Contact Rate Research Articles

Advancing Indoor Epidemiological Surveillance: Integrating Real-Time Object Detection and Spatial Analysis for Precise Contact Rate Analysis and Enhanced Public Health Strategies

In response to escalating concerns about the indoor transmission of respiratory diseases, this study introduces a sophisticated software tool engineered to accurately determine contact rates among individuals in enclosed spaces—essential for public health surveillance and disease transmission mitigation. The tool applies YOLOv8, a cutting-edge deep learning model that enables precise individual detection and real-time tracking from video streams. An innovative feature of this system is its dynamic circular buffer zones, coupled with an advanced 2D projective transformation to accurately overlay video data coordinates onto a digital layout of the physical environment. By analyzing the overlap of these buffer zones and incorporating detailed heatmap visualizations, the software provides an in-depth quantification of contact instances and spatial contact patterns, marking an advancement over traditional contact tracing and contact counting methods. These enhancements not only improve the accuracy and speed of data analysis but also furnish public health officials with a comprehensive framework to develop more effective non-pharmaceutical infection control strategies. This research signifies a crucial evolution in epidemiological tools, transitioning from manual, simulation, and survey-based tracking methods to automated, real time, and precision-driven technologies that integrate advanced visual analytics to better understand and manage disease transmission in indoor settings.

Abstract 4137986: Evaluation of an AI-Based Clinical Trial Screening Method Through a Randomized Controlled Implementation Study

Background: Clinical trial screening is labor-intensive, time-consuming, and error prone. We have developed RECTIFIER, an AI-based clinical trial screening tool, to enhance the efficiency and accuracy of patient recruitment. This study aims to evaluate RECTIFIER's effectiveness compared to manual screening in a randomized implementation study. Methods: This study was designed as an implementation study as part of an active heart failure trial named COPILOT-HF (NCT05734690). Potential eligible patients were identified via a structured electronic medical record query and randomized to be screened for clinical trial eligibility either by RECTIFIER or manually by clinical staff. The outcome measures included the number of patients contacted, and the number of patients reached for clinical trial enrollment. Data was collected over a period of 3 months. Results: A total of 3834 patients were included in the study, with 1919 patients randomized to the RECTIFIER group and 1915 patients to the manual screening group (Figure). Study staff could manually screen only 1367 patients at the end of the 3-month period. RECTIFIER identified more eligible patients compared to manual screening (833[43.4%] vs. 284[14.8%], p<0.001). The most common reason for exclusion was absence of symptomatic heart failure in both groups (287 in RECTIFIER 304 in manual screening). Screening via RECTIFIER also led to a higher contact rate, with 455 patients being contacted compared to 216 in the manual group (23.7% vs. 11.3%, p<0.001). The percentage of patients who could be reached for an enrollment call was also higher in the RECTIFIER group, with 330 patients responding versus 164 in the manual group (17.2% vs. 8.6%, p<0.001). Conclusion: Screening via RECTIFIER significantly outperformed manual screening in identifying eligible patients, contacting them, and eliciting responses. These results suggest that integrating AI into clinical trial recruitment processes can enhance efficiency and effectiveness, potentially leading to increased patient participation in clinical trials. Future studies with sufficient power should assess recruitment endpoints and explore scalability.

Towards development of the 4c-based method detecting interactions of plasmid dna with host genome

Chromosome conformation capture techniques have revolutionized our understanding of chromatin architecture and dynamics at the genome-wide scale. In recent years, these methods have been applied to a diverse array of species, revealing fundamental principles of chromosomal organization. However, structural organization of the extrachromosomal entities, like viral genomes or plasmids, and their interactions with the host genome, remain relatively underexplored. In this work, we introduce an enhanced 4C-protocol tailored for probing plasmid DNA interactions. We design specific plasmid vector and optimize protocol to allow high detection rate of contacts between the plasmid and host DNA.

The impact of screening for tuberculosis exposure in the household in children with tuberculosis disease: A difficult riddle to solve.

Tuberculosis (TB) infection is transmitted by sharing the same airway with people with active TB. Children are often not considered the source of TB bacilli, and index case investigation is carried out after diagnosis. Here, we describe the impact of the presence of a household index case on childhood TB disease. The data of patients aged between 1 month and 18 years who were diagnosed with TB were collected. We compared patients according to whether they had an index case in the household or not. A total of 202 TB patients were enrolled, of whom 62 (30.7%) had a household index case. There was no significant difference in having a household index case between TB patients under the age of five (23.3%) and older children (33.8%) (p = .140). Pulmonary TB was present in 61.4% of the cases, and extrapulmonary TB was present in 38.6% of the cases. The rate of patients who had a household index case was significantly higher in pulmonary TB (46.8%) compared to extrapulmonary TB (5.1%) (p < .001). Pulmonary TB patients with a history of household contact were more likely to have diagnostic radiological findings (93.1%) compared to those without (75.8%) (p = .009). However, pulmonary TB patients without household contact history had a higher rate of diagnostic microbiological findings (59.1%) and constitutional symptoms (63.6%) (p = .019 and p = .013, respectively). Household contact research is an important epidemiological tool. However, considering the contact rates in the household, new and more comprehensive public health programs are required to prevent the spread of childhood tuberculosis.

Malaria mosquitoes, Plasmodium parasites and skin microbiota, towards control of malaria: A review

Vector-borne pathogens are transmitted by bites of infected arthropod species. The pathogens require two different host species to complete their lifecycle, usually a vertebrate and an invertebrate host, of which the latter transmits the pathogen between vertebrate hosts. Blood-feeding mosquitoes are important vectors of several human pathogens, including arboviruses namely: chikungunya, dengue fever, Rift Valley fever, yellow fever and Zika transmitted by Aedes mosquitoes amongst others. Culex mosquitoes on the other hand transmit Saint Louis and Japanese encephalitis, lymphatic filariasis, West Nile fever and Rift Valley Fever virus while Anopheles mosquitoes transmit malaria. The contact rate between vectors and their vertebrate hosts affects the intensity of pathogen transmission, and hence disease epidemiology. The ability of vectors to locate their blood hosts therefore is crucial in disease maintenance and perseverance. Host odour is known to play an important role in mosquito host-seeking behaviour and hence influences the contact rate between vectors and hosts. This literature review focuses on interactions between malaria parasites, humans, mosquitoes and how skin bacterial volatiles mediate host-seeking behaviour of mosquitoes.

Time to Ring in the Body Checking, Head Contact, and Suspected Injury Rates in Youth Ringette: A Video-Analysis Study in Youth Ringette and Female Ice Hockey.

To compare physical contacts (PCs), including head contacts (HCs), suspected concussion, and nonconcussion injury incidence rates between youth ringette and female ice hockey. Cross-sectional. Alberta ice arenas. Players participating in 8 U16AA (ages 14-15 years) ringette and 8 U15AA (ages 13-14 years) female ice hockey games during the 2021 to 2022 season. Dartfish video-analysis software was used to analyze video recordings. Univariate Poisson regression analyses (adjusted for cluster by team-game, offset by game minutes) were used to estimate PCs (including HCs) and suspected injury (concussion and nonconcussion) and concussion-specific IRs and incidence rate ratios (IRRs) to compare sports. Proportions of all PCs that were body checks (level 4-5 trunk PC) and direct HCs (HC1) penalized were reported. Ringette had a 2.6-fold higher rate of body checking compared with hockey (IRR = 2.63, 95% CI: 1.59-4.37). Ringette also had a 2-fold higher rate of HC1 compared with hockey (IRR = 2.08, 95% CI: 1.37-3.16). A 3.4-fold higher rate of suspected injury was found in ringette (IRR = 3.37, 95% CI: 1.40-8.15). There was no significant difference in suspected concussion IRs in ringette compared with hockey (IRR = 1.93, 95% CI: 0.43-8.74). Despite being prohibited in both sports, only a small proportion of body checks (Ringette = 18%; Hockey = 17%) and HC1 (Ringette = 6%; Hockey = 6%) were penalized. Higher rates of body checking, HC1, and suspected injuries were found in ringette compared with female ice hockey. Body checking and HC1 were rarely penalized, despite rules disallowing them in both sports. Future research should consider other youth age groups.

Effectiveness of a policy to reduce non-urgent night-time consultations in out-of-hours services

Abstract Background The utilization of Out-of-Hours General Practice (OOH-GP) services in the Netherlands has been increasing steadily. This has placed significant pressure on triagists and GPs to provide accessible and high-quality care, particularly because of patients with low-urgency health problems, who can wait to visit their GP during regular working hours. To alleviate the strain on OOH services during the night, the “spoed=spoed” policy has been implemented. This policy stipulates that only patients with urgent health problems can consult with a GP during the night (11 p.m. to 8 a.m.). However, it remains unclear whether this policy has effectively reduced consultations during the night. Methods For this study, we used pseudonymised data from electronic health records of 2/3 of Dutch OOH services (catchment area of 12.3 million), from Nivel Primary Care Database, from 2020-2023. We analysed the effects of the policy on contact rates and proportion of high-urgency health problems, by comparing OOH services that did and did not implement the policy, by comparing 6 months before and after implementation and by analysing variances across OOH services. Results Overall, there were no differences in the number or proportion of high-urgency consultations across OOH services that did and did not implement spoed=spoed. In those that did, there were no differences before and after implementation. However, certain OOH services exhibited a decrease in consultation, while also showing a higher proportion high-urgency health problems. Conclusions There is currently no definitive evidence regarding the effectiveness of “spoed=spoed”. However we should learn from the varied effects and experiences in different OOH-services, to facilitate further implementation or adaptation of the policy. Key messages • OOH services can and should learn from each other on what solutions are implemented to lower the care-burden during the night. • Policies aimed at reducing the utilization of OOH serviced should consider the conaxt from the patient, health care provider and organization.

Self-rated health in preadolescents as a predictor for prescription redemption and hospital contacts

Abstract Background The decline in self-rated health among children and adolescents raises concerns for their overall well-being and future health outcomes. We examined whether self-rated health in preadolescence predicts both psychiatric and somatic prescription redemption and hospital contacts in later adolescence. Methods This cohort study is part of the Danish National Birth Cohort and focuses on children born between 1996 and 2003. A survey was distributed to 96,382 preadolescents aged 11, who were then followed from 2010 to 2018 (average follow-up of 6.9 years). Data on prescriptions and hospital contacts were obtained from Danish registries. Negative binomial regression was employed to calculate the incidence rate ratio (IRR), comparing preadolescent children who rated their health as poor (‘Not So Good’/’Poor’) to those who rated it as good (‘Excellent’/’Good’). Results Of the 47,365 (49.1%) 11-year-old preadolescents who participated in this study, 5.3% reported experiencing poor self-rated health. Overall, adjusted analyses revealed higher rates of prescription redemptions (IRR 1.63 [95% CI: 1.53; 1.73]) and hospital contacts (IRR 1.86 [95% CI: 1.74; 1.99]) in these children. Poor self-rated health in preadolescence was associated with more somatic (IRR 1.51 [95% CI: 1.40; 1.62]) and psychiatric (IRR 3.04 [95% CI: 2.59; 3.57]) prescriptions, as well as somatic (IRR 1.61 [95% CI: 1.51; 1.72]) and psychiatric (IRR 2.80 [95% CI: 2.42; 3.25]) hospital contacts in adolescence, with similar associations across sexes. Conclusions Poor self-rated health in preadolescence is associated with higher rates of prescription redemption and hospital visits in adolescence, suggesting that perceptions of health in early life influence long-term well-being, especially regarding psychiatric health. This straightforward self-rated health measure offers healthcare professionals valuable insights for identifying children who may require support and early intervention. Key messages • Poor self-rated health in preadolescence predicts higher prescription redemption and hospital visits in adolescence, especially regarding psychiatric health. • Simple self-assessment of health in childhood may have the potential to help identify those needing support and early intervention for long-term well-being.

Model-based estimates of age-structured SARS-CoV-2 epidemiology in households

BackgroundUnderstanding how infectious disease transmission varies from person to person, including associations with age and contact behavior, can help design effective control strategies. Within households, transmission may be highly variable because of differing transmission risks by age, household size, and individual contagiousness. Our aim was to disentangle those factors by fitting mathematical models to SARS-CoV-2 household survey and serologic data.MethodsWe surveyed members of 3,381 Utah households from January-April 2021 and performed SARS-CoV-2 antibody testing on all available members. We paired these data with a probabilistic model of household importation and transmission composed of a novel combination of transmission variability and age- and size-structured heterogeneity. We calculated maximum likelihood estimates of mean and variability of household transmission probability between household members in different age groups and different household sizes, simultaneously with importation probability and probabilities of false negative and false positive test results.Results12.8% of individual participants, residing in 17.4% of the participating households, showed serologic evidence of prior infection or reported a prior positive test on the survey. Serologically positive individuals in younger age groups were less likely than older adults to have tested positive during their infection according to our survey results. Our model results suggested that adolescents and young adults (ages 13–24) acquired SARS-CoV-2 infection outside the household at a rate substantially higher than younger children and older adults. Our estimate of the household secondary attack rate (HSAR) among adults aged 45 and older exceeded HSARs to and/or from younger age groups at a given household size. We found lower HSAR in households with more members, independent of age differences. The age-specific HSAR patterns we found could not be explained by age-dependent biological susceptibility and transmissibility alone, suggesting that age groups contacted each other at different rates within households.ConclusionsWe disentangled several factors contributing to age-specific infection risk, including non-household exposure, within-household exposure to specific age groups, and household size. Within-household contact rate differences played a significant role in driving household transmission epidemiology. These findings provide nuanced insights for understanding community outbreak patterns and mechanisms of differential infection risk.

64 Respiratory outcomes by five years of age among children born preterm: A population-based study using health services data

Abstract Background While neonatal care advancements have led to increased survival of preterm infants, many experience ongoing respiratory complications. Objectives Healthcare administrative data offers a comprehensive measure of neonatal outcomes. Our study used population-based data to describe rates of healthcare contacts for respiratory disease among children born preterm. Design/Methods A retrospective cohort of infants born in British Columbia between 2004-2014 was identified using a provincial birth registry. By linking to population-based healthcare data, we captured population demographics, birth data, and healthcare visits for respiratory causes [outpatient visits, hospitalizations, and intensive care (ICU) admissions] up to 5 years of age. The rate of healthcare visits due to asthma, bronchiolitis, and pneumonia were compared between preterm (22-36 weeks) and term/post-date infants (37-44 weeks GA) using Poisson regression. Results Children born at term (n=413,140) were compared to children born at 34-36 week GA (n=33,227), 28-33 week GA (n=8362), and 22-27 week GA (n=1231). Compared to term infants, rates of hospitalizations and ICU admission for all respiratory causes were higher among children born preterm. Children born 22-27 weeks GA had the highest rates of hospitalization for asthma [rate ratio (RR) 9.4, 95% CI 7.9-11.1], bronchiolitis (RR 10.5, 95% CI 9.3-11.8) and pneumonia (RR 15.9, 95% CI 14.3-17.7). Rates of ICU admission for asthma (RR 27.1, 95% CI 17.2-40.4) and pneumonia (RR 58.1, 95% CI 46.6-71.7) were highest among 22-27 week GA infants. Increased rates persist among children born 34-36 weeks GA, with higher rates of hospitalization for asthma (RR 1.8, 95% CI 1.6-1.9), bronchiolitis (RR 2.1, 95% CI 2.0-2.2), and pneumonia (RR 1.8, 95% CI 1.7-2.0) compared to term infants. Conclusion Preterm infants experience significantly higher rates of outpatient visits, hospitalizations, and ICU admissions for respiratory disease compared to term infants. Healthcare utilization, including ICU admissions, increased with decreasing gestational age. Of note, increased rates of respiratory disease were also found among infants born 34-36 weeks GA. Our study is the first to use population based data to describe rates of healthcare contacts for respiratory disease among preterm infants, providing insight to long-term respiratory disease burden.

Adverse health outcomes in offspring of parents with alcohol-related liver disease: Nationwide Danish cohort study.

Parental drinking can cause harm to the offspring. A parent's diagnosis of alcohol-related liver disease (ALD) might be an opportunity to reach offspring with preventive interventions. We investigated offspring risk of adverse health outcomes throughout life, their association with their parent's educational level and diagnosis of ALD. We used nationwide health registries to identify offspring of parents diagnosed with ALD in Denmark 1996 to 2018 and age- and sex-matched comparators (20:1). We estimated the incidence rate ratios (IRRs) of hospital contacts with adverse health outcomes, overall and in socioeconomic strata. We used a self-controlled design to examine whether health outcomes were more likely to occur during the first year after the parent's ALD diagnosis. The 60,804 offspring of parents with ALD had a higher incidence rate of hospital contacts from age 15 to 60 years for psychiatric disease, poisoning, fracture or injury, alcohol-specific diagnoses, other substance abuse, and of death than comparators. Associations were stronger for offspring with low compared to high socioeconomic position: The IRR for admission due to poisoning was 2.2 versus 1.0 for offspring of an ALD parent with a primary level versus a highly educated ALD parent. Offspring had an increased risk for admission with psychiatric disease and poisoning in the year after their parent's ALD diagnosis. For example, among offspring whose first hospital contact with psychiatric disease was at age 13 to 25 years, the IRR in the first year after their parent's ALD diagnosis versus at another time was 1.29 (95% CI 1.13, 1.47). Main limitation was inability to include adverse health outcomes not involving hospital contact. Offspring of parents with ALD had a long-lasting higher rate of health outcomes associated with poor mental health and self-harm that increased shortly after their parent's diagnosis of ALD. Offspring of parents of low educational level were particularly vulnerable. This study highlights an opportunity to reach out to offspring in connection with their parent's hospitalization with ALD.

Little disease but lots of bites: social, urbanistic, and entomological risk factors of human exposure to Aedes aegypti in South Texas, U.S.

Aedes aegypti presence, human-vector contact rates, and Aedes-borne virus transmission are highly variable through time and space. The Lower Rio Grande Valley (LRGV), Texas, is one of the few regions in the U.S. where local transmission of Aedes-borne viruses occurs, presenting an opportunity to evaluate social, urbanistic, entomological, and mobility-based factors that modulate human exposure to Ae. aegypti. Mosquitoes were collected using BG-Sentinel 2 traps during November 2021 as part of an intervention trial, with knowledge, attitudes, and practices (KAP) and housing quality surveys to gather environmental and demographic data. Human blood samples were taken from individuals and a Bitemark Assay (ELISA) was conducted to quantify human antibodies to the Ae. aegypti Nterm-34kDa salivary peptide as a measure of human exposure to bites. In total, 64 houses were surveyed with 142 blood samples collected. More than 80% of participants had knowledge of mosquito-borne diseases and believed mosquitoes to be a health risk in their community. Our best fit generalized linear mixed effects model found four fixed effects contributed significantly to explaining the variation in exposure to Ae. aegypti bites: higher annual household income, younger age, larger lot area, and higher female Ae. aegypti abundance per trap night averaged over 5 weeks prior to human blood sampling. Most surveyed residents recognized mosquitoes and the threat they pose to individual and public health. Urbanistic (i.e., lot size), social (i.e., income within a low-income community and age), and entomological (i.e., adult female Ae. aegypti abundance) factors modulate the risk of human exposure to Ae. aegypti bites. The use of serological biomarker assays, such as the Bitemark Assay, are valuable tools for surveillance and risk assessment of mosquito-borne disease, especially in areas like the LRGV where the transmission of target pathogens is low or intermittent.

Mobile Phone Syndromic Surveillance for Respiratory Conditions in an Emergency (COVID-19) Context in Colombia: Representative Survey Design.

Syndromic surveillance for respiratory infections such as COVID-19 is a crucial part of the public health surveillance toolkit as it allows decision makers to detect and prepare for new waves of the disease in advance. However, it is labor-intensive, costly, and increases exposure to survey personnel. This study assesses the feasibility of conducting a mobile phone-based respiratory syndromic surveillance program in a middle-income country during a public health emergency, providing data to support the inclusion of this method in the standard infection control protocols at the population level. This study aims to assess the feasibility of a national active syndromic surveillance system for COVID-19 disease in Colombia. In total, 2 pilots of syndromic mobile phone surveys (MPSs) were deployed using interactive voice response technology in Colombia (367 complete surveys in March 2022 and 451 complete surveys in April and May 2022). Respondents aged 18 years and older were sampled using random digit dialing, and after obtaining consent, they were sent a 10-minute survey with modules on sociodemographic status, respiratory symptoms, past exposure to COVID-19 infection and vaccination status, preferences about COVID-19 vaccination, and information source for COVID-19. Pilot 1 used a nationally representative sample while pilot 2 used quota sampling to yield representative results at the regional level. In this work, we assessed the performance characteristics of the survey pilots and compared the demographic information collected with a nationally representative household survey. For both pilots, contact rates were between 1% and 2%, while participation rates were above 80%. The results revealed that younger, female, and higher educated participants were more likely to participate in the syndromic survey. Survey rates as well as demographics, COVID-19 vaccination status, and prevalence of respiratory symptoms are reported for both pilots. We found that respondents of the MPSs are more likely to be younger and female. In a COVID-19 pandemic setting, using an interactive voice response MPS to conduct syndromic surveillance may be a transformational, low-risk, and feasible method to detect outbreaks. This evaluation expects to provide a path forward to the inclusion of MPSs as a traditional surveillance method.

Serological analysis in humans in Malaysian Borneo suggests prior exposure to H5 avian influenza near migratory shorebird habitats

Cases of H5 highly pathogenic avian influenzas (HPAI) are on the rise. Although mammalian spillover events are rare, H5N1 viruses have an estimated mortality rate in humans of 60%. No human cases of H5 infection have been reported in Malaysian Borneo, but HPAI has circulated in poultry and migratory avian species transiting through the region. Recent deforestation in coastal habitats in Malaysian Borneo may increase the proximity between humans and migratory birds. We hypothesise that higher rates of human-animal contact, caused by this habitat destruction, will increase the likelihood of potential zoonotic spillover events. In 2015, an environmentally stratified cross-sectional survey was conducted collecting geolocated questionnaire data in 10,100 individuals. A serological survey of these individuals reveals evidence of H5 neutralisation that persisted following depletion of seasonal H1/H3 HA binding antibodies from the plasma. The presence of these antibodies suggests that some individuals living near migratory sites may have been exposed to H5 HA. There is a spatial and environmental overlap between individuals displaying high H5 HA binding and the distribution of migratory birds. We have developed a novel surveillance approach including both spatial and serological data to detect potential spillover events, highlighting the urgent need to study cross-species pathogen transmission in migratory zones.

The role of asymptomatic cattle for leptospirosis dynamics in a herd with imperfect vaccination

Leptospirosis is an emerging zoonotic disease with high health and economic damage. In this study, we developed a deterministic mathematical model that describes the dynamics of leptospirosis transmission within a cattle herd, incorporating asymptomatic infected and vaccinated compartments. The study examined the transmission role of asymptomatic cattle that contaminate herds without farmers’ knowledge. We proved the well-posedness of the proposed model and found the basic reproduction number using the next-generation matrix. Analytically, we demonstrated that the disease-free equilibrium point is locally and globally asymptotically stable when R0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathscr {R}}_0$$\\end{document} is less than unity and is otherwise unstable. Graphically, we further established the local asymptotic stability of disease-free and endemic equilibria. Sensitivity analysis showed that the contact rate with asymptomatic infected cattle, βA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta _A$$\\end{document}, is the most sensitive parameter in the stated model, followed by the recovery rate of asymptomatic infected cattle, σ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma $$\\end{document}, and the vaccination rate of susceptible cattle, τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au $$\\end{document}. Numerical simulations revealed that a reduction in contact rate with asymptomatic infected cattle significantly reduced pathogen Leptospira transmission in the herd. In addition, fostering the recovery rate of asymptomatic infected cattle can significantly reduce new infections in the herd. Furthermore, augmenting the vaccination rate among susceptible cattle resulted in a notable decrease in disease prevalence within the herd. Findings of this study underscore the remarkable importance of targeted interventions, such as reducing contact rates with asymptomatic infected cattle, increasing recovery rates using proper treatments, and enhancing vaccination efforts to manage leptospirosis transmission in cattle herds.

A mathematical model of Cholera–Typhoid coinfection dynamics with a hygiene-driven contact rate

Waterborne infections such as Cholera and Typhoid remain a huge burden on the public health systems of poor countries in Africa and Asia. The highest disease burden is concentrated in sub-Saharan Africa. In most regions, the recent spike in cases of both infections is attributed to dilapidated infrastructure and poor hygiene. This paper examines the role of poor hygiene in the surge of both infections. We use a system of non-linear ordinary differential equations to model the movement of people between the different classes of infections, and we use a sigmoidal function to model the different levels of hygiene in a community. The findings demonstrate that managing hygiene, even if limited to the direct transmission route, can significantly reduce the prevalence of both infections. This paper presents some of the public health implications of these findings.

An overview of the challenges and methods for defining the wildlife-disease interface in the context of disease spread modelling, including concepts of infectious diseases epidemiology

ABSTRACT The wildlife-domestic interface is a key concept helping us to understand how diseases affect both wild and domestic animal populations, yet how to define and measure it remains a challenge. One tool which can contribute to our understanding of the wildlife-domestic interface is disease spread modelling. This can provide insight into how diseases spread within and between populations, and guide decision-making for disease control, response and surveillance programs. Specifically, quantitative estimation of contact rates permits such disease spread models to be developed and used confidently. Here we present a case study of the potential spread of rabies (an exotic disease in Australia) within the wild dog-domestic dog (Canis familiaris) ecosystem of northern Australia to illustrate the concept of the wildlife-domestic interface and disease transmission. We summarise a decade of research conducted to understand one such interface, the wild-domestic dog interface at one site in northern Australia, for the purposes of exploring the impact of one specific disease, rabies. Over a period of 10 years, free-roaming domestic dogs and wild dogs in the Northern Peninsula Area (NPA) of Cape York, Queensland were studied. Key findings included identification of a small but important group of domestic dogs which regularly roam in bushland areas; peri-urban wild dog activity, particularly in the dry season, likely driven by the availability of food sources; and the potential for interaction between hunting dogs and wild dogs in remote areas, particularly during the wet season. These observations can be used to inform disease spread models and identify strategies to mitigate the risks of disease transmission. However, the collection and incorporation of data into such models needs more consideration regarding what information is usable (such as contact rates) and the best ways to collect it. The scarcity of such models incorporating the wildlife-domestic interface suggests that integrated epidemiological-ecological studies are needed to fill this gap.

A two-strain COVID-19 co-infection model with strain 1 vaccination

COVID-19 has caused substantial morbidity and mortality worldwide. Previous models of strain 1 vaccination with re-infection when vaccinated, as well as infection with strain 2 did not consider co-infected classes. To fill this gap, a two co-circulating COVID-19 strains model with strain 1 vaccination, and co-infected is formulated and theoretically analyzed. Sufficient conditions for the stability of the disease-free equilibrium and single-strain 1 and -strain 2 endemic equilibria are obtained. Results show as expected that (1) co-infected classes play a role in the transmission dynamics of the disease (2) a high efficacy vaccine could effectively help mitigate the spread of co-infection with both strain 1 and 2 compared to the low-efficacy vaccine. Sensitivity analysis reveals that the main drivers of the effective reproduction number Re are primarily the effective contact rate for strain 2 (β2), the strain 2 recovery rate (τ2), and the vaccine efficacy or infection reduction due to the vaccine (η). Thus, implementing intervention measures to mitigate the spread of COVID-19 should not ignore the co-infected individuals who can potentially spread both strains of the disease.

Dynamics and backward bifurcations of SEI tuberculosis models in homogeneous and heterogeneous populations

The main difference between tuberculosis (TB) and other infectious diseases is that the transmission of the bacterium should be considered not only as the development of a primary infection, but also as exogenous reinfection or endogenous reactivation. Moreover, individuals in the population may have heterogeneous contact rates, which can be described by complex networks. To this end, we present two differential equation-based TB models in homogeneous and heterogeneous populations. The first model assumes that the number of contacts per unit time is constant for the whole population, whereas the second model considers the heterogeneous number of contacts per unit time for each individual. We derive the basic reproduction number of each model using the next-generation matrix method, and analyze the dynamical properties of each model in detail. We find that the two models undergo backward bifurcations and have the same threshold condition for backward bifurcation. From this threshold condition, we see that the reduced rate of exogenous reinfection of individuals plays an important role in causing the backward bifurcation. Interestingly, the second model allows the threshold condition for backward bifurcation to be independent of network parameters. Thus, unlike other infectious disease models on complex networks, in controlling the spread of tuberculosis among populations with different numbers of contacts, we only need to focus on disease parameters during treatment. Finally, numerical simulations more intuitively demonstrate the impact of parameter changes on the prevalence of tuberculosis and reveal the model's richer and more interesting dynamical properties, such as bistability. Sensitivity analysis indicates that the basic reproduction number is highly correlated with both the relapse rate of latent individuals progressing to active infection and the probability of healthy individuals becoming infected after contact with the pathogen. Therefore, enhancing the detection and treatment of latent cases and reducing contact between infected and uninfected individuals are the most crucial public health interventions.

Minimal wave speed for a two-group epidemic model with nonlocal dispersal and spatial-temporal delay

In this paper, a two-group SIR reaction-diffusion epidemic model with nonlocal dispersal and spatial-temporal delay based on within-group and inter-group transmission mechanisms is investigated. The basic reproduction number R0 is calculated using the method of next-generation matrix. The critical wave speed cm* is determined by analyzing the distribution of roots of the characteristic equation. When R0&amp;gt;1 and wave speed c⩾cm*, the existence of traveling waves connecting disease-free and endemic steady states is obtained by constructing sub- and super-solutions and a Lyapunov functional, and applying Schauder’s fixed-point theorem and a limit argument. When R0&amp;gt;1 and 0&amp;lt;c&amp;lt;cm*, the nonexistence of traveling waves connecting disease-free and endemic steady states is proven by contradiction and two-sided Laplace transform. This indicates that the critical wave speed cm* is exactly the minimum wave speed. Numerical simulations are carried out to illustrate theoretical results. The dependence of the minimal speed cm* on time delay, diffusion rates and contact rates is discussed, showing that the longer the latent period and the lower the diffusion rates of infected individuals and the inter-group transmission rates between groups, the slower the spread of disease.