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  1. Article ; Online: Is there evidence of sustained human-mosquito-human transmission of the zoonotic malaria Plasmodium knowlesi? A systematic literature review

    Pablo Ruiz Cuenca / Stephanie Key / Kim A. Lindblade / Indra Vythilingam / Chris Drakeley / Kimberly Fornace

    Malaria Journal, Vol 21, Iss 1, Pp 1-

    2022  Volume 19

    Abstract: Abstract Background The zoonotic malaria parasite Plasmodium knowlesi has emerged across Southeast Asia and is now the main cause of malaria in humans in Malaysia. A critical priority for P. knowlesi surveillance and control is understanding whether ... ...

    Abstract Abstract Background The zoonotic malaria parasite Plasmodium knowlesi has emerged across Southeast Asia and is now the main cause of malaria in humans in Malaysia. A critical priority for P. knowlesi surveillance and control is understanding whether transmission is entirely zoonotic or is also occurring through human-mosquito-human transmission. Methods A systematic literature review was performed to evaluate existing evidence which refutes or supports the occurrence of sustained human-mosquito-human transmission of P. knowlesi. Possible evidence categories and study types which would support or refute non-zoonotic transmission were identified and ranked. A literature search was conducted on Medline, EMBASE and Web of Science using a broad search strategy to identify any possible published literature. Results were synthesized using the Synthesis Without Meta-analysis (SWiM) framework, using vote counting to combine the evidence within specific categories. Results Of an initial 7,299 studies screened, 131 studies were included within this review: 87 studies of P. knowlesi prevalence in humans, 14 studies in non-human primates, 13 studies in mosquitoes, and 29 studies with direct evidence refuting or supporting non-zoonotic transmission. Overall, the evidence showed that human-mosquito-human transmission is biologically possible, but there is limited evidence of widespread occurrence in endemic areas. Specific areas of research were identified that require further attention, notably quantitative analyses of potential transmission dynamics, epidemiological and entomological surveys, and ecological studies into the sylvatic cycle of the disease. Conclusion There are key questions about P. knowlesi that remain within the areas of research that require more attention. These questions have significant implications for malaria elimination and eradication programs. This paper considers limited but varied research and provides a methodological framework for assessing the likelihood of different transmission patterns for ...
    Keywords Malaria ; Plasmodium knowlesi ; Non-zoonotic transmission ; Zoonoses ; Macaques ; Simian malaria ; Arctic medicine. Tropical medicine ; RC955-962 ; Infectious and parasitic diseases ; RC109-216
    Subject code 306
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Developing sero-diagnostic tests to facilitate Plasmodium vivax Serological Test-and-Treat approaches

    Thomas Obadia / Narimane Nekkab / Leanne J. Robinson / Chris Drakeley / Ivo Mueller / Michael T. White

    BMC Medicine, Vol 20, Iss 1, Pp 1-

    modeling the balance between public health impact and overtreatment

    2022  Volume 11

    Abstract: Abstract Background Eliminating Plasmodium vivax will require targeting the hidden liver-stage reservoir of hypnozoites. This necessitates new interventions balancing the benefit of reducing vivax transmission against the risk of over-treating some ... ...

    Abstract Abstract Background Eliminating Plasmodium vivax will require targeting the hidden liver-stage reservoir of hypnozoites. This necessitates new interventions balancing the benefit of reducing vivax transmission against the risk of over-treating some individuals with drugs which may induce haemolysis. By measuring antibodies to a panel of vivax antigens, a strategy of serological-testing-and-treatment (PvSeroTAT) can identify individuals with recent blood-stage infections who are likely to carry hypnozoites and target them for radical cure. This provides a potential solution to selectively treat the vivax reservoir with 8-aminoquinolines. Methods PvSeroTAT can identify likely hypnozoite carriers with ~80% sensitivity and specificity. Diagnostic test sensitivities and specificities ranging 50–100% were incorporated into a mathematical model of vivax transmission to explore how they affect the risks and benefits of different PvSeroTAT strategies involving hypnozoiticidal regimens. Risk was measured as the rate of overtreatment and benefit as reduction of community-level vivax transmission. Results Across a wide range of combinations of diagnostic sensitivity and specificity, PvSeroTAT was substantially more effective than bloodstage mass screen and treat strategies and only marginally less effective than mass drug administration. The key test characteristic determining of the benefit of PvSeroTAT strategies is diagnostic sensitivity, with higher values leading to more hypnozoite carriers effectively treated and greater reductions in vivax transmission. The key determinant of risk is diagnostic specificity: higher specificity ensures that a lower proportion of uninfected individuals are unnecessarily treated with primaquine. These relationships are maintained in both moderate and low transmission settings (qPCR prevalence 10% and 2%). Increased treatment efficacy and adherence can partially compensate for lower test performance. Multiple rounds of PvSeroTAT with a lower performing test may lead to similar or higher ...
    Keywords Plasmodium vivax malaria ; Test development ; Serological test-and-treat ; Modeling ; Public health interventions ; Overtreatment ; Medicine ; R
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Record Linkage for Malaria Deaths Data Recovery and Surveillance in Brazil

    Klauss Kleydmann Sabino Garcia / Danielly Batista Xavier / Seyi Soremekun / Amanda Amaral Abrahão / Chris Drakeley / Walter Massa Ramalho / André M. Siqueira

    Tropical Medicine and Infectious Disease, Vol 8, Iss 12, p

    2023  Volume 519

    Abstract: Objective: The objective is to describe the results and the methodological processes of record linkage for matching deaths and malaria cases. Methods: A descriptive cross-sectional study was conducted with probabilistic record linkage of death and ... ...

    Abstract Objective: The objective is to describe the results and the methodological processes of record linkage for matching deaths and malaria cases. Methods: A descriptive cross-sectional study was conducted with probabilistic record linkage of death and malaria cases data in Brazil from 2011 to 2020 using death records from the Mortality Information System (SIM) and epidemiological data from the Notifiable Diseases Information System (Sinan) and Epidemiological Surveillance Information Systems for malaria (Sivep-Malaria). Three matching keys were used: patient’s name, date of birth, and mother’s name, with an analysis of cosine and Levenshtein dissimilarity measures. Results: A total of 490 malaria deaths were recorded in Brazil between 2011 and 2020. The record linkage resulted in the pairing of 216 deaths (44.0%). Pairings where all three matching keys were identical accounted for 30.1% of the total matched deaths, 39.4% of the matched deaths had two identical variables, and 30.5% had only one of the three key variables identical. The distribution of the variables of the matched deaths (216) was similar to the distribution of all recorded deaths (490). Out of the 216 matched deaths, 80 (37.0%) had poorly specified causes of death in the SIM. Conclusions: The record linkage allowed for the detailing of the data with additional information from other epidemiological systems. Record linkage enables data linkage between information systems that lack interoperability and is an extremely useful tool for refining health situation analyses and improving malaria death surveillance in Brazil.
    Keywords malaria ; epidemiology ; public health ; control ; interrupted time series ; Brazil ; Medicine ; R
    Subject code 310
    Language English
    Publishing date 2023-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Two-Faced Immunity? The Evidence for Antibody Enhancement of Malaria Transmission

    Stone, Will / Chris Drakeley / Robert Sauerwein / Teun Bousema

    Trends in parasitology. 2019 Feb., v. 35, no. 2

    2019  

    Abstract: Plasmodium gametocytes can induce an immune response in humans that interferes with the development of sexual-stage parasites in the mosquito gut. Many early studies of the sexual-stage immune response noted that mosquito infection could be enhanced as ... ...

    Abstract Plasmodium gametocytes can induce an immune response in humans that interferes with the development of sexual-stage parasites in the mosquito gut. Many early studies of the sexual-stage immune response noted that mosquito infection could be enhanced as well as reduced by immune sera. For Plasmodium falciparum, these reports are scarce, and the phenomenon is generally regarded as a methodological artefact. Plasmodium transmission enhancement (TE) remains contentious, but the clinical development of transmission-blocking vaccines based on sexual-stage antigens requires that it is further studied. In this essay, we review the early literature on the sexual-stage immune response and transmission-modulating immunity. We discuss hypotheses for the mechanism of TE, suggest experiments to prove or disprove its existence, and discuss its possible implications.
    Keywords antibodies ; antigens ; antiserum ; Culicidae ; digestive system ; gametocytes ; immune response ; malaria ; parasites ; Plasmodium falciparum ; vaccines
    Language English
    Dates of publication 2019-02
    Size p. 140-153.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2036227-4
    ISSN 1471-5007 ; 1471-4922
    ISSN (online) 1471-5007
    ISSN 1471-4922
    DOI 10.1016/j.pt.2018.11.003
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo.

    Rebecca Brown / Tock H Chua / Kimberly Fornace / Chris Drakeley / Indra Vythilingam / Heather M Ferguson

    PLoS Neglected Tropical Diseases, Vol 14, Iss 9, p e

    2020  Volume 0008617

    Abstract: The zoonotic malaria parasite, Plasmodium knowlesi, is now a substantial public health problem in Malaysian Borneo. Current understanding of P. knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in ... ...

    Abstract The zoonotic malaria parasite, Plasmodium knowlesi, is now a substantial public health problem in Malaysian Borneo. Current understanding of P. knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in one district, Kudat. These have incriminated Anopheles balabacensis as the primary vector, and suggest that human exposure to vector biting is peri-domestic as well as in forest environments. To address the limited understanding of vector ecology and human exposure risk outside of Kudat, we performed wider scale surveillance across four districts in Sabah with confirmed transmission to investigate spatial heterogeneity in vector abundance, diversity and infection rate. Entomological surveillance was carried out six months after a cross-sectional survey of P. knowlesi prevalence in humans throughout the study area; providing an opportunity to investigate associations between entomological indicators and infection. Human-landing catches were performed in peri-domestic, farm and forest sites in 11 villages (3-4 per district) and paired with estimates of human P. knowlesi exposure based on sero-prevalence. Anopheles balabacensis was present in all districts but only 6/11 villages. The mean density of An. balabacensis was relatively low, but significantly higher in farm (0.094/night) and forest (0.082/night) than peri-domestic areas (0.007/night). Only one An. balabacensis (n = 32) was infected with P. knowlesi. Plasmodium knowlesi sero-positivity in people was not associated with An. balabacensis density at the village-level however post hoc analyses indicated the study had limited power to detect a statistical association due low vector density. Wider scale sampling revealed substantial heterogeneity in vector density and distribution between villages and districts. Vector-habitat associations predicted from this larger-scale surveillance differed from those inferred from smaller-scale studies in Kudat; highlighting the importance of local ecological context. ...
    Keywords Arctic medicine. Tropical medicine ; RC955-962 ; Public aspects of medicine ; RA1-1270
    Subject code 910
    Language English
    Publishing date 2020-09-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: No evidence of sustained nonzoonotic Plasmodium knowlesi transmission in Malaysia from modelling malaria case data

    Kimberly M. Fornace / Hillary M. Topazian / Isobel Routledge / Syafie Asyraf / Jenarun Jelip / Kim A. Lindblade / Mohammad Saffree Jeffree / Pablo Ruiz Cuenca / Samir Bhatt / Kamruddin Ahmed / Azra C. Ghani / Chris Drakeley

    Nature Communications, Vol 14, Iss 1, Pp 1-

    2023  Volume 8

    Abstract: Abstract Reported incidence of the zoonotic malaria Plasmodium knowlesi has markedly increased across Southeast Asia and threatens malaria elimination. Nonzoonotic transmission of P. knowlesi has been experimentally demonstrated, but it remains unknown ... ...

    Abstract Abstract Reported incidence of the zoonotic malaria Plasmodium knowlesi has markedly increased across Southeast Asia and threatens malaria elimination. Nonzoonotic transmission of P. knowlesi has been experimentally demonstrated, but it remains unknown whether nonzoonotic transmission is contributing to increases in P. knowlesi cases. Here, we adapt model-based inference methods to estimate R C , individual case reproductive numbers, for P. knowlesi, P. falciparum and P. vivax human cases in Malaysia from 2012–2020 (n = 32,635). Best fitting models for P. knowlesi showed subcritical transmission (R C < 1) consistent with a large reservoir of unobserved infection sources, indicating P. knowlesi remains a primarily zoonotic infection. In contrast, sustained transmission (R C > 1) was estimated historically for P. falciparum and P. vivax, with declines in R C estimates observed over time consistent with local elimination. Together, this suggests sustained nonzoonotic P. knowlesi transmission is highly unlikely and that new approaches are urgently needed to control spillover risks.
    Keywords Science ; Q
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Getting to zero

    Tanya L. Russell / Lynn Grignard / Alan Apairamo / Nathan Kama / Albino Bobogare / Chris Drakeley / Thomas R. Burkot

    Malaria Journal, Vol 20, Iss 1, Pp 1-

    micro-foci of malaria in the Solomon Islands requires stratified control

    2021  Volume 9

    Abstract: Abstract Background The Solomon Islands has made significant progress in the control of malaria through vector control, access and use of improved diagnostics and therapeutic drugs. As transmission is reduced there is a need to understand variations in ... ...

    Abstract Abstract Background The Solomon Islands has made significant progress in the control of malaria through vector control, access and use of improved diagnostics and therapeutic drugs. As transmission is reduced there is a need to understand variations in transmission risk at the provincial and village levels to stratify control methods. Methods A cross-sectional survey of malaria in humans was conducted in the Solomon Islands during April 2018. Nineteen villages across 4 provinces were included. The presence of Plasmodium species parasites in blood samples was detected using PCR. Results Blood samples were analysed from 1,914 participants. The prevalence of DNA of Plasmodium falciparum was 1.2 % (n = 23) and for Plasmodium vivax was 1.5 % (n = 28). 22 % (n = 5/23) of P. falciparum DNA positive participants were febrile and 17 % of P. vivax DNA positive participants (n = 5/28). The prevalence of both P. falciparum and P. vivax was extremely spatially heterogeneous. For P. falciparum, in particular, only 2 small foci of transmission were identified among 19 villages. Plasmodium falciparum infections were uniformly distributed across age groups. Insecticide-treated bed net use the night prior to the survey was reported by 63 % of participants and significantly differed by province. Conclusions Malaria transmission across the Solomon Islands has become increasingly fragmented, affecting fewer villages and provinces. The majority of infections were afebrile suggesting the need for strong active case detection with radical cure with primaquine for P. vivax. Village-level stratification of targeted interventions based on passive and active case detection data could support the progress towards a more cost-effective and successful elimination programme.
    Keywords Plasmodium falciparum ; Plasmodium vivax ; Solomon Islands ; Malaria elimination ; Heterogeneous transmission ; Arctic medicine. Tropical medicine ; RC955-962 ; Infectious and parasitic diseases ; RC109-216
    Subject code 572
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Safety monitoring experience of single-low dose primaquine co-administered with artemether–lumefantrine among providers and patients in routine healthcare practice

    Dominic Mosha / Mwaka A. Kakolwa / Muhidin K. Mahende / Honorati Masanja / Salim Abdulla / Chris Drakeley / Roland Gosling / Joyce Wamoyi

    Malaria Journal, Vol 20, Iss 1, Pp 1-

    a qualitative study in Eastern Tanzania

    2021  Volume 10

    Abstract: Abstract Background Primaquine is a gametocytocidal drug recommended by the World Health Organization (WHO) in a single-low dose combined with artemisinin-based combination therapy (ACT) for the treatment and prevention of Plasmodium falciparum malaria ... ...

    Abstract Abstract Background Primaquine is a gametocytocidal drug recommended by the World Health Organization (WHO) in a single-low dose combined with artemisinin-based combination therapy (ACT) for the treatment and prevention of Plasmodium falciparum malaria transmission. Safety monitoring concerns and the lack of a universal validated and approved primaquine pharmacovigilance tool is a challenge for a national rollout in many countries. This study aimed to explore the acceptance, reliability and perceived effectiveness of the primaquine roll out monitoring pharmacovigilance tool (PROMPT). Methods This study was conducted in three dispensaries in the Coastal region of Eastern Tanzania. The study held six in-depth interviews with healthcare providers and six participatory focus group discussions with malaria patients (3) and parents/guardians of sick children (3). Participants were purposively sampled. Thematic analysis was conducted with the aid of NVivo qualitative analysis software. Results The respondents’ general acceptance and perceived effectiveness of the single-low dose primaquine and PROMPT was good. Screening procedure for treatment eligibility and explaining to patients about the possible adverse events was considered very useful for safety reasons. Crushing and dissolving of primaquine tablet to get the appropriate dose, particularly in children, was reported by all providers to be challenging. Transport costs and poor access to the health facility were the main reasons for a patient failing to return to the clinic for a scheduled follow-up visit. Treatment was perceived to be safe by both providers and patients and reported no case of a severe adverse event. Some providers were concerned with the haemoglobin drop observed on day 7. Conclusion Single-low dose primaquine was perceived to be safe and acceptable among providers and patients. PROMPT demonstrated to be a reliable and user-friendly tool among providers. Further validation of the tool by involving the National Malaria Control Programme is pivotal ...
    Keywords Malaria ; Primaquine ; Artemether–lumefantrine ; Safety ; Monitoring ; Arctic medicine. Tropical medicine ; RC955-962 ; Infectious and parasitic diseases ; RC109-216
    Subject code 360
    Language English
    Publishing date 2021-10-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Challenges and opportunities for use of long-lasting insecticidal nets to prevent malaria during overnight travel in Uganda

    Deborah Ekusai-Sebatta / Emmanuel Arinaitwe / Arthur Mpimbaza / Joaniter I. Nankabirwa / Chris Drakeley / Philip J. Rosenthal / Sarah G. Staedke / Herbert Muyinda

    Malaria Journal, Vol 20, Iss 1, Pp 1-

    a qualitative study

    2021  Volume 9

    Abstract: Abstract Background Travel is a well-recognized risk factor for malaria. Within sub-Saharan Africa, travellers from areas of lower to higher transmission intensity are potentially at high risk of malaria. Long-lasting insecticidal nets (LLINs) are the ... ...

    Abstract Abstract Background Travel is a well-recognized risk factor for malaria. Within sub-Saharan Africa, travellers from areas of lower to higher transmission intensity are potentially at high risk of malaria. Long-lasting insecticidal nets (LLINs) are the primary tool for prevention of malaria, and their widespread use has contributed to substantial reductions in malaria burden. However, travellers often fail to use LLINs. To further explore the challenges and opportunities of using LLINs, travellers were interviewed in Uganda. Methods In August and September 2019, 20 participants attending outpatient clinics at Naguru General Hospital in Kampala with a history of travel out of Kampala within the previous 60 days were purposively selected. Data were collected through in-depth interviews and analysed thematically using NVivo 12. Results Of the 20 participants, 13 were male. Thirteen of the 20 participants tested positive for malaria by microscopy, and 5 reported using of LLINs during travel. The main reasons for travel were to attend social events (weddings, funerals, overnight prayers) and for work. travellers who attended social events reported using LLINs less commonly than those who travelled for work. Challenges to using LLINs during travel included: (1) limited access to LLINs; (2) challenges in planning ahead of travel; (3) lack of space or ability to hang LLINs while travelling; (4) impression that LLINs in lodging places were unhygienic; (5) cultural beliefs discouraging use of LLINs during social events; (6) participation in overnight ceremonies; and (7) doubts about efficacy of LLINs. Positive factors influencing use of LLINs during travel included knowledge regarding malaria prevention and good affordability and availability of LLINs. Conclusions Despite good traveller knowledge regarding malaria control measures, use of LLINs was limited. Use of LLINs in the prevention of malaria among travellers from low to high transmission settings needs to be prioritized. This calls for increased behaviour change ...
    Keywords Use of LLINs ; Overnight travel ; Malaria prevention ; Arctic medicine. Tropical medicine ; RC955-962 ; Infectious and parasitic diseases ; RC109-216
    Subject code 380
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article: Freedom from Infection: Confirming Interruption of Malaria Transmission

    Stresman, Gillian / Angus Cameron / Chris Drakeley

    Trends in parasitology. 2017 May, v. 33, no. 5

    2017  

    Abstract: The global reductions in disease burden and the continued spread of drug and insecticide resistance make malaria elimination both viable and imperative, although this may be more easily achieved in some settings compared to others. Whilst the focus has ... ...

    Abstract The global reductions in disease burden and the continued spread of drug and insecticide resistance make malaria elimination both viable and imperative, although this may be more easily achieved in some settings compared to others. Whilst the focus has been on optimal approaches to achieve elimination, less attention has been paid to how to measure the absence of malaria. Measuring the absence of transmission poses a specific challenge in that it involves proving a negative. The concept of freedom from infection, routinely used in veterinary epidemiology, can provide quantitative and reproducible estimates that, if infections were present above a predefined (low) threshold, they would be detected with a known uncertainty. Additionally, these methods are adaptable for both passively and actively collected data as well as combining information when multiple surveillance streams are available. Here we discuss the potential application of this approach to malaria.
    Keywords burden of disease ; drugs ; insecticide resistance ; malaria ; monitoring ; streams ; uncertainty
    Language English
    Dates of publication 2017-05
    Size p. 345-352.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2036227-4
    ISSN 1471-5007 ; 1471-4922
    ISSN (online) 1471-5007
    ISSN 1471-4922
    DOI 10.1016/j.pt.2016.12.005
    Database NAL-Catalogue (AGRICOLA)

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