Anopheline and human drivers of malaria risk in northern coastal, Ecuador: a pilot study

Martin, James A.; Hendershot, Allison; Portilla, Iván Alejandro Saá; English, Dan; Woodruff, M.G.; Vera-Arias, Claudia A.; Salazar-Costa, Bibiana E.; Bustillos, Juan José; Saénz, Fabián E.; Ocaña-Mayorga, Sofía; Koepfli, Cristian; Lobo, Neil F.

doi:10.1186/s12936-020-03426-y

Cited by 16 publications

(20 citation statements)

References 50 publications

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“…2 Malaria Elimination Initiative (MEI), University of California, San Francisco (UCSF), USA. 3 Clinton Health Access Initiative (CHAI), Panama City, Panama. 4 Eck Institute for Global Health, University of Notre Dame (UND), Notre Dame, IN, USA.…”

Section: Abbreviationsmentioning

confidence: 99%

“…Palabras clave: Bionomia, Ny. albimanus, Exofágico, Malaria surveillance is critical to guide the selection of appropriate malaria interventions, the appropriate targeting of these interventions, and the management of expectations of the effects of vector control on local malaria transmission [3].…”

Section: Introductionmentioning

confidence: 99%

“…As of 2019, MINSA and its implementing partners initiated a first pilot distribution campaign of long-lasting insecticidal nets (LLINs) and long-lasting insecticidal hammock nets (LLIHNs) in key areas of Guna Yala [10,25]. While IRS and LLINs have been proven to be highly effective against endophilic and endophagic Anopheles mosquitoes [26,27], contextual effectiveness relies on local vector bionomic characteristics [3].…”

Section: Introductionmentioning

confidence: 99%

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Anopheles drivers of persisting malaria transmission in Guna Yala, Panamá: an operational investigation

Ávila¹,

Vajda

Gutiérrez

et al. 2021

Malar J

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Background Though most of Panamá is free from malaria, localized foci of transmission persist, including in the Guna Yala region. Government-led entomological surveillance using an entomological surveillance planning tool (ESPT) sought to answer programmatically-relevant questions that would enhance the understanding of both local entomological drivers of transmission and gaps in protection that result in persisting malaria transmission to guide local vector control decision-making. Methods The ESPT was used to design a sampling plan centered around the collection of minimum essential indicators to investigate the relevance of LLINs and IRS in the communities of Permé and Puerto Obaldía, Guna Yala, as well as to pinpoint any remaining spaces and times where humans are exposed to Anopheles bites (gaps in protection). Adult Anopheles were collected at three time points via human landing catches (HLCs), CDC Light Traps (LT), and pyrethrum spray catches (PSCs) during the rainy and dry seasons. Mosquitoes were identified to species via molecular methods. Insecticide susceptibility testing of the main vector species to fenitrothion was conducted. Results In total, 7537 adult Anopheles were collected from both sites. Of the 493 specimens molecularly confirmed to species, two thirds (n = 340) were identified as Nyssorhynchus albimanus, followed by Anopheles aquasalis. Overall Anopheles human biting rates (HBRs) were higher outdoors than indoors, and were higher in Permé than in Puerto Obaldía: nightly outdoor HBR ranged from 2.71 bites per person per night (bpn) (Puerto Obaldía), to 221.00 bpn (Permé), whereas indoor nightly HBR ranged from 0.70 bpn (Puerto Obaldía) to 81.90 bpn (Permé). Generally, peak biting occurred during the early evening. The CDC LT trap yields were significantly lower than that of HLCs and this collection method was dropped after the first collection. Pyrethrum spray catches resulted in only three indoor resting Anopheles collected. Insecticide resistance (IR) of Ny. albimanus to fenitrothion was confirmed, with only 65.5% mortality at the diagnostic time. Conclusion The early evening exophagic behaviour of Anopheles vectors, the absence of indoor resting behaviours, and the presence of resistance to the primary intervention insecticide demonstrate limitations of the current malaria strategy, including indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs), and point to both gaps in protection and to the drivers of persisting malaria transmission in Guna Yala. These findings highlight the need for continued and directed entomological surveillance, based on programmatic questions, that generates entomological evidence to inform an adaptive malaria elimination strategy.

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Section: Abbreviationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Anopheles drivers of persisting malaria transmission in Guna Yala, Panamá: an operational investigation

Ávila¹,

Vajda

Gutiérrez

et al. 2021

Malar J

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“…Human behavior-adjusted biting rates and the protections afforded by ITNs were generated using HLRs, HBOs and ITN survey data as in Monroe et. al, 2020 [ 12 , 13 ].…”

Section: Methodsmentioning

confidence: 99%

Human behavior determinants of exposure to Anopheles vectors of malaria in Sumba, Indonesia

et al. 2022

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Malaria vector control interventions in Sumba, Indonesia, have not been able to eliminate malaria. Human drivers of exposure to Anopheles bites were investigated as part of a larger clinical trial evaluating the impact of a spatial repellent product on malaria incidence. Human behavioral observations (HBOs) evaluating temporal and spatial presence, sleeping behaviors, and insecticide treated net (ITN) use, were collected parallel to entomological collections—indoor and outdoor human landing catches (HLCs), and house hold surveys. Data demonstrates that mosquito access to humans, enabled by structurally open houses, is evident by the similar entomological landing rates both inside and outside households. The presence of animals inside houses was associated with increased mosquito entry–however, the number of humans present inside houses was not related to increased mosquito landing. Analyzing mosquito landing rates with human behavior data enables the spatial and temporal estimation of exposure to Anopheles bites, accounting for intervention (ITN) presence and usage. Human behavior adjusted exposure to Anopheles bites was found to be highest in the early in the evening, but continued at lower levels throughout the night. Over the night, most exposure (53%) occurred when people were indoors and not under the protection of nets (asleep or awake) followed by exposure outside (44%). Characterized gaps in protection are outdoor exposure as well as exposure indoors–when awake, and when asleep and not using ITNs. Interestingly, in the primary trial, even though there was not a significant impact of the spatial repellent on vector biting rates by themselves (16%), when factoring in human behavior, there was approximately 28% less exposure in the intervention arm than in the placebo arm. The treated arm had less human behavior adjusted bites in all spaces evaluated though there was proportionally higher exposure indoors. This analysis points to the importance of using HBOs both towards understanding gaps in protection as well as how interventions are evaluated. To mitigate ongoing transmission, understanding context specific spatial and temporal exposure based on the interactions of vectors, humans and interventions would be vital for a directed evidence-based control or elimination strategy.

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“…During 2019, 790 cases were registered in provinces of the Amazon region: Morona Santiago with 521 cases in Pastaza and 372 in Orellana, i.e., 84% of active transmission in the country (7). In these areas, malaria transmission is related to rainfall increases favoring the availability of habitats for larvae, the development of settlements in forest areas, oil or mining extraction activities, and the migration from neighboring communities in Colombia or Perú, with the subsequent risk of introducing parasites in decreased-transmission areas or maintaining transmission in active areas (8).…”

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confidence: 99%

Characterization of an outbreak of malaria in a non-endemic zone on the coastal region of Ecuador

2021

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Introduction: Malaria is a vector-borne disease widely distributed in the Amazon region and the coastal area of northern Ecuador. Its epidemiology involves related factors such as human settlements, vector reproduction sites, mobility, productive activity, and the response capacity of health systems, among others.Objective: To describe malaria transmission by Plasmodium vivax in a non-endemic area of Ecuador by analyzing the epidemiological and entomological factors involved.Materials and methods: We conducted the epidemiological study of the cases reported in the Salinas canton and the characterization of vector breeding sites through captures of larvae and adult mosquitoes by human capture of resting mosquitoes.Results: We detected 21 cases of malaria with local transmission related to the presence of initial cases in Venezuelan migrant patients and identified Anopheles albimanus as the predominant vector in natural breeding sites such as estuaries, wells, and water channels.Conclusions: We detected an outbreak of malaria triggered by imported cases from Venezuela. Climatic, social, environmental, and ecological conditions have favored the development of the vector maintaining the transmission cycle. Strategies to control imported malaria should be multiple including early case detection and control of productive breeding sites to avoid local transmission.

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Anopheline and human drivers of malaria risk in northern coastal, Ecuador: a pilot study

Cited by 16 publications

References 50 publications

Anopheles drivers of persisting malaria transmission in Guna Yala, Panamá: an operational investigation

Anopheles drivers of persisting malaria transmission in Guna Yala, Panamá: an operational investigation

Human behavior determinants of exposure to Anopheles vectors of malaria in Sumba, Indonesia

Characterization of an outbreak of malaria in a non-endemic zone on the coastal region of Ecuador

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