Polio is a serious, highly infectious disease which most often affects children and can lead to respiratory problems, paralysis, and even death. It has been eradicated in the United States but is still present in other countries such as Pakistan, Afghanistan, and certain African nations.
Polio spreads through the poliovirus, which is transmitted from person to person through contaminated feces and other vehicles: the virus is contracted orally and then multiplies in the intestines. Defecation releases the virus into the outside environment, allowing it to spread to others through infected water or food, which is especially common in countries with underdeveloped sanitation systems or hygienic practices. Children who haven’t been toilet-trained are especially likely to transmit the virus to others, and there is some evidence that flies can also transmit the virus.
The majority of people infected with polio don’t show any symptoms at all, which makes it easy to spread quickly – potentially to hundreds of others – without medical professionals being aware until a case of paralysis is confirmed. A single case of paralysis is considered an epidemic because of this likelihood of widespread infection to the community, and in fact poses a risk to the entire population, since people can contract polio and bring it back from their travels.
One quarter of people will show flulike symptoms such as fever, fatigue, nausea, stomach pains, and body aches. In some cases (about 1 in 200), the virus attacks the nervous system through the brain and spinal cord, causing paralysis; this can be fatal if the muscles that control breathing become paralyzed as well.
There is no cure for polio – it can only be prevented through vaccination. The vaccination, administered in four doses, lasts a lifetime and is 99% effective after the third dose. It is safe for people with a compromised immune system, and although many adults are not vaccinated, they should get a vaccination before traveling to countries where polio still exists.