Perhaps antivax folks should spend some time in an iron lung or wearing braces. Polio cases surged in the 1950s, yet today we live with little fear because of the polio vaccine. Its easy to become complacent and selfish when epidemics are rare in ones particular affluent society. Polio reached epidemic proportions in the early 1900s in countries with relatively high standards of living, at a time when other diseases such as diphtheria, typhoid, and tuberculosis were declining. Indeed, many scientists think that advances in hygiene paradoxically led to an increased incidence of polio. The theory is that in the past, infants were exposed to polio, mainly through contaminated water supplies, at a very young age. Infants’ immune systems, aided by maternal antibodies still circulating in their blood, could quickly defeat poliovirus and then develop lasting immunity to it. However, better sanitary conditions meant that exposure to polio was delayed until later in life, on average, when a child had lost maternal protection and was also more vulnerable to the most severe form of the disease.
Posted on: Wed, 25 Jun 2014 02:47:39 +0000
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