Pneumonia is the single biggest killer of children in the world. Although deaths are rare here in New Zealand, our children have rates of pneumonia hospitalisation five times greater than the United States and other developed countries, predominantly among disadvantaged children.

Why are we so concerned about early childhood pneumonia? Young infants and children are more susceptible to pneumonia than adults. Pneumonia is a chest infection - the term chest infection just sounds less threatening.

It can start as a "cold" with runny nose, sore throat and mild cough but then develops into either a wheezing illness with breathing difficulties (bronchiolitis) or breathing difficulties with cough and fever but no wheeze (pneumonia). In infants this is usually caused by virus infection of the lungs, although bacterial infection can follow.

Pneumonia can have serious consequences, including further infections, further admissions over the next years, or the development of irreversible lung scarring (bronchiectasis). New Zealand children are 18 times more likely to develop bronchiectasis than children in Britain, with even higher risks in Maori and Pacific children.

The type and frequency of the lung scarring seen here is only found in other severely disadvantaged communities such as Australian Aboriginal, Native American and Native Alaskan communities.

As well as the social, emotional and economic implications for families, there are economic implications for health services.

It has been calculated that childhood pneumonia has direct medical costs of over $7 million per year for New Zealand. The indirect costs are even higher.

So why do New Zealand children have this appalling health statistic with such a long health shadow? There is good evidence that our houses are not child-friendly and are cold, damp and overcrowded.

Our immunisation rates remain low making children more susceptible.

We cannot immunise against every organism, but pneumonia and/or irreversible scarring has been shown with whooping cough (pertussis), influenza, measles, HiB (haemophilus influenzae), TB and pneumococcus which we can immunise against.

Immunisation also reduces the risk of death during influenza epidemics.

Smoking during pregnancy has a permanent effect on children's lungs and a smoking environment in the house and car continues the damage and/or creates new inflammation of the lungs.

Breast-feeding provides protection as well as nutrition, and there is good evidence that malnutrition is linked to the frequency of chest infections. Babies who are three months or younger at the start of winter are more susceptible to respiratory illnesses and therefore require more protection.

Hand washing and good hygiene also have a big role to play in the prevention of these illnesses. A large number of children in a home or attendance at day care increase the risk of chest infections.

While respiratory secretions (coughing and sneezing) transmits viruses between adults and children and between children, hand contact is also a major cause of cross-infections.

The tragedy is that many of these factors contributing to high rates of Third World diseases among our children are preventable. So what can we do?

We paediatricians ask individuals, health professionals and politicians to focus on 10 things.

1. Make sure our children are breast-fed if possible, and then continue to be well nourished.

2. Remember babies are vulnerable, especially in winter, and protect them.

3. Wash hands well and frequently, particularly when in contact with children and infants

4. Reduce smoke exposure during pregnancy, at home and in the car and make the "quit" programmes more accessible.

5. Know that a persistent cough is not normal and needs assessment.

6. Know that a wet cough is abnormal and needs investigation and/or treatment.

7. The main caregivers of our at-risk children are disadvantaged young women. At a societal, governmental, community and health service level we need to value and support them.

8. Make every house where children live "fit for a baby" with increased social housing for the disadvantaged and improved rental housing.

9. Provide effective immunisation programmes for all children.

10. Don't continue to view the appalling health of our disadvantaged children as "normal" or acceptable.

As a nation we cannot continue to ignore such severe, preventable illness in our children, or to accept it as "usual", and do nothing to provide access to appropriate care.

If we achieved these 10 points, we would not only prevent pneumonia, we would also decrease the incidence of skin infections, rheumatic fever, kidney damage, meningitis, bone infections, rickets, iron deficiency ... and more.

These third world illnesses are rare for the advantaged children in New Zealand and in comparable countries such as the Britain and the US.

But New Zealand has two populations of children - the advantaged who enjoy First World health and the disadvantaged who suffer Third World health. Until we get this sorted, we cannot truthfully say that New Zealand is one of the best countries to bring up children.

* Written jointly by Adrian Trenholme, paediatrician, Kidz First Children's Hospital, Auckland; Cass Byrnes, senior lecturer in the department of paediatrics, University of Auckland, and honorary consultant in paediatric respiratory medicine at the Starship hospital; and Associate Professor Cameron Grant, department of paediatrics, University of Auckland, and a paediatrician at the Starship.