Infectious disease epidemiology

Based on the our October paper "A Generalized Viral Infection Mathematical Model Derived from Covid-19 Simulation", at a conceptual level higher than the classic SIR/SEIR model, we have established the 6 laws of infection regarding the final infection ratio within any given population without any artificial intervention and have shown the final infection ratio in a natural, non-interfered pandemic must fall within a specified lower and upper bound as 1 − 1 R 2 0 ≤ F R ≤ 2 (1 − 1 R 0). Whereas R 0 is the intrinsic R 0 value of the disease. In this paper, we show how human intervention strategies alter the previous assumptions based on 2 factors. First, artificial intervention with cycles of restricting measures and relaxations. Based on our May paper "The Predictions on Worldwide Covid-19 Pandemic Cases Based on Historical Data", we have already demonstrated the dynamic falling R 0 (t) curve during lock down measures. With more historical data and observation, we now expand the scope to include a dynamic rising R 0 (t) curve following the relaxation of measures, completing the cycle of restriction and relaxation. Second, the introduction of vaccination at a steady rate introduced a new variable into the existing infection model, we denote it as function V (t). We demonstrate the optimal strategies of vaccination interpreted within our existing established framework.

Καθόλη τη διάρκεια της ανθρώπινης ιστορίας, αναρίθμητες επιδημίες και πανδημίες έχουν αφανίσει τον ανθρώπινο πληθυσμό. Αν και στο παρελθόν τεχνολογικοί και επιστημονικοί περιορισμοί μειονεκτούσαν τον άνθρωπο, πρέπει να επισημανθεί πως πολλές από τις εξάρσεις διάφορων ασθενειών ήταν και είναι αποφευκτές. Το συγκεκριμένο άρθρο θα επιχειρήσει μια ιστορική ανάλυση κάποιων χαρακτηριστικών πανδημιών και θα προτείνει συστάσεις για τον καλύτερο και αποτελεσματικότερο έλεγχο και περιορισμό μελλοντικών πανδημιών.

The systematic review focused on the prognosis, mortality, medications, and promising vaccines for COVID-19. COVID-19 severity varies. Mild cases often recover within two weeks, while people with severe diseases may take 3 – 6 weeks to recover. Among people who died, the time from the onset of symptom to death ranged from 2 – 8 weeks. Children constitute a small percentage of reported cases, with around 1% of cases under 10 years and 4% aged 10 to 19 years. The risk of death is below 0.5% in those younger than 50 years, while more than 8% in those older than 70. Most of the people who die of COVID-19 have pre-existing conditions, including diabetes mellitus, cardiovascular disease, and hypertension. The impact of COVID-19 and its rate of mortality are different for both men and women; mortality rate is higher in men. As of May 2020, it is not known if past infection provides long-term and effective immunity in those who recover from the viral disease. Some of the infected people were reported to develop protective antibodies; the acquired immunity is presumed possible, based on other coronaviruses’ behaviour. The total infection fatality rate (IFR) is estimated to be 0.66%. No approved vaccine to treat the disease yet. International research on medicines and vaccines in COVID-19 is underway by academic groups, industry researchers, and government organizations. As of May 2020, there are over 300 active clinical trials underway. Many existing medications are under evaluation for COVID-19 treatment, including remdesivir, chloroquine, lopinavir/ritonavir, hydroxychloroquine, and lopinavir/ritonavir combined with interferon beta; as of May 2020, there is tentative evidence for remdesivir efficacy. Other candidates in trials are vasodilators, immune therapies, lipoic acid, corticosteroids, recombinant angiotensin-converting enzyme 2, bevacizumab, etc. Preliminary evidence suggests hydroxychloroquine might have anti-cytokine storm properties. Transferring concentrated and purified antibodies produced by immune systems of those who recovered from COVID-19 to those who need them is being investigated as non-vaccine method of passive immunization.

Background: A wide range of pharmaceutical products are needed for diagnosis, treatment, and prevention of HIV/AIDS. However, interrupted supplies and stock-outs are the major challenges in the supply chain of ARV medicines and related commodities. The aim of this study was to assess the supply chain management of HIV/AIDS related commodities in public health facilities of Addis Ababa, Ethiopia. Methods: A descriptive cross-sectional survey complemented by qualitative method was conducted in 24 public health facilities (4 hospitals and 20 health centers). A semi-structured questionnaire and observation check list were used to collect data on HIV/AIDS related service, reporting and ordering; receiving, transportation and storage condition of ARV medicines and test kits; and supportive supervision and logistics management information system. In addition, in-depth interview with flexible probing techniques was used to complement the quantitative data with emphasis to the storage condition of ARV medicines and test kits. Quantitative data was analyzed using SPSS version-20. Analysis of qualitative data involved rigorous reading of transcripts in order to identify key themes and data was analyzed using thematic approach. Results: The study revealed that 16 health centers and one hospital had recorded and reported patient medication record. Six months prior to the study, 14 health centers and 2 hospitals had stopped VCT services for one time or more. Three hospitals and 18 health centers claimed to have been able to submit the requisition and report concerning ARV medicines to Pharmaceutical Fund and Supply Agency according to the specific reporting period. More than three-fourth of the health centers had one or more emergency order of ARV medicines on the day of visit, while all of hospitals had emergency order more than 3 times within 6 months prior to the study. All of the hospitals and nearly half of the health centers had an emergency order of test kits more than 3 times in the past 6 months. Overall, nearly 3/4th of the health facilities faced stock-out of one or more ARV medicines and test kits on the day of visit. Conclusion: There was no adequate data on patient medication record and stock status of HIV/AIDS related commodities. Moreover there were frequent stock-outs of ARV medicines and HIV test kits, which was an indicator of the weak supply chain management. Hospitals and health centers, therefore, should devise a system to capture and make use of patient medication record and stock status information so as to ensure continuous supply of the commodities.

A cross-sectional epidemiological survey for paracoccidioidomycosis and histoplasmosis, including skin tests with paracoccidioidin and histoplasmin, physical examinations and X-rays, wasconducted among three Tupi-Monde Amerindian populations from Brazilian Amazonia. The study followed the diagnosis of an increasing number of cases of paracoccidioidomycosis among the Surui in recent years. Positivity rates to paracoccidioidin and histoplasmin (>5 mm of intradermal induration 24-48 h post-injection) were 438% and 78-7% for the Surui, 64% and 58% for the Gaviao and 149% and 805% for the Zoro, respectively. There was no significant difference in the results for males and females but marked differences were noted across age groups. The results of the univariate analysis were confirmed after adjustment for confounding variables by multiple logistic regression analysis: paracoccidioidin positivity was relatively high in the Surui and histoplasmin positivity was relatively high in the Surui and Zoro. The Surui's greater exposure to Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis, is probably associated with their adoption of new subsistence practices. The epidemiology of this mycosis among the Tupi-Monde appears to be related to the environmental and socioeconomic changes taking place in Amazonia.

Purpose: To determine the effect of caffeine on blink rate of adults Method: A total of 100 subjects aged 18-50 years participated in the study. The subjects were allowed to rest for 5 minutes and then conversed for 1 minute during which the subjects talked with the researcher on general issues to make for relaxation. The number of blinks per minute was noted and recorded. After which the subjects were given 1.5 grams of Nescafe coffee powder, mixed with 50 millilitres of water, under room temperature. Each subject drank the coffee drink comfortably and the exact time of coffee intake noted. Number of blinks at 15 minutes was taken after each subject consumed Nescafe coffee. Blink rate was taken for each subject at 30, 45 and 60, minutes after coffee consumption. Results: Mean baseline blink rate was 16.17 blink/min. 15 minutes post consumption of coffee, mean blink rate decreased to 14.00 blink/min. 30 minutes post consumption of coffee, mean blink rate decreased to 12.89 blink/min. 45 minutes post consumption of coffee, mean blink rate further decreased to 11.03 blink/min. Mean blink rate at 60 minutes post consumption of coffee was 14.84 blink/min. Conclusion: This study showed that caffeine significantly decreased blink rate during conversation. Blink rate at 60 minutes was noted to be gradually returning to baseline blink rate. This suggests that the effects if caffeine on blink rate in adults may last for an hour before it gradually diminishes. This study also compared the effect of caffeine based on gender and found no significant difference between blink rate in both sexes. However, there was an effect in respect to age. Older people had a significantly decreased blink rate after consumption of coffee with respect to time.

Aml Ghouraba[1], , Asmaa Darwish[2], Rehab Elbanhawy[3], Rasha A. Mohamed[4], Ahmed Mohamed[5], Ahmed Abdalla[6] [1][3][4 ABSTRACT Rheumatoid arthritis (RA) can be defined as an autoimmune inflammatory disease which is represented in about1% of the world population and occurs in the middle age with increasing frequency in older population. RA has several types which can be caused by joint inflammation or bone or joint damage. Scientists were unable to determine the causes of such inflammation until few years ago when some evidences or clues were unveiled that involved mainly genetics and environmental factors. Although there is no known complete cure of RA, treatment aim to achieve several goals which are pain relief, slow joint degeneration and improve patient well-being. To achieve that, several approaches could be applied including lifestyle, medication, routine monitoring and surgery.

Background: SLC10A1 gene codes NTCP, a receptor through which the hepatitis B virus (HBV) gets access into hepatocytes-a stage of the viral cycle necessary for replication. Polymorphism variants of SLC10A1 play roles in HBV infection, viral clearance, treatment outcome, and complications, in diverse ethnic groups and countries. However, no such study has been conducted in the Ghanaian population, a country with HBV endemicity. Therefore, an exploratory study was conducted to investigate the presence of three (3) single nucleotide polymorphisms (SNPs) in the SLC10A1 gene (rs2296651, rs61745930, and rs4646287) and assessed the risk of HBV infection among the Ghanaian population.

Hepatitis B virus (HBV) is causally linked to acute and chronic form of hepatitis, which due to continuous immune mediated inflammation and scarring may lead to cirrhosis and/or hepatocellular carcinoma. HBV spread via exchange of infected bodily fluids underlie unique public health considerations due to similarities with other community related issues such as sexually transmitted diseases (eg HIV) blood borne pathogens (Hepatitis-C) and perinatal transmissions (TORCH complex).

Background Identified in December 2019 in the city of Wuhan, China, the outbreak of COVID-19 spread throughout the world and its impacts affect different populations differently, where countries with high levels of social and economic inequality such as Brazil gain prominence, for understanding of the vulnerability factors associated with the disease. Given this scenario, in the absence of a vaccine or safe and effective antiviral treatment for COVID-19, nonpharmacological measures are essential for prevention and control of the disease. However, many of these measures are not feasible for millions of individuals who live in territories with increased social vulnerability. The study aims to analyze the spatial distribution of COVID-19 incidence in Brazil’s municipalities (counties) and investigate its association with sociodemographic determinants to better understand the social context and the epidemic’s spread in the country. Methods This is an analytical ecological study using da...

BACKGROUND Timely initiating antenatal care (ANC) is crucial in the countries that have high maternal morbidity and mortality. However, in developing countries including Ethiopia, pregnant mother's time to initiate antenatal care was not well-studied. Therefore, this study aimed to assess time to first ANC and its predictors among pregnant women in Ethiopia. METHODS A community-based cross-sectional study was conducted among 7,543 pregnant women in Ethiopia using the Ethiopian Demographic Health Survey (EDHS), 2016 data. A two-stage stratified cluster sampling was employed. The Kaplan-Meier (KM) method was used to estimate time to first antenatal care visit. Cox-gamma shared frailty model was applied to determine predictors. Adjusted Hazard Ratio (AHR) with 95% confidence interval was reported as the effect size. Model adequacy was assessed by using the Cox-Snell residual plot. Statistical significance was considered at p value <0.05. For data management and analysis Stata 14...

* N.B.: Even in "wealthy" countries, not all patients need colonoscopy, which should be reserved in particular for those with alarm symptoms or signs and those over the age of 50. The need for investigations and for sigmoidoscopy and colonoscopy, in particular, should also be dictated by the characteristics of the patient (presenting features, age, etc.) and the geographical location (i.e., whether or not in an area of high prevalence for inflammatory bowel disease, celiac disease, colon cancer, or parasitosis). One could argue, for example, that a 21-year-old woman with symptoms of IBS with diarrhea and no alarm features merits, at most, celiac serology and thyroid evaluation (where appropriate). In general, the diagnosis is "safer" in patients with constipation, whereas in patients with severe diarrhea, there is a greater need to consider tests to exclude organic pathology.

Background:
Understanding public behavioral responses to the coronavirus disease (COVID-19) epidemic and the accompanying infodemic is crucial to controlling the epidemic.

Objective:
The aim of this study was to assess real-time public awareness and behavioral responses to the COVID-19 epidemic across 12 selected countries.

Methods:
Internet surveillance was used to collect real-time data from the general public to assess public awareness and rumors (China: Baidu; worldwide: Google Trends) and behavior responses (China: Ali Index; worldwide: Google Shopping). These indices measured the daily number of searches or purchases and were compared with the numbers of daily COVID-19 cases. The trend comparisons across selected countries were observed from December 1, 2019 (prepandemic baseline) to April 11, 2020 (at least one month after the governments of selected countries took actions for the pandemic).

Results:
We identified missed windows of opportunity for early epidemic control in 12 countries, when public awareness was very low despite the emerging epidemic. China's epidemic and the declaration of a public health emergency of international concern did not prompt a worldwide public reaction to adopt health-protective measures; instead, most countries and regions only responded to the epidemic after their own case counts increased. Rumors and misinformation led to a surge of sales in herbal remedies in China and antimalarial drugs worldwide, and timely clarification of rumors mitigated the rush to purchase unproven remedies.
Conclusions:
Our comparative study highlights the urgent need for international coordination to promote mutual learning about epidemic characteristics and effective control measures as well as to trigger early and timely responses in individual countries.

Early release of official guidelines and timely clarification of rumors led by governments are necessary to guide the public to take rational action.

Mostly self-limited with an idiopathic or infectious etiology, pericarditis may be fatal in rare occasions. Thiny layer surrounding myocardium is infected especially by viral organisms. Here, a recent Turkish and world literature will be reviewed and cases of Epstein Barr virus, H1N1 virus as well as tuberculosis microorganisms leading to pericarditis and even tamponade will be discussed. You will also find rare parasitic infestations presenting with pericardial effusion, constrictive and crystal pericarditis of infectious origin and read other rare metabolic associations such as myxedema and uremia.

O estudo tem como objetivo analisar pesquisas sobre as infecções hospitalares neonatais prevalentes em unidades de terapia intensiva. Trata-se de uma revisão integrativa da literatura realizada nas bases de dados Medline e ScienceDirect. Foram selecionados 20 artigos que atenderam aos critérios de inclusão da pesquisa: estudos primários, disponíveis na integra de forma eletrônica e publicados no período de 2011 a 2015. Os dados foram processados no software IRAMUTEC e analisados pela
classificação hierárquica descendente, análise de similitude e nuvem de palavras. Os resultados foram apresentados em 04 classes, a saber: 1-O Staphylococcus aureus resistente a meticilina em infecções na Unidade de Terapia Intensiva Neonatal - UTIN; 2- Vigilância
aos casos de infecção em UTIN; 3- Distribuição topográfica das infecções neonatais em UTI; 4- Fatores de risco para
desenvolvimento de infecções em UTIN e 5- Medidas de Prevenção e controle de infecções neonatais em UTI. A prevalência de
infecção em unidade de terapia intensiva é elevada e possui relação com fatores intrínsecos ao neonato, bem como ao ambiente hospitalar. Concluiu-se que há necessidade da adoção de uma política efetiva de prevenção e controle das infecções hospitalares para diminuir os índices de infecções neonatais em unidades de terapia intensiva. Descritores: Unidade de terapia intensiva. Infecção hospitalar. Fatores de risco. Neonatal.

Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000–2018 geospatial estimates of anemia prevalence in women of reproductive age (15–49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organization’s Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where lar...

Este trabajo parte de una revisión de fuentes hemerográficas y bibliográficas para tratar el tema de investigación sobre la fiebre aftosa y el rifle sanitario dentro de la ciudad de Guanajuato cuyo objetivo se aborda en la problemática del qué ocurrió dentro de los municipios de la región y como tuvo repercusiones de nivel, incluso internacional. El tema de la Contingencia actual por la causa del SARS-COV 2: Coronavirus-19 ha infringido no solo el conocimiento del virus en cualquier dimensión de su conocimiento sino hasta la re-investigación de los conceptos que lo relacionan o la reciprocidad de entre epidemias mortales provocadas en nuestra sociedad. En el caso de la fiebre aftosa afecta principalmente al ganado pero también ha provocado desequilibrios en varias partes alrededor del mundo. 1 La llamada fiebre aftosa (FA), también conocida como Glosopeda o Foot and Mouth disease por la World Organisation for animal Health, proviene de

Background: Over the past centuries, mortality and morbidity patterns have been changing all over the world albeit with variations in timing and pace. These changes have been referred to as the epidemiologic transition. The main features of the transition include a decline in mortality, an increase in life expectancy, and a shift in the leading causes of morbidity and mortality from infectious and parasitic diseases to non-communicable, chronic, degenerative diseases. The transition is linked to improvements and advances in nutrition, hygiene and sanitation, and medical knowledge and technology. As such, the epidemiologic transition is related to the demographic transition and the nutritional transition, and is part of a more broadly defined health transition. Objectives: This paper was aimed at studying these shifts in pattern of mortality, life expectancy, and causes of death. Methods: Relevant literature was reviewed from medical journals, library research, Pub Med search, Google search and search using other internet search engines. The key words for the search were "Epidemiologic transition", "Developing countries", "Diseases" and "health related events". Result: Several studies have given perspectives on epidemiologic transition, the factors that are responsible for the transition, the effects on the health of man, the scenarios in developed world and in the developing countries. Also highlighted are the challenges posed to humanity and possible measures to arrest the situation. Conclusion: It is obvious that epidemiologic transition is a reality that is present with humanity. In the developing world we have more problems on our hand as we have not succeeded in controlling the communicable diseases and the non-communicable diseases mostly nutrition-related are becoming predominant. This calls for action to prevent the dire consequences of double burden of disease arising from inaction.

Digital dermatitis (DD) is an infectious bacterial disease affecting cattle feet. Footbaths are a common herd-level control method for DD; however, variations in product, concentration, and frequency of use complicate comparisons between protocols. The objective of this systematic review was to evaluate all walk-through footbath protocols reported that determined efficacy for prevention and treatment of DD lesions in dairy cattle. An extensive literature search was conducted, including electronic databases and gray literature updated until March 2018. Studies identified included all liquid walk-through footbath protocols that were compared to other footbath protocols or no footbath. Only studies with treatment or prevention of DD lesions as an outcome were included. Literature search and subsequent screening identified 14 publications with 24 treatment comparisons and 24 prevention comparisons. Studies included mostly had low and/or unclear risks of bias. Descriptive analyses were performed according to prevention and treatment outcomes, with case and success definitions summarized as odds ratios (OR). A subsequent network meta-analysis was conducted of 11 studies, comparing 17 protocol comparisons for the prevention outcome and 10 studies comparing 19 protocol comparisons for the treatment outcome, using semi-informative priors in a Bayesian statistical framework. Results of a random effects Bayesian network meta-analysis indicated only 5% copper sulfate used at least 4 times/wk was superior to both no footbath (OR: 5.26; 95% CrI: 1.27-28.8) and a water placebo (OR: 9.47; 95% CrI: 1.03-85.8) in treatment of DD. No other protocol was associated with a reduction in DD, and there were no differences in pair-wise comparisons between any active treatments. Unfortunately, for both outcomes (treatment and prevention), small sample sizes (adjusted for clustering) limited the power to detect substantial differences between protocol effects. Thus, despite widespread use of footbaths, limited strength of evidence for use remains and standardized protocols with large sample sizes are needed to further investigate effectiveness of footbath protocols for control of DD. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

This paper examines the ways in which the third plague pandemic was documented and visualized in relation to rapidly evolving ideas about disease, medicine, and the environment by engaging with a set of photo-albums produced in late nineteenth-century Bombay. As one of the first examples of epidemiological photography, a new genre of photography that had developed at the turn of the century in the wake of the bubonic plague epidemic, the photo-albums serve as a significant archive of late nineteenth-century colonial epidemiological, visual, and urban practices. Through my analysis of the Bombay photographs, I aim to foreground the environmental and biological contexts of cultural practices, focusing on the multiple ways in which non-human materials such as water, air, light, and microorganisms can drive and effect image making. I thus propose an epistemological shift in our reading of colonial photography that foregrounds the dynamic materiality of the natural world.

Premessa Mi è stato fortemente suggerito di condividere qualsiasi cosa , fino ad ora, sia riuscito o meno a realizzare su questo argomento , seppure in maniera provvisoria ed incompleta , anche allo scopo di evitare ad altri gli errori ed i vicoli ciechi in cui mi sono imbattuto o le conclusioni, anche errate, a cui sono giunto. Nella versione precedente di queste note (e molto probabilmente anche nella versione attuale) sono presenti passaggi poco chiari , scritti di getto allo scopo di condividere subito le ipotesi di lavoro. Questo progetto si pone come obbiettivo quello di sviluppare e valutare l'opportunità d'impiego di uno strumento di facile ed immediato utilizzo per la previsione dell'andamento di un' epidemia in un ambito circoscritto, con scambi di popolazione con l'esterno limitati e tracciabili, in grado di poter simulare anche l'impatto di eventuali misure d'isolamento della popolazione. Lo sviluppo in ambiente Microsoft-Excel , consente a qualsiasi Ricercatore o Tecnico di potere eventualmente operare facili e veloci modifiche anche sulla struttura del calcolo. Il modello matematico alla base dell'applicazione proposta, simula l'andamento di un'epidemia, in un'area di controllo, attraverso la seguente equazione alle differenze finite , sviluppata in un tabulato di calcolo Excel :

The origins and global spread of two recent, yet quite different, pandemic diseases is discussed and reviewed in depth: Candida auris, a eukaryotic fungal disease, and COVID- 19 (SARS-CoV-2), a positive strand RNA viral respiratory disease. Both these diseases dis- play highly distinctive patterns of sudden emergence and global spread, which are not easy to understand by conventional epidemiological analysis based on simple infection- driven human- to-human spread of an infectious disease (assumed to jump suddenly and thus genetically, from an animal reservoir). Both these enigmatic diseases make sense however under a Panspermia in-fall model and the evidence consistent with such a model is critically reviewed.

In hospital care, management of the risk of infection represents a crucial issue. Nevertheless, this question remains a neglected area in anthropological research, especially in African countries. To shed new light on this question, we conducted an anthropological investigation in the infectious disease department of a hospital in Niger. Daily observation of the work of the hospital staff for a total period of 6 months was spread out over 2008 and 2009. During our prolonged stay, we also collected 64 in-depth interviews of health care workers and attendants in the department. This study method made it possible to describe many of the practices and discourses related to the issues of medical and personal care and hospital hygiene and to compare the practices observed to standard principles for preventing hospital-acquired infections. Our ethnographic attention to the behavior of the actors showed the absence of formal spatial segmentations between different activities. The care provided by the untrained relatives serving as personal attendants introduced territorial enclaves governed by home hygiene standards into the interior of technical spaces. At the same time, privatizing equipment and space for their diverse activities, the medical staff disrupted technical chains and generated the recurrent crossing of microbial geographies. These results allow us to offer two principal guidelines for improving the quality of care and the management of risks of infection in hospitals in West Africa: (1) the essential role of the attendants in the care provided to hospital inpatients must be officially taken into account, especially by including them in the organization of medical hygiene procedures; (2) the different overlapping technical activities and social activities in the work space must be limited by their geographic and architectural segmentation.

Why do parasites harm their host? The persistence of this question in the history of the life sciences rests partly on a seeming biological paradox. In effect, although the annihilation of the host by a parasite could be depicted as a crude example of “the survival of the fittest,” situations where the host dies rapidly often amount to a pyrrhic
victory because parasitic colonies harboured within it may die as well before the transmission stage. So why would natural selection favour high virulence if this results in both the host’s and the pathogen’s deaths? From the last quarter of the nineteenth century to the
late 1970s, it was often considered that, all else being equal, pathogen’s evolution towards harmlessness was the expected outcome of long-term biological associations, as it would ensure the survival of both species. Frequently dismissed today as naively adaptationist, this perspective was however widely defended by some of those who pioneered an ecological, even evolutionary view of disease in the early-twentieth century, and was often ascribed to
American bacteriologist and comparative pathologist Theobald Smith (1859-1934). Since the early 1980s, the mathematical model of the trade-off – based on the idea that pathogens face several compromises between their mode of transmission, the level of virulence, and the cost of resistance – has challenged the assumed tendency towards harmlessness and has gained currency. This paper first analyzes Theobald Smith’s conception of disease, his experimental work on Texas cattle fever, and his formulation of the “law of declining virulence.” The following sections then trace the legacy of this model of disease evolution from circa 1900 to its widespread acceptance in the mid-twentieth century and until its
downfall in the 1980s. Particular attention is given to the case of the myxoma virus and how it acted as an empirical confirmation of Smith’s model in the 1950s. Finally, the paper examines both significant empirical and theoretical challenges to the avirulence model. The
present study not only fills a gap in the history of disease transmission and ecology but also sheds light on the intermingled relationship between bacteriology, evolutionary biology, and public health in the past century.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The coronavirus disease (COVID-19) is a severe, ongoing, novel pandemic that emerged in Wuhan, China, in December 2019. As of January 21, 2021, the virus had infected approximately 100 million people, causing over 2 million deaths. This article analyzed several time series forecasting methods to predict the spread of COVID-19 during the pandemic's second wave in Italy (the period after October 13, 2020). The autoregressive moving average (ARIMA) model, innovations state space models for exponential smoothing (ETS), the neural network autoregression (NNAR) model, the trigonometric exponential smoothing state space model with Box-Cox transformation, ARMA errors, and trend and seasonal components (TBATS), and all of their feasible hybrid combinations were employed to forecast the number of patients hospitalized with mild symptoms and the number of patients hospitalized in the intensive care units (ICU). The data for the period February 21, 2020-October 13, 2020 were extracted from the website of the Italian Ministry of Health (www. salute. gov. it). The results showed that (i) hybrid models were better at capturing the linear, nonlinear, and seasonal pandemic patterns, significantly outperforming the respective single models for both time series, and (ii) the numbers of COVID-19-related hospitalizations of patients with mild symptoms and in the ICU were projected to increase rapidly from October 2020 to mid-November 2020. According to the estimations, the necessary ordinary and intensive care beds were expected to double in 10 days and to triple in approximately 20 days. These predictions were consistent with the observed trend, demonstrating that hybrid models may facilitate public health authorities' decision-making, especially in the short-term.

A rudimentary, low-cost, positive pressure, pulmonary mechanical ventilator with minimal automation may adversely affect the prognosis and medical outcome while possibly giving rise to complications that increase morbidity and mortality in patients of respiratory diseases; while complicating the process of weaning.