Communicable Diseases

Communicable Diseases

What is a communicable disease definition?

Communicable diseases are illnesses that spread from one person to another or from an animal to a person, or from a surface or a food. Diseases can be transmitted during air travel through: direct contact with a sick person.

There are over 80 different types of communicable diseases. Most common communicable disease at present:


Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus.

Most people who fall sick with COVID-19 will experience mild to moderate symptoms and recover without special treatment. However, some will become seriously ill and require medical attention.
The virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing or breathe. These particles range from larger respiratory droplets to smaller aerosols.

You can be infected by breathing in the virus if you are near someone who has COVID-19, or by touching a contaminated surface and then your eyes, nose or mouth. The virus spreads more easily indoors and in crowded setting


There are four types of influenza viruses: A, B, C, and D.

Flu (influenza) is an infection of the nose, throat and lungs, which are part of the respiratory system. Influenza is commonly called the flu, Most people with the flu get better on their own. But sometimes, influenza and its complications can be deadly. People at higher risk of developing flu complications include:

• Young children under age 2
• Adults older than age 65
• Residents of nursing homes and other long-term care facilities
• People who are pregnant or plan to be pregnant during flu season
• People with weakened immune systems


Respiratory syncytial virus, also called human respiratory syncytial virus and human orthopneumovirus, is a common, contagious virus that causes infections of the respiratory tract.

People infected with RSV usually show symptoms within 4 to 6 days after getting infected. Symptoms of RSV infection usually include;
• Runny nose
• Decrease in appetite
• Coughing
• Sneezing
• Fever
• Wheezing
These symptoms usually appear in stages and not all at once. In very young infants with RSV, the only symptoms may be irritability, decreased activity, and breathing difficulties.


Norovirus causes diarrhoea and vomiting. It is one of the most common stomach bugs in Ireland. It’s also called the ‘winter vomiting bug’.

Norovirus causes inflammation of the stomach or intestines. This is called acute gastroenteritis. A person usually develops symptoms 12 to 48 hours after being exposed to norovirus.

The most common symptoms of norovirus are:
• Diarrhoea.
• Vomiting.
• Nausea.
• Stomach pain


Measles is a highly infectious viral illness. Measles starts with cold-like symptoms that develop about 10 days after you get infected. You will then get a measles rash a few days later.

The illness usually lasts 7 to 10 days.


Shingles is a viral infection that causes a painful rash. Shingles can occur anywhere on your body. It typically looks like a single stripe of blisters that wraps around the left side or the right side of your torso.

Shingles is caused by the varicella-zoster virus — the same virus that causes chickenpox. After you’ve had chickenpox, the virus stays in your body for the rest of your life. Years later, the virus may reactivate as shingles.


Methicillin-resistant Staphylococcus aureus (MRSA) is a cause of staph infection that is difficult to treat because of resistance to some antibiotics. Staph infections—including those caused by MRSA—can spread in hospitals, other healthcare facilities, and in the community where you live, work, and go to school.

Tuberculosis (TB)

Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person. It mainly affects the lungs, but it can affect any part of the body, including the tummy (abdomen), glands, bones and nervous system.

Hep A

Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. The virus is one of several types of hepatitis viruses that cause liver inflammation and affect your liver’s ability to function. You’re most likely to get Hepatitis A from contaminated food or water or from close contact with a person or object that’s infected. Mild cases of hepatitis A don’t require treatment. Most people who are infected recover completely with no permanent liver damage.

Practicing good hygiene, including washing hands frequently, can prevent the spread of the virus. The Hepatitis A vaccine can protect against hepatitis A.


Monkeypox is a viral infection that spreads from person to person through very close contact.

Healthcare-associated infections

Healthcare-associated infections are infections normally acquired by patients during their stay in a hospital or another healthcare setting. Although some of these infections can be treated easily, others may more seriously affect a patient’s health, increasing their stay in the hospital and hospital costs, and causing considerable distress to these patients.

The best way to prevent infection is through good professional practice including hand hygiene and appropriate care when caring for clients. Although many clients acquire Healthcare Associated Infections in a hospital setting, they can just as easily happen in other areas such as residential facilities, outpatient services and even in a client’s home.

To view information on Healthcare Associated Infections please click the links below:


Proper hand hygiene is the most important, simplest, and least expensive means of reducing the prevalence of HAIs and the spread of antimicrobial resistance (AMR). Cleaning hands healthcare workers can prevent the spread of microorganisms, including those that are resistant to antibiotics and are becoming difficult, if not impossible, to treat. The 5 Moments for (WHO) hand hygiene approach defines the key moments when health-care workers should perform hand hygiene.

1. before touching a patient,
2. before clean/aseptic procedures,
3. after body fluid exposure/risk,
4. after touching a patient, and
5. after touching patient surroundings.

Despite acknowledgement of the critically important role of hand hygiene in reducing the transmission of pathogenic microorganisms, overall compliance with hand hygiene is less than optimal in many healthcare settings worldwide. In most healthcare institutions, adherence to recommended hand-washing practices remains unacceptably low. Hand hygiene reflects awareness, attitudes and behaviours towards infection prevention and control. 

How can help prevent healthcare-associated infections (HAIs)?

You and your family can help make sure you’re doing as much as possible to keep you safe from HAIs. Take the following steps:
• Keep your hands clean. Regular hand washing is one of the best ways to remove germs, avoid getting sick, and prevent spreading germs. Ask anyone who will be touching you to wash their hands first.
• Ask your healthcare workers what they’re doing to keep you safe from infection. Don’t be afraid to speak up.
• Ask your doctor what the healthcare team does to prevent infection during and after surgery. Ask how you can prepare for surgery to help prevent infection.
• If you have a catheter, ask each day if it’s necessary.
• Ask if tests will be done to make sure you are prescribed the correct antibiotic. Take antibiotics only when your provider thinks you need them. Ask if your antibiotic is necessary. If you take antibiotics when you don’t need them, you’re only exposing yourself to unnecessary risk of side effects and potentially serious infections in the future. If you do need antibiotics, take them exactly as they’re prescribed.
• Recognize the signs of skin infection. Redness, draining, or pain around the surgical or catheter insertion sites are signs of infection. These symptoms often come with a fever. Tell your doctor right away if you have these symptoms.
• Get the flu vaccine and other necessary vaccinations to avoid complications later.
• Watch for diarrhoea, which can be deadly with the C. diff infection. If you have diarrhoea three or more times in 24 hours, tell your doctor, especially if you’re taking an antibiotic.

What are the 8 ways to prevent the spread of communicable diseases?

Learn these healthy habits to protect yourself from disease and prevent germs and infectious diseases from spreading.
#1 Handle & Prepare Food Safely. Food can carry germs
#2 Wash Hands Often
#3 Clean & Disinfect Commonly Used Surfaces
#4 Cough and Sneeze into a Tissue or Your Sleeve
#5 Don’t Share Personal Items
#6 Get Vaccinated
#7 Avoid Touching Wild Animals
#8 Stay Home When Sick

Notifiable infectious diseases are reported to the MOH for their investigation and control. Investigation and control measures are carried out, using nationally and locally developed guidelines and standards. These diseases are also reported, in an anonymised format, to the Health Protection Surveillance Centre (HPSC) for national surveillance.

All medical practitioners, including clinical directors of diagnostic laboratories, are required to notify the Medical Officer of Health (MOH) / Director of Public Health of certain infectious diseases. The MOH investigates these diseases and controls the risk with the support of colleagues within and outside the department.  The MOH also reports notifiable infectious diseases onwards to the Health Protection Surveillance Centre (HPSC).Information is available from the HPSC , please see links below for further information.