scholarly journals Modeling the Effects of Relapse in the Transmission Dynamics of Malaria Parasites

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Ricardo Águas ◽  
Marcelo U. Ferreira ◽  
M. Gabriela M. Gomes
Keyword(s):  
At Risk ◽  
Mathematical Models ◽  
Plasmodium Vivax ◽  
Drug Administration ◽  
Plasmodium Species ◽  
Clinical Malaria ◽  
Transmission Dynamics ◽  
Ecological Interactions ◽  
Infection Rates ◽  
Mosquito Abundance

Often regarded as “benign,”Plasmodium vivaxinfections lay in the shadows of the much more virulentP. falciparuminfections. However, about 1.98 billion people are at risk of both parasites worldwide, stressing the need to understand the epidemiology ofPlasmodium vivax, particularly under the scope of decreasingP. falciparumprevalence and ecological interactions between both species. Two epidemiological observations put the dynamics of both species into perspective: (1) ACT campaigns have had a greater impact onP. falciparumprevalence. (2) Complete clinical immunity is attained at younger ages forP. vivax, under similar infection rates. We systematically compared two mathematical models of transmission for both Plasmodium species. Simulations suggest that an ACT therapy combined with a hypnozoite killing drug would eliminate both species. However,P. vivaxelimination is predicted to be unstable. Differences in age profiles of clinical malaria can be explained solely byP. vivax's ability to relapse, which accelerates the acquisition of clinical immunity and serves as an immunity boosting mechanism.P. vivaxtransmission can subsist in areas of low mosquito abundance and is robust to drug administration initiatives due to relapse, making it an inconvenient and cumbersome, yet less lethal alternative toP. falciparum.

Spatiotemporal distributed lag modelling of multiple Plasmodium species in a malaria elimination setting

2021 ◽  
Vol 30 (1) ◽  
pp. 22-34
Author(s):  
Chawarat Rotejanaprasert ◽  
Duncan Lee ◽  
Nattwut Ekapirat ◽  
Prayuth Sudathip ◽  
Richard J Maude
Keyword(s):  
Data Streams ◽  
Malaria Elimination ◽  
Parasite Species ◽  
Climatic Factors ◽  
Plasmodium Species ◽  
Clinical Malaria ◽  
Spatiotemporal Patterns ◽  
Distributed Lag ◽  
Multiple Data

In much of the Greater Mekong Sub-region, malaria is now confined to patches and small foci of transmission. Malaria transmission is seasonal with the spatiotemporal patterns being associated with variation in environmental and climatic factors. However, the possible effect at different lag periods between meteorological variables and clinical malaria has not been well studied in the region. Thus, in this study we developed distributed lagged modelling accounting for spatiotemporal excessive zero cases in a malaria elimination setting. A multivariate framework was also extended to incorporate multiple data streams and investigate the spatiotemporal patterns from multiple parasite species via their lagged association with climatic variables. A simulation study was conducted to examine robustness of the methodology and a case study is provided of weekly data of clinical malaria cases at sub-district level in Thailand.

scholarly journals The effects of flooding and weather conditions on leptospirosis transmission in Thailand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sudarat Chadsuthi ◽  
Karine Chalvet-Monfray ◽  
Anuwat Wiratsudakul ◽  
Charin Modchang
Keyword(s):  
Sensitivity Analysis ◽  
Public Education ◽  
Mathematical Models ◽  
Disease Transmission ◽  
Transmission Rate ◽  
Weather Conditions ◽  
Transmission Dynamics ◽  
Multiplication Rate ◽  
High Degree ◽  
Transmission Models

AbstractThe epidemic of leptospirosis in humans occurs annually in Thailand. In this study, we have developed mathematical models to investigate transmission dynamics between humans, animals, and a contaminated environment. We compared different leptospire transmission models involving flooding and weather conditions, shedding and multiplication rate in a contaminated environment. We found that the model in which the transmission rate depends on both flooding and temperature, best-fits the reported human data on leptospirosis in Thailand. Our results indicate that flooding strongly contributes to disease transmission, where a high degree of flooding leads to a higher number of infected individuals. Sensitivity analysis showed that the transmission rate of leptospires from a contaminated environment was the most important parameter for the total number of human cases. Our results suggest that public education should target people who work in contaminated environments to prevent Leptospira infections.

scholarly journals Engineering Analysis of Cost to Protect Workers from Diacetyl Exposure and the Economic Benefit of Noncompliance

2018 ◽  
Vol 35 (2) ◽  
Author(s):  
Drew Peake ◽  
Greg Hait
Keyword(s):  
At Risk ◽  
Drug Administration ◽  
Economic Benefit ◽  
Food And Drug Administration ◽  
Engineering Analysis ◽  
Regulatory Standard ◽  
Substitute Products ◽  
The U.S

Large commercial bakeries use artificial butter flavor (containing diacetyl) in its recipes, and have for more than 40 years. In 2012, a health-based exposure threshold was published for diacetyl by the American Conference of Governmental Industrial Hygienists (ACGIH). Bakery managers typically knew what was necessary to protect workers from exposure. However, for a variety of reasons, most did little to control exposure: The Food and Drug Administration said diacetyl was generally recognized as safe; substitute products had not been demonstrated as less harmful; and no regulatory standard had been established. This study develops the costs that would have been necessary to protect workers, using the U.S. EPA model (known as BEN) to calculate the economic benefit of noncompliance, and offers a characterization of the profit incentive to place workers at risk.

scholarly journals Serologic Markers in Relation to Parasite Exposure History Help to Estimate Transmission Dynamics of Plasmodium vivax

PLoS ONE ◽  
2011 ◽  
Vol 6 (11) ◽  
pp. e28126 ◽  
Author(s):  
Fadile Yildiz Zeyrek ◽  
Nirianne Palacpac ◽  
Fehmi Yuksel ◽  
Masanori Yagi ◽  
Kaori Honjo ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Transmission Dynamics ◽  
Serologic Markers ◽  
Exposure History ◽  
Parasite Exposure

Observations on the field transmission dynamics of Schistosoma mansoni and S. mattheei in southern Natal, South Africa

Parasitology ◽  
1985 ◽  
Vol 91 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Fiona A. Donnelly ◽  
C. C. Appleton
Keyword(s):  
South Africa ◽  
Schistosoma Mansoni ◽  
Transmission Dynamics ◽  
Small Rivers ◽  
Seasonal Patterns ◽  
Infection Rates ◽  
Intermediate Hosts ◽  
Low Oxygen ◽  
Transmission Season ◽  
Extensive Growth

Cercarial transmission of Schistosoma mansoni and S. mattheei was monitored in two small rivers near Durban, South Africa. The seasonal patterns recorded corresponded to those already documented for these parasites. Tn the case of S. mansoni, however, this was interrupted at the height of the transmission season. The reason for this was believed to be very low oxygen concentrations in the snail habitat due to unusually extensive growth of the plant Ludwigia stolonifera over the water. The failure of the spring rains, which would normally have flushed the system is seen as contributing to this phenomenon. Infection rates in the snail intermediate hosts were low ( > 10%). A preponderance of male worms of both schistosome species was noted.

Eye on China

2020 ◽  
Vol 24 (01) ◽  
pp. 6-10
Keyword(s):  
At Risk ◽  
Human Activity ◽  
Drug Administration ◽  
Tracking System ◽  
Robotic Prostatectomy ◽  
Plant Biodiversity ◽  
Research Fronts ◽  
The Us ◽  
Chinese Plant

The following topics are under this section: First robotic prostatectomy conducted in Shanghai Leveraging on intelligent tech to assist patients to get back on their feet Research Fronts 2019 released: China is reducing its gap with the US in frontier research Human activity puts Chinese plant biodiversity at risk, study finds Structural understanding of alginate enzymes for bioconversion China’s National Vaccine Tracking System set to be completed in 2020 China’s amended drug administration law kicks in

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