Mixing patterns and the spread of close-contact infectious diseases

Introduction: Understanding human mixing patterns relevant to infectious diseases spread through close contact is vital for modelling transmission dynamics and optimisation of disease control strategies. Mixing patterns in low-income countries like Malawi are not well understood. Methodology: We conducted a social mixing survey in urban Blantyre, Malawi between April and July 2021 (between the 2nd and 3rd wave of COVID-19 infections). Participants living in densely-populated neighbourhoods were randomly sampled and, if they consented, reported their physical and non-physical contacts within and outside homes lasting at least 5 minutes during the previous day. Age-specific mixing rates were calculated, and a negative binomial mixed effects model was used to estimate determinants of contact behaviour. Results: Of 1,201 individuals enrolled, 702 (58.5%) were female, the median age was 15 years (interquartile range [IQR] 5-32) and 127 (10.6%) were HIV-positive. On average, participants reported 10.3 contacts per day (range: 1-25). Mixing patterns were highly age-assortative, particularly those within the community and with skin-to-skin contact. Adults aged 20-49y reported the most contacts (median:11, IQR: 8-15) of all age groups; 38% (95%CI: 16-63) more than infants (median: 8, IQR: 5-10), who had the least contacts. Household contact frequency increased by 3% (95%CI 2-5) per additional household member. Unemployed participants had 15% (95%CI: 9-21) fewer contacts than other adults. Among long range (>30 meters away from home) contacts, secondary school children had the largest median contact distance from home (257m, IQR 78-761). HIV-positive status in adults >18 years-old was not associated with increased contact patterns (1%, 95%CI -9-12). During this period of relatively low COVID-19 incidence in Malawi, 301 (25.1%) individuals stated that they had limited their contact with others due to COVID-19 precautions; however, their reported contacts were not fewer (8%, 95%CI 1-13). Conclusion: In urban Malawi, contact rates, are high and age-assortative, with little behavioural change due to either HIV-status or COVID-19 circulation. This highlights the limits of contact-restriction-based mitigation strategies in such settings and the need for pandemic preparedness to better understand how contact reductions can be enabled and motivated. Keywords: Social contacts, Transmission, Mixing data, Infectious disease, Malawi, Africa

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Infection in the Graeco-Roman era with the emphasis on epidemic ilness.

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie ◽

10.4102/satnt.v32i1.331 ◽

2013 ◽

Vol 32 (1) ◽

Author(s):

Louise Cilliers ◽

Francois P. Retief

Keyword(s):

Infectious Diseases ◽

19Th Century ◽

Close Contact ◽

Acquired Immunity ◽

Epidemic Disease ◽

Western History ◽

History Of ◽

Pathogenic Organisms ◽

Micro Organisms ◽

The 19Th Century

In this article the views of the ancient Greeks and Romans on the etiology of infectious diseases are assessed. It appeared that these views were remarkably correct in many respects: Hippocrates for instance believed that an imbalance in the humours preceded disease, while we know today that a malnourished body predisposes a patient to epidemic disease. Further acute observations were recorded during the plague which afflicted Athenians in the 5th century BC, when it was noted that the disease (probably smallpox) was spread by close contact with patients and that the same person never contracted the disease twice – the first description in Western history of acquired immunity. The ancients’ theories of miasmata and ‘seeds of disease’ in the air were the forerunners of what is today identified as pathological micro-organisms causing disease. Little progress in the study of the etiology of infectious diseases was made since Graeco-Roman times, in fact, in the 19th century it was still believed in London that infection was the result of ‘bad air’. The problem was eventually solved when in the 19th century Robert Koch, with the help of the microscope, discovered the pathogenic organisms causing infectious diseases. In many respects the scientific discoveries during the last two centuries merely confirmed the observations of the ancient Greeks and Romans made more than 2000 years ago.

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Germs on a Plane: The Transmission and Risks of Airplane-Borne Diseases

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198118799709 ◽

2018 ◽

Vol 2672 (29) ◽

pp. 93-102 ◽

Cited By ~ 1

Author(s):

Nereyda L. Sevilla

Keyword(s):

Public Health ◽

Infectious Diseases ◽

Close Contact ◽

Air Travel ◽

Economic Consequences ◽

Disease Spread ◽

Pneumonic Plague ◽

Health Authorities ◽

Public Health Authorities ◽

The Impact

This research explored the role of air travel in the spread of infectious diseases, specifically severe acute respiratory syndrome (SARS), H1N1, Ebola, and pneumonic plague. Air travel provides the means for such diseases to spread internationally at extraordinary rates because infected passengers jump from coast to coast and continent to continent within hours. Outbreaks of diseases that spread from person to person test the effectiveness of current public health responses. This research used a mixed methods approach, including use of the Spatiotemporal Epidemiological Modeler, to model the spread of diseases, evaluate the impact of air travel on disease spread, and analyze the effectiveness of different public health strategies and travel policies. Modeling showed that the spread of Ebola and pneumonic plague is minimal and should not be a major air travel concern if an individual becomes infected. H1N1 and SARS have higher infection rates and air travel will facilitate the spread of disease nationally and internationally. To contain the spread of infectious diseases, aviation and public health authorities should establish tailored preventive measures at airports, capture contact information for ticketed passengers, expand the definition of “close contact,” and conduct widespread educational programs. The measures will put in place a foundation for containing the spread of infectious diseases via air travel and minimize the panic and economic consequences that may occur during an outbreak.

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Social Contacts and Mixing Patterns Relevant to the Spread of Infectious Diseases

PLoS Medicine ◽

10.1371/journal.pmed.0050074 ◽

2008 ◽

Vol 5 (3) ◽

pp. e74 ◽

Cited By ~ 1206

Author(s):

Joël Mossong ◽

Niel Hens ◽

Mark Jit ◽

Philippe Beutels ◽

Kari Auranen ◽

...

Keyword(s):

Infectious Diseases ◽

Social Contacts ◽

Mixing Patterns

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Aerosol Management in Dentistry: An Update for Safe Covid-19 Clinical Practice

10.47363/jprsr/2021(2)110 ◽

2021 ◽

pp. 1-6

Author(s):

Kaur Ishdeep ◽

◽

Kaur Arshdeep ◽

Keyword(s):

Infectious Diseases ◽

High Speed ◽

Dental Treatment ◽

Close Contact ◽

Hospital Setting ◽

High Volume ◽

Worker Safety ◽

Potential Hazard ◽

Healthcare Settings ◽

Cdc Guidelines

Patient safety and health worker safety from infectious diseases as well as occupational hazards is of utmost importance in every field of medicine. Bioaerosols and splatters generated by air syringes, ultrasonic scalers and high-speed turbine handpieces during dental treatment pose a potential hazard of infection not only to the patients but, to the dentists, dental hygienists, dental assistants as well as other healthcare workers. Severe infectious diseases such as Severe Acute Respiratory Syndrome (SARS), influenza, measles, tuberculosis, hepatitis, HIV AIDS can be transmitted through aerosols. With the emergence of β-coronavirus (COVID-19), questions concerning the protection from such viral transmission in dental hospital setting have arisen due to close contact and its transmission through the exposure of saliva, blood and other body fluids. Guidelines from regulatory organizations such as CDC regarding infection control in healthcare settings and infection prevention practices should be strictly followed.A systematic electronic search with relevant key terms viz. Aerosol Management, Dental Aerosols, Dentistry and COVID-19, Dental Unit Waterlines, Preprocedural Mouth rinsing, High Volume Suction Evacuators (HVE) and CDC Guidelines was executed in PubMed and Medline databases for literature extraction and data has been interpreted by including articles based on predefined inclusion criteria .In this review article, we address the importance of understanding and implementation of dental safety by following various systems for management of dental aerosols

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Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011

10.1101/2020.09.30.20204891 ◽

2020 ◽

Cited By ~ 2

Author(s):

Thang Van Hoang ◽

Pietro Coletti ◽

Yimer Wasihun Kiffe ◽

Kim Van Kerckhove ◽

Sarah Vercruysse ◽

...

Keyword(s):

Large Scale ◽

Close Contact ◽

Social Contact ◽

Contact Rates ◽

Contact Patterns ◽

Time Period ◽

Social Mixing ◽

Mixing Patterns ◽

Contact Survey ◽

The Impact

AbstractBackgroundIn 2010-2011, we conducted a social contact survey in Flanders, Belgium, aimed at improving and extending the design of the first social contact survey conducted in Belgium in 2006. This second social contact survey aimed to enable, for the first time, the estimation of social mixing patterns for an age range of 0 to 99 years and the investigation of whether contact rates remain stable over this 5-year time period.MethodsDifferent data mining techniques are used to explore the data, and the age-specific number of social contacts and the age-specific contact rates are modelled using a GAMLSS model. We compare different matrices using assortativeness measures. The relative change in the basic reproduction number (R0) and the ratio of relative incidences with 95% bootstrap confidence intervals (BCI) are employed to investigate and quantify the impact on epidemic spread due to differences in gender, day of the week, holiday vs. regular periods and changes in mixing patterns over the 5-year time gap between the 2006 and 2010-2011 surveys. Finally, we compare the fit of the contact matrices in 2006 and 2010-2011 to Varicella serological data.ResultsAll estimated contact patterns featured strong homophily in age and gender, especially for small children and adolescents. A 30% (95% BCI [17%; 37%] ) and 29% (95% BCI [14%; 40%] ) reduction in R0 was observed for weekend versus weekdays and for holiday versus regular periods, respectively. Significantly more interactions between people aged 60+ years and their grandchildren were observed on holiday and weekend days than on regular weekdays. Comparing contact patterns using different methods did not show any substantial differences over the 5-year time period under study.ConclusionsThe second social contact survey in Flanders, Belgium, endorses the findings of its 2006 predecessor and adds important information on the social mixing patterns of people older than 60 years of age. Based on this analysis, the mixing patterns of people older than 60 years exhibit considerable heterogeneity, and overall, the comparison of the two surveys shows that social contact rates can be assumed stable in Flanders over a time span of 5 years.

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Red fox viromes across an urban-rural gradient

10.1101/2020.06.15.153858 ◽

2020 ◽

Author(s):

Sarah J Campbell ◽

Wilbur Ashley ◽

Margarita Gil-Fernandez ◽

Thomas M. Newsome ◽

Francesca Di Giallonardo ◽

...

Keyword(s):

Infectious Diseases ◽

Urban Areas ◽

Red Fox ◽

Disease Risk ◽

Close Contact ◽

Food Resources ◽

Human Populations ◽

Red Foxes ◽

Domestic Species ◽

Rabbit Haemorrhagic Disease

AbstractThe Red fox (Vulpes vulpes) has established large populations in Australia’s urban and rural areas since its introduction following European settlement. Foxes’ cryptic and highly adaptable nature allows them to invade cities and live among humans while remaining largely unnoticed. Urban living and access to anthropogenic food resources also influences fox ecology. Urban foxes grow larger, live at higher densities and are more social than their rural counterparts. These ecological changes in urban red foxes are likely to impact the pathogens that they harbour, and foxes could pose a disease risk to humans and other species that share these urban spaces. To assess this possibility, we used a meta-transcriptomic approach to characterise the viromes of urban and rural foxes across the Greater Sydney region in Australia. Urban and rural foxes differed significantly in virome composition, with rural foxes harbouring a greater abundance of viruses compared to their urban counterparts. In contrast, urban fox viromes comprised a greater diversity of viruses compared to rural foxes. We identified nine potentially novel vertebrate-associated viruses in both urban and rural foxes, some of which are related to viruses associated with disease in domestic species and humans. These included members of the Astroviridae, Picobirnaviridae, Hepeviridae and Picornaviridae as well as rabbit haemorrhagic disease virus-2 (RHDV2). This study sheds light on the viruses carried by urban and rural foxes and emphasises the need for greater genomic surveillance of foxes and other invasive species at the human-wildlife interface.ImportanceUrbanisation of wild environments is increasing as human populations continue to expand. Remnant pockets of natural environments and other green spaces in urban landscapes provide invasive wildlife such as red foxes with refuges within urban areas, where they thrive on the food resources provisioned by humans. Close contact between humans, domestic species and foxes likely increases the risk of novel pathogen emergence. Indeed, the vast majority of emerging infectious diseases in humans originate in wild animals. Here, we explored potential differences in viromes between urban fox invaders and their rural counterparts. Viromes of foxes and their ectoparasites comprise a diversity of viruses including those from the Astroviridae, Picobirnaviridae, Hepeviridae, Caliciviridae and Picornaviridae. Microbial surveillance in foxes and other urban wildlife is vital for monitoring viral emergence and for the prevention of infectious diseases.

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Inferring high-resolution human mixing patterns for disease modeling

Nature Communications ◽

10.1038/s41467-020-20544-y ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

Dina Mistry ◽

Maria Litvinova ◽

Ana Pastore y Piontti ◽

Matteo Chinazzi ◽

Laura Fumanelli ◽

...

Keyword(s):

Infectious Diseases ◽

Disease Transmission ◽

Disease Modeling ◽

Population Level ◽

Effective Population ◽

Human Contact ◽

Contact Patterns ◽

Data Driven Approach ◽

Mixing Patterns ◽

The Impact

AbstractMathematical and computational modeling approaches are increasingly used as quantitative tools in the analysis and forecasting of infectious disease epidemics. The growing need for realism in addressing complex public health questions is, however, calling for accurate models of the human contact patterns that govern the disease transmission processes. Here we present a data-driven approach to generate effective population-level contact matrices by using highly detailed macro (census) and micro (survey) data on key socio-demographic features. We produce age-stratified contact matrices for 35 countries, including 277 sub-national administratvie regions of 8 of those countries, covering approximately 3.5 billion people and reflecting the high degree of cultural and societal diversity of the focus countries. We use the derived contact matrices to model the spread of airborne infectious diseases and show that sub-national heterogeneities in human mixing patterns have a marked impact on epidemic indicators such as the reproduction number and overall attack rate of epidemics of the same etiology. The contact patterns derived here are made publicly available as a modeling tool to study the impact of socio-economic differences and demographic heterogeneities across populations on the epidemiology of infectious diseases.

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Online respondent-driven detection for enhanced contact tracing of close-contact infectious diseases: benefits and barriers for public health practice

BMC Infectious Diseases ◽

10.1186/s12879-021-06052-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Yannick B. Helms ◽

Nora Hamdiui ◽

Renske Eilers ◽

Christian Hoebe ◽

Nicole Dukers-Muijrers ◽

...

Keyword(s):

Public Health ◽

Infectious Diseases ◽

Large Scale ◽

Close Contact ◽

Public Health Practice ◽

Contact Tracing ◽

Health Practice ◽

Structured Interviews ◽

Online Questionnaire ◽

Index Cases

Abstract Background Online respondent-driven detection (RDD) is a novel method of case finding that can enhance contact tracing (CT). However, the advantages and challenges of RDD for CT have not yet been investigated from the perspective of public health professionals (PHPs). Therefore, it remains unclear if, and under what circumstances, PHPs are willing to apply RDD for CT. Methods Between March and April 2019, we conducted semi-structured interviews with Dutch PHPs responsible for CT in practice. Questions were derived from the ‘diffusion of innovations’ theory. Between May and June 2019, we distributed an online questionnaire among 260 Dutch PHPs to quantify the main qualitative findings. Using different hypothetical scenarios, we assessed anticipated advantages and challenges of RDD, and PHPs’ intention to apply RDD for CT. Results Twelve interviews were held, and 70 PHPs completed the online questionnaire. A majority of questionnaire respondents (71%) had a positive intention towards using RDD for CT. Anticipated advantages of RDD were ‘accommodating easy and autonomous participation in CT of index cases and contact persons’, and ‘reaching contact persons more efficiently’. Anticipated challenges were ‘limited opportunities for PHPs to support, motivate, and coordinate the execution of CT’, ‘not being able to adequately convey measures to index cases and contact persons’, and ‘anticipated unrest among index cases and contact persons’. Circumstances under which PHPs anticipated RDD applicable for CT included index cases and contact persons being reluctant to share information directly with PHPs, digitally skilled and literate persons being involved, and large scale CT. Circumstances under which PHPs anticipated RDD less applicable for CT included severe consequences of missing information or contact persons for individual or public health, involvement of complex or impactful measures for index cases and contact persons, and a disease being perceived as severe or sensitive by index cases and their contact persons. Conclusions PHPs generally perceived RDD as a potentially beneficial method for public health practice, that may help overcome challenges present in traditional CT, and could be used during outbreaks of infectious diseases that spread via close contact. The circumstances under which CT is performed, appear to strongly influence PHPs’ intention to use RDD for CT.

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