Essential Epidemiological Concepts and Terms .

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Basic Epidemiological Concepts and Terms. Incidence: # of new cases of disease/total # at risk. Incidence rate: Incidence/unit of time. Cumulative Incidence: Incidence measured over longer period Prevalence: # cases (or # with defined condition) existing at specific time.
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Essential Epidemiological Concepts and Terms Incidence: # of new instances of illness/aggregate # at hazard. Rate: Incidence/unit of time. Combined Incidence: Incidence measured over longer period Prevalence: # cases (or # with characterized condition) existing at particular time. Predominance rate: # of such cases/add up to # at hazard. P = I X D, where D is length

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Basic Epidemiological Concepts and Terms Risk - The quantity of people who are uncovered and turn out to be poorly separated by the quantity of those uncovered Relative Risk - The danger of disease for people uncovered isolated by the danger of sickness for those not uncovered

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Example What Are Relative Risks for Each Food Item???

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Basic Epidemiological Concepts and Terms Odds for Cases - Number of cases presented to a component partitioned by the quantity of cases not presented to the variable Odds for Controls - Number of controls presented to an element separated by the quantity of controls not presented to the element Odds Ratio - Odds for cases isolated by chances for controls OR = O cases/O controls

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Example What is Odds Ratio??? On the other hand = (a/c)/(b/d) = promotion/bc

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Koch\'s Postulates Organism must be reliably present in ailing state Organism must be isolatable and culturable Cultured creature must incite malady when acquainted with powerless host

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Basic Epidemiological Concepts and Terms Confounding-when an element is connected with the presentation one is concentrating on and which in the meantime is connected with the result Causation-nine criteria laid out by Sir Austin Bradford Hill in 1965. Quality (is the hazard so expansive that we can without much of a stretch preclude different variables) Consistency (have the outcomes have been repeated by various specialists and under various conditions) Specificity (is the introduction connected with a particular malady rather than an extensive variety of ailments) Temporality (did the presentation go before the illness) Biological angle (are expanding exposures connected with expanding dangers of sickness) Plausibility (is there a dependable logical instrument that can clarify the affiliation) Coherence (is the affiliation predictable with the common history of the ailment) Experimental confirmation (does a physical mediation demonstrate comes about steady with the affiliation) Analogy (is there a comparable result that we can attract a relationship to)

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Dynamic Population Model SIR Model (n = S + I + R) S= Susceptibles I= Infectious R=Resistants

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What is an infection? " Virus " is from the Greek importance for " harm " and was at first depicted by Edward Jenner in 1796.

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Viruses littlest (0.02-0.3 micrometers breadth) least difficult (nucleic corrosive + protein coat (+ lipoprotein envelope) ) circular (icosahedral) or pole molded (helical) no natural action outside of host cells/or host living beings commit intracellular parasites; select host cell to make new infections, regularly decimating the phone non-encompassed infections are most steady in the earth protein coat presents strength enteric and respiratory infections are most critical for ecological wellbeing transmitted by immediate and roundabout contact, fecally tainted water, nourishment, fomites and air.

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Recognition of infections F How long infections have been inside our middle? 1500 BC: Leg disfigurements characteristic of poliomyelitis, scars demonstrative of smallpox. Amid the 1800\'s , every single irresistible operator were thought to be infections until Koch created immaculate culture methods which permitted the detachment and development of microscopic organisms. In the late 1800\'s: Bacteria were refined and set up as sickness bringing on operators. It then got to be conceivable to recognize them from the " filterable operators ", those ready to go through exceptional channels intended to keep the entry of microorganisms. The primary infections depicted were foot and mouth illness (a picornavirus), 1898, Yellow fever (a flavivirus), 1900, Rous sarcoma infection (an oncogenic retrovirus), 1906.

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Viral maladies have assumed a noteworthy part in mankind\'s history over whatever time scale we investigate: Over the previous 1000 years: Smallpox and measles were conveyed to North and South America by early European pioneers/conquerers. These maladies, for which the local American populaces had no gained incomplete resistance, executed substantial portions of the populaces, and were a central point in the demolition of these social orders. In the course of recent years: A recently developed strain of flu murdered 20 million individuals in 1918-1919 in the quick fallout of World War I. After 10 years, polio got to be a standout amongst the most dreaded diseases of youngsters and youthful grown-ups (counting Franklin D. Roosevelt, the U.S. President all through the Depression and World War II). As the 20 th century entered its last 20 years, another ~100% deadly infection, HIV , spread quickly around the globe by means of body liquid transmission.

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Over the previous 10 years: As the worldwide HIV pestilence proceeds, sporadic cases and episodes in people of some non-human host infections, for example, Ebola and Hanta raise the worry about future scourges by different infections in the new century. Ebola infection Four Corners Virus (Hanta)

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Virus Composition nucleic corrosive: RNA or DNA twofold or single-stranded one piece or different, hereditarily unmistakable pieces speak to separate qualities some have various duplicates of same quality direct, round or circular+supercoiled

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Proteins : Structural proteins Non-basic proteins Envelope: lipid bilayer layer + glycoproteins) normally obtained from host cell layers Virion (Viral Particle)

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Some popular shapes papillomavirus parvovirus adenovirus morbillivirus 100 nm 1 nm = 1 millionth of a mm 100 nm = 1 ten thousandth of a mm

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Some popular shapes 100 nm influenzavirus parainfluenza infection poxvirus herpesvirus

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Groups, sorts (sero-sorts) , detaches and "strains" Type - A particular antigen Type - A Type - B Group particular antigen segregate Type - C Group (e.g.. noroviruses) Type - C particular antigen

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Errors in replication prompt "quasispecies" persevering disease blend of variation infections (quasispecies)

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GI.1_Norwalk GI.2_Southampton GI.4_Chiba GI GI.5_Musgrove GI.6_Hesse GI.3_Desert Shield GI.7_Winchester GIII GI.8_Boxer GIII.1_Jena GIII.2_CH126 GII.1_Hawaii GII.12_Wortley GII.16_Tiffin GII.2_Melksham GII.5_Hillingdon GII.10_Erfurt GII.13_Fayetteville GII.17_CS-E1 GII.3_Toronto GII.6_Seacroft GII.7_Leeds GII.8_Amsterdam GII.9_Virginia Beach GII.14_M7 GII GII.11_SW918 GII.4_Bristol GIV GII.15_J23 GV GIV.1_Alphatron GV.1_Murine .10 Genotypes: ex. 29 Clusters of Noroviruses Clusters contrast by ≥ 20% amino corrosive pairwise separate Genogroups vary by 44-55% amino corrosive pairwise remove

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A General Caution! Sub-atomic sub-writing is somewhat similar to the illustration of the visually impaired men and the elephant – you can get a totally unique picture of what you\'re managing relying upon which part of the monster you\'re looking at!

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Release of infection or by sprouting (without death of cell, non-cytopathic) Release by lysis of cell (cytopathic)

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Patterns of illness clinical signs infection shedding intense infection hard to distinguish intermittent unending moderate

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Enteric Viruses: Localized: caliciviruses astroviruses adenoviruses rotaviruses Generalized: enteroviruses hepatitis An and E infections Respiratory Viruses: Localized: rhinoviruses coronaviruses Orthomyxoviruses(Flu) paramyxoviruses Generalized: herpesviruses measles mumps Virus Infections: Some Important Viruses Cause Localized Infections and Others Systemic Infections

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How are infections arranged ? Various leveled infection characterization: ( arrange) family - subfamily - class - species - strain/sort All families have the postfix viridae, e.g.: * Poxviridae * Herpesviridae * Parvoviridae * Retroviridae Genera have the addition infection. Inside the Picornaviridae there are 5 genera: * enterovirus (nutritious tract), species e.g. poliovirus 1, 2, 3 * cardiovirus (neurotropic), species e.g. mengovirus * rhinovirus (nasopharyngeal area), species e.g. Rhinovirus 1a * apthovirus (cloven footed creatures ), species e.g. FMDV-C * hepatovirus (liver), species e.g. Hepatitis An infection

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Virus naming and characterization Usually in light of information accessible at the season of disclosure: i Disease they are connected with, e.g.: Poxvirus, Hepatitis infection, HIV, measles infection ii Cytopathology they cause, e.g.: Respiratory Syncytial infection, Cytomegalovirus iii Site of disconnection, e.g.: Adenovirus, Enterovirus, Rhinovirus iv Places found or individuals that discovered them, e.g.: Epstein-Barr infection, Rift Valley Fever v Biochemical highlights, e.g.: Retrovirus, Picornavirus, Hepadnavirus

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"Irresistible" An E F, G, ? Other * Viral hepatitis NANB "Serum" B C D These naming traditions can prompt perplexity later, e.g., viral hepatitis is created by no less than 6 distinctive infections Enterically transmitted Parenterally transmitted * 10-20% of instances of assumed viral hepatitis are still not represented

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Thus, Different infections can bring about (almost) similar side effects. e.g., the hepatitis infections However, extraordinary individuals from similar gathering can bring about various side effects. e.g., the herpes infections

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Rotavirus Virus Classification is currently construct basically in light of examination of the molecule: Morphology: by electron microscopy Serology: antigenic cross-reactivity Genetic material: type of nucleic corrosive ssDNA (+ or - strand) dsDNA ssRNA (+ or - strand) dsRNA segmented RNA hereditary association succession homology DNA arrangement Hybridization

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Viral Gastroenteritis It is believed that infections are in charge of up to 3/4 of every single infective diarrhoea. Viral gastroent

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