To theeditor:The incidence of depression and obesity is on the rise,posing significant public health concerns.While the literature largely supports a positive correlation between depression and body mass index(BMI),I2...To theeditor:The incidence of depression and obesity is on the rise,posing significant public health concerns.While the literature largely supports a positive correlation between depression and body mass index(BMI),I2 earlier studies have suggested an inverse relationship or indicated a lack of association between depression and obesity.展开更多
Unrecorded alcohol includes illegally distributed alcohol as well as homemade or surrogate alcohol which is unintended for consumption by humans(e.g.,cosmetics containing alcohol).The highest unrecorded alcohol consum...Unrecorded alcohol includes illegally distributed alcohol as well as homemade or surrogate alcohol which is unintended for consumption by humans(e.g.,cosmetics containing alcohol).The highest unrecorded alcohol consumption occurs in Eastern Europe and some of these countries have an over proportional liver cirrhosis mortality.Compounds besides ethanol have been hypothesized as being responsible for this observation.On the other hand,chemical investigations were unable to prove that unrecorded alcohol regularly contains contaminants above toxicological thresholds.However,illegally produced spirits regularly contain higher percentages of alcohol(above 45%by volume),but for considerably less costs compared with licit beverages,potentially causing more problematic patterns of drinking.In this review,it is investigated whether patterns of drinking rather than product composition can explain the liver cirrhosis mortality rates.Statistical examination of World Health Organization country data shows that the originally detected correlation of the percentage of unrecorded alcohol consumption and liver cirrhosis mortality rates disappears when the data is adjusted for the prevalence of heavy episodic drinking.It may be concluded that there is currently a lack of data to demonstrate causality between the composition of illicit spirits(e.g.,higher levels of certain contaminants in home-produced products)and liver toxicity on a population scale.Exceptions may be cases of poisoning with antiseptic liquids containing compounds such as polyhexamethyleneguanidine,which were reported to be consumed as surrogate alcohol in Russia,leading to an outbreak of acute cholestatic liver injury,histologically different from conventional alcoholic liver disease.展开更多
Background:Dietary Reference Intakes are used to guide the energy intake of the Canadian Armed Forces(CAF)field rations provided to military personnel deployed for training or operations.However,the high energy expend...Background:Dietary Reference Intakes are used to guide the energy intake of the Canadian Armed Forces(CAF)field rations provided to military personnel deployed for training or operations.However,the high energy expenditures likely to occur under harsh environmental/metabolically challenging deployment conditions may not be adequately considered.This study examined the Ad libitum energy and nutrient intakes of CAF personnel(n=18)consuming field rations in a resting thermoneutral environment and during a day of standardized strenuous infantry activities at varying environmental temperatures.Methods:Dietary intake was assessed using a measured food intake/food waste method during the experimental treatment and for 6 h after treatment.Four treatments were administered in a randomized counterbalanced design:exercise(as standardized infantry activities)in the heat(30℃),exercise in the cold(–10℃),exercise in temperate thermoneutral(21℃)air temperatures and a resting(sedentary)trial(21℃).Results:The average Ad libitum consumption of field rations was 70%of the provided total energy(2776±99 kcal/8 h)during all treatments.Even with an acute challenge of increased energy expenditure and temperature stress in the simulated field conditions,participants’energy intakes(1985±747 kcal/8 h)under hot,cold and temperate treatments did not differ from energy intake during the sedentary condition(1920±640 kcal/8 h).Participants’energy intakes(1009±527 kcal/6 h)did not increase during the 6 h posttreatment period when the stresses of the strenuous physical activities and the harsh environmental temperatures had subsided.Conclusions:These results should be considered when planning the provision of field rations for CAF personnel expected to be engaged in strenuous physical activities with prolonged exposure to temperature extremes.展开更多
The study of the origin of SARS coronavirus(SARS CoV)and SARS-like coronavirus(SL-CoV)is very important for the prevention of novel human infections with these viruses.Recently,Ge et al.suggest that Chinese horseshoe ...The study of the origin of SARS coronavirus(SARS CoV)and SARS-like coronavirus(SL-CoV)is very important for the prevention of novel human infections with these viruses.Recently,Ge et al.suggest that Chinese horseshoe bats are natural reservoirs of SARSCoV[1].But this conclusion is incorrect.It should be"Chinese horseshoe bats are natural reservoirs of SLCoV"[2-7].The paper also has several methodological problems,leading to errors in the conclusions.展开更多
BACKGROUND Solid organ transplantation is a life-saving intervention for end-stage organ disease.Post-transplant diabetes mellitus(PTDM)is a common complication in solid organ transplant recipients,and significantly c...BACKGROUND Solid organ transplantation is a life-saving intervention for end-stage organ disease.Post-transplant diabetes mellitus(PTDM)is a common complication in solid organ transplant recipients,and significantly compromises long-term survival beyond a year.AIM To perform a systematic review and meta-analysis to estimate incidence of PTDM and compare the effects of the 3 major immunosuppressants on incidence of PTDM.METHODS Two hundred and six eligible studies identified 75595 patients on Tacrolimus,51242 on Cyclosporine and 3020 on Sirolimus.Random effects meta-analyses was used to calculate incidence.RESULTS Network meta-analysis estimated the overall risk of developing PTDM was higher with tacrolimus(OR=1.495%CI:1.0–2.0)and sirolimus(OR=1.8;95%CI:1.5–2.2)than with Cyclosporine.The overall incidence of PTDM at years 2-3 was 17%for kidney,19%for liver and 22%for heart.The risk factors for PTDM most frequently identified in the primary studies were age,body mass index,hepatitis C,and African American descent.CONCLUSION Tacrolimus tends to exhibit higher diabetogenicity in the short-term(2-3 years post-transplant),whereas sirolimus exhibits higher diabetogenicity in the longterm(5-10 years post-transplant).This study will aid clinicians in recognition of risk factors for PTDM and encourage careful evaluation of the risk/benefit of different immunosuppressant regimens in transplant recipients.展开更多
Introduction: While exposure to environmental peanut during infancy appears to promote sensitization by the epicutaneous route, early and frequent peanut ingestion during infancy may prevent peanut allergy through ora...Introduction: While exposure to environmental peanut during infancy appears to promote sensitization by the epicutaneous route, early and frequent peanut ingestion during infancy may prevent peanut allergy through oral tolerance. Due to parental occupation, the offspring of peanut farmers are likely exposed to peanut protein in their environment, but they may also have early introduction into their diet due to ready access. The purpose of this study was to determine the prevalence of peanut allergy in offspring of peanut farmers. Methods: A survey was mailed by the National Peanut Board to peanut farmers in the United States collecting information on peanut consumption, peanut reactions, physician-confirmed peanut allergy (PA), epinephrine auto-injector prescription and history of other allergies in offspring. Egg allergy (EA) served as a comparator to peanut allergy. Results: Of 10,349 households surveyed, 1050 responses were received (2493 offspring, participation rate 10%). The self-reported prevalence of peanut allergy in the general population in the USA is 0.9%, 1.3%, and 0.7% for children 0 - 5 years, 6 - 10 years, and 11 - 17 years, respectively. In offspring of peanut farmers, PA vs EA was reported in 3.69% (10/271) vs 2.6% (7/271), 2.8% (14/493) vs 2.0% (10/493), and 1.48% (37/2493) vs 1.4% (35/2493) of offspring ≤10 years, offspring ≤15 years and all offspring, respectively. Physician-confirmed PA was reported in 3.3% (9/271), 2.6% (13/493), and 1.24% (31/2493) in the three groups, respectively. Physician-confirmed PA with epinephrine auto-injector prescription was reported in1.8% (5/271), 1.8% (9/493), and 0.68% (17/2493) in the three groups, respectively. Conclusions: We found that the self-reported prevalence of peanut allergy in offspring of peanut farmers was similar to that reported in the general population. This is a unique population that may provide insight into factors that influence development of peanut allergy.展开更多
The coronavirus(COVID-19)pandemic has caused severe medical emergencies,economic depression,inflation,social distress,and research burden worldwide.Despite the severity of the spreading COVID-19,individual governments...The coronavirus(COVID-19)pandemic has caused severe medical emergencies,economic depression,inflation,social distress,and research burden worldwide.Despite the severity of the spreading COVID-19,individual governments and the World Health Organization have mandated several safety protocols including quarantine,physical distancing,advanced research in decoding the disease mechanism to build an effective vaccine,and promoting mental health to achieve the aim of coping through this infectious pandemic.Around the globe,mental health research emphasizes how social isolation impacts anxiety and depression,however,the cause of mental health depletion due to the type of individual's living accommodation(apartment and house)during a pandemic remains unexplored.The apartments have high elevation and high population density while the houses have low elevation and low population density as they are more spaced apart.This paper presents a novel hypothesis to maintain/enhance individuals’mental health during the pandemic,known as“Modi’s Pandemic Infrastructure Hypothesis”,which suggests that individuals residing in varying living accommodations(i.e.apartment or house)would exhibit a significant difference in the experienced pandemic(i.e.COVID-19)anxiety due to varying amount of experienced“silent stress”.Hence,any type of infrastructure(medical,residential,educational,or corporate)should be designed following the public survey of that geographic area based on hypotheses laid in this paper,to minimize the magnitude of“silent stress”.“Silent stress”can be defined as the stress that is unknowingly experienced in the assimilated living accommodation,which is responsible for depleting individuals’mental health and affecting the ability to cope with the pandemic.In support of this novel hypothesis,previous research has demonstrated that the number of coronavirus per unit area has a positive association with elevation above the ground level while a negative association with the population density.Although the scientific data supports the idea that there would be an equal trade-off in the quantity of coronavirus around an individual in both types of accommodation,however,psychologically the public would perceive it differently.Along with the two key variables(i.e.elevation and population density),other influencing factors would be taken into account while determining the magnitude of silent stress,pandemic anxiety,and the best type of infrastructure.In conclusion,this promising hypothesis will not only help the government to build anxiety-free infrastructure for pandemic times but also increase the effectiveness of medical treatments as mental health and strength is the best medicine to defeat severe diseases.展开更多
Objective:Leptin(LEP)is an obesity-associated adipokine associated with tumor cell growth.We examined the relevance of genetic variants of LEP and leptin receptor(LEPR)to colorectal cancer(CRC)survival by using data f...Objective:Leptin(LEP)is an obesity-associated adipokine associated with tumor cell growth.We examined the relevance of genetic variants of LEP and leptin receptor(LEPR)to colorectal cancer(CRC)survival by using data from the Newfoundland Familial Colorectal Cancer Study.Methods:A total of 532 patients newly diagnosed with CRC between 1997 and 2003 were followed up until April 2010.Data on their demographics and lifestyles were collected via questionnaires.Genotyping of blood samples was performed with the Illumina Human Omni-Quad Bead chip.Multivariable Cox models were used to assess the relationships of 35 tag single-nucleotide polymorphisms(SNPs)in LEP and LEPR with overall survival(OS),disease-free survival(DFS),and CRC-specific survival.Results:At the gene level,LEP was associated with DFS(P=0.017),and LEPR was associated with both DFS(P=0.021)and CRCspecific survival(P=0.013)in patients with CRC.In single-SNP analysis,LEP rs11763517,LEPR rs9436301,and LEPR rs7602 were associated with DFS after adjustment for multiple testing.The LEPR haplotypes G-C-T(rs7534511-rs9436301-rs1887285)and A-A-G(rs7602-rs970467-rs9436748)were associated with prolonged OS among patients with CRC overall(G-C-T:HR,0.63;95%CI,0.43–0.93;A-A-G:HR,0.59;95%CI,0.38–0.91)and those diagnosed with colon cancer(G-C-T:HR,0.54;95%CI,0.34–0.86;A-A-G:HR,0.49;95%CI,0.29–0.83).Similar results were observed for DFS.Moreover,significant interactions were found among LEPR rs7602(A vs.G),LEPR rs1171278(T vs.C),red meat intake,and BMI status:the associations between these variants and prolonged DFS were limited to patients with below-median red meat consumption and body mass index(BMI)<25 kg/m2.Conclusions:Polymorphic variations in the LEP and LEPR genes were associated with survival of patients after CRC diagnosis.The LEP/LEPR-CRC survival association was modified by participants’red meat intake and BMI.展开更多
Urban agriculture is gaining recognition for its potential contributions to environmental resilience and climate change adaptation,providing advantages such as urban greening,reduced heat island effects,and decreased ...Urban agriculture is gaining recognition for its potential contributions to environmental resilience and climate change adaptation,providing advantages such as urban greening,reduced heat island effects,and decreased air pollution.Moreover,it indirectly supports communities during weather events and natural disasters,ensuring food security and fostering community cohesion.However,concerns about planetary health risks persist in highly urbanized and climate-affected areas.Employing electronic databases such as Web of Science and PubMed and adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines,we identified 55 relevant papers to comprehend the planetary health risks associated with urban agriculture,The literature review identified five distinct health risks related to urban agriculture:(1)trace metal risks in urban farms;(2)health risks associated with wastewater irrigation;(3)zoonotic risks;(4)other health risks;and(5)social and economic risks.The study highlights that urban agriculture,while emphasizing environmental benefits,particularly raises concerns about trace metal bioaccumulation in soil and vegetables,posing health risks for populations.Other well studied risks included wastewater irrigation and backyard livestock farming.The main limitations in the available literature were in studying infectious diseases and antibiotic resistance associated with urban agriculture.展开更多
Background:Esotropia is a common concern in pediatric ophthalmology consultations.While most cases stem from strabismus,it is crucial for physicians to differentiate atypical features that might indicate underlying or...Background:Esotropia is a common concern in pediatric ophthalmology consultations.While most cases stem from strabismus,it is crucial for physicians to differentiate atypical features that might indicate underlying organic causes,such as VI nerve palsy,hinting at the presence of intracranial spaceoccupying lesions.Although the occurrence of cerebral aneurysms in children is rare,they can have severe consequences.Case Description:Here,we described an extremely rare case of giant basilar fusiform aneurysm measuring 4.0 cm×3.9 cm×3.9 cm in an otherwise healthy 8-year-old child,and analyzed its atypical features that suggested an intracranial etiology.We further described an endovascular approach,performed by interventional radiologists,and discussed its advantages over the conventional neurosurgery.The patient continued to be followed by our multidisciplinary team.He had a stable post-operative course and made an excellent recovery neurologically.At the 1-year follow-up,he was orthophoria with excellent vision and stereopsis.Conclusions:To our knowledge,this is the first pediatric case in Canada where a giant intracranial aneurysm was treated endovascularly.The salient red flags—progressive incomitant esotropia and diplopia,the presence of myopia(rather than hyperopia),nystagmus and abnormal saccadic movements—should be astutely recognized by clinicians as intracranial giant aneurysms carry a poor prognosis.A multidisciplinary approach is essential for the management of such cases.展开更多
Background:Tuberculosis(TB)is a major global health threat and the leading infectious disease cause of death worldwide.Access to and retention in TB care remains a challenge for patients,particularly those living in r...Background:Tuberculosis(TB)is a major global health threat and the leading infectious disease cause of death worldwide.Access to and retention in TB care remains a challenge for patients,particularly those living in rural and remote settings.This qualitative study explored barriers and facilitators to accessing and maintaining contact with TB care services in communities in Xigaze(Shigatse)prefecture,Xizang Autonomous Region(Tibet Autonomous Region),China from the perspective of persons impacted by TB.Methods:We conduced in-depth interviews with 23 participants impacted by TB in four rural districts in Xigaze prefecture,Xizang Autonomous Region,China between April 2019 and November 2020.Interviews were conducted in Tibetan and Mandarin,transcribed in Mandarin and translated into English.Transcripts were checked against recordings by native Tibetan and Mandarin speakers.QSR NVivo12 software was used for framework analysis guided by an access to care conceptual framework by Levesque et al.Results:Overall patients reported low awareness of and an indiferent attitude towards TB,although all reported understanding the need to adhere to treatment.Participants reported complex pathways to care,often requiring visits to multiple healthcare facilities.Some participants reported visiting traditional Tibetan medicine(TTM)providers.Participants reported various barriers to accessing care including challenges physically reaching care,out-of-pocket payments for tests,diagnostics and transport.Barriers to maintaining care included medication side efects and worry about treatment efectiveness.Enablers to accessing care identifed included knowledge or past experience with TB,integrated models of TTM and western care,supportive village doctors who conducted home visits,free TB treatment and other subsidies,as well as having family support with care and social support as barriers and facilitators to maintaining treatment.Conclusions:We identifed barriers and facilitators to accessing services in rural communities in Xigaze from the perspective of persons impacted by TB.Challenges include complex pathways to care,travel distances,wait times and low awareness.Tuberculosis care in the region could be strengthened by ongoing culturally tailored educational campaigns to increase awareness,partnerships with TTM providers,providing comprehensive treatment subsidies and strengthening the role of family members in comprehensive TB care.展开更多
Suicide is the second leading cause of death in youth globally; however, there is uncertainty about how best to intervene. Suicide rates are typically higher in males than females, while the converse is true for suici...Suicide is the second leading cause of death in youth globally; however, there is uncertainty about how best to intervene. Suicide rates are typically higher in males than females, while the converse is true for suicide attempts. We review this "gender paradox" in youth, and in particular, the age-dependency of these sex/gender differences and the developmental mechanisms that may explain them. Epidemiologic, genetic,neurodevelopmental and psychopathological research have identified suicidal behaviour risks arising from genetic vulnerabilities and sex/gender differences in early adverse environments, neurodevelopment, mental disorder and their complex interconnections. Further, evolving sex-/gender-defined social expectations and norms have been thought to influence suicide risk. In particular, how youth perceive and cope with threats and losses(including conforming to others' or one's own expectations of sex/gender identity) and adapt to pain(through substance use and helpseeking behaviours). Taken together, considering brain plasticity over the lifespan, these proposed antecedents to youth suicide highlight the importance of interventions that alter early environment(s)(e.g., childhood maltreatment) and/or one's ability to adapt to them. Further, such interventions may have more enduring protective effects, for the individual and for future generations, if implemented in youth.展开更多
Platelets are nuclear cell fragments produced by megakaryocytes.Inactive platelets circulate in the blood until activation by extemal stimuli to execute important biological functions,including hemostasis,inflammation...Platelets are nuclear cell fragments produced by megakaryocytes.Inactive platelets circulate in the blood until activation by extemal stimuli to execute important biological functions,including hemostasis,inflammation,tissue remodelling,and blood vessel formation.Platelets can reflect cancer cells'pathogenesis through a process known as tumour-educated platelets(TEPs).展开更多
This study aimed to identify subtypes of genomic variants associated with the efficacy of immune checkpoint inhibitors(ICIs)by conducting systematic literature search in electronic databases up to May 31,2021.The main...This study aimed to identify subtypes of genomic variants associated with the efficacy of immune checkpoint inhibitors(ICIs)by conducting systematic literature search in electronic databases up to May 31,2021.The main outcomes including overall survival(OS),progression-free survival(PFS),objective response rate(ORR),and durable clinical benefit(DCB)were correlated with tumor genomic features.A total of 1546 lung cancer patients with available genomic variation data were included from 14 studies.The Kirsten rat sarcoma viral oncogene homolog G12C(KRAS^(G12C))mutation combined with tumor protein P53(TP53)mutation revealed the promising efficacy of ICI therapy in these patients.Furthermore,patients with epidermal growth factor receptor(EGFR)classical activating mutations(including EGFRL858Rand EGFRΔ19)exhibited worse outcomes to ICIs in OS(adjusted hazard ratio(HR),1.40;95%confidence interval(CI),1.01-1.95;P=0.0411)and PFS(adjusted HR,1.98;95%CI,1.49-2.63;P<0.0001),while classical activating mutations with EGFR^(T790)Mshowed no difference compared to classical activating mutations without EGFR^(T790)Min OS(adjusted HR,0.96;95%CI,0.48-1.94;P=0.9157)or PFS(adjusted HR,0.72;95%CI,0.39-1.35;P=0.3050).Of note,for patients harboring the Usher syndrome type-2A(USH2A)missense mutation,correspondingly better outcomes were observed in OS(adjusted HR,0.52;95%CI,0.32-0.82;P=0.0077),PFS(adjusted HR,0.51;95%CI,0.38-0.69;P<0.0001),DCB(adjusted odds ratio(OR),4.74;95%CI,2.75-8.17;P<0.0001),and ORR(adjusted OR,3.45;95%CI,1.88-6.33;P<0.0001).Our findings indicated that,USH2A missense mutations and the KRAS^(G12C)mutation combined with TP53 mutation were associated with better efficacy and survival outcomes,but EGFR classical mutations irrespective of combination with EGFR^(T790)Mshowed the opposite role in the ICI therapy among lung cancer patients.Our findings might guide the selection of precise targets for effective immunotherapy in the clinic.展开更多
In February 2022,Kubo et al.and the Liver Cancer Study Group of Japan published a clinical practice guideline for the treatment of intrahepatic cholangiocarcinoma(iCCA)(1).Their guideline consists of a treatment algor...In February 2022,Kubo et al.and the Liver Cancer Study Group of Japan published a clinical practice guideline for the treatment of intrahepatic cholangiocarcinoma(iCCA)(1).Their guideline consists of a treatment algorithm for iCCA with five background statements,16 clinical questions and one clinical topic discussion(1).展开更多
Background:Tuberculosis(TB)is an infectious disease of major public health concern.The disease has demonstrated large space-time variations.This study aims to explore the space-time dynamics of TB cases in an economic...Background:Tuberculosis(TB)is an infectious disease of major public health concern.The disease has demonstrated large space-time variations.This study aims to explore the space-time dynamics of TB cases in an economically and geographically dynamic province in China with specific references of TB control for policy makers.Methods:Data on all reported TB cases from 2009 to 2012 were collected from the TB program at the Zhejiang Provincial Center for Disease Control and Prevention.We employed time series and exploratory spatial data analyses,including Moran’s I,Local Getis’s G_(i)^(*),and Kulldorff’s space-time scan statistics,to identify the temporal trends and spatial patterns of TB at a county level.Results:A total of 147,941 TB cases were reported during 2009–2012 in Zhejiang.A higher proportion of TB cases were younger,male,and registered permanent residents among all TB cases notified in the province.TB cases were reported most frequently in April with small peaks in June,July,and October.This disease was spatially clustering with Moran’s I values ranged from 0.29 to 0.32(p<0.001).A most likely cluster and ten secondary clusters were identified,mainly concentrated in the southeast and west counties of the province.Conclusions:This study identified seasonal patterns and significant space-time clusters of TB cases in Zhejiang,China.Poverty,migration,and seasonal effects may play important roles in potential clusters.展开更多
The incidence of breast cancer is on a rise worldwide;it is a disease having a complex etiology.Besides genetics,environmental and other lifestyle factors play a role in the development of the disease.There has been a...The incidence of breast cancer is on a rise worldwide;it is a disease having a complex etiology.Besides genetics,environmental and other lifestyle factors play a role in the development of the disease.There has been a keen interest in studying associations between breast cancer and exposures to emerging environmental chemicals,which mimic estrogens or influence estrogen levels and signaling in the human body.The common consequence of an endocrine disrupting chemical exposure is that it may have an impact on breast cancer etiology by stimulating formation as well as progression of breast cancer.Exposures to selected emerging environmental contaminants such as alkylphenols(APs),bisphenol A(BPA),parabens,perfluoroalkyl substances(PFASs),phthalates,polybrominated diphenyl ethers(PBDEs),synthetic musks and triclosan,and their probable role in breast cancer development are reviewed.Studies evaluated include the experimental in vitro and in vivo studies as well as human population based studies.In vitro and in vivo evidences indicate that a number of emerging environmental contaminants may play a role in the initiation and/or progression of breast cancer.Although exposures have been assessed in some human populations,breast and other cancer risks associated with these exposures are largely unknown.Efforts should be focussed on the evaluation of these environmental exposures in human populations and their interactions with each other and other genetic and lifestyle risk factors.展开更多
Mathematical models are often regarded as recent innovations in the description and analysis of infectious disease outbreaks and epidemics,but simple mathematical expressions have been in use for projection of epidemi...Mathematical models are often regarded as recent innovations in the description and analysis of infectious disease outbreaks and epidemics,but simple mathematical expressions have been in use for projection of epidemic trajectories for more than a century.We recently introduced a single equation model(the incidence decay with exponential adjustment,or IDEA model)that can be used for short-term epidemiological forecasting.In the mid-19th century,Dr.William Farr made the observation that epidemic events rise and fall in a roughly symmetrical pattern that can be approximated by a bell-shaped curve.He noticed that this time-evolution behavior could be captured by a single mathematical formula(“Farr's law”)that could be used for epidemic forecasting.We show here that the IDEA model follows Farr's law,and show that for intuitive assumptions,Farr's Law can be derived from the IDEA model.Moreover,we show that both mathematical approaches,Farr's Law and the IDEA model,resemble solutions of a susceptible-infectious-removed(SIR)compartmental differential-equation model in an asymptotic limit,where the changes of disease transmission respond to control measures,and not only to the depletion of susceptible individuals.This suggests that the concept of the reproduction number eR 0T was implicitly captured in Farr's(pre-microbial era)work,and also suggests that control of epidemics,whether via behavior change or intervention,is as integral to the natural history of epidemics as is the dynamics of disease transmission.展开更多
The use of masks as a means of reducing transmission of COVID-19 outside healthcare settings has proved controversial.Masks are thought to have two modes of effect:they prevent infection with COVID-19 in wearers;and p...The use of masks as a means of reducing transmission of COVID-19 outside healthcare settings has proved controversial.Masks are thought to have two modes of effect:they prevent infection with COVID-19 in wearers;and prevent transmission by individuals with subclinical infection.We used a simple next-generation matrix approach to estimate the conditions under which masks would reduce the reproduction number of COVID-19 under a threshold of 1.Our model takes into account the possibility of assortative mixing,where mask users interact preferentially with other mask users.We make 3 key observations:1.Masks,even with suboptimal efficacy in both prevention of acquisition and transmission of infection,could substantially decrease the reproduction number for COVID-19 if widely used.2.Widespread masking may be sufficient to suppress epidemics where R has been brought close to 1 via other measures(e.g.,distancing).3.“Assortment”within populations(the tendency for interactions between masked individuals to be more likely than interactions between masked and unmasked individuals)would rapidly erode the impact of masks.As such,mask uptake needs to be fairly universal to have an effect.This simple model suggests that widespread uptake of masking could be determinative in suppressing COVID-19 epidemics in regions with R(t)at or near 1.展开更多
文摘To theeditor:The incidence of depression and obesity is on the rise,posing significant public health concerns.While the literature largely supports a positive correlation between depression and body mass index(BMI),I2 earlier studies have suggested an inverse relationship or indicated a lack of association between depression and obesity.
基金Supported by The Ontario Ministry of Health and Long Term Care to CAMH for the salaries of scientists and infrastructureThe contents of this paper are solely the responsibility of the authors and do not necessarily represent the official views of the Ministry of Health and Long Term Care
文摘Unrecorded alcohol includes illegally distributed alcohol as well as homemade or surrogate alcohol which is unintended for consumption by humans(e.g.,cosmetics containing alcohol).The highest unrecorded alcohol consumption occurs in Eastern Europe and some of these countries have an over proportional liver cirrhosis mortality.Compounds besides ethanol have been hypothesized as being responsible for this observation.On the other hand,chemical investigations were unable to prove that unrecorded alcohol regularly contains contaminants above toxicological thresholds.However,illegally produced spirits regularly contain higher percentages of alcohol(above 45%by volume),but for considerably less costs compared with licit beverages,potentially causing more problematic patterns of drinking.In this review,it is investigated whether patterns of drinking rather than product composition can explain the liver cirrhosis mortality rates.Statistical examination of World Health Organization country data shows that the originally detected correlation of the percentage of unrecorded alcohol consumption and liver cirrhosis mortality rates disappears when the data is adjusted for the prevalence of heavy episodic drinking.It may be concluded that there is currently a lack of data to demonstrate causality between the composition of illicit spirits(e.g.,higher levels of certain contaminants in home-produced products)and liver toxicity on a population scale.Exceptions may be cases of poisoning with antiseptic liquids containing compounds such as polyhexamethyleneguanidine,which were reported to be consumed as surrogate alcohol in Russia,leading to an outbreak of acute cholestatic liver injury,histologically different from conventional alcoholic liver disease.
基金funded in part by Defence Research&Development Canada(DRDC)approved by the Canadian Forces Surgeon General’s Health Research Programthe Department of National Defence(DND)policy。
文摘Background:Dietary Reference Intakes are used to guide the energy intake of the Canadian Armed Forces(CAF)field rations provided to military personnel deployed for training or operations.However,the high energy expenditures likely to occur under harsh environmental/metabolically challenging deployment conditions may not be adequately considered.This study examined the Ad libitum energy and nutrient intakes of CAF personnel(n=18)consuming field rations in a resting thermoneutral environment and during a day of standardized strenuous infantry activities at varying environmental temperatures.Methods:Dietary intake was assessed using a measured food intake/food waste method during the experimental treatment and for 6 h after treatment.Four treatments were administered in a randomized counterbalanced design:exercise(as standardized infantry activities)in the heat(30℃),exercise in the cold(–10℃),exercise in temperate thermoneutral(21℃)air temperatures and a resting(sedentary)trial(21℃).Results:The average Ad libitum consumption of field rations was 70%of the provided total energy(2776±99 kcal/8 h)during all treatments.Even with an acute challenge of increased energy expenditure and temperature stress in the simulated field conditions,participants’energy intakes(1985±747 kcal/8 h)under hot,cold and temperate treatments did not differ from energy intake during the sedentary condition(1920±640 kcal/8 h).Participants’energy intakes(1009±527 kcal/6 h)did not increase during the 6 h posttreatment period when the stresses of the strenuous physical activities and the harsh environmental temperatures had subsided.Conclusions:These results should be considered when planning the provision of field rations for CAF personnel expected to be engaged in strenuous physical activities with prolonged exposure to temperature extremes.
文摘The study of the origin of SARS coronavirus(SARS CoV)and SARS-like coronavirus(SL-CoV)is very important for the prevention of novel human infections with these viruses.Recently,Ge et al.suggest that Chinese horseshoe bats are natural reservoirs of SARSCoV[1].But this conclusion is incorrect.It should be"Chinese horseshoe bats are natural reservoirs of SLCoV"[2-7].The paper also has several methodological problems,leading to errors in the conclusions.
文摘BACKGROUND Solid organ transplantation is a life-saving intervention for end-stage organ disease.Post-transplant diabetes mellitus(PTDM)is a common complication in solid organ transplant recipients,and significantly compromises long-term survival beyond a year.AIM To perform a systematic review and meta-analysis to estimate incidence of PTDM and compare the effects of the 3 major immunosuppressants on incidence of PTDM.METHODS Two hundred and six eligible studies identified 75595 patients on Tacrolimus,51242 on Cyclosporine and 3020 on Sirolimus.Random effects meta-analyses was used to calculate incidence.RESULTS Network meta-analysis estimated the overall risk of developing PTDM was higher with tacrolimus(OR=1.495%CI:1.0–2.0)and sirolimus(OR=1.8;95%CI:1.5–2.2)than with Cyclosporine.The overall incidence of PTDM at years 2-3 was 17%for kidney,19%for liver and 22%for heart.The risk factors for PTDM most frequently identified in the primary studies were age,body mass index,hepatitis C,and African American descent.CONCLUSION Tacrolimus tends to exhibit higher diabetogenicity in the short-term(2-3 years post-transplant),whereas sirolimus exhibits higher diabetogenicity in the longterm(5-10 years post-transplant).This study will aid clinicians in recognition of risk factors for PTDM and encourage careful evaluation of the risk/benefit of different immunosuppressant regimens in transplant recipients.
文摘Introduction: While exposure to environmental peanut during infancy appears to promote sensitization by the epicutaneous route, early and frequent peanut ingestion during infancy may prevent peanut allergy through oral tolerance. Due to parental occupation, the offspring of peanut farmers are likely exposed to peanut protein in their environment, but they may also have early introduction into their diet due to ready access. The purpose of this study was to determine the prevalence of peanut allergy in offspring of peanut farmers. Methods: A survey was mailed by the National Peanut Board to peanut farmers in the United States collecting information on peanut consumption, peanut reactions, physician-confirmed peanut allergy (PA), epinephrine auto-injector prescription and history of other allergies in offspring. Egg allergy (EA) served as a comparator to peanut allergy. Results: Of 10,349 households surveyed, 1050 responses were received (2493 offspring, participation rate 10%). The self-reported prevalence of peanut allergy in the general population in the USA is 0.9%, 1.3%, and 0.7% for children 0 - 5 years, 6 - 10 years, and 11 - 17 years, respectively. In offspring of peanut farmers, PA vs EA was reported in 3.69% (10/271) vs 2.6% (7/271), 2.8% (14/493) vs 2.0% (10/493), and 1.48% (37/2493) vs 1.4% (35/2493) of offspring ≤10 years, offspring ≤15 years and all offspring, respectively. Physician-confirmed PA was reported in 3.3% (9/271), 2.6% (13/493), and 1.24% (31/2493) in the three groups, respectively. Physician-confirmed PA with epinephrine auto-injector prescription was reported in1.8% (5/271), 1.8% (9/493), and 0.68% (17/2493) in the three groups, respectively. Conclusions: We found that the self-reported prevalence of peanut allergy in offspring of peanut farmers was similar to that reported in the general population. This is a unique population that may provide insight into factors that influence development of peanut allergy.
文摘The coronavirus(COVID-19)pandemic has caused severe medical emergencies,economic depression,inflation,social distress,and research burden worldwide.Despite the severity of the spreading COVID-19,individual governments and the World Health Organization have mandated several safety protocols including quarantine,physical distancing,advanced research in decoding the disease mechanism to build an effective vaccine,and promoting mental health to achieve the aim of coping through this infectious pandemic.Around the globe,mental health research emphasizes how social isolation impacts anxiety and depression,however,the cause of mental health depletion due to the type of individual's living accommodation(apartment and house)during a pandemic remains unexplored.The apartments have high elevation and high population density while the houses have low elevation and low population density as they are more spaced apart.This paper presents a novel hypothesis to maintain/enhance individuals’mental health during the pandemic,known as“Modi’s Pandemic Infrastructure Hypothesis”,which suggests that individuals residing in varying living accommodations(i.e.apartment or house)would exhibit a significant difference in the experienced pandemic(i.e.COVID-19)anxiety due to varying amount of experienced“silent stress”.Hence,any type of infrastructure(medical,residential,educational,or corporate)should be designed following the public survey of that geographic area based on hypotheses laid in this paper,to minimize the magnitude of“silent stress”.“Silent stress”can be defined as the stress that is unknowingly experienced in the assimilated living accommodation,which is responsible for depleting individuals’mental health and affecting the ability to cope with the pandemic.In support of this novel hypothesis,previous research has demonstrated that the number of coronavirus per unit area has a positive association with elevation above the ground level while a negative association with the population density.Although the scientific data supports the idea that there would be an equal trade-off in the quantity of coronavirus around an individual in both types of accommodation,however,psychologically the public would perceive it differently.Along with the two key variables(i.e.elevation and population density),other influencing factors would be taken into account while determining the magnitude of silent stress,pandemic anxiety,and the best type of infrastructure.In conclusion,this promising hypothesis will not only help the government to build anxiety-free infrastructure for pandemic times but also increase the effectiveness of medical treatments as mental health and strength is the best medicine to defeat severe diseases.
基金grants from the National Natural Science Foundation of China(Grant No.82003533)the CNS-ZD Tizhi and Health Fund(Grant No.CNS-ZD2020-82)+3 种基金funded by the Canadian Institutes of Health Research Team grant(Grant No.CIHR-CPT79845)Canadian Institutes of Health Research Team in Interdisciplinary Research on Colorectal Cancer Studentship(Grant No.205835)the National Cancer Institutes of Health under RFA#CA-08-502cooperative agreements with members of the Colon Cancer Family Registry and principal investigators:Ontario Registry for Studies of Familial Colorectal Cancer(Grant No.U01 CA074783)。
文摘Objective:Leptin(LEP)is an obesity-associated adipokine associated with tumor cell growth.We examined the relevance of genetic variants of LEP and leptin receptor(LEPR)to colorectal cancer(CRC)survival by using data from the Newfoundland Familial Colorectal Cancer Study.Methods:A total of 532 patients newly diagnosed with CRC between 1997 and 2003 were followed up until April 2010.Data on their demographics and lifestyles were collected via questionnaires.Genotyping of blood samples was performed with the Illumina Human Omni-Quad Bead chip.Multivariable Cox models were used to assess the relationships of 35 tag single-nucleotide polymorphisms(SNPs)in LEP and LEPR with overall survival(OS),disease-free survival(DFS),and CRC-specific survival.Results:At the gene level,LEP was associated with DFS(P=0.017),and LEPR was associated with both DFS(P=0.021)and CRCspecific survival(P=0.013)in patients with CRC.In single-SNP analysis,LEP rs11763517,LEPR rs9436301,and LEPR rs7602 were associated with DFS after adjustment for multiple testing.The LEPR haplotypes G-C-T(rs7534511-rs9436301-rs1887285)and A-A-G(rs7602-rs970467-rs9436748)were associated with prolonged OS among patients with CRC overall(G-C-T:HR,0.63;95%CI,0.43–0.93;A-A-G:HR,0.59;95%CI,0.38–0.91)and those diagnosed with colon cancer(G-C-T:HR,0.54;95%CI,0.34–0.86;A-A-G:HR,0.49;95%CI,0.29–0.83).Similar results were observed for DFS.Moreover,significant interactions were found among LEPR rs7602(A vs.G),LEPR rs1171278(T vs.C),red meat intake,and BMI status:the associations between these variants and prolonged DFS were limited to patients with below-median red meat consumption and body mass index(BMI)<25 kg/m2.Conclusions:Polymorphic variations in the LEP and LEPR genes were associated with survival of patients after CRC diagnosis.The LEP/LEPR-CRC survival association was modified by participants’red meat intake and BMI.
文摘Urban agriculture is gaining recognition for its potential contributions to environmental resilience and climate change adaptation,providing advantages such as urban greening,reduced heat island effects,and decreased air pollution.Moreover,it indirectly supports communities during weather events and natural disasters,ensuring food security and fostering community cohesion.However,concerns about planetary health risks persist in highly urbanized and climate-affected areas.Employing electronic databases such as Web of Science and PubMed and adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines,we identified 55 relevant papers to comprehend the planetary health risks associated with urban agriculture,The literature review identified five distinct health risks related to urban agriculture:(1)trace metal risks in urban farms;(2)health risks associated with wastewater irrigation;(3)zoonotic risks;(4)other health risks;and(5)social and economic risks.The study highlights that urban agriculture,while emphasizing environmental benefits,particularly raises concerns about trace metal bioaccumulation in soil and vegetables,posing health risks for populations.Other well studied risks included wastewater irrigation and backyard livestock farming.The main limitations in the available literature were in studying infectious diseases and antibiotic resistance associated with urban agriculture.
文摘Background:Esotropia is a common concern in pediatric ophthalmology consultations.While most cases stem from strabismus,it is crucial for physicians to differentiate atypical features that might indicate underlying organic causes,such as VI nerve palsy,hinting at the presence of intracranial spaceoccupying lesions.Although the occurrence of cerebral aneurysms in children is rare,they can have severe consequences.Case Description:Here,we described an extremely rare case of giant basilar fusiform aneurysm measuring 4.0 cm×3.9 cm×3.9 cm in an otherwise healthy 8-year-old child,and analyzed its atypical features that suggested an intracranial etiology.We further described an endovascular approach,performed by interventional radiologists,and discussed its advantages over the conventional neurosurgery.The patient continued to be followed by our multidisciplinary team.He had a stable post-operative course and made an excellent recovery neurologically.At the 1-year follow-up,he was orthophoria with excellent vision and stereopsis.Conclusions:To our knowledge,this is the first pediatric case in Canada where a giant intracranial aneurysm was treated endovascularly.The salient red flags—progressive incomitant esotropia and diplopia,the presence of myopia(rather than hyperopia),nystagmus and abnormal saccadic movements—should be astutely recognized by clinicians as intracranial giant aneurysms carry a poor prognosis.A multidisciplinary approach is essential for the management of such cases.
基金funded by TB REACH,a special initiative of Stop TB Partnership(Grant Number:STBP/TBREACH/GSA/W6–5).
文摘Background:Tuberculosis(TB)is a major global health threat and the leading infectious disease cause of death worldwide.Access to and retention in TB care remains a challenge for patients,particularly those living in rural and remote settings.This qualitative study explored barriers and facilitators to accessing and maintaining contact with TB care services in communities in Xigaze(Shigatse)prefecture,Xizang Autonomous Region(Tibet Autonomous Region),China from the perspective of persons impacted by TB.Methods:We conduced in-depth interviews with 23 participants impacted by TB in four rural districts in Xigaze prefecture,Xizang Autonomous Region,China between April 2019 and November 2020.Interviews were conducted in Tibetan and Mandarin,transcribed in Mandarin and translated into English.Transcripts were checked against recordings by native Tibetan and Mandarin speakers.QSR NVivo12 software was used for framework analysis guided by an access to care conceptual framework by Levesque et al.Results:Overall patients reported low awareness of and an indiferent attitude towards TB,although all reported understanding the need to adhere to treatment.Participants reported complex pathways to care,often requiring visits to multiple healthcare facilities.Some participants reported visiting traditional Tibetan medicine(TTM)providers.Participants reported various barriers to accessing care including challenges physically reaching care,out-of-pocket payments for tests,diagnostics and transport.Barriers to maintaining care included medication side efects and worry about treatment efectiveness.Enablers to accessing care identifed included knowledge or past experience with TB,integrated models of TTM and western care,supportive village doctors who conducted home visits,free TB treatment and other subsidies,as well as having family support with care and social support as barriers and facilitators to maintaining treatment.Conclusions:We identifed barriers and facilitators to accessing services in rural communities in Xigaze from the perspective of persons impacted by TB.Challenges include complex pathways to care,travel distances,wait times and low awareness.Tuberculosis care in the region could be strengthened by ongoing culturally tailored educational campaigns to increase awareness,partnerships with TTM providers,providing comprehensive treatment subsidies and strengthening the role of family members in comprehensive TB care.
基金Supported by The Canadian Institutes of Health Research,No.319379
文摘Suicide is the second leading cause of death in youth globally; however, there is uncertainty about how best to intervene. Suicide rates are typically higher in males than females, while the converse is true for suicide attempts. We review this "gender paradox" in youth, and in particular, the age-dependency of these sex/gender differences and the developmental mechanisms that may explain them. Epidemiologic, genetic,neurodevelopmental and psychopathological research have identified suicidal behaviour risks arising from genetic vulnerabilities and sex/gender differences in early adverse environments, neurodevelopment, mental disorder and their complex interconnections. Further, evolving sex-/gender-defined social expectations and norms have been thought to influence suicide risk. In particular, how youth perceive and cope with threats and losses(including conforming to others' or one's own expectations of sex/gender identity) and adapt to pain(through substance use and helpseeking behaviours). Taken together, considering brain plasticity over the lifespan, these proposed antecedents to youth suicide highlight the importance of interventions that alter early environment(s)(e.g., childhood maltreatment) and/or one's ability to adapt to them. Further, such interventions may have more enduring protective effects, for the individual and for future generations, if implemented in youth.
文摘Platelets are nuclear cell fragments produced by megakaryocytes.Inactive platelets circulate in the blood until activation by extemal stimuli to execute important biological functions,including hemostasis,inflammation,tissue remodelling,and blood vessel formation.Platelets can reflect cancer cells'pathogenesis through a process known as tumour-educated platelets(TEPs).
基金the National Natural Science Foundation of China(Nos.21976155,81802881,and 81773016)the Zhejiang Provincial Natural Science Foundation of China(No.LY18C060001)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences(CIFMS)(No.2019-I2M-5-044),China。
文摘This study aimed to identify subtypes of genomic variants associated with the efficacy of immune checkpoint inhibitors(ICIs)by conducting systematic literature search in electronic databases up to May 31,2021.The main outcomes including overall survival(OS),progression-free survival(PFS),objective response rate(ORR),and durable clinical benefit(DCB)were correlated with tumor genomic features.A total of 1546 lung cancer patients with available genomic variation data were included from 14 studies.The Kirsten rat sarcoma viral oncogene homolog G12C(KRAS^(G12C))mutation combined with tumor protein P53(TP53)mutation revealed the promising efficacy of ICI therapy in these patients.Furthermore,patients with epidermal growth factor receptor(EGFR)classical activating mutations(including EGFRL858Rand EGFRΔ19)exhibited worse outcomes to ICIs in OS(adjusted hazard ratio(HR),1.40;95%confidence interval(CI),1.01-1.95;P=0.0411)and PFS(adjusted HR,1.98;95%CI,1.49-2.63;P<0.0001),while classical activating mutations with EGFR^(T790)Mshowed no difference compared to classical activating mutations without EGFR^(T790)Min OS(adjusted HR,0.96;95%CI,0.48-1.94;P=0.9157)or PFS(adjusted HR,0.72;95%CI,0.39-1.35;P=0.3050).Of note,for patients harboring the Usher syndrome type-2A(USH2A)missense mutation,correspondingly better outcomes were observed in OS(adjusted HR,0.52;95%CI,0.32-0.82;P=0.0077),PFS(adjusted HR,0.51;95%CI,0.38-0.69;P<0.0001),DCB(adjusted odds ratio(OR),4.74;95%CI,2.75-8.17;P<0.0001),and ORR(adjusted OR,3.45;95%CI,1.88-6.33;P<0.0001).Our findings indicated that,USH2A missense mutations and the KRAS^(G12C)mutation combined with TP53 mutation were associated with better efficacy and survival outcomes,but EGFR classical mutations irrespective of combination with EGFR^(T790)Mshowed the opposite role in the ICI therapy among lung cancer patients.Our findings might guide the selection of precise targets for effective immunotherapy in the clinic.
文摘In February 2022,Kubo et al.and the Liver Cancer Study Group of Japan published a clinical practice guideline for the treatment of intrahepatic cholangiocarcinoma(iCCA)(1).Their guideline consists of a treatment algorithm for iCCA with five background statements,16 clinical questions and one clinical topic discussion(1).
基金supported by the General Research Fund grant through the Hong Kong Research Grants Council(ref CUHK 14411614).
文摘Background:Tuberculosis(TB)is an infectious disease of major public health concern.The disease has demonstrated large space-time variations.This study aims to explore the space-time dynamics of TB cases in an economically and geographically dynamic province in China with specific references of TB control for policy makers.Methods:Data on all reported TB cases from 2009 to 2012 were collected from the TB program at the Zhejiang Provincial Center for Disease Control and Prevention.We employed time series and exploratory spatial data analyses,including Moran’s I,Local Getis’s G_(i)^(*),and Kulldorff’s space-time scan statistics,to identify the temporal trends and spatial patterns of TB at a county level.Results:A total of 147,941 TB cases were reported during 2009–2012 in Zhejiang.A higher proportion of TB cases were younger,male,and registered permanent residents among all TB cases notified in the province.TB cases were reported most frequently in April with small peaks in June,July,and October.This disease was spatially clustering with Moran’s I values ranged from 0.29 to 0.32(p<0.001).A most likely cluster and ten secondary clusters were identified,mainly concentrated in the southeast and west counties of the province.Conclusions:This study identified seasonal patterns and significant space-time clusters of TB cases in Zhejiang,China.Poverty,migration,and seasonal effects may play important roles in potential clusters.
基金This project was funded by Canadian Cancer Society Grant#700865.The authors wish to thank Ivana Kosarac and Xinghua Fan at Health Canada for their review of the draft manuscript.
文摘The incidence of breast cancer is on a rise worldwide;it is a disease having a complex etiology.Besides genetics,environmental and other lifestyle factors play a role in the development of the disease.There has been a keen interest in studying associations between breast cancer and exposures to emerging environmental chemicals,which mimic estrogens or influence estrogen levels and signaling in the human body.The common consequence of an endocrine disrupting chemical exposure is that it may have an impact on breast cancer etiology by stimulating formation as well as progression of breast cancer.Exposures to selected emerging environmental contaminants such as alkylphenols(APs),bisphenol A(BPA),parabens,perfluoroalkyl substances(PFASs),phthalates,polybrominated diphenyl ethers(PBDEs),synthetic musks and triclosan,and their probable role in breast cancer development are reviewed.Studies evaluated include the experimental in vitro and in vivo studies as well as human population based studies.In vitro and in vivo evidences indicate that a number of emerging environmental contaminants may play a role in the initiation and/or progression of breast cancer.Although exposures have been assessed in some human populations,breast and other cancer risks associated with these exposures are largely unknown.Efforts should be focussed on the evaluation of these environmental exposures in human populations and their interactions with each other and other genetic and lifestyle risk factors.
基金This work was supported by a grant from the Canadian Immunization Research Network(#00161651)to Ms.Nasserie and Dr.Fisman.
文摘Mathematical models are often regarded as recent innovations in the description and analysis of infectious disease outbreaks and epidemics,but simple mathematical expressions have been in use for projection of epidemic trajectories for more than a century.We recently introduced a single equation model(the incidence decay with exponential adjustment,or IDEA model)that can be used for short-term epidemiological forecasting.In the mid-19th century,Dr.William Farr made the observation that epidemic events rise and fall in a roughly symmetrical pattern that can be approximated by a bell-shaped curve.He noticed that this time-evolution behavior could be captured by a single mathematical formula(“Farr's law”)that could be used for epidemic forecasting.We show here that the IDEA model follows Farr's law,and show that for intuitive assumptions,Farr's Law can be derived from the IDEA model.Moreover,we show that both mathematical approaches,Farr's Law and the IDEA model,resemble solutions of a susceptible-infectious-removed(SIR)compartmental differential-equation model in an asymptotic limit,where the changes of disease transmission respond to control measures,and not only to the depletion of susceptible individuals.This suggests that the concept of the reproduction number eR 0T was implicitly captured in Farr's(pre-microbial era)work,and also suggests that control of epidemics,whether via behavior change or intervention,is as integral to the natural history of epidemics as is the dynamics of disease transmission.
基金The research was supported by a grant to DNF from the Canadians Institutes for Health Research(2019 COVID-19 rapid researching funding OV4-170360).
文摘The use of masks as a means of reducing transmission of COVID-19 outside healthcare settings has proved controversial.Masks are thought to have two modes of effect:they prevent infection with COVID-19 in wearers;and prevent transmission by individuals with subclinical infection.We used a simple next-generation matrix approach to estimate the conditions under which masks would reduce the reproduction number of COVID-19 under a threshold of 1.Our model takes into account the possibility of assortative mixing,where mask users interact preferentially with other mask users.We make 3 key observations:1.Masks,even with suboptimal efficacy in both prevention of acquisition and transmission of infection,could substantially decrease the reproduction number for COVID-19 if widely used.2.Widespread masking may be sufficient to suppress epidemics where R has been brought close to 1 via other measures(e.g.,distancing).3.“Assortment”within populations(the tendency for interactions between masked individuals to be more likely than interactions between masked and unmasked individuals)would rapidly erode the impact of masks.As such,mask uptake needs to be fairly universal to have an effect.This simple model suggests that widespread uptake of masking could be determinative in suppressing COVID-19 epidemics in regions with R(t)at or near 1.
