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.

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.