scholarly journals Malaria Elimination: The Role and Value of Sero-Surveillance

2021 ◽  
Author(s):  
Kingsley Badu ◽  
Amma Aboagyewa Larbi ◽  
Kwadwo Boampong
Keyword(s):  
Malaria Transmission ◽  
Malaria Elimination ◽  
Diagnostic Testing ◽  
Plasmodium Species ◽  
Parasite Prevalence ◽  
Molecular Testing ◽  
Direct Function ◽  
Individual Level ◽  
Western Africa ◽  
Parasite Exposure

As countries move from intense malaria transmission to low transmission there will be a demand for more sensitive tools and approaches in tracking malaria transmission dynamics. Surveillance tools that are sensitive in tracking real time infectious bites as well as infectious reservoir will be preferred to counting number of cases in the hospital or parasite prevalence. The acquisition and maintenance of anti-malarial antibodies is a direct function of parasite exposure, seroprevalence rates has been used as an efficient tool in assessing malaria endemicity and confirming malaria elimination. Plasmodium antibodies are explicit biomarkers that can be utilised to track parasite exposure over more extensive time spans than microscopy, rapid diagnostic testing or molecular testing and the conventional entomological inoculation rate. Seroprevalence studies can therefore help monitor the impact of malaria control interventions, especially when the parasite occurrence is low. As a result, antibody responses to Anopheles salivary proteins or Plasmodium species may potentially offer reliable information of recent or past exposure; recognise short-term or gradual changes in exposure to Plasmodium infection or to estimate individual-level exposure to infection. This book chapter will present about four studies we have conducted across eastern and western Africa on the efficiency of salivary gland proteins and antimalarial antibodies in tracking malaria transmission intensity. We hope that these could be used as surveillance tools in malaria elimination efforts.

scholarly journals Host age modulates within-host parasite competition

2015 ◽  
Vol 11 (5) ◽  
pp. 20150131 ◽  
Author(s):  
Rony Izhar ◽  
Jarkko Routtu ◽  
Frida Ben-Ami
Keyword(s):  
Evolutionary Dynamics ◽  
Parasite Prevalence ◽  
Host Age ◽  
Individual Level ◽  
Pasteuria Ramosa ◽  
Age Dependent ◽  
The Individual ◽  
Host Parasite ◽  
Parasite Exposure ◽  
Age At Exposure

In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa , we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters.

scholarly journals Natural Infections With Different Plasmodium Species Induce Antibodies Reactive to A Chimeric Plasmodium Vivax Recombinant Protein

2020 ◽  
Author(s):  
Jessica N McCaffery ◽  
Balwan Singh ◽  
Douglas Nace ◽  
Alberto Moreno ◽  
Venkatachalam Udhayakumar ◽  
...  
Keyword(s):  
Malaria Elimination ◽  
Malaria Incidence ◽  
Binding Capacity ◽  
Specific Antigen ◽  
Plasmodium Species ◽  
Chimeric Protein ◽  
Population Level ◽  
Parasite Prevalence ◽  
Antibody Detection ◽  
Plasma Samples

Abstract Background: As malaria incidence and transmission in a region decreases, it becomes increasingly difficult to identify areas of active transmission. Improved methods for identifying and monitoring foci of active malaria transmission are needed in areas of low parasite prevalence in order to achieve malaria elimination. Serological assays can provide population-level infection history to inform elimination campaigns.Methods: A bead-based multiplex antibody detection assay was used to evaluate a chimeric P. vivax MSP1 protein (PvRMC-MSP1), designed to be broadly immunogenic for use in vaccine studies, to act as a pan-malaria serological tool based on its ability to capture IgG in plasma samples obtained from naturally exposed individuals. Samples from 236 US travelers with PCR confirmed infection status from all four major Plasmodium species infecting humans, P. falciparum, P. vivax, P. malariae, and P. ovale were tested for IgG capture using PvRMC-MSP1 as well as the four recombinant MSP1-19 kD isoforms representative of these Plasmodium species.Results: Regardless of infecting Plasmodium species, a majority of plasma samples from infected US travelers provided a high assay signal to the PvRMC-MSP1 chimeric protein. Most individuals that responded to the PmMSP1 or PoMSP1 antigen also responded to PvRMC-MSP1, with very few individuals responding to PmMSP1 or PoMSP1 antigens alone. When grouped by active infection, we observed that plasma from P. vivax-infected individuals produced increased assay signals in response to the PvRMC-MSP1 chimera as compared to the recombinant PvMSP1 for 89.5% (34/38) of individuals. PvRMC-MSP1 also showed improved ability to capture IgG antibodies from P. falciparum-infected individuals when compared to the capture by recombinant PvMSP1. Conclusions: These results support further study of designed antigens as an approach for increasing sensitivity or broadening binding capacity to improve existing serological tools for determining population-level exposure to Plasmodium species. Including both broad-reacting and Plasmodium species-specific antigen-coated beads in an assay panel could provide a nuanced view of population-level exposure histories, an extensive IgG profile, and detailed seroestimates. A more sensitive serological tool for detection of P. vivax exposure would aid malaria elimination campaigns in co-endemic areas and regions where P. vivax is the dominant parasite.

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.

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 Malaria Trigram: improving the visualization of recurrence data for malaria elimination

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Cleber Matos de Morais ◽  
Kayo Henrique de Carvalho Monteiro ◽  
Jose Diego Brito-Sousa ◽  
Wuelton Marcelo Monteiro ◽  
Vanderson Souza Sampaio ◽  
...  
Keyword(s):  
Malaria Elimination ◽  
Brazilian Amazon ◽  
Amazon Region ◽  
Primary Data ◽  
Malaria Surveillance ◽  
Historical Representation ◽  
Policy Makers ◽  
Individual Level ◽  
Public Health Professionals ◽  
Brazilian Amazon Region

Abstract Background Although considerable success in reducing the incidence of malaria has been achieved in Brazil in recent years, an increase in the proportion of cases caused by the harder-to-eliminate Plasmodium vivax parasite can be noted. Recurrences in P. vivax malaria cases are due to new mosquito-bite infections, drug resistance or especially from relapses arising from hypnozoites. As such, new innovative surveillance strategies are needed. The aim of this study was to develop an infographic visualization tool to improve individual-level malaria surveillance focused on malaria elimination in the Brazilian Amazon. Methods Action Research methodology was employed to deal with the complex malaria surveillance problem in the Amazon region. Iterative cycles were used, totalling four cycles with a formal validation of an operational version of the Malaria Trigram tool at the end of the process. Further probabilistic data linkage was carried out so that information on the same patients could be linked, allowing for follow-up analysis since the official system was not planned in such way that includes this purpose. Results An infographic user interface was developed for the Malaria Trigram that incorporates all the visual and descriptive power of the Trigram concept. It is a multidimensional and interactive historical representation of malaria cases per patient over time and provides visual input to decision-makers on recurrences of malaria. Conclusions The Malaria Trigram is aimed to help public health professionals and policy makers to recognise and analyse different types of patterns in malaria events, including recurrences and reinfections, based on the current Brazilian health surveillance system, the SIVEP-Malária system, with no additional primary data collection or change in the current process. By using the Malaria Trigram, it is possible to plan and coordinate interventions for malaria elimination that are integrated with other parallel actions in the Brazilian Amazon region, such as vector control management, effective drug and vaccine deployment strategies.

scholarly journals The Impact of 3 Years of Targeted Indoor Residual Spraying With Pirimiphos-Methyl on Malaria Parasite Prevalence in a High-Transmission Area of Northern Zambia

2019 ◽  
Vol 188 (12) ◽  
pp. 2120-2130 ◽  
Author(s):  
Marisa A Hast ◽  
Mike Chaponda ◽  
Mbanga Muleba ◽  
Jean-Bertin Kabuya ◽  
James Lupiya ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Malaria Control ◽  
Malaria Parasite ◽  
Control Measure ◽  
Indoor Residual Spraying ◽  
Parasite Prevalence ◽  
Organophosphate Insecticide ◽  
Malaria Burden ◽  
Pirimiphos Methyl ◽  
The Impact

Abstract Malaria transmission in northern Zambia has increased in the past decade, despite malaria control activities. Evidence-based intervention strategies are needed to effectively reduce malaria transmission. Zambia’s National Malaria Control Centre conducted targeted indoor residual spraying (IRS) in Nchelenge District, Luapula Province, from 2014 to 2016 using the organophosphate insecticide pirimiphos-methyl. An evaluation of the IRS campaign was conducted by the Southern Africa International Centers of Excellence for Malaria Research using actively detected malaria cases in bimonthly household surveys carried out from April 2012 to July 2017. Changes in malaria parasite prevalence after IRS were assessed by season using Poisson regression models with robust standard errors, controlling for clustering of participants in households and demographic, geographical, and climatological covariates. In targeted areas, parasite prevalence declined approximately 25% during the rainy season following IRS with pirimiphos-methyl but did not decline during the dry season or in the overall study area. Within targeted areas, parasite prevalence declined in unsprayed households, suggesting both direct and indirect effects of IRS. The moderate decrease in parasite prevalence within sprayed areas indicates that IRS with pirimiphos-methyl is an effective malaria control measure, but a more comprehensive package of interventions is needed to effectively reduce the malaria burden in this setting.

scholarly journals Laboratory Diagnosis of Neonatal Herpes Simplex Virus Infections

2019 ◽  
Vol 57 (5) ◽  
Author(s):  
William J. Muller ◽  
Xiaotian Zheng
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Diagnostic Testing ◽  
Laboratory Diagnosis ◽  
Clinical Findings ◽  
Molecular Testing ◽  
Virus Infections ◽  
Neonatal Herpes ◽  
Neonatal Herpes Simplex ◽  
Simplex Virus

ABSTRACT Herpes simplex virus (HSV) is a common and often benign infection in humans; although it less commonly affects newborns, infection in this age group can be devastating. Newborns often present with nonspecific clinical findings, making timely and accurate diagnosis of infection critical. A wide variety of tests are available for detecting herpes simplex virus infection, but only a subset are useful and validated in the newborn population. The current review summarizes available diagnostic testing for neonatal disease, including discussing limitations, unmet needs, and emerging data on molecular testing methods.

scholarly journals Molecular Diagnostic Testing for Aspergillus

2016 ◽  
Vol 54 (11) ◽  
pp. 2655-2660 ◽  
Author(s):  
Margaret V. Powers-Fletcher ◽  
Kimberly E. Hanson
Keyword(s):  
Direct Detection ◽  
Diagnostic Testing ◽  
Molecular Diagnostic ◽  
Molecular Testing ◽  
Content Type ◽  
Clinical Specimens ◽  
Molecular Tests ◽  
Assay Performance ◽  
Clinical Mycology ◽  
Invasive Infections

The direct detection ofAspergillusnucleic acid in clinical specimens has the potential to improve the diagnosis of aspergillosis by offering more rapid and sensitive identification of invasive infections than is possible with traditional techniques, such as culture or histopathology. Molecular tests forAspergillushave been limited historically by lack of standardization and variable sensitivities and specificities. Recent efforts have been directed at addressing these limitations and optimizing assay performance using a variety of specimen types. This review provides a summary of standardization efforts and outlines the complexities of molecular testing forAspergillusin clinical mycology.

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