Polio (a.k.a. poliomyelitis) has been around for centuries. It is a potentially disabling and life-threatening disease caused by the poliovirus. The virus spreads from person to person and can infect a person’s spinal cord, causing paralysis (that means can’t move parts of the body).
In the early-to-mid 20th century, it was one of the most feared diseases in industrialized countries, as it paralyzed hundreds of thousands of children and, to a lesser extent, adults, every year.
President Franklin Delano Roosevelt had polio, as did actors Mia Farrow, Alan Alda and Donald Sutherland, and musicians Itzhak Perman, Judy Collins, Joni Mitchell and Neil Young. Francis Ford Coppola, Arthur C. Clarke and Jack Nicklaus were other celebrities who had childhood polio.
Thanks to science and medicine, the first polio vaccine, developed by Jonas Salk, was introduced in the early 1950s and improvements in the vaccine continued from there. From the World Health Organization (WHO):
National Immunization Days were coordinated in 19 European and Mediterranean countries in 1995, and in 23 African countries in 2004. By 1994, polio had been eliminated from the Americas, and by 2000 the Western Pacific was polio free.
By 2003, polio remained endemic in only 6 countries – and by 2006, that number had dropped to 4.
The 21st century saw further advances, with cases brought down by more than 99% worldwide in less than 2 decades.
WHO’s South-East Asia region was certified polio-free in 2014, the African region in 2020, and the Eastern Mediterranean region has restricted the virus’s reach to just a handful of districts.
As at July 2021, only 2 cases of wild poliovirus have been recorded globally this year to date: one each in Afghanistan and Pakistan.
One type of polio vaccine, the oral polio vaccine (OPV) was developed by physician and microbiologist Albert Sabin.
Sabin’s vaccine was live-attenuated (using the virus in weakened form) and could be given orally, as drops or on a sugar cube. Some countries, mainly poorer countries where there’s less follow-through of multi-step vaccinations such as the Salk vaccine, continue to use that type of vaccine to this day.
While OPV is safe and effective, in areas where Salk vaccination coverage is low, the weakened vaccine virus originally contained in OPV can begin to circulate in undervaccinated communities. When this happens, if it’s allowed to circulate for a long enough time, it may genetically revert to a ‘strong’ virus. That “strong” virus would be able to cause paralysis, resulting in what is known as circulating vaccine-derived polioviruses (cVDPVs).
This, on top of parents in first world countries who refuse to get their children vaccinated, has caused the cVDPVs to spread faster. With that, as of last week the CDC has named 31 countries where travelers are at high risk for the disease. They include:
- Afghanistan
- Algeria
- Benin
- Botswana
- Burundi
- Cameroon
- Canada
- Central African Republic
- Chad
- Côte d’Ivoire
- Democratic Republic of the Congo
- Djibouti
- Egypt (healthcare facilities, refugee camps, and humanitarian aid settings only)
- The Gambia
- Ghana
- Indonesia
- Israel
- Madagascar
- Malawi
- Mali
- Mozambique
- Niger
- Nigeria
- Pakistan
- Republic of the Congo
- Somalia
- Sudan
- Togo
- United Kingdom
- Yemen
- Zambia
PC: CDC
From the CDC:
What can travelers do to prevent polio?
Get the polio vaccine
Children should be up to date on their routine polio vaccines.
Adult travelers should get an inactivated polio vaccine booster if they:
- are going to a destination that has circulating poliovirus;
- have completed their routine polio vaccine series; and
- have not already received one adult booster dose.
Clinician Information
Ensure that anyone unvaccinated, incompletely vaccinated, or with an unknown polio vaccination status completes the routine polio vaccine series before international travel.
As you can see, even adults from the U.S. who were vaccinated against polio during childhood should consider getting a booster shot before travel to the above countries. Better safe than sorry.
Feature Photo: NIH
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1 comment
Seeing Canada on the list is surprising.