Diseases we immunise against in NZ

Diphtheria

Diphtheria is a serious bacterial disease.  Infection causes a membrane to develop in the back of the throat, which may block breathing.  The bacteria also produce a toxin which damages he heart and nerves, the kidneys and other organs.  The death rate is around on in ten cases.  Diphtheria usually only occurs in New Zealand when a traveller brings it in from a country that does not have the disease under control.

Tetanus

Tetanus is caused by a toxin produced by tetanus spores. The spores mainly exist in soil and in the gut of animals.  They can enter the body through broken skin, even trivial wounds, after contact with bacteria in the soil or animal faeces. Any unimmunised person is at risk because it is not possible to develop protection from this disease in any way other than immunisation. Patients experience rigid muscles and very painful spasms caused by the toxin. About one in ten patients die.

Whooping cough (Pertussis)

Whooping cough is a highly infectious bacterial infection.  It is spread through the air by droplets, mostly when sneezing or coughing. It causes severe coughing spells, sometimes vomiting, and a whooping sound (like a gasping intake of breath).  Whooping cough can last up to three months and is sometimes referred to as the ‘100 day cough’.  New Zealand has regular epidemics, as do many other countries. It is a very difficult disease to control because it is very easy to catch and the protection from both the vaccine and the disease decreases over time.

Around seven out of ten babies who catch whooping cough before the age of six months require hospitalisation and one in 30 of those who are hospitalised die.  Severe coughing can temporarily stop the oxygen supply to the brain (hypoxia). In around two per 1,000 children, whopping cough leads to permanent brain damage, paralysis, deafness or blindness. Secondary infections such a pneumonia and ear infections can also occur.

Polio

Polio is an illness of the intestine (bowel) caused by three types of poliovirus. Most cases have no symptoms; however infections can cause meningitis and paralysis.  The paralysis is long term.  Two to ten percent of cases are fatal. Post polio syndrome can occur years after infection, where patients experience muscle pain and severe weakness.  New Zealand is polio free, however polio has not been eradicated from some other countries and it may only be a plane ride away from re-introduction to New Zealand, making continued immunisation necessary.

Hepatitis B

Hepatitis B is caused by a virus which infects cells of the liver. It is spread via infected blood or the exchange of body fluids; it is possible for an infected child to pass the virus onto another child through a playground accident. The virus can survive in dried blood for over one week. The disease can be serious and occasionally fatal although often there are no symptoms.  A chronic carrier state can develop (particularly if infection occurs very young) and this can lead to cirrhosis of the liver and liver cancer much later in life.  Carriers can go on to infect other people.

Hib disease

Haemophilus influenzae type b (Hib) disease is caused by a bacterium. It can cause severe throat inflammation, pneumonia, meningitis (inflammation of the protective layer over the brain), and infection of the blood (septicaemia), skin and joints, mainly in infants and young children. It is rare in New Zealand now, with only a few cases every year, but it was the most common cause of meningitis in children under five years before the introduction of Hib vaccine.

Pneumococcal disease

The bacteria Streptococcus pneumoniae can cause infections in different parts of the body such as the sinuses (sinusitis) and in the ear (otitis media or middle ear infection). It is the leading cause of bacterial pneumonia and can also result in other serious illnesses including septicaemia (blood infection) and meningitis (inflammation of the protective layer over the brain). About half the children with pneumococcal meningitis will go on to have long-term disabilities. Pneumoccal infections can be difficult to treat because some of the bacteria are resistant to antibiotics.  Older people and children under two years old have the highest risk of serious disease (1).

Measles (English measles)

Measles is caused by a highly infectious virus. Symptoms include fever, runny nose, and “pink eye” (conjunctivitis) followed by a rash that lasts up to a week. Complications occur in around one out of ten cases. These include ear infections, pneumonia, diarrhoea or croup. One in 1,000 cases develop brain inflammation that can result in death or permanent brain damage. In well nourished populations around one in 1,000 cases die. Some countries have eradicated measles but New Zealand still has periodic measles epidemics because of low immunisation rates.

Mumps

Mumps is caused by a highly infectious virus.  Symptoms of mumps include fever, headache, swelling, and tenderness of one or more salivary glands (the swelling usually shows on the neck, just below the earlobe).  At least a third of mumps infections in children have no symptoms.  Adults are more likely to experience severe mumps disease.  Viral meningitis occurs in up to 15% of  mumps cases. Brain inflammation occurs in one in 6,000 cases, of which around 60 die.  deafness occurs in one in 15,000 cases.

Rubella (German measles)

Rubella is caused by a virus.  It is usually a mild disease in children; however when it occurs in pregnant women (particularly during the first trimester of pregnancy) it usually results in severe damage to the developing baby.  This includes damage to the brain, heart, and eyes; deafness, mental retardation and behavioural problems.

Meningococcal disease

Meningococcal disease is caused by different types of meningococcal bacteria.  The disease can result in severe illnesses including pneumonia, meningitis (inflammation of the protective layer over the brain) and septicaemia (blood infection).  In the early stages meningococcal disease may look like influenza.  It can progress quickly and be difficult to diagnose.  A baby or child might have a fever, by crying or unsettled, refuse drinks or feeds, vomit, be sleepy, floppy or hard to wake, dislike bright lights and/or rash or spots.

The meningococcal B vaccine (MeNZB), made to control the epidemic of the New Zealand only meningococcal B disease, will not be available after March 2011.  The New Zealand only meningococcal B disease does still occur in small numbers, at approximately the same rate as other meningococcal diseases (2).  The other meningococcal vaccines are not available free in New Zealand and can be purchased through your family doctor.  The age at which they can be given varies, depending on the vaccine.

Rotavirus

Rotavirus is a highly infectious virus of the intestine (bowel) that causes watery diarrhoea, and is often accompanied by vomiting, abdominal pain and fever.  Dehydration can be very severe and cause death if untreated.  Rotovirus infections occur most commonly in infants and children  between 6-24 months of age (3), by the age of five years 95% of children worldwide have been infected (3).  It is the leading cause of severe acute gastroenteritis in infants, accounting for about half of all hospitalisations for gastroenteritis in children under five years of age.  The spread of infection  within families and institutions is common as large amounts of rotavirus are present in the faeces of infected individuals. It is easily picked up via contact with virus present on peoples hands, hard surfaces, toys, utensils and other objects.

The oral rotavirus vaccine is not available free in New Zealand and can be purchased through your family doctor. Two doses must be given, separated by at least 4 weeks, between the ages of 6-24 weeks old.

Chicken Pox (varicella)

Chicken pox is a highly infectious disease caused by a virus.  The illness begins with fever and/or feeling generally unwell for a day or two followed by a rash.  Chicken pox is usually a mild, self-limiting disease in otherwise healthy children. The severity of disease can be greater in adults.  Complications include serious skin infection, unsteady gait (walk), low platelet count, pneumonia and inflammation of the joints, kidneys and liver.  In New Zealand there are approximately 50,000 chicken pox infections most years, with 150-200 resulting in hospitalisation, one or two resulting in long-term disability or death. Once every couple of years a baby is born with severe congenital varicella syndrome (a collection of physical abnormalities and mental retardation). Although children with immune system problems are at highest risk of getting chicken pox two thirds of complications occur in otherwise healthy children.

The chicken pox vaccine is not available free in New Zealand and can be purchased through your family doctor.  It can be given from nine months of age.

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References

(1)  Heffernan HM, Martin D, Communicable Disease Group Institute of Environmental Science and Research Ltd (ESR). Invasive pneumococcal disease in New Zealand, 2008. Porirua: Institute of Environmental Science and Research Limited: 2009.

(2)  Martin D. The epidemiology of meningococcal disease in New Zealand in 2009.  Porirua: Institute of Environmental Science and Research Limited: 2010.

(3)  Marshall GS. Rotavirus Disease and Prevention Through Vaccination.  Pediatr Infect Dis J. 2009;28 (4):351-64