Routes Of Pathogen Transmission Research Articles

Host attraction and host feeding patterns indicate generalist feeding of Culex pipiens s.s. and Cx. torrentium

BackgroundMosquito host feeding patterns are an important factor of the species-specific vector capacity determining pathogen transmission routes. Culex pipiens s.s./Cx. torrentium are competent vectors of several arboviruses, such as West Nile virus and Usutu virus. However, studies on host feeding patterns rarely differentiate the morphologically indistinguishable females.MethodsWe analyzed the host feeding attraction of Cx. pipiens and Cx. torrentium in host-choice studies for bird, mouse, and a human lure. In addition, we summarized published and unpublished data on host feeding patterns of field-collected specimens from Germany, Iran, and Moldova from 2012 to 2022, genetically identified as Cx. pipiens biotype pipiens, Cx. pipiens biotype molestus, Cx. pipiens hybrid biotype pipiens × molestus, and Cx. torrentium, and finally put the data in context with similar data found in a systematic literature search.ResultsIn the host-choice experiments, we did not find a significant attraction to bird, mouse, and human lure for Cx. pipiens pipiens and Cx. torrentium. Hosts of 992 field-collected specimens were identified for Germany, Iran, and Moldova, with the majority determined as Cx. pipiens pipiens, increasing the data available from studies known from the literature by two-thirds. All four Culex pipiens s.s./Cx. torrentium taxa had fed with significant proportions on birds, humans, and nonhuman mammals. Merged with the data from the literature from 23 different studies showing a high prevalence of blood meals from birds, more than 50% of the blood meals of Cx. pipiens s.s. were identified as birds, while up to 39% were human and nonhuman mammalian hosts. Culex torrentium fed half on birds and half on mammals. However, there were considerable geographical differences in the host feeding patterns.ConclusionsIn the light of these results, the clear characterization of the Cx. pipiens s.s./Cx. torrentium taxa as ornithophilic/-phagic or mammalophilic/-phagic needs to be reconsidered. Given their broad host ranges, all four Culex taxa could potentially serve as enzootic and bridge vectors.Graphical

The phenomenon of attachment and feeding of unfed ticks (Ixodoidea) on fed and feeding specimens of the same or different species: biological and epidemiological issues

Hyperparasitism, characterized by attachment and feeding of unfed ticks on engorged or feeding specimens of the same species (tick-to-tick attachment and feeding) has been extensively documented in laboratory colonies of ticks of the Ixodoidea superfamily. Existing literature generally assumes that hyperparasitism operates similarly across tick species in both main families, Argasidae and Ixodidae. However, a closer examination of the available data reveals distinct biological mechanisms underlying this phenomenon in different groups. In argasid ticks, hyperparasitism in laboratory colonies primarily involves unfed specimens stealing blood from their fed relatives, especially under stress of starvation or overcrowding. It remains uncertain whether this behavior of argasid ticks occurs under field conditions. If it does happen naturally, it may have originated as a consequence of the nidicolous lifestyle exhibited by soft ticks. In Ixodes ticks (Ixodinae or Prostriata), hyperparasitism of males on unfed or feeding females appears to be a side-effect in the male attempts to copulate while hyperparasitism in Amblyomminae (Metastriata) ticks is likely an aberration in feeding. This difference between Argasidae and Ixodidae may stem from independent adaptation to blood-feeding within the two Ixodoidea families. Experimental evidence of pathogen transmission between aggressor and victim during hyperparasitic feeding has only been demonstrated under laboratory conditions specifically in Ornithodoros species (Argasidae). The practical importance of this route of pathogen transmission is still unclear. Although there is an assumption in the literature that hyperparasitic pathogen transmission occurs in the taiga tick Ixodes persulcatus, it is important to know that no current data is available to support this presumption.

Future research perspective on the interfacial physics of non-invasive glaucoma testing in pathogen transmission from the eyes.

Non-contact tonometry (NCT) is a non-invasive ophthalmologic technique to measure intraocular pressure (IOP) using an air puff for routine glaucoma testing. Although IOP measurement using NCT has been perfected over many years, various phenomenological aspects of interfacial physics, fluid structure interaction, waves on corneal surface, and pathogen transmission routes to name a few are inherently unexplored. Research investigating the interdisciplinary physics of the ocular biointerface and of the NCT procedure is sparse and hence remains to be explored in sufficient depth. In this perspective piece, we introduce NCT and propose future research prospects that can be undertaken for a better understanding of the various hydrodynamic processes that occur during NCT from a pathogen transmission viewpoint. In particular, the research directions include the characterization and measurement of the incoming air puff, understanding the complex fluid-solid interactions occurring between the air puff and the human eye for measuring IOP, investigating the various waves that form and travel; tear film breakup and subsequent droplet formation mechanisms at various spatiotemporal length scales. Further, from an ocular disease transmission perspective, the disintegration of the tear film into droplets and aerosols poses a potential pathogen transmission route during NCT for pathogens residing in nasolacrimal and nasopharynx pathways. Adequate precautions by opthalmologist and medical practioners are therefore necessary to conduct the IOP measurements in a clinically safer way to prevent the risk associated with pathogen transmission from ocular diseases like conjunctivitis, keratitis, and COVID-19 during the NCT procedure.

High prevalence of Enterovirus E, Bovine Kobuvirus, and Astrovirus revealed by viral metagenomics in fecal samples from cattle in Central Colombia

Livestock plays a crucial role in ensuring food security and driving the global economy. However, viral infections can have far-reaching consequences beyond economic productivity, affecting the health of cattle, as well as posing risks to human health and other animals. Identifying viruses present in fecal samples, a primary route of pathogen transmission, is essential for developing effective prevention, control, and surveillance strategies. Viral metagenomic approaches offer a broader perspective and hold great potential for detecting previously unknown viruses or uncovering previously undescribed agents. Ubaté Province is Colombia's dairy capital and a key center for livestock production in the country. Therefore, the purpose of this study was to characterize viral communities in fecal samples from cattle in this region. A total of 42 samples were collected from three municipalities in Ubaté Province, located in central Colombia, using a convenient non-probabilistic sampling method. We utilized metagenomic sequencing with Oxford Nanopore Technologies (ONT), combined with diversity and phylogenetic analysis. The findings revealed a consistent and stable viral composition across the municipalities, primarily comprising members of the Picornaviridae family. At the species level, the most frequent viruses were Enterovirus E (EVE) and Bovine Astrovirus (BoAstV). Significantly, this study reported, for the first time in Colombia, the presence of viruses with veterinary importance occurring at notable frequencies: EVE (59%), Bovine Kobuvirus (BKV) (52%), and BoAstV (19%). Additionally, the study confirmed the existence of Circular replicase-encoding single-stranded (CRESS) Virus in animal feces. These sequences were phylogenetically grouped with samples obtained from Asia and Latin America, underscoring the importance of having adequate representation across the continent. The virome of bovine feces in Ubaté Province is characterized by the predominance of potentially pathogenic viruses such as BoAstV and EVE that have been reported with substantial frequency and quantities. Several of these viruses were identified in Colombia for the first time. This study showcases the utility of using metagenomic sequencing techniques in epidemiological surveillance. It also paves the way for further research on the influence of these agents on bovine health and their frecuency across the country.

Risk and countermeasure of laboratory-acquired infection based on pathogen transmission routes

Laboratory-acquired infection (LAI) is an important issue in laboratory biosafety for pathogenic microorganism, which aims to prevent the spread of infectious pathogens and protect laboratory personnel from potentially harmful microorganisms. Previous LAI reports provided a source of information for understanding the transmission routes and therapies helping to develop targeted prevention and response programs and to comprehensively ensure the biosafety of laboratories. In this study, from the perspective of the transmission routes of agents, the biosafety risks were discussed from four aspects: skin, eye, or mucous membrane exposure, contaminated sharp inoculation or bites from infected animals and arthropod vectors, ingestion or hand-to-mouth exposure, and inhalation of infectious aerosols. The development and evolution of LAI were reviewed, and appropriate countermeasures and suggestions were proposed accordingly.

Crayfish population size under different routes of pathogen transmission.

We present an epidemiological model for the crayfish plague, a disease caused by an invasive oomycete Aphanomyces astaci, and its general susceptible freshwater crayfish host. The pathogen shows high virulence with resulting high mortality rates in freshwater crayfishes native to Europe, Asia, Australia, and South America. The crayfish plague occurrence shows complicated dynamics due to the several types of possible infection routes, which include cannibalism and necrophagy. We explore this complexity by addressing the roles of host cannibalism and the multiple routes of transmission through (1) environment, (2) contact, (3) cannibalism, and (4) scavenging of infected carcasses. We describe a compartment model having six classes of crayfish and a pool of crayfish plague spores from a single nonevolving strain. We show that environmental transmission is the decisive factor in the development of epidemics. Compared with a pathogen-free crayfish population, the presence of the pathogen with a low environmental transmission rate, regardless of the contact transmission rate, decreases the crayfish population size with a low risk of extinction. Conversely, a high transmission rate could drive both the crayfish and pathogen populations to extinction. High contact transmission rate with a low but nonzero environmental transmission rate can have mixed outcomes from extinction to large healthy population, depending on the initial values. Scavenging and cannibalism have a relevant role only when the environmental transmission rate is low, but scavenging can destabilize the system by transmitting the pathogen from a dead to a susceptible host. To the contrary, cannibalism stabilizes the dynamics by decreasing the proportion of infected population. Our model provides a simple tool for further analysis of complex host parasite dynamics and for the general understanding of crayfish disease dynamics in the wild.

Structural Drivers of Vulnerability at the Human-Rodent Interface in the Limpopo National Park, Mozambique

Abstract This socio-anthropological study investigates the relations between humans and rodents in an area adjacent to the Limpopo National Park in Mozambique. Designed as part of the larger researcher on mammarenaviruses, it explores the social dimensions of the rodent-human interface, considering its spatial and temporal variability. Its results contribute to our understanding of the socio-ecological context in which new pathogens or new routes of pathogen transmission could arise and potentially spread diseases. A vulnerability-based approach was used to assess human exposure, sensibility and capacity to adapt to rodents. This study revealed: (i) Local knowledge of the dynamic of rodent populations over the last few decades, with new invasive rodents displacing native species; (ii) the social-ecological factors thought to be behind this invasion: climate change, new infrastructure (e.g., construction of a dam), new agricultural practices (e.g., cultivation of sunflowers) and policies (human resettlement); (iii) the significant impact associated with new invasive rodents (e.g., crop losses, damage to belongings), the limited capacity for individual and collective interventions to mitigate damage, and the little concern shown for rodent-related diseases; (iv) women and girls’ high vulnerability to potential rodent-borne diseases due to frequent direct and indirect contact with rodents in the domestic space; and (v) the added-value of using a vulnerability-based methodology, over the more commonly used Knowledge-Attitudes-Practices (KAP) methodology, to map the structural factors shaping the human-rodent interface and its dynamic. Our findings suggest that the vulnerability-based approach could offer an opportunity to better respond to the One Health ambition by integrating social dimensions of health and grasping the complexity of the social and material context in which new pathogens could emerge and spread. One Health Statement The present socio-anthropological study of the human-rodent interface comes in complement to a previous eco-epidemiological survey focusing on the rodent-virus interface. It explores the cultural and social dimensions of the interactions between rodent-human, considering spatial and temporal variability. In doing so, it contributes to the understanding of the socio-ecological dynamic, in which new viral transmission can occur and disease spread. It exemplifies, based on local knowledge, how socio-ecological changes can create new routes for the emerging virus and highlights the vulnerability of the exposed human population to address the potential related health risks. This multidisciplinary and dynamic approach of how humans and rodents interact, and how these interactions are shaped by their changing environment is a contribution to a systemic approach to health, in line with the One health paradigm.

The distinct microbial community patterns and pathogen transmission routes in intensive care units

While the microbiome in indoor environments such as hospitals has drawn increasing attention, the transmission routes especially for pathogens in ICUs remain largely unexamined. In this study, we have explored the distinct bacterial communities of ICU compared with Non-ICU in hospital wards. We have then clarified their different transmission patterns by means of microbial source tracking, with results suggesting that bedrail and inside floor were hubs in two wards, respectively. Streptococcus , Staphylococcus were identified as “Transfer-Easy taxa” that were found in both ICU and Non-ICU settings, with potential pathogenicity and cases recorded. We have also detected another 15 pathogenic genera in hospital environment, including Pseudomonas and Acinetobacter , and charted how these pathogenic microorganisms affect patients, demonstrating that there were far more strong routes for pathogens transmitted from environment to patients in ICU. In summary, this work investigates patterns of bacterial transmission in hospital settings, highlights pathogenic genera that are likely to transfer from the environment to humans and cause nosocomial infection, which could provide guidance for healthcare system monitoring and co-infection avoidance. • Microbial community patterns and transmission routes differ between ICU and non-ICU wards. • Several genera with strong transmission capacity could transfer from the outside environment to patients. • A group of pathogens discovered in ICU wards indicate a high probability of co-infection.

Extended-spectrum beta-lactamase-producing Escherichia coli from pork in Muang district, Chiang Mai Province, Thailand.

Contaminated pork is one of the transmission routes for pathogens. Extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli is one of the critical threats to global public health. This study aimed to examine pork from different types of markets in Muang district, Chiangmai Province, Thailand, for a proportion of ESBL-producing E. coli, antibiotic resistance of ESBL-producing E. coli and ESBL-producing E. coli genotypes. Samples were collected from different market types; fresh markets, pork stores, and supermarkets, enriched and inoculated on selective media. Extended-spectrum beta-lactamases-producing E. coli was identified using double-disk diffusion method according to Clinical and Laboratory Standards Institute 2016. Antibiotic susceptibility test was performed through VITEK® System and ESBL-encoding genes were detected using a multiplex polymerase chain reaction. About 69% of the samples were positive to ESBL-producing E. coli and showed high rates of resistance for ampicillin (100%), piperacillin (100%), cefalexin (100%), cefpodoxime (100%), cefovecin (100%) and ceftiofur (100%), gentamycin (89.86%), and tetracycline (TE) (84.06%). All isolates were multiple drug resistant; resistance patterns of beta-lactams, aminoglycosides, TEs, nitrobenzene derivatives, and sulfonamide groups were observed. The ESBL-producing E. coli-positive isolates carried blaCTX-M groups (100%), blaTEM (98.55%), and blaSHV (1.45%). None of blaOXA was found in this study. Extended-spectrum beta-lactamases-producing E. coli was found in various types of markets; all isolates were detected as multidrug-resistant. The dissemination of such strains can conceivably cause concerning public health, implying that supervised antimicrobial use in pork production and sanitary food preparation is recommended.

Core Genome Multilocus Sequence Typing Scheme for Improved Characterization and Epidemiological Surveillance of Pathogenic Brucella.

ABSTRACTBrucellosis poses a significant burden to human and animal health worldwide. Robust and harmonized molecular epidemiological approaches and population studies that include routine disease screening are needed to efficiently track the origin and spread of Brucella strains. Core genome multilocus sequence typing (cgMLST) is a powerful genotyping system commonly used to delineate pathogen transmission routes for disease surveillance and control. Except for Brucella melitensis, cgMLST schemes for Brucella species are currently not established. Here, we describe a novel cgMLST scheme that covers multiple Brucella species. We first determined the phylogenetic breadth of the genus using 612 Brucella genomes. We selected 1,764 genes that were particularly well conserved and typeable in at least 98% of these genomes. We tested the new scheme on 600 genomes and found high agreement with the whole-genome-based single nucleotide polymorphism (SNP) analysis. Next, we applied the scheme to reanalyze the genome of Brucella strains from epidemiologically linked outbreaks. We demonstrated the applicability of the new scheme for high-resolution typing required in outbreak investigations as previously reported with whole-genome SNP methods. We also used the novel scheme to define the global population structure of the genus using 1,322 Brucella genomes. Finally, we demonstrated the possibility of tracing distribution of Brucella strains by performing cluster analysis of cgMLST profiles and found nearly identical cgMLST profiles in different countries. Our results show that sequencing depth of more than 40-fold is optimal for allele calling with this scheme. In summary, this study describes a novel Brucella-wide cgMLST scheme that is applicable in Brucella molecular epidemiology and helps in accurately tracking and thus controlling the sources of infection. The scheme is publicly accessible and should represent a valuable resource for laboratories with limited computational resources and bioinformatics expertise.

Infectious diseases reported in warm‐water marine fish cage culture in East and Southeast Asia—A systematic review

East and Southeast Asia have the largest share of mariculture production in Asia, and most of this is cage farming. An increase in marine fish consumption in the region has led to an expansion of marine cage culture over the last decade, which has resulted in an increase in the incidence of infectious diseases within this sector. Knowledge about pathogens, their distribution and clinical signs can help establish appropriate preventive and control strategies. We systematically reviewed the literature for infectious diseases affecting fish in marine cage culture in East and Southeast Asia, using two scientific databases, Scopus and Aquaculture Compendium, as well as two government-based databases, quarterly aquatic animal disease reports published by the Network of Aquaculture Centres in Asia-Pacific, and the fish health data published by the World Animal Health Information System (OIE). We also discussed the transmission routes of pathogens and potential environmental triggers for outbreaks when the information was available. Our review revealed that Vibrio spp., followed by parasitic monogeneans, trematodes and copepods are the most commonly reported pathogens in the literature. There were a few reports of viral pathogens, such as iridoviruses and nervous necrosis virus, but these were more commonly reported in the government surveillance documents. The results of this review can help inform surveillance programmes, improve the early detection of disease on farms and identify pathogens of concern for developing preventive and control strategies.

Whole-genome sequencing surveillance and machine learning for healthcare outbreak detection and investigation: A systematic review and summary.

Whole-genome sequencing (WGS) has traditionally been used in infection prevention to confirm or refute the presence of an outbreak after it has occurred. Due to decreasing costs of WGS, an increasing number of institutions have been utilizing WGS-based surveillance. Additionally, machine learning or statistical modeling to supplement infection prevention practice have also been used. We systematically reviewed the use of WGS surveillance and machine learning to detect and investigate outbreaks in healthcare settings. We performed a PubMed search using separate terms for WGS surveillance and/or machine-learning technologies for infection prevention through March 15, 2021. Of 767 studies returned using the WGS search terms, 42 articles were included for review. Only 2 studies (4.8%) were performed in real time, and 39 (92.9%) studied only 1 pathogen. Nearly all studies (n = 41, 97.6%) found genetic relatedness between some isolates collected. Across all studies, 525 outbreaks were detected among 2,837 related isolates (average, 5.4 isolates per outbreak). Also, 35 studies (83.3%) only utilized geotemporal clustering to identify outbreak transmission routes. Of 21 studies identified using the machine-learning search terms, 4 were included for review. In each study, machine learning aided outbreak investigations by complementing methods to gather epidemiologic data and automating identification of transmission pathways. WGS surveillance is an emerging method that can enhance outbreak detection. Machine learning has the potential to identify novel routes of pathogen transmission. Broader incorporation of WGS surveillance into infection prevention practice has the potential to transform the detection and control of healthcare outbreaks.

Clinical features of endophthalmitis clusters after cataract surgery and practical recommendations to mitigate risk: systematic review.

Intraocular transmission of exogenous pathogens in cataract surgery can lead to endophthalmitis. This review evaluates the features of endophthalmitis clusters secondary to pathogen transmission in cataract surgery. Articles reporting on pathogen transmission in cataract surgery were identified via searches of Ovid MEDLINE, EMBASE, and Cochrane CENTRAL, and a total of 268 eyes from 24 studies were included. The most common source of infectious transmission was attributed to a contaminated intraocular solution (ie, irrigation solution, viscoelastic, or diluted antibiotic; n = 10). Visual acuity at presentation with infectious features was 1.89 logMAR (range: 1.35 to 2.58; ∼counting fingers) and 1.33 logMAR (range: 0.04 to 3.00; Snellen: ∼20/430) at last follow-up. Patients with diabetes had worse outcomes compared with patients without diabetes. The most frequently isolated pathogen from the infectious sources was Pseudomonas sp. (50.0%). This review highlights the various routes of pathogen transmission during cataract surgery and summarizes recommendations for the detection, prevention, and management of endophthalmitis clusters.

Host selection pattern and flavivirus screening of mosquitoes in a disturbed Colombian rainforest

Studies on the feeding behavior of hematophagous insects, particularly those of medical importance, are relevant for tracking possible pathogen transmission routes and identifying biases in the choice of vertebrates. We evaluated host selection of blood-feeding mosquitoes in a disturbed forest in the Magdalena Medio valley in Colombia from March 2017 to April 2018, after the introduction of Zika virus to the Americas from the 2015–2016 outbreak. We estimated vertebrate diversity and collected blood-engorged female mosquitoes. Genomic DNA/RNA was extracted from the mosquito’s abdomen for vertebrate host identification and pathogen detection. We performed conventional PCR and sequencing, using universal primers targeting vertebrate regions of the eukaryotic mitochondrial genome to determine bloodmeal host. Additionally, we tested for the presence of flaviviruses in all mosquito samples with RT-PCR. Based on the identity and quantity of detected bloodmeals, we performed mosquito-vertebrate interaction network analysis and estimated topology metrics. In total, we collected 292 engorged female mosquitoes representing 20 different species. Bloodmeal analyses identified 26 vertebrate species, the majority of which were mammals (N = 16; 61.5%). No flaviviruses of medical importance were detected from the samples. Although feeding patterns varied, network analyses showed a high degree of specialization by mosquitoes and revealed ecological and phylogenetic relationships among the host community. We conclude that host selection or preference by mosquitoes is species specific.

Establishment of a Rhesus Macaque Model for Scrub Typhus Transmission: Pilot Study to Evaluate the Minimal Orientia tsutsugamushi Transmission Time by Leptotrombidiumchiangraiensis Chiggers.

Recently, an intradermal inoculation of the rhesus macaque model of scrub typhus has been characterized at our institution. The current project was to establish a rhesus macaque model of scrub typhus using the naturally infected chigger challenge method that faithfully mimics the natural route of pathogen transmission to fully understand the host-pathogen-vector interactions influencing pathogen transmission. Unlike the needle-based inoculation route, Orientia tsutsugamushi-infected chiggers introduce both pathogen and chigger saliva into the host epidermis at the bite site. However, information on the interaction or influence of chigger saliva on pathogenesis and immunity of host has been limited, consequently hindering vaccine development and transmission-blocking studies. To characterize chigger inoculated O. tsutsugamushi in rhesus macaques, we determined the minimum chigger attachment time required to efficiently transmit O. tsutsugamushi to the immunocompetent hosts and preliminary assessed clinical parameters, course of bacterial infection, and host’s immunological response to identifying potential factors influencing pathogen infection. Chigger infestation on hosts resulted in: (i) Rapid transmission of O. tsutsugamushi within 1 h and (ii) antigen-specific type I and II T-cell responses were markedly increased during the acute phase of infection, suggesting that both systems play critical roles in response to the pathogen control during the primary infection. In summary, we demonstrate that O. tsutsugamushi infection in rhesus macaques via chigger challenge recapitulates the time of disease onset and bacteremia observed in scrub typhus patients. Levels of proinflammatory cytokines and chemokines were positively correlated with bacteremia.

The Pathogens Spillover and Incidence Correlation in Bumblebees and Honeybees in Slovenia.

Slovenia has a long tradition of beekeeping and a high density of honeybee colonies, but less is known about bumblebees and their pathogens. Therefore, a study was conducted to define the incidence and prevalence of pathogens in bumblebees and to determine whether there are links between infections in bumblebees and honeybees. In 2017 and 2018, clinically healthy workers of bumblebees (Bombus spp.) and honeybees (Apis mellifera) were collected on flowers at four different locations in Slovenia. In addition, bumblebee queens were also collected in 2018. Several pathogens were detected in the bumblebee workers using PCR and RT-PCR methods: 8.8% on acute bee paralysis virus (ABPV), 58.5% on black queen cell virus (BQCV), 6.8% on deformed wing virus (DWV), 24.5% on sacbrood bee virus (SBV), 15.6% on Lake Sinai virus (LSV), 16.3% on Nosema bombi, 8.2% on Nosema ceranae, 15.0% on Apicystis bombi and 17.0% on Crithidia bombi. In bumblebee queens, only the presence of BQCV, A. bombi and C. bombi was detected with 73.3, 26.3 and 33.3% positive samples, respectively. This study confirmed that several pathogens are regularly detected in both bumblebees and honeybees. Further studies on the pathogen transmission routes are required.

In situ measurements of human cough aerosol hygroscopicity.

The airborne dynamics of respiratory droplets, and the transmission routes of pathogens embedded within them, are governed primarily by the diameter of the particles. These particles are composed of the fluid which lines the respiratory tract, and is primarily mucins and salts, which will interact with the atmosphere and evaporate to reach an equilibrium diameter. Measuring organic volume fraction (OVF) of cough aerosol has proved challenging due to large variability and low material volume produced after coughing. Here, the diametric hygroscopic growth factors (GF) of the cough aerosol produced by healthy participants were measured in situ using a rotating aerosol suspension chamber and a humidification tandem differential mobility analyser. Using hygroscopicity models, it was estimated that the average OVF in the evaporated cough aerosol was 0.88 ± 0.07 and the average GF at 90% relative humidity (RH) was 1.31 ± 0.03. To reach equilibrium in dry air the droplets will reduce in diameter by a factor of approximately 2.8 with an evaporation factor of 0.36 ± 0.05. Hysteresis was observed in cough aerosol at RH = ∼35% and RH = ∼65% for efflorescence and deliquescence, respectively, and may depend on the OVF. The same behaviour and GF were observed in nebulized bovine bronchoalveolar lavage fluid.

Comparative Analysis of the Vertical Risk of Transmission of Some Blood-Borne Infections in the Republic of Guinea

The aim of our work was to compare the HBV, HCV and HIV vertical transmission risk in the Republic of Guinea.Materials and methods. The material for the study was 305 blood plasma samples from pregnant women living in Conakry, Republic of Guinea. The samples were examined for the presence of serological (HBsAg, antibodies antiHBs IgG, anti-HBcore IgG, anti-HCV IgG, Ag/Ab-HIV) and molecular (HBV DNA, HCV RNA, HIV RNA) markers.Results and discussion. When assessing the overall prevalence of serological markers among patients, the incidence of HBV markers was 76.06 %. Antibodies to HCV were detected only in 1 case, which amounted to 0.32 %. HIV markers were detected in 3 cases, which amounted to 0.98 %. The prevalence of HBsAg in the group under examination significantly differed between the groups of pregnant women aged 13–19 years (17.33 %) and 20–24 years (12.12 %), p<0.0001, RR=5.107 with 95 % CI: 2.458–10.612. When assessing the overall prevalence of molecular-biological markers among patients, we did not detect HIV RNA, in one patient, HCV RNA was determined, which was 0.32 %, while the incidence of HBV DNA was 20 %. Among HBsAg-positive individuals, HBV DNA was detected in 86.11 %, which was 10.16 % of the total group. Among the HBsAg-negative individuals, HBV DNA was detected in 11.15 % (9.84 % of the total group). It should be noted that in nine cases, HBV DNA was detected without any serological markers, which amounted to 14.75 % (2.95 % of the total group). Assessment of the blood-borne infections prevalence in pregnant women is significant for the subsequent identification of pathogen transmission routes in order to control and/or prevent the spread of infection.

A model of infection in honeybee colonies with social immunity.

Honeybees (Apis mellifera) play a significant role in the pollination of various food crops and plants. In the past decades, honeybee management has been challenged with increased pathogen and environmental pressure associating with increased beekeeping costs, having a marked economic impact on the beekeeping industry. Pathogens have been identified as a contributing cause of colony losses. Evidence suggested a possible route of pathogen transmission among bees via oral-oral contacts through trophallaxis. Here we propose a model that describes the transmission of an infection within a colony when bee members engage in the trophallactic activity to distribute nectar. In addition, we examine two important features of social immunity, defined as collective disease defenses organized by honeybee society. First, our model considers the social segregation of worker bees. The segregation limits foragers, which are highly exposed to pathogens during foraging outside the nest, from interacting with bees residing in the inner parts of the nest. Second, our model includes a hygienic response, by which healthy nurse bees exterminate infected bees to mitigate horizontal transmission of the infection to other bee members. We propose that the social segregation forms the first line of defense in reducing the uptake of pathogens into the colony. If the first line of defense fails, the hygienic behavior provides a second mechanism in preventing disease spread. Our study identifies the rate of egg-laying as a critical factor in maintaining the colony's health against an infection. We propose that winter conditions which cease or reduce the egg-laying activity combined with an infection in early spring can compromise the social immunity defenses and potentially cause colony losses.

Association between intrahospital transfer and hospital-acquired infection in the elderly: a retrospective case–control study in a UK hospital network

BackgroundIntrahospital transfers have become more common as hospital staff balance patient needs with bed availability. However, this may leave patients more vulnerable to potential pathogen transmission routes via increased exposure...