scholarly journals Identifying Plasmodium falciparum transmission patterns through parasite prevalence and entomological inoculation rate

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin Amoah ◽  
Robert S McCann ◽  
Alinune N Kabaghe ◽  
Monicah Mburu ◽  
Michael G Chipeta ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Entomological Inoculation Rate ◽  
Control Strategies ◽  
Parasite Prevalence ◽  
Temporal Variations ◽  
Spatial And Temporal Patterns ◽  
Delayed Effect ◽  
Geostatistical Methods ◽  
Malaria Epidemiology ◽  
The Relationship

Background:Monitoring malaria transmission is a critical component of efforts to achieve targets for elimination and eradication. Two commonly monitored metrics of transmission intensity are parasite prevalence (PR) and the entomological inoculation rate (EIR). Comparing the spatial and temporal variations in the PR and EIR of a given geographical region and modelling the relationship between the two metrics may provide a fuller picture of the malaria epidemiology of the region to inform control activities.Methods:Using geostatistical methods, we compare the spatial and temporal patterns of Plasmodium falciparum EIR and PR using data collected over 38 months in a rural area of Malawi. We then quantify the relationship between EIR and PR by using empirical and mechanistic statistical models.Results:Hotspots identified through the EIR and PR partly overlapped during high transmission seasons but not during low transmission seasons. The estimated relationship showed a 1-month delayed effect of EIR on PR such that at lower levels of EIR, increases in EIR are associated with rapid rise in PR, whereas at higher levels of EIR, changes in EIR do not translate into notable changes in PR.Conclusions:Our study emphasises the need for integrated malaria control strategies that combine vector and human host managements monitored by both entomological and parasitaemia indices.Funding:This work was supported by Stichting Dioraphte grant number 13050800.

scholarly journals Identifying Plasmodium falciparum transmission patterns through parasite prevalence and entomological inoculation rate

2021 ◽  
Author(s):  
Benjamin Amoah ◽  
Robert S. McCann ◽  
Alinune N. Kabaghe ◽  
Monicah Mburu ◽  
Michael G. Chipeta ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Entomological Inoculation Rate ◽  
Control Strategies ◽  
Parasite Prevalence ◽  
Delayed Effect ◽  
Low Transmission ◽  
Geostatistical Methods ◽  
High Transmission ◽  
Using Data ◽  
The Relationship

AbstractMonitoring malaria transmission is a critical component of efforts to achieve targets for elimination and eradication. Two commonly monitored metrics of transmission intensity are parasite prevalence (PR) and the entomological inoculation rate (EIR). Using geostatistical methods, we investigate the relationship between Plasmodium falciparum PR and EIR using data collected over 38 months in a rural area of Malawi. Our results indicate that hotspots identified through the EIR and PR partly overlapped during high transmission seasons but not during low transmission seasons. The estimated relationship showed a one-month delayed effect of EIR on PR such that at low transmission levels increases in EIR are associated with rapid rise in PR, but at high transmission levels, decreases in EIR do not translate into notable reductions in PR. Our study emphasises the need for integrated malaria control strategies that combines vector and human host managements monitored by both entomological and parasitaemia indices.

scholarly journals Statics and Dynamics of Malaria Transmission: The Relationship between Prevalence in Humans and Mosquitoes.

2020 ◽  
Author(s):  
Santiago Movilla Blanco
Keyword(s):  
Malaria Transmission ◽  
Degrees Of Freedom ◽  
Control Strategies ◽  
Transmission Efficiency ◽  
Malaria Epidemiology ◽  
Mosquito Mortality ◽  
Statics And Dynamics ◽  
Simplifying Assumptions ◽  
The Impact ◽  
The Relationship

Abstract The present paper explores a simple dynamic model from which we review the classic formulae in malaria epidemiology that relate entomological parameters to malaria transmission. In addition, we document the dynamics of malaria, illustrating the impact of control strategies and how the bites per mosquito have a larger effect on transmission intensity than the mosquito mortality, the ratio of mosquitoes to humans, or the transmission efficiency. The model has been built following the System Dynamics methodology, explicitly representing the variables, the feedbacks and the nonlinearities, i.e. the structure that governs the dynamics of the disease. In this sense, the paper offers a new way to obtain the most representative malaria indicators derived from stock-and-flow diagrams that encompass the causal relationships that exist between the attributes of such a system. Based on the obtained formulae from the human and mosquito sectors, we are able to eliminate three degrees of freedom, allowing us to calculate the temporal steady state relationship between Plasmodium falciparum prevalence in humans and mosquitoes. The model is generic in nature and may be parameterized to portray a wide variety of locations, different malaria parasites, vector species, and to cater for seasonality. Given that the model includes the principle mechanisms of malaria transmission, it acts as a foundation for simulations that represent the dynamics between humans and mosquitoes. Such model has been developed based on a number of simplifying assumptions. To the extent possible, the validity of the model under these assumptions has been analyzed by way of mathematic equations.

scholarly journals Predictors of treatment failures of plasmodium falciparum malaria in Vietnam: a 4-year single‐centre retrospective study

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Minh Cuong Duong ◽  
Oanh Kieu Nguyet Pham ◽  
Phong Thanh Nguyen ◽  
Van Vinh Chau Nguyen ◽  
Phu Hoan Nguyen
Keyword(s):  
Plasmodium Falciparum ◽  
Treatment Failure ◽  
Severe Malaria ◽  
Falciparum Malaria ◽  
Control Strategies ◽  
Artemisinin Resistance ◽  
Plasmodium Falciparum Malaria ◽  
Molecular Technique ◽  
Drug Resistant ◽  
Public Health Burden

Abstract Background Drug-resistant falciparum malaria is an increasing public health burden. This study examined the magnitude of Plasmodium falciparum infection and the patterns and predictors of treatment failure in Vietnam. Methods Medical records of all 443 patients with malaria infection admitted to the Hospital for Tropical Diseases between January 2015 and December 2018 were used to extract information on demographics, risk factors, symptoms, laboratory tests, treatment, and outcome. Results More than half (59.8%, 265/443, CI 55.1–64.4%) of patients acquired Plasmodium falciparum infection of whom 21.9% (58/265, CI 17.1–27.4%) had severe malaria, while 7.2% (19/265, CI 4.6–10.9%) and 19.2% (51/265, CI 14.7–24.5%) developed early treatment failure (ETF) and late treatment failure (LTF) respectively. Among 58 patients with severe malaria, 14 (24.1%) acquired infection in regions where artemisinin resistance has been documented including Binh Phuoc (11 patients), Dak Nong (2 patients) and Gia Lai (1 patient). Under treatment with intravenous artesunate, the median (IQR) parasite half-life of 11 patients coming from Binh Phuoc was 3 h (2.3 to 8.3 h), two patients coming from Dak Nong was 2.8 and 5.7 h, and a patient coming from Gia Lai was 6.5 h. Most patients (98.5%, 261/265) recovered completely. Four patients with severe malaria died. Severe malaria was statistically associated with receiving treatment at previous hospitals (P < 0.001), hepatomegaly (P < 0.001) and number of inpatient days (P < 0.001). Having severe malaria was a predictor of ETF (AOR 6.96, CI 2.55–19.02, P < 0.001). No predictor of LTF was identified. Conclusions Plasmodium falciparum remains the prevalent malaria parasite. Despite low mortality rate, severe malaria is not rare and is a significant predictor of ETF. To reduce the risk for ETF, studies are needed to examine the effectiveness of combination therapy including parenteral artesunate and a parenteral partner drug for severe malaria. The study alerts the possibility of drug-resistant malaria in Africa and other areas in Vietnam, which are known as non-endemic areas of anti-malarial drug resistance. A more comprehensive study using molecular technique in these regions is required to completely understand the magnitude of drug-resistant malaria and to design appropriate control strategies.

scholarly journals Genetic diversity and population structure of Plasmodium falciparum in Nigeria: insights from microsatellite loci analysis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Fehintola V. Ajogbasile ◽  
Adeyemi T. Kayode ◽  
Paul E. Oluniyi ◽  
Kazeem O. Akano ◽  
Jessica N. Uwanibe ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plasmodium Falciparum ◽  
Population Structure ◽  
Microsatellite Loci ◽  
Control Strategies ◽  
Population Diversity ◽  
Parasite Population ◽  
Nested Polymerase Chain Reaction ◽  
Public Health Burden ◽  
Genetic Diversity And Structure

Abstract Background Malaria remains a public health burden especially in Nigeria. To develop new malaria control and elimination strategies or refine existing ones, understanding parasite population diversity and transmission patterns is crucial. Methods In this study, characterization of the parasite diversity and structure of Plasmodium falciparum isolates from 633 dried blood spot samples in Nigeria was carried out using 12 microsatellite loci of P. falciparum. These microsatellite loci were amplified via semi-nested polymerase chain reaction (PCR) and fragments were analysed using population genetic tools. Results Estimates of parasite genetic diversity, such as mean number of different alleles (13.52), effective alleles (7.13), allelic richness (11.15) and expected heterozygosity (0.804), were high. Overall linkage disequilibrium was weak (0.006, P < 0.001). Parasite population structure was low (Fst: 0.008–0.105, AMOVA: 0.039). Conclusion The high level of parasite genetic diversity and low population structuring in this study suggests that parasite populations circulating in Nigeria are homogenous. However, higher resolution methods, such as the 24 SNP barcode and whole genome sequencing, may capture more specific parasite genetic signatures circulating in the country. The results obtained can be used as a baseline for parasite genetic diversity and structure, aiding in the formulation of appropriate therapeutic and control strategies in Nigeria.

scholarly journals CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

2021 ◽  
Author(s):  
Lovel Kukuljan ◽  
Franci Gabrovšek ◽  
Matthew D. Covington ◽  
Vanessa E. Johnston
Keyword(s):  
Temporal Variations ◽  
Observation Point ◽  
Spatially Distributed ◽  
Combined Action ◽  
Karst Systems ◽  
The Relationship ◽  
Co2 Dynamics ◽  
Global Carbon

AbstractUnderstanding the dynamics and distribution of CO2 in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO2. We show (1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and (2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO2. Namely, in the terminal chamber of the passage, the pCO2 is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rates and pCO2, which enter via small conduits and fractures embedded in a CO2-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO2 inflows, high and persistent gradients in pCO2 are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m are observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.

scholarly journals On the Relationship between Teleconnections and Taiwan's Streamflow: Evidence of Climate Regime Shift and Implications for Seasonal Forecasting

2016 ◽  
Author(s):  
Chia-Jeng Chen ◽  
Tsung-Yu Lee
Keyword(s):  
Large Scale ◽  
Critical Role ◽  
Phase Relationship ◽  
Temporal Variations ◽  
Pacific Basin ◽  
Climate Regime ◽  
Quasi Biennial Oscillation ◽  
Teleconnection Patterns ◽  
Integrated Response ◽  
The Relationship

Abstract. Interannual variations of catchment streamflow represent an integrated response to anomalies in regional moisture transport and atmospheric circulations, ultimately linked to large-scale climate oscillations. This study investigates the relationship between Taiwan's long-term summertime (July to September, JAS) streamflow and manifold teleconnection patterns. Lagged correlation analysis is conducted to calculate how JAS streamflow data derived at 28 upstream and 13 downstream gauges in Taiwan correlate with 14 teleconnection indices in the concurrent or preceding seasons. Out of the many indices, the West-Pacific and Pacific-Japan (PJ) patterns, both of which play a critical role in determining cyclonic activity in the western North Pacific basin, exhibit the highest concurrent correlations (most significant r = 0.48) with the JAS flows in Taiwan. At a one-month lead time, on the other hand, the Quasi-Biennial Oscillation significantly correlate with the JAS flows (most significant r = −0.66), indicating some forecasting utility. By further examining the correlation results using a 20-year moving window, peculiar temporal variations and possible climate regime shifts (CRS) can be revealed. To identify suspicious, abrupt changes in the correlation, a CRS test is employed. The late 1970s and 1990s are identified as two significant change points, and during the intermediate period, a marked in-phase relationship (r ~ 0.9) between Taiwan's streamflow and the PJ index is observed. It is verified that the two shifts are in concordance with the alteration of large-scale circulations in the Pacific basin. Discussion about the changes in pattern correlation and composite maps before and after the change point is carried out, and our results suggest that empirical forecasting techniques should take into account the effect of CRS on predictor screening.

scholarly journals Analysing Tuberculosis Trends in South Asia

2018 ◽  
Vol 8 (6) ◽  
pp. 5245
Author(s):  
Kumar Abhishek ◽  
M. P Singh ◽  
Md. Sadik Hussain
Keyword(s):  
Sri Lanka ◽  
World Health Organization ◽  
South Asia ◽  
Causes Of Death ◽  
Temporal Variations ◽  
World Health ◽  
Spatial And Temporal Variations ◽  
The World ◽  
Health Organization ◽  
The Relationship

<p>Tuberculosis (TB) has been one of the top ten causes of death in the world. As per the World Health Organization (WHO) around 1.8 million people have died due to tuberculosis in 2015. This paper aims to investigate the spatial and temporal variations in TB incident in South Asia (India, Bangladesh, Pakistan, Maldives, Nepal, and Sri-Lanka). Asia had been counted for the largest number of new TB cases in 2015. The paper underlines and relates the relationship between various features like gender, age, location, occurrence, and mortality due to TB in these countries for the period 1993-2012.</p>

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