This section contains information on diseases which cause substantial risk of either mortality (death) or morbidity (serious illness). These diseases may or may not be treatable. For example, Hib meningitis is a relatively uncommon disease and can be treated if recognised in time. However, because it is so serious and has a high death rate (of up to 5 percent) which has not changed over many years, prevention is very important.

Other information on vaccine preventable diseases in adults or in travellers can be found on the following pages of this website:
Vaccine preventable disease for travellers
Vaccine preventable diseases in adults 

Diphtheria

• Diphtheria is caused by a bacterium which produces a toxin (poison) that inflames the membranes of the nose and throat resulting in blocked airways, which may lead to death by suffocation.
• The toxin can seriously damage heart muscle, adrenal tissue and the nervous system, leading to complications such as paralysis and heart failure.
• Because people can carry the disease without having symptoms themselves, the only effective way of trying to prevent the disease is by immunisation.

Tetanus (Lockjaw)

• Tetanus spores are present in the soil with the resultant bacteria producing a toxin causing painful muscle spasms which can lead to death. The shorter the incubation period the greater the likelihood of death.
• Two tetanus-related deaths were reported in Ireland between 1988 and 2004.
• Young children and people over 60 are most at risk of developing tetanus.
• Tetanus cannot be eradicated from the soil but the disease can be prevented through vaccination.

Pertussis (Whooping cough)

• Pertussis is caused by bacteria that affect the throat and airways, resulting in paroxysmal coughing and vomiting.
• The illness can last for up to 3 months, causing unnecessary suffering to the child and severe disruption to the whole family.
• Death is most common in babies, especially those under 6 months of age.
• Serious complications include convulsions, lung damage, pneumonia, brain damage and bleeding into the covering of the eyes.

Haemophilus influenzae type b (Hib)

• Hib is caused by a bacterium, which is commonly found in the nose and throat of healthy people but can cause serious infection especially in very young infants and individuals with a weakened immune system.
• Since Hib vaccine was introduced in 1992 there has been a dramatic decrease in the number of invasive Hib cases reported in Ireland.
• Hib bacteria can spread via the bloodstream to cause infection in other parts of the body.
• Invasive infection can cause complications including meningitis which can be fatal in up to 5% of cases; and and epiglottitis which can block the entrance of the windpipe and may lead to death by suffocation in up to 10% of cases.

Pneumococcal disease

• Pneumococcal disease is the term used to describe infections caused by the bacterium Streptococcus pneumoniae (also called pneumococcus). 
• Transmission is by aerosol, droplets or direct contact with respiratory secretions of someone carrying the organism. Transmission usually requires either frequent or prolonged close contact. There is a seasonal variation in pneumococcal disease, with peak levels in the winter months although the disease occurs year round.
• Infection can cause bronchitis, ear infection and sinusitis. Invasive pneumococcal disease can affect the lungs to cause pneumonia, or the brain to cause meningitis.

Meningococcal meningitis C (Men C)

• Meningococcal meningitis is caused by the bacteria Neisseria meningitidis. There are different types of the bacteria, and prior to the introduction of vaccination against type C, group B and C strains accounted for over 99% of all invasive meningococcal disease in Ireland.
• Babies and teenagers are at most risk of meningitis (inflammation of the lining of the brain) or septicaemia (blood poisoning) caused by the meningococcal group C type of bacteria. Both are very serious, life threatening illnesses. 
• Since the introduction of the Men C vaccine into the Irish schedule in 2000, there has been a 97% reduction in the incidence of serogroup C disease.

Poliomyelitis (Polio)

• Polio is caused by a virus which attacks the linings of the brain and the nerves which carry impulses to the muscles.
• Infection can cause permanent paralysis in the legs, arms and/or muscles used for breathing and there is a risk of death if breathing muscles become paralysed.
• It is a disease only of humans spread by contamination of hands, food or water from the faeces of an infected person.
• The World Health Organization aim to eradicate polio worldwide and campaigns are in place to target the few remaining countries where polio still exists.   

Measles

• Measles is a highly infectious virus. One case of measles could infect 15 to 20 susceptible people.
• It is not a minor disease of childhood. Death is more common in children under one year of age, and is lowest in children aged 1-9; however, the risk of death rises again in teenagers and adults.
• Complications occur in up to 30% of cases.  They include ear infections, pneumonia, diarrhoea, convulsions and encephalitis. A rare, but fatal, complication called subacute sclerosing panencephalitis (SSPE) can occur following an earlier measles infection which may not have been recognised.

Mumps

• Mumps is caused by a virus and characterised by the swelling, either unilateral (one side) or bilateral (two sides), of the parotid salivary glands.
• Complications include meningitis, encephalitis, sensorineural hearing loss, pancreatitis, and inflammation of the testes (orchitis) or ovaries (oophoritis).

Rubella (German Measles)

• Rubella is caused by a virus and is a mild infectious illness.
• However, if it is contracted in early pregnancy it can cause foetal damage in up to 85% of cases.
• Babies may be stillborn or suffer one or multiple defects including blindness, cataracts, deafness or impaired hearing, heart damage, intrauterine growth retardation, mental retardation and inflammatory lesions of the brain, liver, lungs and bone marrow.

Tuberculosis (TB)

• TB is caused by bacteria usually infecting the respiratory tract, although the infection can spread to other parts of the body.
• It is acquired through airborne transmission of infected droplets from a person with the infection, often a member of the same household.
• Symptoms of TB depend on the site of infection; and include fever, tiredness, loss of appetite, weight loss and night sweats. A persistent productive cough is typically present in cases TB infection in the lungs (pulmonary TB). 
• The disease is more common in areas of the world where poverty, malnutrition, poor general health and social disruption are present.

Hepatitis B

• Hepatitis B is a blood borne viral infection which can be identified by jaundice and fever.
• It can cause chronic infection and may result in cirrhosis and liver cancer.
• A carrier remains a source of infection for others.
• In Ireland, Hepatitis B immunisation is now included in the routine childhood vaccination programme.

 Influenza (Flu)

• Influenza is an acute viral infection of the respiratory tract. There are three main types of influenza virus: A, B and C. Influenza A and influenza B are responsible for most clinical illness. Influenza A viruses cause outbreaks most years and are usually the cause of epidemics.
• Transmission is by aerosol, droplets or direct contact with respiratory secretions of someone with infection. Influenza spreads rapidly, especially in closed communities.
• The disease may be characterised by the sudden onset of fever, chills, headache and extreme fatigue. Other common symptoms include a dry cough, sore throat and muscle aches. The illness may be complicated by otitis media, bronchitis, pneumonia or by meningitis.

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