Host resistance and immunity - Essay Example

AGENTS OF INFECTIOUS DISEASES al Affiliation) Introduction Biological agents such as parasites and viruses cause infectious diseases. Microbes invade host organisms and lead to disease infections. Pathogens are microbes that cause these diseases. Bacteria and viruses are the most common pathogens that cause diseases. These microbes cause diseases by either stimulating the immune system of the host body to mount a defense reaction or interrupting an essential body process. Immune responses against the microbes are often more destructive than the direct damage caused by the microbe.

The damages include inflammation and high fever. A detrimental colonization of the pathogen in the host body results in an infection. Variables that determine the outcome of a host body encounter with a pathogen include the infectivity, pathogenicity, virulence, toxigenicity, resistance, and antigenicity of the pathogens (Qureshi, S. 1999).There are however three characteristics that ought to worry any individual exposed to a disease. They include pathogenicity, virulence, and toxigenicity.PathogenicityPathogenicity of an infection involves a mechanism that leads to the initiation of signs and symptoms of the bacterial or viral infections.

An environment that favours the growth of the agent in the host body and its ability to damage the host determines the resultant outcome of the association between disease causing agent and the host body. High pathogenicity levels increases the risk of acquiring an infection. Therefore, once an individual gets exposed to a disease, the pathogenicity of the disease causing agent determines the possibility of the infection. On the other hand, if the bacteria or parasite turns out to be non-pathogenic, the risks of getting infection are low (Qureshi, S. 1999).VirulenceVirulence refers to the severity of an infection and therefore a highly virulent strain produces severe infections.

High virulent strains utilize resources from the host body and leads to tissue damage in host bodies. This increases the possibility of an infection and may lead to death of the host. Virulent strains speed up their growth in order to obtain transmission to new hosts. These strains struggle to gain subsequent transmission before killing the former host. Therefore, once an individual gets exposed to a disease, the virulence of the disease determines the level of damage. To counter an infection, one need to consider immediate treatment before multiplication of a strain that may be detrimental to one or more individuals (Sansonetti, P 2010).

ToxigenicityToxigenicity refers to the ability of the agent to produce a toxin, which forms the main disease-causing element in a virus or bacteria. There are two types of toxins produced by disease causing parasites. They include exotoxins and endotoxins. Endotoxins of gram-negative bacteria are majorly complex lipopolisacharides from bacterial cell walls and they exhibit heat stable properties. Endotoxins exhibit symptoms such as fever; hypotension, leucopenia, and May often lead to death. Exotoxins on the other hand have various medical importances though they also cause diseases such as diarrhea.

In this case, the types of toxins released by a strain determine the severity of a disease infection. The more fatal the toxins, the higher the possibility of a severe infection (Sansonetti, P 2010).Secondary characteristicsInfectivity is the ability of an agent to enter a host and multiply into an infectious dose thereby causing an infection. However, the fact that an agent can enter a host and cause an infection turns out to be less important. The most important part is the severity of the infection.

Infections are normal occurrences in our day-to-day activities some are fatal while some can be easily be treated. Therefore, the major concern ought to be the level damage likely to be caused by the infection (Sansonetti, P 2010).Resistance refers to the ability of an agent to. Survive under adverse environmental conditions. However, this aspect does not pose any danger because there are two types of pathogens. Pathogenic and non-pathogenic parasites. Some agents can survive under adverse environmental conditions but do not pose any danger to the host body; on the contrary, they find a balanced environment with the host body leading to a symbiotic kind of relationship that leads to mutual benefit between the agent and the host (Linnemeyer & paul, 2008).

Antigenicity refers to the ability of the agent to induce antibody production in the host. Agents with high antigenicity have low re-infection rate while agents with low antigenicity rate have a high re-infection rate. However, I would argue that re-infection ought not to be the cause of worry once an individual gets exposed to a disease. The important step needs to be dealing with the first infection other than concentrating on gaining acquired immunity through the infection. The disease could be fatal enough to compromise your immune system and may lead to death before one gets to benefit from the acquired immunity (Linnemeyer & paul, 2008).

ConclusionAll these characteristics are vital when considering a means to counter-attack a disease but it’s clear that some are of more importance than the others while trying to counter attack an infection.ReferencesLinnemeyer, Paul A., (2008) Understanding the Immune System: An Overview. Seattle Treatment Education Project. Retrieved December 3, 2012 from at http://www.thebody.com/content/art1788.html.Qureshi, S. T., Skamene, E., & Malo, D. (1999). Comparative genomics and host resistance against infectious diseases.

Emerging Infectious Disease, 5(1). Retrieved December 3, 2012 fromhttp://www.cdc.gov/ncidod/eid/vol5no1/qureshi.htmSansonetti, P. J. (2010). Bacterial virulence: Basic principles, models and global approaches. Weinheim: Wiley-VCH.