Browsing by Author "Hamilton-West, Christopher"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Exposure Practices to Animal-Origin Influenza A Virus at the Animal-Human Interface in Poultry and Swine Backyard Farms
    (2024) Baumberger, Cecilia; Anriquez, Gustavo; Galdames, Pablo; Palma, Tamara; Gonzalez, Maria Antonieta; Orozco, Katherinne; Oyarzun, Cristobal; Rojas, Camila; Marambio, Victor; Ruiz, Soledad; Di Pillo, Francisca; Schultz-Cherry, Stacey; Jimenez-Bluhm, Pedro; Rushton, Jonathan; Hamilton-West, Christopher
    Aim: Backyard production systems (BPS) represent an interface of contact between people, domestic and wild animals. Studies conducted in Chile during the last decade have provided extensive evidence of influenza A virus (IAV) circulation in backyard poultry and swine. The aim of this study was to investigate exposure practices of humans to animal-origin IAV within backyards. Methods and Results: Backyard farmers and household members of a total of 101 BPS in the proximity of wetlands located throughout Chile were interviewed between 2021 and 2022. Data were collected on the nature of human-animal contacts through participation in productive activities conducted within backyards, which was used to estimate participants' exposure risk to animal-origin IAV. Additionally, RT-qPCR and serologic IAV active surveillance was carried out in backyard animals. Multilinear regression was used to identify factors associated with exposure risk. Overall, IAV prevalence was 10.1% (95% CI: 4.7%-15.5%) and seroprevalence was 43.5% (95% CI: 29.7%-54.2%), both at the BPS level. Of 180 interviewees, 86% reported par-ticipating regularly in poultry or swine exposure activities within the backyard. A greater participation of male participants was observed when evaluating swine exposure activities, while female participation was greater for some activities related to poultry handling. Handwashing was a very extended hygiene practice; however, the use of personal protective equipment was uncom-mon. Different factors related to participants, households and backyards were associated with an increased exposure risk of participants to animal-origin IAV: (i) older age, (ii) less years of education, (iii) no off-farm work, (iv) greater backyard production value and (v) greater household consumption of backyard products.
  • Thumbnail Image
    Item
    Long-Term Interactions of Salmonella Enteritidis With a Lytic Phage for 21 Days in High Nutrients Media
    (FRONTIERS MEDIA SA, 2022) Barron-Montenegro, Rocio; Rivera, Dacil; Serrano, Maria Jesus; Garcia, Rodrigo; alvarez, Diana M.; Benavides, Julio; Arredondo, Fernanda; alvarez, Francisca P.; Bastias, Roberto; Ruiz, Soledad; Hamilton-West, Christopher; Castro-Nallar, Eduardo; Moreno-Switt, Andrea I.
    Salmonella spp. is a relevant foodborne pathogen with worldwide distribution. To mitigate Salmonella infections, bacteriophages represent an alternative to antimicrobials and chemicals in food animals and food in general. Bacteriophages (phages) are viruses that infect bacteria, which interact constantly with their host. Importantly, the study of these interactions is crucial for the use of phages as a mitigation strategy. In this study, experimental coevolution of Salmonella Enteritidis (S. Enteritidis) and a lytic phage was conducted in tryptic soy broth for 21 days. Transfer to fresh media was conducted daily and every 24 hours, 2 mL of the sample was collected to quantify Salmonella OD600 and phage titter. Additionally, time-shift experiments were conducted on 20 colonies selected on days 1, 12, and 21 to evaluate the evolution of resistance to past (day 1), present (day 12), and future (day 21) phage populations. The behavior of the dynamics was modeled and simulated with mathematical mass-action models. Bacteria and phage from days 1 and 21 were sequenced to determine the emergence of mutations. We found that S. Enteritidis grew for 21 days in the presence and absence of the phage and developed resistance to the phage from day 1. Also, the phage was also able to survive in the media for 21 days, however, the phage titer decreased in approx. 3 logs PFU/mL. The stability of the lytic phage population was consistent with the leaky resistance model. The time-shift experiments showed resistance to phages from day 1 of at least 85% to the past, present, and future phages. Sequencing of S. Enteritidis showed mutations in genes involved in lipopolysaccharide biosynthesis genes rfbP and rfbN at day 21. The phage showed mutations in the tail phage proteins responsible for recognizing the cell surface receptors. These results suggest that interactions between bacteria and phage in a rich resource media generate a rapid resistance to the infective phage but a fraction of the population remains susceptible. Interactions between Salmonella and lytic phages are an important component for the rational use of phages to control this important foodborne pathogen.
  • No Thumbnail Available
    Item
    Novel Low Pathogenic Avian Influenza H6N1 in Backyard Chicken in Easter Island (Rapa Nui), Chilean Polynesia
    (2022) Di Pillo, Francisca; Baumberger, Cecilia; Salazar, Carla; Galdames, Pablo; Ruiz, Soledad; Sharp, Bridgett; Freiden, Pamela; Tan, Shaoyuan; Schultz-Cherry, Stacey; Hamilton-West, Christopher; Jimenez-Bluhm, Pedro
    Little is known about the prevalence of avian influenza viruses (AIV) in wildlife and domestic animals in Polynesia. Here, we present the results of active AIV surveillance performed during two sampling seasons in 2019 on Easter Island (Rapa Nui). Tracheal and cloacal swabs as well as sera samples were obtained from domestic backyard poultry, while fresh faeces were collected from wild birds. In addition to detecting antibodies against AIV in 46% of the domestic chickens in backyard production systems tested, we isolated a novel low pathogenic H6N1 virus from a chicken. Phylogenetic analysis of all genetic segments revealed that the virus was closely related to AIV's circulating in South America. Our analysis showed different geographical origins of the genetic segments, with the PA, HA, NA, NP, and MP gene segments coming from central Chile and the PB2, PB1, and NS being closely related to viruses isolated in Argentina. While the route of introduction can only be speculated, our analysis shows the persistence and independent evolution of this strain in the island since its putative introduction between 2015 and 2016. The results of this research are the first evidence of AIV circulation in domestic birds on a Polynesian island and increase our understanding of AIV ecology in region, warranting further surveillance on Rapa Nui and beyond.
  • No Thumbnail Available
    Item
    Remote Sensing and Ecological Variables Related to Influenza A Prevalence and Subtype Diversity in Wild Birds in the Lluta Wetland of Northern Chile
    (2023) Ruiz, Soledad; Galdames, Pablo; Baumberger, Cecilia; Gonzalez, Maria Antonieta; Rojas, Camila; Oyarzun, Cristobal; Orozco, Katherinne; Mattar, Cristian; Freiden, Pamela; Sharp, Bridgette; Schultz-Cherry, Stacey; Hamilton-West, Christopher; Jimenez-Bluhm, Pedro
    The Lluta River is the northernmost coastal wetland in Chile, representing a unique ecosystem and an important source of water in the extremely arid Atacama Desert. During peak season, the wetland is home to more than 150 species of wild birds and is the first stopover point for many migratory species that arrive in the country along the Pacific migratory route, thereby representing a priority site for avian influenza virus (AIV) surveillance in Chile. The aim of this study was to determine the prevalence of influenza A virus (IAV) in the Lluta River wetland, identify subtype diversity, and evaluate ecological and environmental factors that drive the prevalence at the study site. The wetland was studied and sampled from September 2015 to October 2020. In each visit, fresh fecal samples of wild birds were collected for IAV detection by real-time RT-PCR. Furthermore, a count of wild birds present at the site was performed and environmental variables, such as temperature, rainfall, vegetation coverage (Normalized Difference Vegetation Index-NDVI), and water body size were determined. A generalized linear mixed model (GLMM) was built to assess the association between AIV prevalence and explanatory variables. Influenza positive samples were sequenced, and the host species was determined by barcoding. Of the 4349 samples screened during the study period, overall prevalence in the wetland was 2.07% (95% CI: 1.68 to 2.55) and monthly prevalence of AIV ranged widely from 0% to 8.6%. Several hemagglutinin (HA) and neuraminidase (NA) subtypes were identified, and 10 viruses were isolated and sequenced, including low pathogenic H5, H7, and H9 strains. In addition, several reservoir species were recognized (both migratory and resident birds), including the newly identified host Chilean flamingo (Phoenicopterus chilensis). Regarding environmental variables, prevalence of AIV was positively associated with NDVI (OR = 3.65, p < 0.05) and with the abundance of migratory birds (OR = 3.57, p < 0.05). These results emphasize the importance of the Lluta wetland as a gateway to Chile for viruses that come from the Northern Hemisphere and contribute to the understanding of AIV ecological drivers.
  • No Thumbnail Available
    Item
    Swine Backyard Production Systems in Central Chile: Characterizing Farm Structure, Animal Management, and Production Value Chain
    (2023) Baumberger, Cecilia; Di Pillo, Francisca; Galdames, Pablo; Oyarzun, Cristobal; Marambio, Victor; Jimenez-Bluhm, Pedro; Hamilton-West, Christopher
    Simple Summary The central zone of Chile concentrates an important number of backyard production systems, where poultry species are the most commonly present in backyards, followed by swine. There is compelling evidence in the scientific literature indicating the circulation of zoonotic pathogens among backyard poultry and swine. As a result, backyards represent a significant animal-human interface that warrants further investigation. Previous studies have characterized poultry backyards in Chile; however, swine backyards have not yet been characterized. Therefore, the objectives of this study were to characterize swine backyard production systems in the central zone of Chile and to describe the value chain of swine backyard production. We found that backyard production is carried out in the context of the low implementation of biosecurity measures and that in most backyards, there is no animal health management in place; thus, the sanitary status of pigs is usually unknown. Moreover, a significant amount of movement of animals and animal products between different backyards was identified. These results suggest that swine backyards have biosecurity deficiencies that may play an important role in the risk of introduction and dissemination of animal pathogens or the emergence of zoonotic diseases and therefore require special attention. Backyard production systems (BPS) are highly distributed in central Chile. While poultry BPS have been extensively characterized, there remains a notable gap in the characterization of swine BPS in central Chile. In addition, there is evidence that zoonotic pathogens, such as influenza A virus and Salmonella spp., are circulating in backyard poultry and pigs. A total of 358 BPS located in central Chile were evaluated between 2013 and 2015 by interviewing farm owners. Severe deficiencies in biosecurity measures were observed. The value chain of swine backyard production identified food, veterinary care (visits and products), and replacement or breeding animals as the primary inputs to the backyard. The most common origin of swine replacements was from outside the BPS (63%). The main outputs of the system were identified as meat and live animals, including piglets and breeding animals. In 16% of BPS, breeding animals were lent to other BPS, indicating the existence of animals and animal product movement in and out of backyard farms. Results from this study indicate that swine BPS in central Chile represents an animal-human interface that demands special attention for implementing targeted preventive measures to prevent the introduction and spread of animal pathogens and the emergence of zoonotic pathogens.
  • No Thumbnail Available
    Item
    Widespread Environmental Presence of Multidrug-Resistant Salmonella in an Equine Veterinary Hospital That Received Local and International Horses
    (2020) Soza-Ossandon, Paula; Rivera, Dacil; Tardone, Rodolfo; Riquelme-Neira, Roberto; Garcia, Patricia; Hamilton-West, Christopher; Adell, Aiko D.; Gonzalez-Rocha, Gerardo; Moreno-Switt, Andrea, I
    Salmonella entericais a highly infectious microorganism responsible for many outbreaks reported in equine hospitals. Outbreaks are characterized by high morbidity and mortality rates, nosocomial transmission to other patients, zoonotic transmission to hospital personnel, and even closure of facilities. In this study, 545 samples (environmental and hospitalized patients) were collected monthly during a 1-year period from human and animal contact surfaces in an equine hospital that received local and international horses. A total of 22Salmonellaisolates were obtained from human contact surfaces (e.g., offices and pharmacy) and animal contact surfaces (e.g., stalls, surgery room, and waterers), and one isolate from a horse. Molecular serotyping revealed 18 isolates asSalmonellaTyphimurium and three asSalmonellaInfantis. Nineteen isolates were resistant to at least one antimicrobial class, and only two isolates were susceptible to all antimicrobials tested. In addition, we identified nine multidrug-resistant (MDR) isolates inS. Typhimurium, which displayed resistance to up to eight antimicrobials (i.e., amoxicillin/clavulanate, ampicillin, ciprofloxacin, chloramphenicol, streptomycin, gentamicin, trimethoprim/sulfamethoxazole, and tetracycline). Pulsed-field gel electrophoresis (PFGE) revealed the presence of three PFGE patterns permanently present in the environment of the hospital during our study. The persistent environmental presence of MDRSalmonellaisolates, along with the fact that local and international horses are attended in this hospital, highlights the importance of improving biosecurity programs to prevent disease in horses and the hospital personnel and also for the global dissemination and acquisition of MDRSalmonella.