2.3 Infection and the immune system?

Prevention of infectious diseases is seen universally as beneficial to the health of society. Few have considered the possibility that, through the process of generations of natural selection, these diseases could have played a role in the development of the immune system (Scheibner, 2000).

The long-term impact of vaccination is not well understood (Baggott, 2000).  Some studies have found that childhood infections seem to give protection from other diseases. Alm, Swartz, Lilja, Scheynius and Pershagen (1999) found that children who took fewer antibiotics had a lower rate of immunisation  and also had a lower prevalence of asthma , eczema and hay fever than the controls. 

Bodner, Anderson, Reid and Godden (2000) reported that children who contracted measles are less likely to go on and develop asthma, a disease that was extremely rare thirty years ago and now kills 2000 people per year in the UK (McTaggart, 1996).
 
Hurwitz and Morgenstern concluded that DPT vaccination increased the risk of allergy but cautioned that the small numbers of children who do not vaccinate limit the ability of studies to make firm causal inferences about the true magnitude of the effect. Ethical issues prevent these studies being done because a comparison random group would not be vaccinated.

Shaheen, Aaby and Hall (1996) found a specific inverse relationship between contracting measles and atopic diseases.  Kemp, Pearce and Fitzharris (1997) found that a small sample of children who did not have DPT or polio immunisation did not suffer from asthma or other allergic illnesses compared with 23 per cent. of the main sample who suffered asthma episodes and 30 per cent. who suffered other allergic illnesses.  

Kramer, Heinrich, Wjst and Wichmann (1999) supported the hypothesis that early infection may protect against allergies later in life. Gibbon, Smith, Egger, Betts and Phillips (1997) found that children who suffered infections in the first year of life were less likely to develop insulin dependent diabetes. Classen and Classen (1999) found that immunised children had twice the incidence of diabetes type 1. however the majority of studies contradict these findings.

Nevertheless, as many as one in 20 people in Europe and North America have some kind of autoimmune disorder (Wraith, Goldman and Lambert, 2003), a massive increase since the elimination of what were once considered normal childhood illnesses. Brunkreft and Holgate (2002) blame air pollution and Kleinhart (2000) proposes the “hygiene hypothesis” as a possible factor.

There is no doubt that vaccination reduced the incidence of death from measles and other childhood diseases in Cuba at a time when sanitation, nutrition and housing was poor.  Cuba now has achieved life expectancy and infant mortality rates similar to developed countries. However, it also has a high prevalence of eczema and asthma similar to North America and Europe (MacDonald,1999). Johnston and Openshaw (2001), while praising the impact of mass immunisation, challenge the medical profession to find ways of producing the protective effects of early childhood infections in young children. The question for health promoters is whether to limit themselves to the evidence or take a more philosophical approach to the subject of immunisation.