Question

2. SELECT AN INFECTIOUS AGENT AND CREATE THE CHAIN OF INFECTION AS PER THE MODEL. IDENTIFY WHAT STEPS CAN BE TAKEN TO BREAK THAT CHAIN. (note – you cannot select E. Coli but you can get creative!).

Let's examine the chain of infection as it applies to this situation.

INFECTIOUS AGENT

RESERVOIR

PORTAL OF EXIT

MODE OF TRANSMISSION

PORTAL OF ENTRY

SUSCEPTIBLE HOST

Answer 1

Infectious disease can be caused by an agent, often called as microorganism. This microorganism can either damage or weakened a person’s health. Infectious disease can be spread from one person to another. They can either directly (skin contact) or indirectly ( contaminated food or water). There are various agents which cause infection like bacteria, viruses, fungi, protozoans, and worms.

Chain of Infection:

Infectious agent: Bacteria are able to survive within our human body. The capsule which surrounds the bacteria plays an important role in producing diseases. They also release toxins that might cause damage tissues. They are very large to be seen under a light microscope. eg.Streptococci are 0.75 micrometre in diameter. Bacterial infections are mainly caused by pneumococci, staphylococci, and streptococci.

Reservoir: Reservoir can be person, animal, arthropod, plant, soil and substance where an infectious agent can lives and multiplies for their survival, and then it reproduces. Human beings are the reservoir for infections like measles, rubella, chicken pox, etc. So, for Streptococci reservoir is we human. Reservoirs are long-term host of an infectious disease.

Portal of Exit: Portal of exit is the media through which a microorganism leave their host to enter into another host. So, poratl of exit could be the nose or mouth when someone sneezes or coughs and in faeces. In particular, the throat is colonized, preferably in the winter months. As virulence is the M protein, which enables the propagation of the streptococci in the host only.

Mode of Transmission: Once the pathogen enters the host cell it reproduces in such a manner that it can be transmitted to a susceptible host. Transmission takes place through respiratory droplets or it can be direct contact with infected people or carriers. Transmission through objects are very rare. Sometimes outbreaks might occur due to intake of contaminated foods.

Portal Entry: The pathogens gain entry into the human host through the skin and mucous membranes i.e the tissues that line the nose, mouth, and upper respiratory tract. The infectious agents may cause disease like boils. It may invade into bloodstream and carried throughout the body. Thus, it produce blood infection or other infection such as meningitis. While those agents swallowed in food and drink can attack the wall of the intestinal tract and cause disease. Infectious agents can also enter through the genital tract, causing the acute inflammatory reaction of gonorrhea in the genital and pelvic organs.

Susceptible Host: The disease like pharyngitis and tonsillitis are common in children aged 5 to15 years. Most of us have developed a throat or skin infection through lifetime. But the throat infections may be subclinical, that means health is not altered. But people having chronic illnesses such as cancer and diabetes, those on dialysis and those who are under medications like steroids have a higher risk than healthy people.

Steps to be taken to break the chain: No vaccines are available till now. Most bacterial infections can be treated with antibiotics. On the other hand foodborne disease can be prevented by pasteurising milk and milk products, and careful storage of foods. The role of antibiotic therapy may be appropriate for those at higher risk of infection. People with skin lesions should be excluded from food handling until the infection is healed properly.