Optimal virulence is a long-term evolutionary strategies adopted by pathogen to maximize its persistence within a host population. Optimal virulence suggested the relationship between host and parasites in ecosystem. The parasite's fitness is measure by how effective it is in transmitting offspring to hosts. Virulence is considered by most biologists to be an unavoidable consequence of host resource exploitation (Dybdahl and Storfer, 2003). In order to live longer in a host body a pathogen should evolve to minimize virulence. The agreement was that after some time, destructiveness directed and parasitic connections developed toward beneficial fundamental interaction . This linear perspective has been tested. A pathogen that is excessively limited …show more content…
These three simulation help to explain the life chronicle strategy of parasites, including reproduction, migration within the host, and virulence.The three hypotheses are the trade-off hypothesis, the short-sighted evolution hypothesis, and the coincidental evolution hypothesis. All of these pass ultimate explanations for virulence in pathogen s. The trade-off hypothesis stated that at one time, some biologist argued that pathogens would tend to evolve toward ever decreasing virulence because the death of the host is ultimately harmful to the pathogen living inside. For example, if the host dies, the pathogen population inside may die out entirely. Therefore, it was believed that less virulent pathogens that allowed the host to move around and interact with other hosts should have greater success reproducing and dispersing. But this is not necessarily the case. For example, if the host dies, the pathogen population interior may die out entirely. Therefore, it was believed that less virulent pathogens that allowed the host to movement around and interact with other should have greater success reproducing and dispersing. Pathogen strains that kill the host can multiply in frequency as long as the pathogen can transmit itself to a new host, whether before or after the host dies. The development of virulency in pathogens is a balance between the costs and welfare of virulency to the pathogen. For example, …show more content…
These traits include the ability to reproduce sooner, reproduce faster, reproduce in higher numbers, live longer, survive against antibody, or survive in parts of the body the pathogen does not normally infiltrate. These traits typically arise due to mutation , which occur more frequently in pathogen populations than in host populations, due to the pathogen rapid lifetime and immense numbers. After only a few lifetime , the mutations that enhance rapid reproduction or dispersal will increase in frequency. The same mutations that enhance the procreation and dispersion of the pathogen also enhance its virulency and causing much harm. If the pathogen's virulency kills the host and interferes with its own transmitting to a new host, virulency will be selected against. But as long as transmission continues despite the virulency , virulent pathogens will have the advantage. So, for example, virulence often increase within families, where transmission from one host to the next is likely, no matter how sick the host. Similarly, in crowded conditions such as refugee camps, virulence tends to increase over time since new hosts cannot escape the likelihood of transmission
Thomas disccuseed thr “paranoid delusions on a societal scale,” that we have against human diseases or our “enemies.” The book contiuniuously uses anaphora by saying that diseases result from “inconclusive negoitions for symbiosis” and misinterpretation of biology” The fact that bacteria can only be harmful from practiacally harming themselves is an interesting point to point out. That shows the reader that the only way they could be harmed from bacteria, wouls be if the bacteria had gotten itself “sick” first. Thomas talks about certain microorganisms that have “advantages in their ability to affect himan beinhg, but that there is nothing to be gained, in an evolutionary sense, by the capacity to caue illness or death.” Another reassuraing statement for readers is when he says, pathogenicy is a disadvantage for most microbes because they are carrying
However, evidence such as fossils is more than enough to lend support and disprove any other theory to the development of species. Examples used by Root-Bernstein and McEachron also provide strong support to evolution. The authors detail how natural selection works in both insects and germs to create organisms better adapted to methods of control. Disease used to run rampant, until the creation of vaccines which led to many diseases becoming extinct. Root-Bernstein and McEachron note that the diseases that have survived to this day have been constantly mutating and evolving to become more resistant to any attempts at suppression. The same can be said for insects that have been consistently exposed to pesticides. The ones that survived the pesticides were able to reproduce and pass along a resistance to their offspring which in turn makes the species more resilient and better suited to their
Bloodborne pathogens are viruses that deteriorate cells within the body. A virus is a submicroscopic parasitic organism that feeds on cells. Viruses are dependent on cells for their nutrients so the virus survive and reproduce. Every virus consists of either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). A virus can contain a strand of one or the other, but not both. This RNA or DNA is contained within a protein shell for protection. A virus is a parasite that is dependent upon cells for metabolic and reproductive requirements. By using the cell the virus makes the host very ill by redirecting cellular activity to make more viruses.
Kopp, Elizabeth, and Medzhitov, Ruslan. “A Plague on Host Defense.” The Journal of Experimental Medicine. .
The objective of the host is to "escape" from the pathogen. This can be done through the use of the immune system or by quickly dying. When a host dies with the pathogen still inside, the pathogen dies as well. Resistance to invaders evolved as a result of the development of the mechanism of immunity. The development of immunity depends on the recognition of differences in chemical structures of substances.
This presents a potent example. With a pathogen like a cold, generation time is short, mutation rates are high, and genetic information can spread rapidly through a population. Therefore, evolution (a shift in gene frequencies within a population through time) can occur in weeks (as opposed to the slower pace most commonly associated with evolution). Evolution occurs via natural selection. Pathogens meet the requirements of natural selection by having variability of heritable traits which impact their reproductive success in comparison to others in the population. Consider the heritable and highly variable trait of virulence. Evolution predicts that those pathogens with high virulence must also have successful transmission when their host is
Merriam-Webster defines ‘parasite’ as ‘an organism that lives in or on another organism and benefits by deriving nutrients at the host 's expense’.
Besides reproduction, a microbe needs a suitable environment to survive. In most cases this environment is a large animal population. With this type of environment a microbe is able to survive by, ironically, not killing everyone off. If a population is small and dense, the microbe will spread to all the animals in the immediate area and, if lethal, kill the entire species off. This not only ends the existence of the animal in this immediate population, but the existence of the microbe since it has no carrier to leach itself to. Therefore, the ideal population for a deadly microbe is a population t...
131). This has happened because of modern methods of farming of wanting animals or crops that is genetically similar and easier to care for. It has become easier to produce food because of the large scale that is now used for farming. (Roberge 2015). With this low diversity, the resistance to a disease is reduced or gone, and it is harder to find a gene that can stop the disease (Roberge 2015). The industry having low genetic differences in a species makes the impact from an attack worse, increasing the damage it does to everyone. A person could launch an attack at fewer points since the disease could easily spread because the resistance is
Pathogens are a type of microorganism that spreads viral and bacterial diseases. These diseases when present in human blood and body fluids are known as blood borne pathogens, and can spread from one person to another. (Worcester polytechnic institute) The most serious types of blood borne diseases are the hepatitis B virus (HBV) and hepatitis C virus (HCV), which can cause liver damage; and HIV (human immunodeficiency virus), which is responsible for causing AIDS (acquired immune deficiency syndrome). The blood borne pathogens can be spread when the blood or body fluids (semen, vaginal fluid, breast milk, and amniotic fluid) of an infected individual comes into contact with mucous membranes or an open sore or cut on the skin of another person. Mucus membranes are located in the eyes, nose, mouth, and other areas as well. ("Bloodborne pathogens: MedlinePlus Medical Encyclopedia") Two of the most common ways that pathogens are transmitted is through the exchange of fluids during sexual intercourse or by sharing infected IV needles. (Worcester polytechnic institute)
our everyday lives bacteria is constantly surrounding us, some of the bacterium that we encounter are beneficial to us but then there are the ones that are severely detrimental to our health. The way that they effect a persons body can differ from person to person. Many of the “microscopic foes” are very resilient and have a very fast reproduction rate. Not only do they reproduce quickly they sometimes seem to outsmart our immune system and not allow our bodies to fight the infection making it almost impossible to stop them. One thing that a lot if people rely on is the assistance of prescription drugs to get them better but even the drugs are not being effective and we can’t stop the pathogens from invading our personal places such as work, home, school, or anywhere. Even though modern medicine is advancing the pathogens could still get the get the best of us. The scary thing is we never know when the next pandemic or epidemic is going to arise. All it needs is some ordinary microbe to swap genes with a deadly germ to produce a “super pathogen” and it could happen to anyone, anywhere, as it did to Jeannie Brown who is from “our neck of the woods”.
...sease will spread to become an outbreak as it has a higher likelihood of spreading throughout the population before it is recognized as a new disease and treatment has begun. Factors such as high population density, high speed air travel and antibiotic resistance aid the spread of the disease and contribute to it becoming an outbreak. Epidemiology and other safety measures aid in the protection of the population from outbreaks of disease and alter the susceptibility of the human race to outbreaks of disease.
On the other hand, cells that have resistance from the start or acquire it later may survive. At the same time, when antibiotics attack disease-causing bacteria, they also attack benign bacteria. This process eliminates drug-susceptible bacteria and favors bacteria that are resistant. Two things happen, populations of non-resistant and harmless bacteria are diminished, and because of the reduction of competition from these harmless and/or susceptible bacteria, resistant forms of disease-causing bacteria proliferate. As the resistant forms of the bacteria proliferate, there is more opportunity for genetic or chromosomal mutation (spontaneous DNA mutation (1)) or transformation, that comes about either through a form of microbial sex (1) or through the transference of plasmids, small circles of DNA (1), which allow bacteria to interchange genes with ease.
of parasites do not kill the host from feeding, whereas a predator will kill it’
The movie Outbreak is a wonderful portrayal of how the Chain of Infection works in an epidemic and pandemic outbreak of a disease. The shows how quickly the disease gained power and was responsible for sickness and death in a small community. Pathogens that invade the body have 5 requirements for a successful invasion on their host whether it is a human or animal. I will further review how the movie successfully reflects the reservoir/host, portal of exit, mode of transmission, portal of entry and susceptible host to provide the perfect Outbreak of the disease. The same model still used today in science.