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Endemism (epidemiology)
In epidemiology, an infection is said to be endemic in a specific population or populated place when that infection is constantly maintained at a baseline level without extra infections being brought into the group as a result of travel or similar means. An endemic disease always has a steady, predictable number of people getting sick, but that number can be high ('' hyperendemic'') or low (''hypoendemic''), and the disease can be severe or mild. Also, a disease that is usually endemic can become epidemic. For example, chickenpox is endemic (steady state) in the United Kingdom, but malaria is not. Every year, there are a few cases of malaria reported in the UK, but these do not lead to sustained transmission in the population due to the lack of a suitable vector (mosquitoes of the genus '' Anopheles''). Consequently, the number of people infected by malaria is too variable to be called endemic. However, the number of people who get chickenpox in the UK varies little from yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Force Of Infection
In epidemiology, force of infection (denoted \lambda) is the rate at which susceptible individuals acquire an infectious disease. Because it takes account of susceptibility it can be used to compare the rate of transmission between different groups of the population for the same infectious disease, or even between different infectious diseases. That is to say, \lambda is directly proportional to \beta; the effective transmission rate. : \lambda = \frac Such a calculation is difficult because not all new infections are reported, and it is often difficult to know how many susceptibles were exposed. However, \lambda can be calculated for an infectious disease in an endemic state if homogeneous mixing of the population and a rectangular population distribution (such as that generally found in developed countries), rather than a pyramid, is assumed. In this case, \lambda is given by: : \lambda = \frac where A is the average age of infection. In other words, A is the avera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease Outbreak
In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire continent. The number of cases varies according to the disease-causing agent, and the size and type of previous and existing exposure to the agent. Outbreaks include many epidemics, which term is normally only for infectious diseases, as well as diseases with an environmental origin, such as a water or foodborne disease. They may affect a region in a country or a group of countries. Pandemics are near-global disease outbreaks when multiple and various countries around the Earth are soon infected. Definition The terms "outbreak" and "epidemic" have often been used interchangeably. Researchers Manfred S. Green and colleagues propose that the latter term be restricted to larger events, pointing out that '' Chambers Concise Dictionary'' and ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seasonal Flu
Flu season is an annually recurring time period characterized by the prevalence of an outbreak of influenza (flu). The season occurs during the cold half of the year in each hemisphere. It takes approximately two days to show symptoms. Influenza activity can sometimes be predicted and even tracked geographically. While the beginning of major flu activity in each season varies by location, in any specific location these minor epidemics usually take about three weeks to reach its pinnacle, and another three weeks to significantly diminish. Annually, about 3 to 5 million cases of severe illness and 290,000 to 650,000 deaths from seasonal flu occur worldwide. Cause Three virus families, Influenza virus A, B, and C are the main infective agents that cause influenza. During periods of cooler temperature, influenza cases increase roughly tenfold or more. Despite the higher incidence of manifestations of the flu during the season, the viruses are actually transmitted throughou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidemic
An epidemic (from Ancient Greek, Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of patients among a given population within an area in a short period of time. Epidemics of infectious diseases are generally caused by several factors including a significant change in the ecology of the areal population (e.g., increased stress maybe additional reason or increase in the density of a vector species), the introduction of an emerging pathogen to an areal population (by movement of pathogen or host) or an unexpected genetic change that is in the pathogen reservoir. Generally, epidemics concerns with the patterns of infectious disease spread. An epidemic may occur when host immunity to either an established pathogen or newly emerging novel pathogen is suddenly reduced below that found in the endemic equilibrium and the transmission threshold is exceeded. For example, in meningococcal infections, an attack rate in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporadic Disease
In epidemiology, sporadic is a term used to refer to a disease which occurs only infrequently, haphazardly, irregularly or occasionally from time to time in a few isolated places with no discernible temporal or spatial pattern, as opposed to a recognizable epidemic or endemic pattern. The cases are so few (single or in a cluster) and separated so widely in time and place that there exists little or no connection within them. They also do not show a recognizable common source of infection.According to : "...sporadic cases do not necessarily share a single specific common contaminated source..." In the United States, tetanus, rabies, and plague are considered examples of sporadic diseases. Although the tetanus-causing bacteria ''Clostridium tetani'' is present in the soil everywhere in the United States, tetanus infections are very rare and occur in scattered locations because most individuals have either received vaccinations or clean wounds appropriately. Similarly the country record ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typhoid Fever
Typhoid fever, also known as typhoid, is a disease caused by '' Salmonella'' serotype Typhi bacteria. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several days. This is commonly accompanied by weakness, abdominal pain, constipation, headaches, and mild vomiting. Some people develop a skin rash with rose colored spots. In severe cases, people may experience confusion. Without treatment, symptoms may last weeks or months. Diarrhea may be severe, but is uncommon. Other people may carry the bacterium without being affected, but they are still able to spread the disease. Typhoid fever is a type of enteric fever, along with paratyphoid fever. ''S. enterica'' Typhi is believed to infect and replicate only within humans. Typhoid is caused by the bacterium ''Salmonella enterica'' subsp. ''enterica'' serovar Typhi growing in the intestines, peyers patches, mesenteric lymph nodes, spleen, liver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperendemic
In epidemiology, the term hyperendemic disease is used to refer to a disease which is constantly and persistently present in a population at a high rate of incidence and/or prevalence (occurrence) and which equally affects (i.e. which is equally endemic in) all age groups of that population. It is one of the various degrees of endemicity (i.e. degrees of transmission of an infectious disease). Definitions According to a more precise definition given by the Robert Koch Institute in Germany, hyperendemicity is not necessarily associated with a high incidence rate. A hyperendemic disease is one which is ubiquitously present with ongoing circulation in an endemic region with a high prevalence rate. As a result, a hyperendemic region shows a relatively low incidence rate but at the same time it poses a high risk of infection to people coming into the region. According to another definition discussing malaria, a hyperendemic region is defined to be one with a seasonally high degree of en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunity (medical)
In biology, immunity is the capability of multicellular organisms to resist harmful microorganisms. Immunity involves both specific and nonspecific components. The nonspecific components act as barriers or eliminators of a wide range of pathogens irrespective of their antigenic make-up. Other components of the immune system adapt themselves to each new disease encountered and can generate pathogen-specific immunity. Immunity is a complex biological system that can recognize and tolerate whatever belongs to the self, and to recognize and reject what is foreign (non-self). Innate and adaptive Innate Immunity First off, the immune system is a system in the body of animals that enables animals to avoid or limit many infections caused by pathogens. Pathogens are disease causing agents, causing a wide range of illnesses. As for Diseases it's when structure of an organism is negatively affected other than external injury. Both diseases and pathogens affect the immune system causing ill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holoendemic
A disease is holoendemic when essentially every individual in a population is infected. Although the infection is ubiquitous, symptoms of disease do not appear equally across age groups. The young are more likely to express pathogenic responses, whilst the older hosts will carry the disease asymptomatically, or with reduced damage, due to adaptive immunity. Therefore, holoendemic diseases differ from hyperendemic diseases, of which symptoms are expressed equally by members across all age groups of a population. Holoendemicity is frequently seen with malaria, specifically the strain caused by ''Plasmodium falciparum'', in several regions of sub-Saharan Africa (one study found that 98.6% of the population had traces of the pathogen within a 4 month period). While individuals of all ages risk exposure to malaria, those under the age of five are particularly susceptible to the disease. Children account for the majority of both local and global malaria cases because they lack the adaptiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemic COVID-19
the global COVID-19 pandemic is still ongoing, but the disease may shift from a pandemic stage to an endemic stage in the future. Endemicity is characterized by people continuing to be infected and becoming ill, but in relatively stable numbers compared to the preceding pandemic. The observed behavior of the SARS-CoV-2 virus suggests it is unlikely it will die out, and the lack of a COVID-19 vaccine that provides long-lasting immunity against infection means it cannot be eradicated. From 2021 onwards, politicians and health officials in some countries have said that COVID-19 is endemic or that the country was beginning to transition to an endemic phase. These include Cambodia, Finland, Indonesia, Malaysia, Mexico, the Philippines, Singapore, Spain and Vietnam. Background There is no single agreed definition of what it means precisely for COVID-19 to become endemic. During the course of the COVID-19 pandemic, it became apparent that the SARS-CoV-2 virus was unlikely to die o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemism
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example '' Cytisus aeolicus'' is an endemite of the Italian flora. '' Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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