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Epidemiology, Disease Transmission, Prevention, and Control
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
After sufficient data is collected, it may be possible to do a rough case count to get an idea of the magnitude of the problem. Available data should be arranged according to the time and the place where it was collected, and the population affected. This is an application of descriptive epidemiology. An epidemic curve may be drawn from these data. The shape of the curve may allow for prediction about the course of the outbreak. A spot map of the location of cases where infection occurred may indicate the course of the infection, the existence of a reservoir and a method of transmission of the infection. Data on age, sex, occupation, and socioeconomic status of affected individuals as well as their other characteristics, may reveal information about the disease and its means of spread.
Public Health Response to the Initiation and Spread of Pandemic COVID-19 in the United States, February 24–April 21, 2020
Published in William C. Cockerham, Geoffrey B. Cockerham, The COVID-19 Reader, 2020
The findings in this report are subject to at least five limitations. First, the various factors facilitating viral spread described in this report occurred simultaneously; therefore, it is not possible to quantify the relative contribution of each to the outbreak trajectory in the United States. Second, the examples of factors contributing to amplification are illustrative and not meant to be comprehensive. Third, because the mitigation strategies highlighted here were implemented concurrently, the ability to estimate the relative impact of each intervention is limited. Fourth, the epidemic curve presented was likely affected by limited testing, particularly in the early phases of the outbreak. Finally, the case counts presented are an underestimate of the actual number of COVID-19 cases in the United States.
Infectious Disease Data from Surveillance, Outbreak Investigation, and Epidemiological Studies
Published in Leonhard Held, Niel Hens, Philip O’Neill, Jacco Wallinga, Handbook of Infectious Disease Data Analysis, 2019
Outbreak investigation refers to the context of the epidemiological study, rather than to a distinct epidemiological design or method. Epidemiological outbreak investigations for disease control are usually done following a number of specific steps [16]. After the outbreak is confirmed and a representative sample or all cases has been identified, descriptive epidemiological analyses are a key step to generate hypotheses. Descriptive epidemiology in outbreak investigation and surveillance require identical analyses: a description of cases by time, place, person, and type. A description of cases by time, i.e. the “epidemic curve” can be particularly informative to hypothesize whether the outbreak is due to a point source. Hypotheses testing about the cause of the outbreak usually requires an analytical epidemiological study, e.g., a cohort, case-control, cross-sectional, or ecological design (see previous discussion).
Estimation of the doubling time and reproduction number for COVID-19
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Shamim Ahmed, Mohammad Shemanto, Hasin Azhari, Golam Zakaria
The R0 depends on β. By controlling this parameter, the value of R0 can be controlled. A public health strategy viz. flatten the curve was introduced during the COVID-19 (Wiles 2020). The curve being flattened is the epidemic curve, a visual representation of the number of infected people needing health care over time. Flattening the curve means slowing the spread of the epidemic so that the peak number of people requiring care at a time is reduced, and the health care system is not overload. This concept is useful for the decision-makers to evaluate the impact of transmission mitigation strategies and to evaluate whether the different measures have been able to flatten the epidemic curve (Anderson et al. 2020).
The Covid-19 pandemic in low- and middle-income countries, who carries the burden? Review of mass media and publications from six countries
Published in Pathogens and Global Health, 2021
Dhia Joseph Chackalackal, Ahmed Asa’Ad Al-Aghbari, Su Yeon Jang, Tatiana Rivera Ramirez, Jose Vincent, Anand Joshi, Megha Raj Banjara, Peter Asaga, Rocio Cardenas Sanchez, Maria Angelica Carrillo, Juan Manuel Villa, Sonia Diaz Monsalve, Axel Kroeger
After the start of the Covid-19 (SARS-CoV-2) outbreak in early December 2019, a visit by a WHO-expert team to China documented the lockdown strategy of the government.1 At the same time a mathematical model suggested that the expected high epidemic wave in an uncontrolled situation could be converted into a long-lasting, low epidemic curve through strict transmission control.2 These were major contributions to the decision of governments to drastically restrict people's movements by closing businesses, schools, universities, public events and others (lockdown strategy) in order to enable the health services to cope with the large number of severe cases. This medical-epidemiological view did not consider the societal aspects of the strategy in spite of warnings by economists.3 When the epidemic reached the high-income countries (HICs) of Europe, the medical-epidemiological lockdown model was adopted quickly neglecting the impact of these measures on the economy and public society. But what does lockdown mean for low- and middle-income countries (LMICs), where societies and health services are less organized and the public sector is less able to economically support the informal sector and the mass of impoverished people? The concern of massive collateral damage due to stringent mitigation strategies has already been voiced by authors in richer countries criticizing that ‘this diffuse form of warfare, aimed at “flattening” the epidemic curve generally rather than protecting the especially vulnerable’ cannot be the solution.4 What are the impacts of ‘flattening of the curve’ by employing the lockdown model and ‘social distancing’ for LMICs where the informal sector is predominant, and the poverty levels are high?
Histamine poisoning from insect consumption: an outbreak investigation from Thailand
Published in Clinical Toxicology, 2018
Summon Chomchai, Chulathida Chomchai
On 25 July 2014, the investigators started by meeting the attending physicians and the local outbreak investigation team who were in direct contact with the affected students during the outbreak the day before. A retrospective cohort design was selected because all the students who attended the seminar were available for interview [8]. Standard food poisoning investigation form issued by the Bureau of Epidemiology, Ministry of Public Health of Thailand (MOPH) was used with some modifications to cover the issues of histamine poisoning. For the case definition of histamine poisoning, the investigators suggested that the team utilize a modified version of the 2011 criteria for scombroid toxin (histamine) published in the United States Center of Disease Control and Prevention’s Guide to Confirming an Etiology in Foodborne Disease Outbreak (Table 1) [9]. Interviews of affected persons were conducted by local health officers who were familiar with the standard food poisoning form and were educated regarding histamine poisoning. The data collected included age, gender, year group, symptoms and their onsets, food and beverages that were consumed before the symptoms developed, medical history and allergy and medication history. Data on clinical symptoms and signs, treatment and clinical course of each patient were extracted from the medical records of patients who presented at the hospital. Any available clotted blood samples were sent for serum butyrylcholinesterase and tryptase analysis. An epidemic curve was generated from the collected data. Patients who experienced at least one of the symptoms listed in the case definition were considered symptomatic and plotted in the epidemic curve. The vender of the fried insects was interviewed by the local health officers for information regarding the source and method of preparation of the insects.