
Contact Networks ◽  
Mosquito Population Dynamics

AbstractDengue, chikungunya and zika are all transmitted by the Aedes aegypti mosquito. Despite the strong influence of host spatial distribution and movement patterns on the ability of mosquito vectors to transmit pathogens, there is little understanding how these complex interactions modify the spread of disease in spatially heterogeneous populations. In light of present fears of a worldwide zika epidemic, and failures to eradicate dengue and chikungunya; there is a pressing need to get a better picture of how high-resolution details such as human movement in a small landscape, modify the patterns of transmission of these diseases and how different mosquito-control interventions could be affected by these movements.In this work we use a computational agent-based model (ABM) to simulate mosquito-human interactions in two different levels of spatial heterogeneity, with human movement, and in the presence of three mosquito-control interventions (spatial spraying, the release of Wolbachia-infected mosquitoes and release of insects with dominant lethal gene). To analyse the results from each of these experiments we examined mosquito population dynamics and host to host contact networks that emerged from the distribution of consecutive bites across humans. We then compared results across experiments to understand the differential effectiveness of different interventions in both the presence and absence of spatial heterogeneities, and analysed network measures of epidemiological relevance (degree probability distributions, mean path length, network density and small-worldness).From our experiments we conclude that spatial heterogeneity greatly influences how a pathogen may spread in a host population when mediated by a mosquito vector, and that these important heterogeneities also strongly affect effectiveness of interventions. Finally, we demonstrate that these host to host vectorial-contact networks can provide operationally important information to inform selection of optimal vector-control strategies.Author SummaryMosquito-borne diseases’ transmission patterns arise from the complex interactions between hosts and vector. Because these interactions are influenced by host and vector behaviour, spatial constraints, and other factors they are amongst the most difficult to understand. In this work, we use our computational agent-based model: SoNA3BS; to simulate two spatially different settings in the presence and absence of three different mosquito-control interventions: fogging, the release of Wolbachia-infected mosquitoes and the release of insects with dominant lethal gene. Throughout these simulations, we record mosquito population dynamics and mosquito bites on persons. We then compare mosquito population dynamics to the vectorial-contact networks (that emerge from subsequent mosquito bites between humans) and, after performing these comparisons, we proceeded to show that even when mosquito population sizes are almost equal in both spatial settings, the resulting vectorial-contact networks are radically different. This has profound implications in our understanding of how mosquito-borne diseases spread in human populations and is relevant to the effective use of resources allocated to stop these pathogens from causing more harm in human populations.

scholarly journals Rift Valley fever in northern Senegal : a modelling approach to analyse the processes underlying virus circulation recurrence

2019 ◽  
Author(s):  
B. Durand ◽  
M. Lo Modou ◽  
A. Tran ◽  
A. Ba ◽  
F. Sow ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Vertical Transmission ◽  
Rainy Season ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Mosquito Population ◽  
Temporary Pond ◽  
Valley Fever ◽  
Vector Population ◽  
Mosquito Population Dynamics

AbstractRift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area [1]. To calibrate the model, serological surveys were performed in 2015-2016 on both resident and nomadic herds in the same area. Mosquito population dynamics were obtained from a published model trained in the same region [2]. Model comparison techniques were used to compare five different scenarios of virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate of 15.3%, n=222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in West Africa (12.4%, n=660). Multivariate analysis of serological data suggested an amplification of the transmission cycle during the rainy season with a peak of circulation at the end of that season. The best scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals arriving during the 2nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence rate (4%) found in nomadic herds sampled during the 2nd half of the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal.Author summaryRift Valley fever (RVF) is one of the most important vector borne disease in Africa, seriously affecting the health of domestic ruminants and humans and leading to severe economic consequences. This disease is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. Two non-exclusive mechanisms may support this endemicity: recurrent introductions of the virus by nomadic animals, and vertical transmission of the virus (i.e. from infected female mosquito to eggs) in local Aedes populations. The authors followed up during 1 year resident and nomadic herds. They used the data thus obtained to model a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics. They found that the best scenario explaining RVF remanence combined yearly introductions of RVFV by nomadic herds, with a proportion of viraemic predicted to be larger in animals arriving during the 2nd half of the rainy season, which is consistent with an amplification of virus circulation in the area during the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, their results demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal.

scholarly journals Risk factors associated with Ctenocephalides felis flea infestation of peri-urban goats: a neglected parasite in an under-appreciated host

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Julia Rose Dahm ◽  
Jordana Burdon Bailey ◽  
Robert F. Kelly ◽  
Patrick Chikungwa ◽  
Julius Chulu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Urban Communities ◽  
Control Strategies ◽  
Animal Health ◽  
Animal Husbandry ◽  
Ctenocephalides Felis ◽  
Disease Spread ◽  
Health Concern ◽  
Cross Sectional ◽  
Flea Infestation

AbstractGoats are critical in mixed smallholder agricultural systems in lower and middle-income countries, while fleas are important human and animal health concerns around the world. Convenience sampling was used to describe and consider risk factors for flea infestations of peri-urban goats, with the aim of informing the iterative development of animal husbandry and management based control strategies. Seven hundred and ninety-two goats were examined in 228 households across 10 peri-urban communities surrounding Blantyre in southern Malawi. The prevalence of Ctenocephalides felis fleas was 18.3, 37.1 and 100% at the levels of individual goats, households and communities, respectively, highlighting a neglected human and animal health concern. Constant introduction of new livestock coupled to a lack of biosecurity within communities, the ubiquitous presence of dog and cat hosts for C. felis, the frequency and thoroughness of cleaning overnight goat accommodation, and goat age less than 12 months old were identified as risk factors for flea infestation. This focal cross-sectional study highlights the significance of fleas in peri-urban communities and uncovers trends and commonalities that are needed to inform sustainable disease management. The majority of the peri-urban goat keepers were female, had resided in the same community throughout their whole life and had primary level education. Advice on the planned management of fleas in livestock needs to be tailored towards this demographic group. This approach affords an opportunity to promote public health measures to address household flea infestations and zoonotic disease spread.

scholarly journals Trends of HIV/AIDS Highlighted the Progresses and Challenges in Prevention and Control From 1990 to 2019

2021 ◽  
Author(s):  
Zejin Ou ◽  
Huan He ◽  
Danfeng Yu ◽  
Yongzhi Li ◽  
Yuanhao Liang ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Control Strategies ◽  
Health Concern ◽  
Effective Prevention ◽  
Global Trends ◽  
Life Years ◽  
Disease Study ◽  
And Control ◽  
Increasing Trends ◽  
Hiv Aids

Abstract Background HIV/AIDS is a critical public health concern worldwide. This article aimed to demonstrate th trends of HIV/AIDS burden from 1990 to 2019.Methods Data was extracted from the Global Burden of Disease study (GBDs) 2019. Estimated annual percentage change (EAPC) and age-standardized rate (ASR) were estimated to quantify the trends at global, regional and national levels.Results During the period 1990-2004, the trend in incidence of HIV/AIDS was stable globally. Whereas the trends in prevalence, death and disability-adjusted life years (DALYs) had pronounced increasing trends, with the respective EAPCs were 7.47 (95%confidence interval [CI]: 5.84 to 9.12), 10.85(95%CI: 8.90 to 12.84), and 10.40(95%CI: 8.47 to 12.36). Meanwhile, the pronounced increasing trends were seen in low-resource settings, particularly that of death in Oceania and South Asia, in which the respective EAPCs were 44.76 (95%CI: 40.81 to 48.82) and 40.82 (95%CI: 34.31 to 47.64). However, the global trends in incidence, death and DALYs of HIV/AIDS pronouncedly decreased from 2005 to 2019, with the respective EAPCs were −2.68(95%CI: −2.82 to −2.53), −6.73(95%CI: −6.98 to −6.47) and −6.75(95%CI: −6.95 to −6.54). Whereas prevalence showed increasing trend (EAPC: 0.71, 95%CI: 0.54 to 0.87). Decreasing trends of HIV/AIDS were observed in most regions and countries, particularly that of death and DALYs in Burundi respectively were −15.28 (95%CI: −16.08 to −14.47) and −15.07 (95%CI: −15.79 to −14.33). Conclusions Decreasing trends of HIV/AIDS were observed worldwide over the past 15 years. However, HIV/AIDS remains one of the most critical causes of health loss worldwide, which emphasized the effective prevention and control strategies.

Probing the application of OmpA-derived peptides to disrupt the acquisition of ‘Candidatus Liberibacter asiaticus’ by Diaphorina citri

2021 ◽  
Author(s):  
Marcus Vinicius Merfa e Silva ◽  
Eduarda Regina Fischer ◽  
Mariana de Souza e Silva ◽  
Carolina Sardinha Francisco ◽  
Helvécio Coletta-Filho ◽  
...  
Keyword(s):  
Control Strategies ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
In Planta ◽  
Host Interaction ◽  
Vector Population ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Bacterial Outer Membrane

Huanglongbing (HLB) is currently the most devastating disease of citrus worldwide. Both bacteria ‘Candidatus Liberibacter asiaticus’ (CLas) and ‘Ca. Liberibacter americanus’ (CLam) are associated with HLB in Brazil, but with a strong prevalence of CLas over CLam. Conventionally, HLB management focuses on controlling the insect vector population (Diaphorina citri; also known as Asian citrus psyllid – ACP) by spraying insecticides, an approach demonstrated to be mostly ineffective. Thus, development of novel more efficient HLB control strategies is required. The multifunctional bacterial outer membrane protein OmpA is involved in several molecular processes between bacteria and their hosts and has been suggested as a target for bacterial control. Curiously, OmpA is absent in CLam in comparison to CLas, suggesting a possible role on host-interaction. Therefore, in the current study, we have treated ACPs with different OmpA-derived peptides aiming to evaluate the acquisition of CLas by the insect vector. Treatment of psyllids with 5 µM of Pep1, Pep3, Pep5 and Pep6 in artificial diet significantly reduced the acquisition of CLas, while increasing the concentration of Pep5 and Pep6 to 50 µM abolished this process. In addition, in planta treatment with 50 µM of Pep6 also significantly decreased the acquisition of CLas and sweet orange plants stably absorbed and maintained this peptide for as long as three months post the final application. Together, our results demonstrate the promising use of OmpA-derived peptides as a novel biotechnological tool to control CLas.

scholarly journals Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies

Insects ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 173 ◽  
Author(s):  
Samuel Karungu ◽  
Evans Atoni ◽  
Joseph Ogalo ◽  
Caroline Mwaliko ◽  
Bernard Agwanda ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Mosquito Control ◽  
Control Strategies ◽  
Mosquito Species ◽  
Disease Outbreaks ◽  
Health Concern ◽  
Public Health Concern ◽  
Vector Management ◽  
Invasive Mosquito ◽  
Parasitic Pathogens

Kenya is among the most affected tropical countries with pathogen transmitting Culicidae vectors. For decades, insect vectors have contributed to the emergence and distribution of viral and parasitic pathogens. Outbreaks and diseases have a great impact on a country’s economy, as resources that would otherwise be used for developmental projects are redirected to curb hospitalization cases and manage outbreaks. Infected invasive mosquito species have been shown to increasingly cross both local and global boarders due to the presence of increased environmental changes, trade, and tourism. In Kenya, there have been several mosquito-borne disease outbreaks such as the recent outbreaks along the coast of Kenya, involving chikungunya and dengue. This certainly calls for the implementation of strategies aimed at strengthening integrated vector management programs. In this review, we look at mosquitoes of public health concern in Kenya, while highlighting the pathogens they have been linked with over the years and across various regions. In addition, the major strategies that have previously been used in mosquito control and what more could be done to reduce or combat the menace caused by these hematophagous vectors are presented.

scholarly journals Mapping Environmental Suitability of Scrub Typhus in Nepal Using MaxEnt and Random Forest Models

2019 ◽  
Vol 16 (23) ◽  
pp. 4845
Author(s):  
Bipin Acharya ◽  
Wei Chen ◽  
Zengliang Ruan ◽  
Gobind Pant ◽  
Yin Yang ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Agricultural Land ◽  
Scrub Typhus ◽  
Control Strategies ◽  
National Level ◽  
Spatial Prediction ◽  
Health Concern ◽  
Environmental Suitability ◽  
And Control

Being a globally emerging mite-borne zoonotic disease, scrub typhus is a serious public health concern in Nepal. Mapping environmental suitability and quantifying the human population under risk of the disease is important for prevention and control efforts. In this study, we model and map the environmental suitability of scrub typhus using the ecological niche approach, machine learning modeling techniques, and report locations of scrub typhus along with several climatic, topographic, Normalized Difference Vegetation Index (NDVI), and proximity explanatory variables and estimated population under the risk of disease at a national level. Both MaxEnt and RF technique results reveal robust predictive power with test The area under curve (AUC) and true skill statistics (TSS) of above 0.8 and 0.6, respectively. Spatial prediction reveals that environmentally suitable areas of scrub typhus are widely distributed across the country particularly in the low-land Tarai and less elevated river valleys. We found that areas close to agricultural land with gentle slopes have higher suitability of scrub typhus occurrence. Despite several speculations on the association between scrub typhus and proximity to earthquake epicenters, we did not find a significant role of proximity to earthquake epicenters in the distribution of scrub typhus in Nepal. About 43% of the population living in highly suitable areas for scrub typhus are at higher risk of infection, followed by 29% living in suitable areas of moderate-risk, and about 22% living in moderately suitable areas of lower risk. These findings could be useful in selecting priority areas for surveillance and control strategies effectively.

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