96. CCA Study Notes: Communicable Diseases, Transmission, Prevention, and Common Infections

The Big Picture

Communicable diseases spread when disease-causing microbes move from one person to another. Exposure does not always lead to infection. The body’s immune response affects what happens next.

For CCA study, focus on how infections spread, how vaccination helps prevent serious illness, the main features of common infections, and the precautions used when supporting clients with communicable diseases.

Look for Nova Scotia CCA Notes throughout this page for current provincial guidance.

Jump to:

Course Notes: Key Ideas You Need to Know

What Is a Communicable Disease?

A pathogen is a microbe that causes illness, infection, or disease.

A communicable disease develops when disease-causing pathogens spread from one person to another. These illnesses usually spread easily. Other names include contagious disease, communicable illness, infectious illness, and infectious disease.

The listed modes of transmission are:

• direct contact
• indirect contact
• airborne transmission
• vehicle transmission
• vector transmission

Examples of communicable diseases include COVID-19, H1N1, hepatitis, sexually transmitted infections, influenza, tuberculosis ⓘ, HIV, and AIDS.

Three Possible Outcomes After Exposure

Being exposed to a pathogen does not always mean infection develops.

1. The immune system destroys the pathogen

The pathogen does not live and grow in the body. Infection does not develop.

If the person has encountered that pathogen before, immunological memory sometimes helps the body fight it without symptoms.

2. The pathogen remains in the body without causing infection

The immune system does not destroy the pathogen, yet the person remains healthy.

This person is a carrier. The pathogen remains inside the body and spreads to other people even though the carrier feels healthy.

A pathogen that does not harm the carrier might harm someone with a weakened immune system. The listed reasons for weakened immunity include fatigue, stress, malnourishment, and other illnesses.

3. An infection develops

An infection sometimes develops after a period of time.

The incubation period is the time between exposure to a pathogen and the beginning of illness. It ranges from hours or days to years, depending on the pathogen.

A person sometimes spreads the pathogen during the incubation period.

The communicable phase is the period when a person is infectious and spreads pathogens to others. Both the incubation period and communicable phase vary between pathogens.

Vaccination and Prevention

Vaccinations help prevent some communicable illnesses from developing into more serious illness in vaccinated people.

Children receive vaccinations against several common childhood illnesses, including measles, mumps, and chickenpox. Immunization schedules change, so current schedules come from health care providers and public health sources.

Pandemics and Influenza

A pandemic occurs when a communicable disease or infection spreads quickly across a country’s population or throughout the world.

Repeated exposure to different influenza strains, including through yearly influenza vaccination, provides some protection against future influenza infections. Influenza viruses usually change only some surface proteins each year. Memory cells often recognize some proteins from later influenza strains.

For unknown reasons, a radical change takes place in a virus three to four times in a century. A completely new virus also sometimes emerges. People lack memory cells for a new virus antigen, which contributes to widespread illness and deaths.

Examples discussed include SARS in 2002 and 2003, COVID-19, and the influenza pandemic of 1918.

Yearly influenza vaccination and health teaching form part of efforts to reduce future influenza pandemics. The influenza vaccine does not provide immunity from COVID-19.

Vaccinations and TB Checks for Health Care Workers

Health care agencies require workers to have routine vaccinations up to date before beginning work.

Important vaccinations and testing include:

• Yearly influenza vaccination: Some agencies require it. It helps protect workers and clients, especially older people and people with weakened immune systems.
• Hepatitis B vaccination: This involves three injections over 6 months. Antibody levels can be checked periodically after vaccination to ensure immunity to hepatitis B.
• Hepatitis A vaccination: Some facilities recommend it for all employees, especially workers who handle food. It is often given along with the hepatitis B vaccine.
• Tuberculosis testing: A support worker who thinks they were exposed to someone suspected of having TB should inform their doctor. New staff and residents in long-term care facilities require a two-step TB skin test, or a chest X-ray when the doctor considers one necessary.

Common Communicable Diseases

Chickenpox and Shingles

Chickenpox mainly occurs in childhood and comes from the varicella-zoster virus. It spreads through the air.

Fever and painful vesicles, which are fluid-filled sacs, occur throughout the body. The incubation period is 14 to 21 days.

If the virus becomes active again later, the illness is called shingles. Shingles causes a painful rash of raised blisters, usually on one side of the body. Anyone who has had chickenpox is at risk of developing shingles. The vesicles are usually found along a nerve root in one area of the body.

Care information includes rest and avoiding scratching or irritating the vesicles. Shingles requires medical advice for medication or treatment. The person should stay away from people who have not had chickenpox.

Chickenpox immunization may be given as long as the person does not have symptoms. A preventive vaccine also reduces the risk of virus reactivation.

Clostridium difficile

Clostridium difficile, or C. difficile, is a bacterial infection spread through direct contact.

Important facts:

• severe diarrhea and abdominal cramping are listed symptoms
• the incubation period is 1 to 10 days
• care includes rest, fluids, treatment of symptoms, and medical care
• handwashing is especially important because hand rubs do not kill these bacteria
• isolation from others is required because it spreads easily
• no immunization is available

Febrile Respiratory Illness

Febrile respiratory illness (FRI) describes respiratory infections spread through droplets. Examples include colds, influenza, influenza-like illness, and pneumonia.

The listed signs are:

• fever greater than 38°C (100.4°F)
• new shortness of breath

Some older people and people with weakened immunity do not develop a high fever.

Symptoms develop within days after exposure. Care includes rest, fluids, treatment of symptoms, medical care, and airborne isolation precautions. Influenza vaccination protects against certain viral strains.

Measles

Measles spreads through the air and through direct droplet transmission.

The listed signs are fever and rash. The illness is sometimes mild enough to pass unnoticed. The incubation period is 6 to 19 days.

Care includes rest, isolation, and cool sponge baths. Measles immunization is given with mumps and rubella immunization as the MMR vaccine.

Rubella

Rubella spreads through droplets and airborne transmission.

It begins with signs of an upper respiratory infection and a fine, raised rash. Its incubation period is 14 to 23 days.

Care includes rest and isolation from people who have not received the vaccine. Rubella vaccination forms part of the MMR vaccine. The vaccine must never be given to women who are pregnant or trying to become pregnant.

MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial infection.

It spreads through direct contact with a person who has MRSA or with a contaminated object.

Its incubation period is 2 to 3 days. Symptoms resemble other skin infections. MRSA also causes pneumonia and necrotizing fasciitis ⓘ in some cases.

Avoid contact with infected people or items. MRSA infections require medical care. No vaccine is currently available.

VRE

Vancomycin-resistant Enterococcus (VRE) is a bacterial infection.

It spreads through direct contact with a person who has VRE or with a contaminated object.

The incubation period is 1 to 8 weeks. Symptoms resemble other skin or diarrheal infections.

Avoid contact with infected items or people. VRE infections require medical care. No vaccine is currently available.

COVID-19

COVID-19 is a highly contagious airborne viral communicable disease. It spreads mainly through close person-to-person contact.

Symptoms sometimes take up to 14 days after exposure to appear. A person with COVID-19 can infect others even without symptoms.

• Presymptomatic means the person has not developed symptoms yet.
• Asymptomatic means the person never develops symptoms.

How COVID-19 Spreads

People within about 2 m (6 ft) of someone with COVID-19, or people in direct contact with that person, face the greatest infection risk. Infection occurs mainly through respiratory droplets.

Coughing, sneezing, singing, talking, and breathing produce droplets of different sizes. Infection occurs when infectious droplets are inhaled or land on mucous membranes ⓘ inside areas such as the nose and mouth.

Larger droplets fall from the air sooner. Smaller droplets and particles spread through the air. The amount of infectious virus in droplets decreases with distance and time.

Small droplets and particles sometimes remain in the air for minutes or hours. Airborne spread has occurred at distances greater than 2 m, especially in enclosed spaces with poor ventilation and when an infected person breathes heavily.

Respiratory droplets also land on objects and surfaces. Surface transmission is described as possible but not a common route of COVID-19 spread.

Rare transmission from people to animals has also occurred. A small number of pets, including cats and dogs, became infected after close contact with people who had COVID-19.

Longer-Term Effects Described With COVID-19

The listed longer-term concerns involve several areas.

Heart, lungs, and brain

• Lasting heart muscle damage has appeared on imaging months after recovery, including after mild illness.
• Pneumonia associated with COVID-19 has caused lasting damage to the alveoli, or tiny air sacs, and scar tissue associated with long-term breathing problems.
• Reported brain-related effects include strokes, seizures, and Guillain-Barré syndrome ⓘ. COVID-19 may also increase the risk of developing Parkinson’s disease and Alzheimer’s disease.

Blood clots and blood vessels

COVID-19 increases the tendency of blood cells to clump and form clots. Large clots are associated with heart attacks and strokes. Much of the heart damage caused by COVID-19 is believed to come from very small clots that block tiny blood vessels in the heart muscle.

Other areas affected by blood clots include the lungs, legs, liver, and kidneys. Blood vessel weakening is linked with potentially lasting liver and kidney problems.

Mood and fatigue

People with severe illness sometimes receive critical care and mechanical breathing assistance. The experience is associated with later post-traumatic stress disorder, depression, and anxiety.

Some people who have had COVID-19 may develop long-term extreme fatigue. These individuals are referred to as long-haulers. Much remains unknown about the long-term effects of COVID-19. Researchers recommend that doctors closely monitor organ function after recovery.

Hepatitis

Hepatitis means inflammation of the liver.

Listed causes include:

• bacterial or viral infection
• parasitic infestation
• alcohol or drugs
• toxins
• transfusion of incompatible blood
• contaminated water or food
• dirty needles or syringes
• unsafe sex

Scientists have identified six hepatitis viruses. Hepatitis A, B, and C cause about 90% of all acute hepatitis cases in Canada.

Some people recover completely, while others become carriers and can spread hepatitis without knowing it. Women who are pregnant or trying to become pregnant should get tested for hepatitis.

Acute and Chronic Hepatitis

Acute hepatitis is the early viral infection of the liver. Recognizable symptoms do not occur in every person.

Listed symptoms include nausea, vomiting, abdominal pain, dark urine, jaundice, light-coloured stools, muscle pain, drowsiness, irritability, itching, diarrhea, and aching joints with redness and swelling.

Acute hepatitis often lasts less than 1 or 2 months.

For mild acute viral hepatitis, the illness usually runs its course without medication or other treatment. Management focuses on good nutrition, preventing further liver damage, and preventing transmission.

Hepatitis lasting longer than 6 months is called chronic hepatitis. Long-term liver damage replaces healthy liver cells with scar tissue. This condition is cirrhosis.

Cirrhosis progresses to complete liver failure in some cases. Liver failure requires liver transplantation.

Hepatitis A, B, and C all spread from person to person. Vaccines are available for hepatitis A and B in the information provided.

Hepatitis A

Hepatitis A spreads through the fecal-oral route. This means traces of feces are swallowed.

Contaminated food, water, cups, bowls, and cutlery spread the virus. Food sources listed include contaminated water or ice, raw or undercooked shellfish, and raw fruits and vegetables.

Risk factors include crowded living conditions, poor sanitation, and poor hygiene.

Clients with fecal incontinence, confusion, or dementia sometimes contaminate items or areas. A support worker caring for these clients should look carefully for contamination.

Ten to fifteen percent of people without symptoms still carry hepatitis A for up to 6 months and spread it to other people, food, or surfaces.

Fatigue and jaundice occur in some people. If you think you have been exposed to hepatitis A, see your doctor immediately. Vaccination can prevent the onset of symptoms if it is given within 2 weeks of exposure.

Children often show no symptoms.

Hepatitis A symptoms are usually mild. The illness usually lasts 1 to 2 weeks, although severe cases last several months. Most people recover without treatment.

The illness does not become chronic. Death is rare among healthy adults. Hepatitis A is more serious during pregnancy, especially during the third trimester.

A person diagnosed with hepatitis A or another gastrointestinal illness should not prepare food or pour water for other people.

Immunity after recovering from hepatitis A or receiving vaccination lasts for life according to the information provided.

Hepatitis B

Hepatitis B is caused by the hepatitis B virus (HBV). It spreads through infected blood and body fluids, including semen and vaginal fluid.

HBV is described as far more infectious than HIV. Vaccination prevents infection.

About 95% of adults recover within 6 months of becoming infected and develop lifelong protection. The remaining 5% develop chronic infection. Chronic hepatitis B is treatable.

It was estimated that less than 1% of Canada’s population was infected with acute or chronic HBV. Infection before age 7 years carries a greater risk of becoming chronic. In 2011, Canada’s reported acute HBV rate was 0.6 cases per 100,000 people.

Listed symptoms include:

• fatigue
• loss of appetite
• fever
• nausea and vomiting
• dark urine
• pale stools
• stomach pain
• joint pain
• jaundice ⓘ

About half of infected people do not develop symptoms until liver damage has already occurred. Symptoms take 2 to 6 months to appear in some people, and infection spreads during this period.

Potential complications of chronic HBV include cirrhosis, liver failure, liver cancer, and premature death.

Infants born to mothers infected with hepatitis B face a high risk of chronic infection. The information provided recommends a special injection immediately after birth and the first vaccine dose within 12 hours of birth.

Hepatitis C

Hepatitis C is caused by the hepatitis C virus (HCV).

It spreads through infected blood and bodily fluids, including semen and vaginal fluid. Infection occurs only when the virus enters the bloodstream.

Listed routes include:

• unsafe sexual practices
• contaminated blood transfusions or organs
• sharing contaminated drug equipment
• tattooing, acupuncture, or piercing with unclean tools or practices
• sharing toothbrushes, razors, scissors, or other personal care items

HCV also passes to an infant during pregnancy or childbirth. Transmission through breastfeeding is described when the mother’s nipples are cracked and bleeding and the baby has bleeding in or around the mouth.

Hepatitis C does not spread through breast milk itself, food, water, kissing, hugging, or shaking hands.

No vaccine against HCV is currently available.

Herpes Simplex Virus

Herpes simplex virus (HSV) is sometimes classified as a sexually transmitted infection, but sexual activity is not required for transmission.

The virus spreads through skin, saliva, or touching an infected area and then another area or person. An infected person sheds the virus even when no sore is present.

Symptoms of a new infection appear about 3 days to 1 week after exposure.

A new infection is associated with fever, tiredness, loss of appetite, and pain or burning at the affected area before lesions develop. Repeated infections are associated with swollen glands and painful fluid-filled sores. The sores and nearby skin also itch, burn, or tingle.

HSV-1 and HSV-2

Two types are described:

• HSV-1: Oral herpes, often called fever blisters or cold sores.
• HSV-2: Genital herpes.

HSV-1 generally causes sores above the waist, especially around the mouth and lips. HSV-2 generally causes sores below the waist, including around the genital or rectal area.

These locations are not absolute. HSV-1 also infects the genital area, and HSV-2 also causes sores around areas such as the eyes or mouth.

Treatment for either type includes prescribed antiviral medication and medication for discomfort.

Dormancy and Outbreaks

HSV enters periods of dormancy, meaning the virus remains inactive for a period.

Listed conditions associated with outbreaks include:

• general illness
• fatigue
• physical or emotional stress
• lowered immunity from AIDS or medications such as chemotherapy or steroids
• trauma to the affected area, including sexual activity
• menstruation

Sexually Transmitted Infections

Sexually transmitted infections (STIs) are infections spread through sexual contact.

Some clients do not know they have an STI. Others know but do not seek treatment, sometimes because of embarrassment.

Chlamydia

Most people do not have symptoms. When symptoms occur, they appear 2 to 6 weeks after exposure.

Listed symptoms include:

• discharge from the vagina or penis
• burning or pain during urination
• pain during sex
• bleeding between periods or after sex
• lower abdominal pain
• burning or itching around the tip of the penis
• testicular pain

Treatment involves prescribed antibiotics after diagnosis is confirmed.

Gonorrhea

Listed symptoms include:

• burning during urination
• urinary frequency and urgency
• vaginal discharge
• urethral discharge

Treatment uses antibiotic medication.

Human Papilloma Virus

Human papilloma virus (HPV) is also called venereal warts.

For clients with male genitalia, warts appear on the penis, anus, or genital area.

For clients with female genitalia, warts appear near the vagina, cervix, and labia.

Treatment includes a special ointment that dries the warts so they fall off. Surgical removal is used when the ointment does not work.

Syphilis

Syphilis develops in stages.

Primary syphilis: Appears 10 to 90 days after exposure. A painless chancre, which is a type of sore, appears on the penis, in the vagina, on the genital area, or elsewhere on the body.

Secondary syphilis: Appears about 2 months after the chancre and lasts up to 1 year. Listed signs include rash, fatigue, loss of appetite, nausea, fever, bone and joint pain, hair loss, and lesions on the lips and genital area.

Tertiary syphilis: Appears 3 to 15 years after infection. Listed effects include cardiovascular and central nervous system damage, blindness, and dementia.

Treatment uses antibiotic medication.

STI Treatment and Prevention Points

People diagnosed with an STI and prescribed medication should take it as directed.

People who test positive should tell sexual partners so those partners receive testing, treatment, or both. A public health nurse can help contact sexual partners as needed.

A person who tests positive should not have oral, anal, or vaginal sex until:

1. the person and their partners finish all medication
2. all test results after treatment are negative

Unprotected sex with an untreated partner creates a risk of reinfection or another STI.

STIs affect more than the genital area. Listed areas include the rectum, ears, mouth, nipples, throat, tongue, eyes, and nose.

To reduce transmission:

• use a condom or dental dam during sexual activity, even when using another form of birth control
• do not share sex toys
• follow Standard Practices at all times
• get tested after unprotected sex or when concerned about STI exposure

Some STIs also spread through broken skin, infected body fluids such as blood, semen, and saliva, or contaminated blood and needles.

Supporting a Client Living With a Communicable Disease

Clients living with a communicable disease sometimes feel shock, embarrassment, or anger.

The support worker should:

• wear the proper PPE listed in the client’s care plan
• follow Standard Practices at all times
• change out of the uniform before leaving the agency or client’s home to reduce the spread of pathogens
• listen to the client and use empathy
• respect confidentiality at all times
• never discuss the client or details about behaviours that placed the client at risk of infection

Listening with empathy shows respect for the client.

Hepatitis A in Children

Hepatitis A occurs more often among preschool and school-aged children than adults.

The virus spreads easily among children. Poor hygiene after bowel movements contaminates cups, dishes, toys, and other surfaces. Young children also place their hands, toys, and other objects in their mouths.

Safety Precautions for Hepatitis

For All Types of Hepatitis

• Proper hand hygiene is essential.
• Assist the client with hand hygiene when needed.
• Always wear gloves and follow Standard Practices during perineal care, care of clients with incontinence, and handling bedpans or rectal thermometers.

Hepatitis A Prevention

Use safe food-handling practices when preparing food.

When travelling to areas where food or water safety is a concern, the listed precautions include:

• drink and use water from a safe supply
• avoid ice cubes
• eat freshly cooked food
• avoid raw fruits and vegetables that do not peel
• speak with a doctor about hepatitis A vaccination before travel
• cook food to a safe internal temperature using a digital thermometer

Hepatitis B and C Prevention

A vaccine protects against hepatitis B. No vaccine protects against hepatitis C in the information provided.

Precautions include:

• do not share needles, syringes, drug solutions, filters, cookers, pipes, straws, or other drug equipment
• remember that cleaning with bleach does not always kill HBV or HCV
• use condoms and dental dams for safer sex
• avoid procedures that penetrate the skin unless needles, materials, and equipment are sterile
• wear latex gloves when contacting another person’s blood or bodily fluids
• do not share razors, scissors, nail clippers, or toothbrushes
• take extra care when travelling in countries where HBV or HCV is widespread

Herpes Simplex and Varicella-Zoster

Herpes simplex and herpes varicella-zoster belong to the same virus family, but they cause different illnesses.

Herpes Simplex	Herpes Varicella-Zoster
Causes cold sores, fever blisters, and genital herpes	Causes chickenpox and shingles
Includes HSV-1 and HSV-2	Same virus is involved in chickenpox and shingles
Remains in the body after infection	Remains in the body after infection
Enters dormant periods	Enters dormant periods
Reactivates when immunity becomes weakened	Reactivates when immunity becomes weakened

Both viruses spread from person to person. Their medical treatment is described as similar and includes antiviral medication and medication for discomfort.

Common Mix-Ups

Wrong Idea	Better Idea
Exposure always causes infection.	Exposure has three possible outcomes. Infection is only one outcome.
A carrier must feel sick.	A carrier remains healthy while carrying a pathogen that spreads to others.
Incubation period and communicable phase mean the same thing.	Incubation runs from exposure to illness onset. The communicable phase is the period when the person is infectious.
The influenza vaccine provides COVID-19 immunity.	The influenza vaccine does not provide immunity from COVID-19.
HSV-1 only occurs above the waist and HSV-2 only occurs below it.	Those are the usual patterns, but each virus also appears in the other region.