Epidemiological interference.

Wherever intensity of disease transmission (size of virus populations) is great, there will be competition among the different viruses for soil. This competition, which is discussed here as epidemiological interference, was seen in a series of studies in West Bengal, India, and in Nepal. Competition for space led to localization of adenovirus types. Competition at different seasons led to striking variation in seasonal prevalence. Competition for soil and delay in natural immunization led to postponement of infection with childhood diseases to adulthood. Finally, the same phenomenon can explain the early continued high prevalence of poliomyelitis virus in children during the first six years of life in rural West Bengal (12).