[Grace]

Thinking of your current or a past practice area provide an example of the train of transmission specific to that area. Fill in all ‘links’ in the chain with an example for each link:

Infectious Agent:

Reservoirs:

Portals of Exit:

Modes of Transmission:

Portals of Entry:

Susceptible Host:

[Priscilla]

Residents in Long-Term Care Homes
Locations: Dining room, Recreation area, Hallways

Infectious Agent: SARS-CoV-2 (Covid-19)

Reservoirs: Residents can be symptomatic, pre-symptomatic, and asymptomatic carriers.

Portals of Exit: Respiratory tract eg. coughing, sneezing, talking, breathing, shouting.

Modes of Transmission: Droplet (main mode)
Respiratory droplets from coughs, sneezes, or speech within close range, usually <2 meters.
Airborne transmission in enclosed & poorly ventilated spaces such as smaller aerosols that remain suspended in air for longer periods.

Portals of Entry: Respiratory tract such as nose & mouth
Mucous membranes such as eye, nose & mouth.

Susceptible Host: Anyone without immunity such as Elderly individuals, Immunocompromised individuals, Unvaccinated individuals.

[Bolatito Esther]

1. Infectious Agent: Escherichia coli (E. coli) is a common bacterium that causes urinary tract infections, often associated with the use of catheters.

2. Reservoir: The patient’s bowel or skin flora, which can harbour bacteria such as Pseudomonas aeruginosa.

3. Portal of Exit: Bacteria present in urinary secretions can exit through the urethral meatus during urination or drainage.

4. Mode of Transmission: improper sterile technique during catheterization or not placing the drainage bag below the bladder level, or a patient who uses a catheter for a long time

5. Portal of Entry: The urinary tract mucosa or the insertion point of the catheter provides a pathway for bacteria to enter the bladder.

6. Susceptible Host: Catheterized patients, compromised immune systems or the elderly age, are more vulnerable to infection.

[Carolina]

Hi Esther,
Thank you for sharing. It is a very good example and I am seeing this in my every day practice in a medicine unit. It is most common in elderly population. However, teaching and following the IPAC principles would help to break the transmission.

[Gemma]

Hi Esther, Thank you for sharing the chain of transmission of e. coli. This really drives the importance of using sterile techniques for procedures such as catheterizations. As we as healthcare providers have the responsibility to do our best to break the chain of transmission to prevent infections from occurring in our patients

[Denise]

Thanks for your clear and well-organized breakdown of the COVID-19 chain of transmission in a long-term care setting. I agree that this environment presents a high-risk situation due to the vulnerability of the residents and the close contact nature of care.
I especially appreciated how you highlighted environmental surfaces as reservoirs, it is a reminder of how critical regular cleaning and disinfection are in these settings. Also, your emphasis on proper IPAC protocols as a key defense against infection was spot on. Even though vaccinations have made a difference, it is true that breakthrough infections still occur, particularly in immunocompromised individuals.
It also made me think about the importance of staff education and compliance. Sometimes transmission happens not because people do not care, but because they are unaware of how even small lapses (like improper mask use or hand hygiene) can break down infection control barriers.

[Shanna]

During my clinical placement on a medicine unit, I saw an example of how infection can spread through the chain of transmission. This involved a patient with C. difficile, a bacteria that causes diarrhea.

Infectious Agent: C. difficile bacteria

Reservoirs: The infected patient

Portals of Exit: The patient’s stool

Modes of Transmission: Indirect contact (a healthcare worker touches a dirty surface or doesn’t clean their hands properly).

Portals of Entry: The mouth, if someone eats or touches their face with dirty hands

Susceptible Host: Another patient who is older, sick, or taking antibiotics

It is important to follow proper hand hygiene, use PPE, and clean equipment to stop the spread of infection.

[Nel]

Hi Shanna!
Thank you for sharing this clear and practical example of how the chain of infection works, especially in the context of C. difficile. Your explanation reinforces the crucial role of proper hand hygiene, PPE use, and thorough environmental cleaning in protecting patients. Personally, if I had to choose one type of isolation I least prefer, it would be C. difficile – not only because of the infection risk but also due to the unpleasant smell and discomfort it often brings. 

[Bolatito Esther]

Hi Mebo
Hepatitis A virus is such a good example.
It is a contagious liver infection caused by the hepatitis A virus. It is usually spread through ingestion of contaminated food or water or close contact with an infected person. Nurses need to recognize the symptoms such as Fatigue, nausea, abdominal pain, jaundice, dark urine, and fever. Some individuals, especially young children, may be asymptomatic.
Good hygiene practices, proper handwashing, and vaccination are highly recommended, especially in outbreak situations.

[Shanna]

Hi Priscilla,

Thanks for sharing this clear example. It shows how easily COVID-19 can spread in long-term care homes, especially in places like dining rooms and recreation areas. I like that you mentioned both droplet and airborne spread. It reminds us why good ventilation, masks, and distancing are important. Older and sick residents are at higher risk, so following all steps in the chain of transmission is very important to keep patients safe.

[Nel]

Infectious Agent: VRE
Reservoirs: contaminated equipment (VS machine, stethoscope, glucometer), colonized oncology patient
Portals of Exit: patient’s skin
Modes of Transmission: indirect contact via contaminated equipment or hands of HCP who have not performed hand hygiene
Portals of Entry: mucous membranes, non-intact skin, hands touching face
Susceptible Host: immunocompromised oncology patients

[Mae Anne Zyrene]

Hi Nel! Thanks for sharing! This shows exactly how easily we can control the spread of VRE if everyone follows the proper protocol of IPAC measures. Working as a PSW at a LTC for awhile and now transitioning as an RPN, it is very easy to compare the workload and see how it can affect the work practice of an individual! I hope everyone is always on top of their IPAC learning and knowledges!

[Mebo]

Infectious Agent: Hepatitis A virus (HAV)

Reservoirs: people infected with HAV, environment for example surfaces

Portals of Exit: feces of infected people

Modes of Transmission: through the stools of infected person

Portals of Entry: fecal -oral route i.e contact of contaminated surfaces, food handlers poor hand hygiene

Susceptible Host: Travelers to poor sanitation places, children in daycare, patients with chronic liver disease, close contact with infected people

[Gurdeep]

Infectious Agent: Clostridioides difficile ( C. diff) cause inflammation to colon and diarrhea

Reservoirs: Resident at my workplace, resident washroom and room.

Portals of Exit: body fluid and diarrhea, contaminated brief.

Modes of Transmission: contact mode of transmission

Portals of Entry: contaminated hand and contaminated utensil .

Susceptible Host: immunosuppressed older adults and resident on antibiotic.

[Mebo]

Thank you for sharing because is very common where I work
C. difficile infections can spread quickly among elderly or immunocompromised residents.
Education and training for staff on IPAC (Infection Prevention and Control) is critical.
Infected residents may need private rooms if available.

[Mae Anne Zyrene]

Location: Long-term care home
Infectious Agent: COVID-19

Reservoirs: Reservoirs can include people, environmental surfaces, water, air, and so on

Portals of Exit: Respiratory tract i.e, coughing, sneezing, talking

Modes of Transmission: COVID-19 is spread in the droplets of saliva or mucous coughed out from an infected person. And if those droplets land on and contaminate an environmental surface, the virus can potentially be transmitted by touching that surface and then rubbing one’s eyes or nose.

Portals of Entry: The portal of entry for the COVID-19 virus is when a susceptible person breathes in the virus carried in droplets from an infected person’s cough, sneeze, sing, or talk.

Susceptible Host: Immunocompromised individuals, Unvaccinated individuals, and everyone in general can still be infected if not careful enough to practice proper IPAC protocols.

[Aleksandra]

Thank you for your post. You did a great job explaining how COVID-19 spreads in a long-term care home using the chain of transmission. It shows why following IPAC practices is so important to protect residents, staff, and visitors.

In long-term care, residents are especially vulnerable because many have weakened immune systems or other health conditions. That’s why it’s so important to wear proper PPE, practice regular hand hygiene, and clean shared surfaces often. Even something as simple as forgetting to wear a mask or not washing hands properly can lead to the spread of the virus.

You also made a good point about surfaces being a possible way COVID-19 can spread. This is why environmental cleaning is a key part of infection prevention. We must also remember that staying home when feeling sick and reporting symptoms early are other important ways to break the chain.

Your post is a great reminder that everyone—staff, visitors, and residents—has a role to play in preventing infections. IPAC isn’t just about rules, it’s about keeping people safe, especially in places like long-term care where the risks are higher. Great work!

[Aleksandra]

Chain of Transmission in a Long-Term Care Home (Norovirus Outbreak)

Infectious Agent:
Norovirus – a highly contagious virus that causes vomiting and diarrhea.

Reservoirs:
An infected resident who is sick with norovirus and shedding the virus in their stool or vomit.

Portals of Exit:
The virus leaves the body through vomit or stool during an episode of illness.

Modes of Transmission:
The virus spreads through contact with contaminated hands, surfaces (like bathroom handles), or shared equipment. It can also be spread through droplets during vomiting.

Portals of Entry:
The virus enters another person’s body when they touch their mouth after contact with contaminated hands, surfaces, or objects.

Susceptible Host:
Other residents, especially older adults with weaker immune systems or other health conditions, who are more likely to get sick once exposed.

Understanding the chain of transmission helps healthcare workers break the chain and stop the spread of infection. Proper hand hygiene, cleaning, using PPE, and isolating sick residents are all ways to stop the virus from moving from one person to another.

[Shiyu]

Thinking of your current or a past practice area provide an example of the train of transmission specific to that area. Fill in all ‘links’ in the chain with an example for each link:

Example of a patient who has C. diff in the hospital.

Infectious Agent: C.diff

Reservoirs: the patient is infected with C. diff and has diarrhea.

Portals of Exit: patient’s stool

Modes of Transmission: Contact, which includes direct or indirect

Portals of Entry: mouth

Susceptible Host: an older patient who has a catheter and is receiving antibiotics

[Carolina]

In my work place (community setting). Influenza A
Infectious Agent:
Influenza A virus which is a respiratory virus that causes seasonal flu outbreaks.

Reservoirs:
patients, healthcare workers, family or community members. Particularly those actively coughing or sneezing.

Portals of Exit:
Respiratory tract – virus exits the body through droplets expelled from the nose or mouth when coughing, sneezing, or talking.

Modes of Transmission:

– Droplet transmission: large respiratory droplets land on mucous membranes within 1–2 meters.

– Indirect contact: touching surfaces contaminated with droplets (e.g., doorknobs, phones) and then touching eyes, nose, or mouth.

Portals of Entry:
Mucous membranes of the nose, mouth, or eyes.

Susceptible Host:
An unvaccinated patients with weakened immune system or a chronic illness, elderly patient or a person with asthma.

[Anthonia]

Thank you for sharing this clear example of the chain of transmission for Influenza A in your community setting. You did a great job highlighting how the virus spreads not only through droplets but also through indirect contact with contaminated surfaces, which is often overlooked. I also appreciate how you pointed out the importance of protecting vulnerable individuals, such as the elderly and those with chronic illnesses. Your reflection is a great reminder of why consistent infection prevention measures like vaccination, hand hygiene, and cleaning are so essential in reducing the spread of influenza.

[Earlnie]

Hi Carolina,

Nice job outlining the transmission chain for influenza A. I like how you emphasized both droplet and indirect contact transmission. It’s a good reminder of how quickly the flu can spread in the community. Including healthcare workers as reservoirs was a great point too. Thanks for sharing your insight!

[Anthonia]

During my clinical placement in the orthopedic unit, I cared for a patient with a surgical site infection caused by Staphylococcus aureus. The bacteria lived in the wound (the reservoir) and left the body through the wound drainage (the portal of exit). I observed that if hand hygiene wasn’t performed properly, the bacteria could spread through touch or shared equipment (mode of transmission). It could then enter another patient’s surgical wound or even through a nurse’s small cut on the hand (portal of entry). The people most at risk were other post-op patients, especially older adults or those with weaker immune systems (susceptible hosts). This experience opened my eyes to how easily infections can spread and how vital it is to follow infection control practices every single time.

[Shiyu]

Hi Anthonia,

Thank you for sharing this example. You did an excellent job of linking each part of the chain of transmission into a real clinical situation. It is true that if hand hygiene is not performed properly, the infection could easily spread to those vulnerable patients. Sometimes, healthcare workers may overlook hand hygiene, especially when the unit gets busy, but it is vital to prevent healthcare-associated infections.

[Earlnie]

MRSA in hospital

– Reservoir: infected patient (skin, nasal passage)

– Portals of exit: skin, nasal secretions, open wounds

– Modes of transmission: contact (direct and indirect – contaminated surfaces/ equipment)

– Portals of entry: broken skin, mucous membranes

– Susceptible host: hospitalized patients with a weakened immune system, recent surgery or open wound

[Gemma]

MRSA in long term care

Infectious Agent:
MRSA (Methicillin-Resistant Staphylococcus aureus) which is an antibiotic resistant bacteria

Reservoirs:
Humans, can also live on surfaces such as bed rails, bedside tables

Portals of Exit:
Broken skin, bodily fluids

Modes of Transmission:
Contact, direct skin contact with the infection (like when providing direct care)
Indirect contact: touching surfaces contaminated with the infectious agent, table tops/bed rails

Portals of Entry:
Broken skin, invasive devices (catheters)

Susceptible Host:
immunocompromised people, people in hospitals, elderly, patients with open wounds

[Fatma]

Hi Gemma ,
Thank you for sharing this clear example of MRSA transmission in long-term care settings. It highlights why consistent infection prevention is so critical, especially for vulnerable populations like the elderly and those with open wounds or invasive devices.

[Fatma]

In oncology units, patients are often immunocompromised, making them highly susceptible to infections, so understanding the Chain of Transmission is essential for prevention. The chain starts with the Infectious Agent, such as influenza, RSV, or multidrug-resistant organisms, followed by the Reservoir, which could be a person, medical equipment, or the healthcare environment. The Portal of Exit is how the pathogen leaves the reservoir, often through coughing, sneezing, or body fluids. The Mode of Transmission in oncology is commonly through direct contact, contaminated surfaces, or droplets. The Portal of Entry includes lines, wounds, or mucous membranes, which are frequent in oncology patients due to invasive procedures. Finally, the Susceptible Host is the immunocompromised cancer patient, whose weakened defenses increase infection risk. By applying strict infection control measures like hand hygiene, PPE use, environmental cleaning, safe handling of devices, and patient education, we can interrupt this chain and prevent the spread of infection.

[Author]

Posts