scholarly journals Mass campaigns combining antimalarial drugs and anti-infective vaccines as seasonal interventions for malaria control, elimination and prevention of resurgence: a modelling study

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Flavia Camponovo ◽  
Chris F. Ockenhouse ◽  
Cynthia Lee ◽  
Melissa A. Penny
Keyword(s):  
Malaria Transmission ◽  
Malaria Incidence ◽  
Intervention Strategy ◽  
Clinical Trial Data ◽  
Health Impact ◽  
Model Parameters ◽  
Targeted Interventions ◽  
Management Intervention ◽  
Malaria Vaccines ◽  
Transmission Interruption

Abstract Background The only licensed malaria vaccine, RTS,S/AS01, has been developed for morbidity-control in young children. The potential impact on transmission of deploying such anti-infective vaccines to wider age ranges, possibly with co-administration of antimalarial treatment, is unknown. Combinations of existing malaria interventions is becoming increasingly important as evidence mounts that progress on reducing malaria incidence is stalling and threatened by resistance. Methods Malaria transmission and intervention dynamics were simulated using OpenMalaria, an individual-based simulation model of malaria transmission, by considering a seasonal transmission setting and by varying epidemiological and setting parameters such as transmission intensity, case management, intervention types and intervention coverages. Chemopreventive drugs and anti-infective vaccine efficacy profiles were based on previous studies in which model parameters were fitted to clinical trial data. These intervention properties were used to evaluate the potential of seasonal mass applications of preventative anti-infective malaria vaccines, alone or in combination with chemoprevention, to reduce malaria transmission, prevent resurgence, and/or reach transmission interruption. Results Deploying a vaccine to all ages on its own is a less effective intervention strategy compared to chemoprevention alone. However, vaccines combined with drugs are likely to achieve dramatic prevalence reductions and in few settings, transmission interruption. The combined mass intervention will result in lower prevalence following the intervention compared to chemoprevention alone and will increase chances of interruption of transmission resulting from a synergistic effect between both interventions. The combination of vaccine and drug increases the time before transmission resurges after mass interventions cease compared to mass treatment alone. Deploying vaccines and drugs together requires fewer rounds of mass intervention and fewer years of intervention to achieve the same public health impact as chemoprevention alone. Conclusions Through simulations we identified a previously unidentified value of deploying vaccines with drugs, namely the greatest benefit will be in preventing and delaying transmission resurgence for longer periods than with other human targeted interventions. This is suggesting a potential role for deploying vaccines alongside drugs in transmission foci as part of surveillance-response strategies.

scholarly journals Community-based molecular and serological surveillance of subclinical malaria in Myanmar

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Katherine O’Flaherty ◽  
Win Han Oo ◽  
Sophie G. Zaloumis ◽  
Julia C. Cutts ◽  
Kyaw Zayar Aung ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Quantitative Polymerase Chain Reaction ◽  
Dried Blood Spots ◽  
Molecular Testing ◽  
Sample Collection ◽  
Malaria Surveillance ◽  
Surveillance Network ◽  
Targeted Interventions ◽  
Residual Malaria Transmission ◽  
Serological Surveillance

Abstract Background In the Greater Mekong Subregion (GMS), current malaria surveillance strategies rely on a network of village health volunteers (VHVs) reporting the results of rapid diagnostic tests (RDTs), known to miss many asymptomatic infections. Integration of more sensitive diagnostic molecular and serological measures into the VHV network may improve surveillance of residual malaria transmission in hard-to-reach areas in the region and inform targeted interventions and elimination responses. However, data on residual malaria transmission that would be captured by these measures in the VHV-led testing and treatment surveillance network in the GMS is unknown. Methods A total of 114 VHVs were trained to collect dried blood spots from villagers undergoing routine RDTs as part of VHV-led active and passive case detection from April 2015 to June 2016. Samples were subjected to molecular testing (quantitative polymerase chain reaction [qPCR]) to determine Plasmodium falciparum and P. vivax infection and serological testing (against P. falciparum and P. vivax antigens) to determine exposure to P. falciparum and P. vivax. Results Over 15 months, 114 VHVs performed 32,194 RDTs and collected samples for molecular (n = 13,157) and serological (n = 14,128) testing. The prevalence of molecular-detectable P. falciparum and P. vivax infection was 3.2% compared to the 0.16% prevalence of Plasmodium spp. by RDT, highlighting the large burden of infections undetected by standard surveillance. Peaks in anti-P. falciparum, but not P. vivax, merozoite IgG seroprevalence coincided with seasonal P. falciparum transmission peaks, even in those with no molecularly detectable parasites. At the individual level, antibody seropositivity was associated with reduced odds of contemporaneous P. falciparum (OR for PfCSP 0.51 [95%CI 0.35, 0.76], p = 0.001, PfAMA1 0.70 [95%CI 0.52, 0.93], p = 0.01, and PfMSP2 0.81 [95%CI 0.61, 1.08], p = 0.15), but not P. vivax infection (OR PvAMA1 1.02 [95%CI 0.73, 1.43], p = 0.89) indicating a potential role of immunity in protection against molecular-detectable P. falciparum parasitaemia. Conclusions We demonstrated that integration and implementation of sample collection for molecular and serological surveillance into networks of VHV servicing hard-to-reach populations in the GMS is feasible, can capture significant levels of ongoing undetected seasonal malaria transmission and has the potential to supplement current routine RDT testing. Improving malaria surveillance by advancing the integration of molecular and serological techniques, through centralised testing approaches or novel point-of-contact tests, will advance progress, and tracking, towards malaria elimination goals in the GMS.

scholarly journals Exploring the Impact of Climate Variability on Malaria Transmission Using a Dynamic Mosquito-Human Malaria Model

2018 ◽  
Vol 10 (1) ◽  
pp. 88-100 ◽  
Author(s):  
Gbenga J. Abiodun ◽  
Peter J. Witbooi ◽  
Kazeem O. Okosun ◽  
Rajendra Maharaj
Keyword(s):  
Climate Variability ◽  
Malaria Transmission ◽  
Malaria Incidence ◽  
Principal Component ◽  
Wavelet Coherence ◽  
Human Malaria ◽  
Kwazulu Natal ◽  
The Impact ◽  
Wavelet Coherence Analysis ◽  
Malaria Model

Introduction: The reasons for malaria resurgence mostly in Africa are yet to be well understood. Although the causes are often linked to regional climate change, it is important to understand the impact of climate variability on the dynamics of the disease. However, this is almost impossible without adequate long-term malaria data over the study areas. Methods: In this study, we develop a climate-based mosquito-human malaria model to study malaria dynamics in the human population over KwaZulu-Natal, one of the epidemic provinces in South Africa, from 1970-2005. We compare the model output with available observed monthly malaria cases over the province from September 1999 to December 2003. We further use the model outputs to explore the relationship between the climate variables (rainfall and temperature) and malaria incidence over the province using principal component analysis, wavelet power spectrum and wavelet coherence analysis. The model produces a reasonable fit with the observed data and in particular, it captures all the spikes in malaria prevalence. Results: Our results highlight the importance of climate factors on malaria transmission and show the seasonality of malaria epidemics over the province. Results from the principal component analyses further suggest that, there are two principal factors associated with climates variables and the model outputs. One of the factors indicate high loadings on Susceptible, Exposed and Infected human, while the other is more correlated with Susceptible and Recovered humans. However, both factors reveal the inverse correlation between Susceptible-Infected and Susceptible-Recovered humans respectively. Through the spectrum analysis, we notice a strong annual cycle of malaria incidence over the province and ascertain a dominant of one year periodicity. Consequently, our findings indicate that an average of 0 to 120-day lag is generally noted over the study period, but the 120-day lag is more associated with temperature than rainfall. This is consistence with other results obtained from our analyses that malaria transmission is more tightly coupled with temperature than with rainfall in KwaZulu-Natal province.

scholarly journals Targeting hotspots to reduce transmission of malaria in Senegal: modeling of the effects of human mobility

2018 ◽  
Author(s):  
Kankoé Sallah ◽  
Roch Giorgi ◽  
El Hadj Ba ◽  
Martine Piarroux ◽  
Renaud Piarroux ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Malaria Incidence ◽  
Human Mobility ◽  
Scaling Up ◽  
Intervention Strategies ◽  
Control Measures ◽  
Transmission Season ◽  
Targeted Interventions ◽  
Additional Control ◽  
Mathematical Simulations

AbstractBackgroundIn central Senegal malaria incidences have declined in recent years in response to scaling-up of control measures, but now remains stable, making elimination improbable. Additional control measures are needed to reduce transmission.MethodsBy using a meta-population mathematical model, we evaluated chemotherapy interventions targeting stable malaria hotspots, using a differential equation framework and incorporating human mobility, and fitted to weekly malaria incidences from 45 villages, over 5 years. Three simulated approaches for selecting intervention targets were compared: a) villages with at least one malaria case during the low transmission season of the previous year; b) villages ranked highest in terms of incidence during the high transmission season of the previous year; c) villages ranked based on the degree of connectivity with adjacent populations.ResultsOur mathematical modeling, taking into account human mobility, showed that the intervention strategies targeting hotspots should be effective in reducing malaria incidence in both treated and untreated areas.ConclusionsMathematical simulations showed that targeted interventions allow increasing malaria elimination potential.

scholarly journals Mosquito Longevity, Vector Capacity, and Malaria Incidence in West Timor and Central Java, Indonesia

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ermi Ndoen ◽  
Clyde Wild ◽  
Pat Dale ◽  
Neil Sipe ◽  
Mike Dale
Keyword(s):  
Malaria Transmission ◽  
Survey Data ◽  
Malaria Incidence ◽  
The State ◽  
Physiological Age ◽  
Anopheline Mosquito ◽  
The West ◽  
Central Java ◽  
Vector Capacity ◽  
West Timor

The aim of this paper was to relate anopheline mosquito longevity to malaria incidence in two areas in Indonesia: West Timor and Central Java. We estimated the physiological age of females captured landing on humans or resting inside and outside buildings. The estimate was based on the state of the ovaries and was used to estimate longevity. The results showed that there were large differences between the two areas surveyed. In West Timor the longevity of the anophelines ranged from 13 to 23 days, sufficient for completing the intrinsic incubation cycle and for malaria transmission, whereas in Central Java the longevity was only 3 days, insufficient both for incubation and for transmission. We concluded that the West Timor study area had a greater risk of malaria transmission than that of Central Java and this was supported by village survey data that showed greater malaria incidence in West Timor than in Central Java.

scholarly journals Modelling the impact of a new tobacco product: review of Philip Morris International’s Population Health Impact Model as applied to the IQOS heated tobacco product

2018 ◽  
Vol 27 (Suppl 1) ◽  
pp. s82-s86 ◽  
Author(s):  
Wendy B Max ◽  
Hai-Yen Sung ◽  
James Lightwood ◽  
Yingning Wang ◽  
Tingting Yao
Keyword(s):  
Population Health ◽  
New Product ◽  
Health Impact ◽  
Tobacco Product ◽  
Dynamic State ◽  
Model Parameters ◽  
Impact Model ◽  
Tobacco Products ◽  
Philip Morris ◽  
The Impact

ObjectivesWe review the Population Health Impact Model (PHIM) developed by Philip Morris International and used in its application to the US Food and Drug Administration (FDA) to market its heated tobacco product (HTP), IQOS, as a modified-risk tobacco product (MRTP). We assess the model against FDA guidelines for MRTP applications and consider more general criteria for evaluating reduced-risk tobacco products.MethodsIn assessing the PHIM against FDA guidelines, we consider two key components of the model: the assumptions implicit in the model (outcomes included, relative harm of the new product vs cigarettes, tobacco-related diseases considered, whether dual or polyuse of the new product is modelled, and what other tobacco products are included) and data used to estimate and validate model parameters (transition rates between non-smoking, cigarette-only smoking, dual use of cigarettes and MRTP, and MRTP-only use; and starting tobacco use prevalence).ResultsThe PHIM is a dynamic state transition model which models the impact of cigarette and MRTP use on mortality from four tobacco-attributable diseases. The PHIM excludes morbidity, underestimates mortality, excludes tobacco products other than cigarettes, does not include FDA-recommended impacts on non-users and underestimates the impact on other population groups.ConclusionThe PHIM underestimates the health impact of HTP products and cannot be used to justify an MRTP claim. An assessment of the impact of a potential MRTP on population health should include a comprehensive measure of health impacts, consideration of all groups impacted, and documented and justifiable assumptions regarding model parameters.

Youth Mentor Dietary Outcomes and Waist Circumference Improvement: Camp NERF Study Findings

2019 ◽  
Vol 21 (6) ◽  
pp. 962-971
Author(s):  
Laura C. Hopkins ◽  
Alison Webster ◽  
Julie A. Kennel ◽  
Kelly M. Purtell ◽  
Carolyn Gunther
Keyword(s):  
Mental Health ◽  
Waist Circumference ◽  
Child Nutrition ◽  
Intervention Strategy ◽  
Health Impact ◽  
Primary Objective ◽  
Positive Role ◽  
Sugar Sweetened Beverage ◽  
The Impact ◽  
Depth Interviews

Background. The health impact of youth mentors serving in the delivery of child nutrition and physical activity (PA) interventions on youth mentors themselves has been understudied. Objective. The primary objective of the current study was to examine the impact of engaging youth mentors in the delivery of a summertime childhood obesity prevention intervention on youth mentors’ behavioral health. Method. Data were collected at baseline and postintervention. A survey of validated nutrition, mental health, PA, and psychosocial questionnaires was administered. Diet was assessed via 24-hour recall. Height, weight, and waist circumference (WC) were measured. In-depth interviews were conducted with youth mentors. Results. Eleven youth mentors enrolled: 60% were female, mean age was 16.1 ± 0.38 years, and 100% were Black. Mean kilocalories ( p = .05), sugar-sweetened beverage intake ( p = .08), and waist circumference ( p = .04) decreased. In-depth interviews were conducted with 11 youth mentors, and three themes emerged: perceived improvement in nutrition, PA, and mental health-related behaviors; formation of a positive role modeling relationship with the child campers; and strengthening of higher education goals and future career aspirations. Conclusions. Youth mentor staffing may be an important intervention strategy for changing health behaviors among youth mentors. Results from this study can be used to inform utilization of youth mentors in the delivery of this and similar health behavior interventions in the future.

scholarly journals Spatial-temporal patterns of malaria incidence in Uganda using HMIS data from 2015 to 2019

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Simon P. Kigozi ◽  
Ruth N. Kigozi ◽  
Catherine M. Sebuguzi ◽  
Jorge Cano ◽  
Damian Rutazaana ◽  
...  
Keyword(s):  
High Risk ◽  
Incidence Rate ◽  
Health Facility ◽  
Malaria Incidence ◽  
Temporal Patterns ◽  
Health Facilities ◽  
Moran’S I ◽  
Moran's I ◽  
Catchment Population ◽  
Targeted Interventions

Abstract Background As global progress to reduce malaria transmission continues, it is increasingly important to track changes in malaria incidence rather than prevalence. Risk estimates for Africa have largely underutilized available health management information systems (HMIS) data to monitor trends. This study uses national HMIS data, together with environmental and geographical data, to assess spatial-temporal patterns of malaria incidence at facility catchment level in Uganda, over a recent 5-year period. Methods Data reported by 3446 health facilities in Uganda, between July 2015 and September 2019, was analysed. To assess the geographic accessibility of the health facilities network, AccessMod was employed to determine a three-hour cost-distance catchment around each facility. Using confirmed malaria cases and total catchment population by facility, an ecological Bayesian conditional autoregressive spatial-temporal Poisson model was fitted to generate monthly posterior incidence rate estimates, adjusted for caregiver education, rainfall, land surface temperature, night-time light (an indicator of urbanicity), and vegetation index. Results An estimated 38.8 million (95% Credible Interval [CI]: 37.9–40.9) confirmed cases of malaria occurred over the period, with a national mean monthly incidence rate of 20.4 (95% CI: 19.9–21.5) cases per 1000, ranging from 8.9 (95% CI: 8.7–9.4) to 36.6 (95% CI: 35.7–38.5) across the study period. Strong seasonality was observed, with June–July experiencing highest peaks and February–March the lowest peaks. There was also considerable geographic heterogeneity in incidence, with health facility catchment relative risk during peak transmission months ranging from 0 to 50.5 (95% CI: 49.0–50.8) times higher than national average. Both districts and health facility catchments showed significant positive spatial autocorrelation; health facility catchments had global Moran’s I = 0.3 (p < 0.001) and districts Moran’s I = 0.4 (p < 0.001). Notably, significant clusters of high-risk health facility catchments were concentrated in Acholi, West Nile, Karamoja, and East Central – Busoga regions. Conclusion Findings showed clear countrywide spatial-temporal patterns with clustering of malaria risk across districts and health facility catchments within high risk regions, which can facilitate targeting of interventions to those areas at highest risk. Moreover, despite high and perennial transmission, seasonality for malaria incidence highlights the potential for optimal and timely implementation of targeted interventions.

scholarly journals Mapping routine malaria incidence at village level for targeted control in Papua New Guinea

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Daniela Rodríguez-Rodríguez ◽  
Seri Maraga ◽  
Sharon Jamea-Maiasa ◽  
Anthony Tandrapah ◽  
Leo Makita ◽  
...  
Keyword(s):  
Papua New Guinea ◽  
Malaria Incidence ◽  
New Guinea ◽  
Malaria Surveillance ◽  
Targeted Interventions ◽  
Surveillance And Response ◽  
Animated Maps ◽  
Response Systems ◽  
Study Sites ◽  
Video Format

Malaria surveillance and response-systems are essential for identifying the areas most affected by malaria and for targeting interventions and optimising resources. This study aimed to assess whether the visualisation of routinely collected health facility data linked to village of residence provides evidence for targeting control interventions in four sentinel health facilities in Papua New Guinea. A video format was used to visualise the dynamics in case incidence over time and space alongside photographs illustrating the context of the data collection in the study sites. Incidence changes overtime were illustrated in animated maps. Despite limitations, this approach appeared useful in sites with very few remaining cases or with increasingly marked heterogeneity. Villages that could benefit from targeted interventions or investigations were identified.

scholarly journals The prevalence and density of asymptomatic Plasmodium falciparum infections among children and adults in three communities of western Kenya

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Christina Salgado ◽  
George Ayodo ◽  
Michael D. Macklin ◽  
Meetha P. Gould ◽  
Srinivas Nallandhighal ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Malaria Incidence ◽  
Experimental Studies ◽  
Low Density ◽  
Healthy Children ◽  
Cross Sectional Survey ◽  
Western Kenya ◽  
Transcriptional Pattern ◽  
Asymptomatic Infections

Abstract Background Further reductions in malaria incidence as more countries approach malaria elimination require the identification and treatment of asymptomatic individuals who carry mosquito-infective Plasmodium gametocytes that are responsible for furthering malaria transmission. Assessing the relationship between total parasitaemia and gametocytaemia in field surveys can provide insight as to whether detection of low-density, asymptomatic Plasmodium falciparum infections with sensitive molecular methods can adequately detect the majority of infected individuals who are potentially capable of onward transmission. Methods In a cross-sectional survey of 1354 healthy children and adults in three communities in western Kenya across a gradient of malaria transmission (Ajigo, Webuye, and Kapsisywa–Kipsamoite), asymptomatic P. falciparum infections were screened by rapid diagnostic tests, blood smear, and quantitative PCR of dried blood spots targeting the varATS gene in genomic DNA. A multiplex quantitative reverse-transcriptase PCR assay targeting female and male gametocyte genes (pfs25, pfs230p), a gene with a transcriptional pattern restricted to asexual blood stages (piesp2), and human GAPDH was also developed to determine total parasite and gametocyte densities among parasitaemic individuals. Results The prevalence of varATS-detectable asymptomatic infections was greatest in Ajigo (42%), followed by Webuye (10%). Only two infections were detected in Kapsisywa. No infections were detected in Kipsamoite. Across all communities, children aged 11–15 years account for the greatest proportion total and sub-microscopic asymptomatic infections. In younger age groups, the majority of infections were detectable by microscopy, while 68% of asymptomatically infected adults (> 21 years old) had sub-microscopic parasitaemia. Piesp2-derived parasite densities correlated poorly with microscopy-determined parasite densities in patent infections relative to varATS-based detection. In general, both male and female gametocytaemia increased with increasing varATS-derived total parasitaemia. A substantial proportion (41.7%) of individuals with potential for onward transmission had qPCR-estimated parasite densities below the limit of microscopic detection, but above the detectable limit of varATS qPCR. Conclusions This assessment of parasitaemia and gametocytaemia in three communities with different transmission intensities revealed evidence of a substantial sub-patent infectious reservoir among asymptomatic carriers of P. falciparum. Experimental studies are needed to definitively determine whether the low-density infections in communities such as Ajigo and Webuye contribute significantly to malaria transmission.

Sign in / Sign up

Export Citation Format

Share Document