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Pathogen and Disease

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Pathogens are described as foreign objects that enter the body of a host to cause bodily harm. They are microorganisms that act as agents of illness to bodies of other organisms. Pathogens may be viruses, bacteria, protozoa or fungi. All these have the ability to cause infections in the organisms which they invade.

Features in control of cross infection

Infection control refers to the practice of preventing healthcare related illness. It involves all measures put in place to ensure that infections are checked and their rise and spread kept to a mere minimal. In the case study, a patient is suspected of being infectious with TB. The hospital management ought to have taken steps to ensure that the spread of the virus is contained. However, they never took the action. Hence, the virus caused the death of the seven patients.

The features in control of cross examination include hand hygiene which has a role to ensure that any food swallowed is fit for consumption. Consuming fit food guarantees the avoidance of introducing any germs into the body. Therefore, what is consumed should be clean. Cleaning, disinfection and sterilization also play a role in promoting healthy conditions thus keeping germs at bay. Such measures are instrumental in ensuring that infections are kept to a bare minimum. Other measures include usage of personal protective equipment, preference for antimicrobial surfaces, vaccination, isolation and training of all the infected people. The hospital in the case study should have exercised some of these measures in a view to preventing the spread of the virus that is behind the death of the seven patients. They could have separated the ailing patient who was suspected to be carrying the TB virus or used other measures like protective covering to stop the spread of the virus at all the costs. Since this was not done, the worst happened and the patients died.

The best practices in cross infection prevention would include adhering to the prescribed health standards in order to stop the spread of any pathogens that may lead to infections. Where a patient is suspected to carry the virus, isolation and proper medication should be accorded to the ailing person so that the pathogen is treated using the appropriate standards. The important action is therefore to prevent occurrence of pathogens and where they arise, measures to contain the spread should be put in place and the subsequent medical attention be accorded to the patients.

Difficulties caused by resistant bacteria

Some bacteria become resistant to antibiotics applied against them. This could be due to incompletion of the prescription or unnecessary use of antibiotics even when one is not supposed to use them. In such cases, bacteria cannot be controlled or killed by antibiotics. Avoiding unnecessary prescription can reduce antibiotic resistant bacteria. This could lead to experiencing more lethal diseases and subsequently present public health issue. Once some antibiotics are used on the resistant bacteria, the bacteria tend to mutate leading to the formation of more resistant ones. Therefore, the effectiveness of the antibiotics is immensely reduced. From the case study, if the TB is not treated, or if medication is not given to a full dose, the virus mutates into a resistant one that does not respond to the antibiotics that are administered. If this happens, no medication would be used to rescue the patient, it would lead to the death of the patient. Therefore, correct prescription must be adhered to avoid potentially dangerous situations (Walters 2002).

The role of the immune system in combating disease

Immune system is a structured and well coordinated network of biological processes that protect the body against any attacks of infection. To effectively perform such a duty, it must be able to detect a whole range of pathogens and its agents or germs and dissociate it from the host’s own healthy tissues and cells. The immune system protects organisms against infections by use of a layered defence of ascending specificity. The immune system has the various components as shown below. Further, reference to how they operate to protect the body is made (Walters 2002).

Physical barriers

The physical barriers deter pathogens like bacteria and viruses from accessing the hosts. Where a germ or an infectious agent breaks the blockade, there is the innate immune system that gives urgent and immediate, but non-specific response. Innate immune response systems are found in all plants and animals. When foreign bodies evade the innate protective framework, vertebrates use a layer of protection which is an adaptive immune system that defends the body. This is an activated innate response. In such a case, the immune system adapts its response during an attack or infection to improve the recognition of the pathogen. The improved response is then maintained after the pathogen has been destroyed and extinguished in a form of an immunological memory and allows the adaptive immune system to mount fast and strong attacks each time the germ in question makes contact with the body (Pamela 2007).

Surface barriers

The body has many barriers which protect organisms against infections. They include chemical, mechanical and biological barriers. The cuticle in leaves, the exoskeleton in insects, shells of eggs and skin present examples of mechanical barriers. These constitute a fast line of defence against infection. Other organs of the body that cannot be mechanically be protected as above include the lungs, intestines etc. Through coughing and sneezing, some organisms mechanically eject pathogens and other foreign bodies from the respiratory tracts. The action of flushing tears urine also expels pathogens from the body while mucus from the respiratory and gastro internal tract helps to detect and trap pathogens.

Chemical barriers too help to fight infections through prevention. The skin and the respiratory system produce antimicrobial peptides such as beta defences. Enzymes in saliva and breast milk also have protection mechanisms. Semen contains elements of zinc which help to kill pathogens. In the stomach, gastric acids and other enzymes aid in digestion of food and offer as defence against any ingested foreign objects.

In the genitourinary and gastrointestinal tracts, commensal flora that serves as a biological barrier through mounting competition with bacteria that are likely to lead to infection is produced. They compete for food, space and sometimes change the conditions within the environment. This keeps the pathogenic bacteria in check thereby significantly reducing their population (Smith 1997).

Innate immune system

Pathogens that successfully get their way into the body of the host encounter the cells and provisions of the innate system. This system is triggered when microbes are identified by pattern recognition receptors which recognise components that are conserved among broad groups of microorganisms. Alternatively, when damaged all send out alarm signals. This system is non-specific, meaning that it responds to pathogens in a generic way. It does not confer long-lasting immunity against a pathogen. It is the dominant system of host defence in many organizations (Smith 1997).

Humoral and chemical barrier

Inflammation constitutes one of the earliest responses by the immune system in response to an infection. Inflammation is produced by eicosanoids and cytokines, which are released by injured or infected cells. The cytokines and other chemicals recruit immune cells to the site of infection and promote healing of any damaged tissues following the destruction of pathogens (Pamela 2007).

The complement system

It is a system that attacks the surfaces of foreign cells. It forms the main humoral part of the innate system. There are many species which complement systems including non-mammals like plants, fish and other invertebrates (Pamela 2007).

Cellular barriers

White blood cells act independently. They are the second arm of the innate immune system. The innate leukocytes include phagocytes, mart cells, eosinophilis, basophilis and normal killer cells. These identify and destroy microorganisms either by attacking big pathogens through contact or through engulfing and then killing microorganisms. They are also vital mediators in the activation of the adaptive immune system (Pamela 2007).

Adaptive immune system

This evolved in vertebrates and allows for a stronger immune response as well as immunological memory, whereby each pathogen is remembered by a particular antigen. It is antigen- certain and requires the identification of specific antigens during antigen presentation. This is aimed at allowing for generation of responses which are tailored to specific pathogens. Where a pathogen infects a body more than once, the specific memory cells are invoked to quickly eliminate the germ (Pamela 2007).


These are cells of a special type of leukocytes. Its main types are B cells and T cells. B cells are involved in the humoral immune response whereas T cells are involved in cell-mediated immune response. B cells identify pathogens when antibodies on their surfaces bind to a specific foreign particle. This antigen/antibody complex is taken up by the B cells and processed by proteolysis into peptides. The B cell then displays these antigenic peptides on its surface MHC cells II molecules. These antibodies circulate in blood plasma and lymph and bind pathogens expressing the antigen and mark them for destruction by complement activation or neutralise challenges directly by producing bacterial toxins or by interacting with the receptors that viruses and bacteria use to infect cells (Malasig 2000).

Natural immunity is the state of one being able to resist infection or illness by the help of the immunity received from the parents. One is born with this type of immunity. The body produces its own white blood cells which also produces antibodies that protect the body against infection. On the other hand, acquired immunity is a defence against infection that is received during one’s lifetime. It is built up after suffering and overcoming an illness. It is immunity which has been acquired via infection or vaccination or by transfer of antibody from an immune donor. Further, active immunity develops when vaccines are used for health purposes after exposure to certain antigens. The body creates its own antibodies after exposure to an antigen. Eventually, passive immunity reflects a case where immunity to particular antigens resulting from genetic traits that are passed on from parents rendering the offspring immune to a particular pathogenic threat. It occurs when antibiotics are passed to one’s body other than from their own bodies (Walters 2002).

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