scholarly journals Dynamics of infectious disease transmission by inhalable respiratory droplets

2010 ◽  
Vol 7 (50) ◽  
pp. 1355-1366 ◽  
Author(s):  
Nikolaos I. Stilianakis ◽  
Yannis Drossinos
Keyword(s):  
Disease Transmission ◽  
Close Contact ◽  
Droplet Diameter ◽  
Droplet Dynamics ◽  
Contact Rates ◽  
Transmission Modes ◽  
Contact Transmission ◽  
Close Contact Transmission ◽  
Respiratory Droplets

Transmission of respiratory infectious diseases in humans, for instance influenza, occurs by several modes. Respiratory droplets provide a vector of transmission of an infectious pathogen that may contribute to different transmission modes. An epidemiological model incorporating the dynamics of inhalable respiratory droplets is developed to assess their relevance in the infectious process. Inhalable respiratory droplets are divided into respirable droplets, with droplet diameter less than 10 µm, and inspirable droplets, with diameter in the range 10–100 µm: both droplet classes may be inhaled or settle. Droplet dynamics is determined by their physical properties (size), whereas population dynamics is determined by, among other parameters, the pathogen infectivity and the host contact rates. Three model influenza epidemic scenarios, mediated by different airborne or settled droplet classes, are analysed. The scenarios are distinguished by the characteristic times associated with breathing at contact and with hand-to-face contact. The scenarios suggest that airborne transmission, mediated by respirable droplets, provides the dominant transmission mode in middle and long-term epidemics, whereas inspirable droplets, be they airborne or settled, characterize short-term epidemics with high attack rates. The model neglects close-contact transmission by droplet sprays (direct projection onto facial mucous membranes), retaining close-contact transmission by inspirable droplets.

scholarly journals Simulating social distancing measures in household and close contact transmission of SARS-CoV-2

2020 ◽  
Vol 36 (5) ◽  
Author(s):  
Carlos Garcia Filho
Keyword(s):  
Close Contact ◽  
Contact Rate ◽  
Rate Reduction ◽  
Agent Based ◽  
Social Distancing ◽  
Infected People ◽  
Contact Transmission ◽  
Close Contact Transmission ◽  
The Relationship ◽  
Close Contacts

We sought to evaluate contact rate reduction goals for household and close contacts and to provide preventive recommendations during the coronavirus pandemic. We applied an agent-based model to simulate the transmission dynamics of SARS-CoV-2 within household or close contacts through a social network of 150 nodes. there is no great difference in total infected people within modifications in number of links per node for networks with average number of links per node greater than three. For six nodes, total infected people are 149.85; for five nodes, 148.97; and for four nodes, 141.57. On the other hand, for three nodes, total infected are 82.39, for two nodes, 13.95; and for one node, 2.96. This model indicates a possible pitfall if social distancing measures are not stepwise suspended and close surveillance of cases are not provided, since the relationship between average links per node and number of infected people seems to be s-shaped, and not linear.

scholarly journals VAKSINASI MASAL COVID-19 DI PELABUHAN LEMBAR LOMBOK BARAT

2021 ◽  
Vol 5 (1) ◽  
pp. 404
Author(s):  
Desi Rofita ◽  
Evi Diliana Rospia ◽  
Dwi Kartika Cahyaningtyas ◽  
Catur Esty Pamungkas ◽  
Aulia Amini ◽  
...  
Keyword(s):  
World Health Organization ◽  
Close Contact ◽  
Herd Immunity ◽  
The Elderly ◽  
Health Problems ◽  
Mass Vaccination ◽  
World Health ◽  
Contact Transmission ◽  
Health Organization ◽  
Close Contact Transmission

ABSTRAKWHO (World  Health  Organization) secara  resmi  mendeklarasikan  virus  corona (Covid-19)  sebagai  pandemi. Virus Covid-19 menyebabkan gejala seperti demam dan batuk, dan kebanyakan bisa sembuh dalam beberapa minggu. Tapi bagi sebagian orang yang berisiko tinggi (kelompok lanjut  usia  dan  orang  dengan masalah  kesehatan  menahun, seperti  penyakit  jantung,  tekanan darah  tinggi,  atau diabetes), virus corona dapat menyebabkan masalah kesehatan yang serius. Ada dua  jalur  utama  penularan COVID-19, yakni penularan droplet pernapasan dan penularan kontak dekat. Dalam rangka penanggulangan pandemi COVID-19 tidak hanya dilaksanakan dari sisi penerapan protokol kesehatan, namun juga intervensi dengan vaksinasi sebagai bagian dari upaya pencegahan dan Pengendalian COVID-19. Kegiatan vaksinasi masal ini bertujuan agar dapat terbentuk herd immunity (kekebalan kelompok) dan berkurangnya angka kematian akibat COVID-19 pada masyarakat.Jenis vaksin yang digunakan pada kegiatan vaksinasi masal ini adalah Moderna. Jumlah responden yang mengikuti kegiatan ini sebanyak 1.581 orang. Hasil pengabdian didapatkan bahwa jumlah yang melakukan vaksinasi sebanyak 1.581 orang yang terdiri remaja sebanyak 60 orang dewasa sebanyak 1497 orang dan lansia sebanyak 24 orang, diberikan vaksin sebanyak 1.536 orang, ditunda sebanyak 45 orang. Kata kunci: vaksinasi; covid-19; komunitas. ABSTRACTWHO (World Health Organization) has officially declared the coronavirus (Covid-19) as a pandemic. The Covid-19 virus causes symptoms such as fever and cough, and most recover within a few weeks. But for some people who are at high risk (the elderly and people with chronic health problems, such as heart disease, high blood pressure, or diabetes), the coronavirus can cause serious health problems. There are two main routes of transmission of COVID-19, namely respiratory droplet transmission and close contact transmission. In the context of dealing with the COVID-19 pandemic, it is not only implemented in terms of implementing health protocols but also interventions with vaccinations as part of efforts to prevent and control COVID-19. This mass vaccination activity aims to form herd immunity and reduce the mortality rate due to COVID-19 in the community. The type of vaccine used in this mass vaccination activity is Moderna. The number of respondents who participated in this activity was 1,581 people. The results of the service found that the number of people who registered for Pcare was 1,581 people, consisting of 60 teenagers, 1497 adults, and 24 elderly people, 1,536 people were given the vaccine, 45 people were delayed. Keywords: vaccination; covid-19; community. 

scholarly journals Relationship between the density of tatami stores and COVID-19 morbidity and mortality in Japan

2021 ◽  
Author(s):  
Soshi Iwasaki ◽  
Yoshiyasu Kigawa ◽  
Kazunobu Takahashi ◽  
Michiaki Yamakage
Keyword(s):  
Disease Transmission ◽  
Low Temperatures ◽  
Close Contact ◽  
Negative Relationship ◽  
Transmission Model ◽  
Primary Mechanism ◽  
Significant Negative Relationship ◽  
Mucous Membranes ◽  
Poor Ventilation ◽  
Respiratory Droplets

Abstract Although the primary mechanism for the spread of coronavirus disease 2019 (COVID-19) infection is through respiratory droplets (1), the virus that causes COVID-19 can survive on smooth surfaces (e.g., stainless steel, plastic, glass) for days at low temperatures (2). Surface transmission represents a possible route of infection, as unwashed hands that touch a contaminated surface can transfer the virus to mucous membranes (e.g., eyes, nose, mouth) (3). However, it is difficult to observe disease transmission directly. Therefore, the Japanese Cluster Countermeasures team has identified the “Three Cs”—Closed spaces with poor ventilation, Crowded places, and Close-contact settings—as factors to avoid to prevent COVID-19 clusters. Identifying other environmental factors that increase or decrease the number of infections would be useful to prevent the spread of COVID-19. Therefore, this study aimed to develop a shoe-related transmission model and enhance COVID-19 transmission route precautions by investigating the associations between the prevalence of COVID-19 and both population density and the distribution of tatami stores in each prefecture in Japan. As a result, a significant negative relationship was observed between the number of tatami stores per 100,000 population and the number of COVID-19 cases and deaths.

Age-prevalence and household clustering ofStrongyloides stercoralisinfection in Jamaica

Parasitology ◽  
1995 ◽  
Vol 110 (1) ◽  
pp. 97-102 ◽  
Author(s):  
J. F. Lindo ◽  
R. D. Robinson ◽  
S. I. Terry ◽  
P. Vogel ◽  
A. A. Gam ◽  
...  
Keyword(s):  
Close Contact ◽  
Spatial Separation ◽  
Strongyloides Stercoralis ◽  
Stool Examination ◽  
Place Of Residence ◽  
General Study ◽  
Reference Case ◽  
Contact Transmission ◽  
Study Population ◽  
Close Contact Transmission

The epidemiology ofStrongyloides stercoraliswas studied in families of clinical (reference) cases and their neighbours at endemic foci in Jamaica. Thirteen foci were studied based on the place of residence of a reference case. For each household of a reference case, the 4 most proximal neighbourhood households (spatial controls) were included in the study. Out of 312 persons contacted 244 were followed up using questionnaires, stool examination and serology. Prevalence of infection based on stool examination was 3·5% and on ELISA 24·2%. Prevalence increased with age but was not related to gender. Reference cases were significantly older than the general study population. The prevalence of infection based on both serology and stool examination was significantly higher in reference than in neighbouring households (the reference cases, themselves, were not included in the analysis). Furthermore, prevalence of infection was highest among persons who shared a bedroom with a reference case and decreased significantly with increasing spatial separation. This is indicative of close contact transmission which has not been previously shown for a geohelminth, but which is common among microparasites.

scholarly journals Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 via Close Contact and Respiratory Droplets Among Human Angiotensin-Converting Enzyme 2 Mice

2020 ◽  
Vol 222 (4) ◽  
pp. 551-555 ◽  
Author(s):  
Linlin Bao ◽  
Hong Gao ◽  
Wei Deng ◽  
Qi Lv ◽  
Haisheng Yu ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Angiotensin Converting Enzyme ◽  
Close Contact ◽  
Converting Enzyme ◽  
Angiotensin Converting Enzyme 2 ◽  
Transmission Modes ◽  
Respiratory Droplets

Abstract We simulated 3 transmission modes, including close-contact, respiratory droplets and aerosol routes, in the laboratory. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be highly transmitted among naive human angiotensin-converting enzyme 2 (hACE2) mice via close contact because 7 of 13 naive hACE2 mice were SARS-CoV-2 antibody seropositive 14 days after being introduced into the same cage with 3 infected-hACE2 mice. For respiratory droplets, SARS-CoV-2 antibodies from 3 of 10 naive hACE2 mice showed seropositivity 14 days after introduction into the same cage with 3 infected-hACE2 mice, separated by grids. In addition, hACE2 mice cannot be experimentally infected via aerosol inoculation until continued up to 25 minutes with high viral concentrations.

scholarly journals Factors Affecting COVID-19 Transmission and Modelling of Close Contact Tracing Strategies

2021 ◽  
Author(s):  
Shahram Yazdani ◽  
Majid Heydari ◽  
Zeynab Foroughi ◽  
Hadi Jabali
Keyword(s):  
Risk Score ◽  
Close Contact ◽  
Transmission Risk ◽  
Contact Tracing ◽  
Rapid Review ◽  
Risk Scores ◽  
Virus Shedding ◽  
Factors Affecting ◽  
Contact Transmission ◽  
Close Contact Transmission

Background: Close contact tracing is an essential measure that countries are applying to combat the epidemic of COVID-19. The purpose of contact tracing is to rapidly identify potentially infected individuals and prevent further spread of the disease. In this study, based on the factors affecting the COVID-19 transmission, a scoring protocol is provided for close contact tracing. Methods: First, the factors affecting the COVID-19 transmission in close contacts were identified by a rapid review of the literature. Data were gathered by searching the Embase, PubMed, Google Scholar, and Scopus databases. Then, by formulating and scoring the identified factors with two sessions of the expert panel, close contact transmission risk score determined, and a protocol for contacts tracing was designed. Results: Close contact transmission risk depends on the contact environment characteristics, the infectivity (virus shedding) of the sentinel case, and contact characteristics. Based on these factors, the close contact transmission risk score and contact tracing protocol were prepared.   Conclusion: The close contact transmission risk scores will provide the ability to contact classifications and developing specific tracing strategies for them. Given that there are not any specific treatments for COVID-19 and lack of universal vaccination, applying nonpharmaceutical measures such as contact tracing along with physical distancing is very crucial. Therefore, we recommended this model to the evaluation of exposure risk and contact tracing.

scholarly journals Relationship between the density of tatami stores and COVID-19 morbidity and mortality in Japan

2020 ◽  
Author(s):  
Soshi Iwasaki ◽  
Yoshiyasu Kigawa ◽  
Kazunobu Takahashi ◽  
Michiaki Yamakage
Keyword(s):  
Disease Transmission ◽  
Low Temperatures ◽  
Close Contact ◽  
Negative Relationship ◽  
Transmission Model ◽  
Primary Mechanism ◽  
Significant Negative Relationship ◽  
Mucous Membranes ◽  
Poor Ventilation ◽  
Respiratory Droplets

Abstract Although the primary mechanism for the spread of coronavirus disease 2019 (COVID-19) infection is through respiratory droplets (1), the virus that causes COVID-19 can survive on smooth surfaces (e.g., stainless steel, plastic, glass) for days at low temperatures (2). Surface transmission represents a possible route of infection, as unwashed hands that touch a contaminated surface can transfer the virus to mucous membranes (e.g., eyes, nose, mouth) (3). However, it is difficult to observe disease transmission directly. Therefore, the Japanese Cluster Countermeasures team has identified the “Three Cs”—Closed spaces with poor ventilation, Crowded places, and Close-contact settings—as factors to avoid to prevent COVID-19 clusters. Identifying other environmental factors that increase or decrease the number of infections would be useful to prevent the spread of COVID-19. Therefore, this study aimed to develop a shoe-related transmission model and enhance COVID-19 transmission route precautions by investigating the associations between the prevalence of COVID-19 and both population density and the distribution of tatami stores in each prefecture in Japan. As a result, a significant negative relationship was observed between the number of tatami stores per 100,000 population and the number of COVID-19 cases and deaths.

Sign in / Sign up

Export Citation Format

Share Document