The environment in childhood and risk of motor neuron disease.

To investigate a possible link between subclinical infection with poliovirus in childhood and increased risk of motor neuron disease in adult life, environmental determinants of infection in early life were compared in 98 cases of motor neuron disease and 335 age and sex matched controls. A weak but consistent relation was found between motor neuron disease and factors in the childhood environment known to increase likelihood of enteric infection. Relative risks associated with spending the first 10 years of life in a house without domestic amenities such as a bathroom, running hot water or flushing lavatory, living in overcrowded conditions, frequent changes of address or having a sibling with paralytic poliomyelitis were all greater than unity, although only those for absence of running hot water and frequent changes of address were statistically significant.