Poliomyelitis: the Disease

Poliomyelitis is an acute disease of the nervous system which can result in paralysis. The accepted dogma is that polio is a communicable disease, and that the infectious agent is the poliovirus, spreading mainly by excretion in the faeces and infection by mouth. Although much has been learned of the structure and replication of the poliovirus from in vitro studies, it has proved difficult to correlate any of these observations with in vivo processes; indeed, our understanding of the pathogenesis of polio has progressed surprisingly slowly over the past 30 years (1). Experts have explained this lack of progress by invoking the complexity of neurovirulence, a phenomenon thought to depend on the interactions of host and virus at many levels. Recovery from polio apparently leaves a permanent immunity against further infection, and this has been exploited in vaccination programmes. The success of vaccination in the developed world has indeed seemed great; the number of cases in the US had fallen from 30,000 in 1955 to a total of 110 in the 5 years between 1969 and 1974. Despite this, polio is still an important disease, since, in the Third World, vaccination has not been accompanied by such a fall in the incidence of polio; only 15% of cases are detected and reported (2); the estimated number of paralytic cases in 1989 was 246,000 (3). The importance of polio, and our failure to understand how the poliovirus causes it, should make us keep an open mind about its aetiology; but there are a number of anomalies in the accepted picture which should lead us to look for other influences which may be at work. Whilst i do not deny the existence of the virus, I believe that the evidence casts doubt on its accepted role as the only agent causing the disease. Indeed, I find it possible to take the heretical view that polio may not be an infectious disease at all, and that other elements of nutrition are the primary cause (4).