Infection - infection means something different from “ disease





INFECTION :

   The word “infection “ means something  different from “ disease,” although the two terms sometimes are confused. Disease is a general word that  describes any abnormality of the human condition or  something that interferes with the normal ,healthy functioning of the body. Diseases include infection  and infestation , among others. Infection is a term that refers. Specifically to any abnormal condition caused by a microbe, such as a bacterium ,virus, or parasite , that has invaded  another organism (like a human )and interfered with some aspect of its function.

    An infestation is similar to an infection.it refer to any abnormal condition cause by an organism larger than a microbe , such as an insect, louse or worm. the phrase “infectious diseases “ is used to refer  to both infections ,regardless of the severity of the condition. An infection beneath a fingernail and  a serious case of hepatitis –C both are considered infectious diseases.

(AINFECTION CONTROL:

infection prevention and control measures aim to ensure the production of those who might be vulnerable to acquiring an infection both in the general community and while receiving care due to health problems, in a range of setting . the basic principle of infection prevention and control is hygiene  

·         infection control is the discipline  concerned with preventing nosocomial or health car-associated infection, a practical (rather than academic ) sub discipline of epidemiology .

·         It is an essential, though often under recognized and under supported , part  of the infrastructure of health care.

·         Infection control address factors   to the spread of  infections infection within the health the care setting ( whether patient to patient  from patient of staff and from staff to patients to staff and from staff  to patients, or among –staff) including prevention (via hand hygiene /hand washing, cleaning /disinfection /sterilization, vaccination, surveillance ),monitoring/investigation of demonstrated or suspected spread of infection within a particular healthy care setting (surveillance and outbreak investigation ), and management (interruption of outbreak).

    It is on this basis that the common title being adopted within health care is “infection prevention and control”

1.Nature of infection  :

            Infection is invasion of an organism’s body by tissues by diseases  causing agent , their multiplication ,and the reaction of host tissues to these organism and the toxins they  produce. Infectious diseases, also known as transmissible diseases,  or communicable  diseases, comprise clinically evident illness(i.e.  chart eristic medical signs and symptoms diseases) resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism.

                 Infection are caused by infectious agent such s viruses, viroid’s and prions, micro-organisms such as bacteria, nematodes such as round worms and pinworms arthropods such as ticks, mites fleas and lice, fungi such as ringworms, and other macro parasites such as tapeworms.

     2. Chain  of infection Transmission :

                 Infectious disease result from the interaction of an agent , a host, and an environment. most of these diseases follow a typical chain of infection starting with a reservoir that contains pathogen and ending  with an infected host. Under standing the chain of infection can help with both the prevention and treatment of infectious diseases

 

The chain of Infection :

Definition :

          The chain of infection is made up of six different links: Pathogen, reservoir ,portal of exit, means of transmission , portal of entry, and the new hot.

     Each link has a unique role in the chain and each can be interrupted, or ‘broken ‘, through various means.

1.      Infectious Agents/The Pathogen :

·         This is the disease causing organism.

·         For many illness and diseases this is a virus or bacterium.

·         In order to break this link, various methods can be us, including   the pasteurization of milk, the chlorination of drinking water , or the use of disinfectants.

2.      The Reservoir :

·         This is the natural environment that the pathogen requires for survival.

·         Reservoirs can be a person , an animal, or an  environment  component ,such as soil or water,

·         This link can be broken through medical treatment and testing, insect and rodent eradication , or quarantine.

3.      The portal of Exit  :

·         This link is needed for the pathogen to leave the reservoir.

·         If the reservoir is a human, then the portal of exit may be saliva , mucous membranes, feces, blood, or nose or throat discharges.

·         By using barrier method , such as condoms or masks, or covering the mouth while coughing , this link can be broken.

 

4.      The means of Transmission  :

·         The pathogen can be transmitted either directly or indirectly.

·         Direct transmission requires close association with the infected host, but not necessarily physical contact.

·         Indirect transmission required a vector, such as n animal or insect.

·         The link can be broken through hand washing, safe sex practices, or avoiding contact with infected individuals.

5.      The portal of entry;

·         Entry of the pathogen can take place in one of three ways: penetration, inhalation , or ingestion

·         The level and severity of an infection may depend on the depth of penetration.

·         Similar to the portal of exit, barrier methods, such as condoms or masks , can be used to break this link , along with other methods, such as insect repellants.

6.      The new host :

·         Once in the new host , various factors influences the severity of infection , including the strength of the immune system and the reproductive rate of the pathogen.

·         Immunization , health promotion , and medical  treatment can be used to break this link in the chain.

 Example :

·         An example of illness resulting from the chain of infection is the common cold.

·         In this case, the pathogen is often referred to as rhinovirus.

·         The reservoir is the another person carrying this virus,  who then propels the virus into the air via a portal of exit, such as a cough or sneeze.

·         The route of transmission is direct to the new host, which takes place through inhalation (the portal of entry) of the virus

 

     Six Elements of infection  :

         There are six elements in the cycle of infection, and all six must be present before the transmission of infection can take place .   

 Elements  in the cycle of infection

 Explanation

Common examples

Infectious agents

When germs enter  the body, they can cause illness

·         Bacteria , virus, fungi, protozoa

Reservoir

Where germs normally live and multiply

·         Humans ,

·         contaminated food , water , toys , sports equipment’s.

·         insects animals , soil

Portal of exit

How germs leave in the body

·         Respiratory tract,

·         intestinal tract,

·         open wounds

·         urinary / genitourinary tract

·         blood and body fluids

Transmission

How germs are spread. Refers to next page for a detailed explanation oh how infections spread.

·         Direct physical contact

·         Respiratory droplet

·         Stool( fecal – oral route )

·         Contact with blood / body fluids

·          Indirect contact

·         Needle stick injury

·         Ingestion of contaminated food and water

·          Contaminated dust particles

·         Contaminated objects

·         Insects/ animals

·          

Portal of entry

How germs enter the body

·         Respiratory tract

·         Intestinal tract

·         Urinary / genitourinary tract

·          Open wounds

·          Mucus membrane , e.g. eye , mouth

Susceptible host

A person who gets an infection because he / she is unable to successfully fight the infection

·         Infants , elderly and debilitated

·          Persons who are ill

·          Children who are not fully immunized or have underdeveloped immune system

·          Person taking certain drugs that lower their defences against germs

·          Persons with underlying disease conditions that lower their defence  against other germs.

     

 

    3. Defence Against infection Natural and Acquired  :

           Infection are the most common cause of human disease. They range from the common cold to debilitating condition like  chronic hepatitis to life –threating disease such as AIDS. Disease-causing microbes (pathogens) attempting to get into the body must first move past the body’s external armour, usually the  skin or cells lining the body’s internal passageways.

·         The skin provides an imposing barrier to invading microbes. It is generally penetrable only through cuts or tiny abrasions.

·         The digestive and respiratory tracts both portals of entry for  a number of microbes-also have  their own level of protection.

·         Microbes entering the nose often cause the nasal surfaces to secrete more protective mucus, and attempts to enter the nose or lungs can trigger a sneeze or cough reflex to force microbial invars out of the respiratory passageways.

·         The microbes  survive the body’s front-line defenses, they still have to find a way through the wall of the digestive, respiratory , or urogenital passage ways to the underlying cell.

·         These passageways are lined with tightly packed epithelial cell covered in a layer of mucus , effectively blocking into deeper cell layers.

Acquired Defences :

        The immune response involves specific body responses to an invading foreign protein, such as bacterial or in some cases , to the body’s own proteins.

·         Inflammatory Response: The inflammatory response is a protective mechanism that eliminates the invading pathogen and allows for tissue repair to occur.

·         Inflammation Helps the body to neutralize, control or eliminate the offending agent and to prepare the site for repair .

·         The cardinal signs of acute infection are redness, heat, swelling, pain and loss of function and usually appear at the site of injury or inflammation.

·         Components of inflammatory process.

(a)    Vascular stage.

(b)   Cellular stage.

(a)   Vascular Stage :   In vascular stag small blood vessel constrict in the area followed by vasodilation of arterioles and venules that supply the area. This increase in blood flow results in redness and heat in the area . histamine also is released leading to an increased permeability of vesls, which allow protein-rich fluid to pour into the area. At this point ,swelling pain and loss of function can occur. The foreign material is called an antigen and the body commonly responds to the   antigen by producing an antibody . this antigen antibody reaction is also known as humoral immunity.

(b)   Cellular stage :

    It also helps the body defends against invaders is a cell mediated defense or cellular immunity. It involves an increase in the number of lymphocytes that destroy or react ith cell the body recognizes as harmful.

 


Post a Comment

0 Comments