Last data update: Nov 04, 2024. (Total: 48056 publications since 2009)
Records 1-6 (of 6 Records) |
Query Trace: Segura T[original query] |
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Automated cooling tower detection through deep learning for Legionnaires' disease outbreak investigations: a model development and validation study
Wong KK , Segura T , Mein G , Lu J , Hannapel EJ , Kunz JM , Ritter T , Smith JC , Todeschini A , Nugen F , Edens C . Lancet Digit Health 2024 6 (7) e500-e506 BACKGROUND: Cooling towers containing Legionella spp are a high-risk source of Legionnaires' disease outbreaks. Manually locating cooling towers from aerial imagery during outbreak investigations requires expertise, is labour intensive, and can be prone to errors. We aimed to train a deep learning computer vision model to automatically detect cooling towers that are aerially visible. METHODS: Between Jan 1 and 31, 2021, we extracted satellite view images of Philadelphia (PN, USA) and New York state (NY, USA) from Google Maps and annotated cooling towers to create training datasets. We augmented training data with synthetic data and model-assisted labelling of additional cities. Using 2051 images containing 7292 cooling towers, we trained a two-stage model using YOLOv5, a model that detects objects in images, and EfficientNet-b5, a model that classifies images. We assessed the primary outcomes of sensitivity and positive predictive value (PPV) of the model against manual labelling on test datasets of 548 images, including from two cities not seen in training (Boston [MA, USA] and Athens [GA, USA]). We compared the search speed of the model with that of manual searching by four epidemiologists. FINDINGS: The model identified visible cooling towers with 95·1% sensitivity (95% CI 94·0-96·1) and a PPV of 90·1% (95% CI 90·0-90·2) in New York City and Philadelphia. In Boston, sensitivity was 91·6% (89·2-93·7) and PPV was 80·8% (80·5-81·2). In Athens, sensitivity was 86·9% (75·8-94·2) and PPV was 85·5% (84·2-86·7). For an area of New York City encompassing 45 blocks (0·26 square miles), the model searched more than 600 times faster (7·6 s; 351 potential cooling towers identified) than did human investigators (mean 83·75 min [SD 29·5]; mean 310·8 cooling towers [42·2]). INTERPRETATION: The model could be used to accelerate investigation and source control during outbreaks of Legionnaires' disease through the identification of cooling towers from aerial imagery, potentially preventing additional disease spread. The model has already been used by public health teams for outbreak investigations and to initialise cooling tower registries, which are considered best practice for preventing and responding to outbreaks of Legionnaires' disease. FUNDING: None. |
Assessments and observations of infection prevention and control practices in US outpatient hemodialysis facilities, 2015-2018: important opportunities for improvement
Gualandi NR , Novosad SA , Perz JF , Hopkins LR , Hsu S , Segura S , Kopp P , Maloney M , McHale E , Mehr J , Perlmutter R , Patel PR . Infect Control Hosp Epidemiol 2024 1-6 Infections cause substantial morbidity and mortality among patients receiving care in outpatient hemodialysis facilities. We describe comprehensive infection prevention assessments by US public health departments using standardized interview and observation tools. Results demonstrated how facility layouts can undermine infection prevention and that clinical practices often fall short of policies. |
Mixed methods community-engaged evaluation: Integrating interventionist and action research frameworks to understand a community-building violence prevention program
Banyard VL , Edwards KM , Rizzo AJ , Segura-Montagut A , Greenberg P , Kearns MC . J Mix Methods Res 2022 While mixed methods research can enhance studies of intervention outcomes and projects where research itself transforms communities through participatory approaches, methodologists need explicit examples. As the field of interpersonal violence prevention increasingly embraces community-level prevention strategies, it may benefit from research methods that mirror community-building prevention processes. A multiphase mixed methods study with sequential and convergent components assessed the feasibility, and impact of a prevention program to change social norms and increase collective efficacy in towns. Joint display analysis created a nuanced picture of the acceptability, feasibility, and impact of the program. This article contributes to the field of mixed methods research by bridging discussions of “interventionist” studies with models of community-based participatory mixed methods research into a combined community-engaged method. © The Author(s) 2022. |
Impact of deltamethrin selection on kdr mutations and insecticide detoxifying enzymes in Aedes aegypti from Mexico.
Contreras-Perera Y , Ponce-Garcia G , Villanueva-Segura K , Lopez-Monroy B , Rodriguez-Sanchez IP , Lenhart A , Manrique-Saide P , Flores AE . Parasit Vectors 2020 13 (1) 224 BACKGROUND: Insecticide resistance is a serious problem for vector control programmes worldwide. Resistance is commonly attributed to mutations at the insecticide's target site or increased activity of detoxification enzymes. METHODS: We determined the knockdown concentration (KC50) and lethal concentration (LC50) of deltamethrin in six natural populations of adult Aedes aegypti from southeastern Mexico. These populations were then selected over five generations using the LC50 from the preceding generation that underwent selection, and the heritability of deltamethrin resistance was quantified. For each generation, we also determined the frequency of the kdr alleles L410, I1016 and C1534, and the levels of activity of three enzyme families (alpha- and beta-esterases, mixed-function oxidases and glutathione S-transferases (GST)) associated with insecticide detoxification. RESULTS: There was an increase in KC50 and LC50 values in the subsequent generations of selection with deltamethrin (FS5vs FS0). According to the resistance ratios (RRs), we detected increases in LC50 ranging from 1.5 to 5.6 times the values of the parental generation and in KC50 ranging from 1.3-3.8 times the values of the parental generation. Triple homozygous mutant individuals (tri-locus, LL/II/CC) were present in the parental generations and increased in frequency after selection. The frequency of L410 increased from 1.18-fold to 2.63-fold after selection with deltamethrin (FS5vs FS0) in the populations analyzed; for I1016 an increase between 1.19-fold to 2.79-fold was observed, and C1534 was fixed in all populations after deltamethrin selection. Enzymatic activity varied significantly over the generations of selection. However, only alpha- esterase activity remained elevated in multiple populations after five generations of deltamethrin selection. We observed an increase in the mean activity levels of GSTs in two of the six populations analyzed. CONCLUSIONS: The high levels of resistance and their association with high frequencies of kdr mutations (V410L, V1016I and F1534C) obtained through artificial selection, suggest an important role of these mutations in conferring resistance to deltamethrin. We highlight the need to implement strategies that involve the monitoring of kdr frequencies in insecticide resistance monitoring and management programmes. |
Molecular Epidemiology of Giardia, Blastocystis and Cryptosporidium among Indigenous Children from the Colombian Amazon Basin.
Sanchez A , Munoz M , Gomez N , Tabares J , Segura L , Salazar A , Restrepo C , Ruiz M , Reyes P , Qian Y , Xiao L , Lopez MC , Ramirez JD . Front Microbiol 2017 8 248 The incidence and prevalence of intestinal parasites in children is most likely due to lack of natural or acquired resistance and differences in behavior and habits closely related to environmental and socioeconomic determinants. The most important protozoa that parasitize humans are Giardia, Entamoeba, Blastocystis, and Cryptosporidium. These parasites present wide intraspecific genetic diversity and subsequently classified into assemblages and subtypes. The Amazon basin is the largest in the world and is the fifth freshwater reserve on the planet. Contradictorily, people living in these areas (Indigenous populations) have poor quality of life, which favors the infection of diseases of fecal-oral transmission. The aim of this work was to unravel the molecular epidemiology of Giardia, Blastocystis and Cryptosporidium across four communities (Puerto Narino, San Juan del Soco, Villa Andrea and Nuevo Paraiso). We obtained 284 fecal samples from children under 15 years old that were analyzed by direct microscopy (261 samples) and Real Time PCR (qPCR) (284 samples). The positive samples for these protozoa were further characterized by several molecular markers to depict assemblages and subtypes. We observed a frequency of Giardia infection by microscopy of 23.7% (62 samples) and by qPCR of 64.8% (184 samples); for Blastocystis by microscopy of 35.2% (92 samples) and by qPCR of 88.7% (252 samples) and for Cryptosporidium only 1.9% (5 samples) were positive by microscopy and qPCR 1.8% (5 samples). Regarding the Giardia assemblages, using the glutamate dehydrogenase (gdh) marker we observed AI, BIII and BIV assemblages and when using triose phosphate isomerase (tpi) we observed assemblages AI, AII, BIII and BIV. In contrast, Blastocystis STs detected were 1, 2, 3, 4, and 6. Lastly, the species C. viatorum, C. hominis (with the subtypes IdA19 and IaA12R8) and C. parvum (with the subtype IIcA5G3c) were identified. We observed a high profile of zoonotic transmission regarding the Giardia assemblages and Blastocystis STs/alleles. Also, we highlight the elevated frequency of infection by these two protozoans suggesting an active transmission in the area. Our findings reinforces the need to deploy better epidemiological surveillance systems for enteric pathogens in the area. |
Knockdown Resistance Mutations in Aedes aegypti (Diptera: Culicidae) From Puerto Rico.
Ponce-Garcia G , Del Rio-Galvan S , Barrera R , Saavedra-Rodriguez K , Villanueva-Segura K , Felix G , Amador M , Flores AE . J Med Entomol 2016 53 (6) 1410-1414 Permethrin resistance is widespread in Aedes aegypti (L.), the main dengue, zika, and chikungunya virus vector in Latin America and the Caribbean. A common mechanism of resistance to pyrethroids-knockdown resistance (kdr)-is conferred through mutations in the insect's voltage-dependent sodium channel. In this mosquito, around 10 replacement substitutions in the voltage-gated sodium channel gene (vgsc) have been reported in pyrethroid-resistant strains. Two of these mutations, named Ile1,016 and Cys1,534, are widespread in mosquito populations from Latin America and the Caribbean. This study assessed the levels of permethrin resistance and the frequency of two kdr mutations in eight Ae. aegypti populations collected in Puerto Rico in 2013. Permethrin resistance factors ranged from 33-214-fold relative to the New Orleans reference strain. The frequency of kdr mutation Ile1,016 ranged from 0.65 to fixation (1.0), and for Cys1,534 frequencies varied from 0.8 to fixation. Alarmingly, two populations-Carolina and Caguas-reached fixation at both loci. Our results suggest that permethrin effectiveness for Ae. aegypti control is compromised in these collections from Puerto Rico. |
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