Happy Friday!
I hope that you had a memorable week. Mine just flew by and I am leaving this morning to teach at a resident education course in Los Angeles, which is a always a terrific experience.
Today is World Polio Day. When I saw that, my first reaction was "What? I thought that we eradicated it!" Almost. The day celebrates global efforts to raise awareness of the importance of polio vaccination to protect every child from the disease, which cannot be treated, just prevented. My father was a Rotarian, and one of the main missions of Rotary Clubs worldwide is to eradicate polio. World Polio Day was established by Rotary International to recognize the birth anniversary of Jonas Salk who led the first team to develop a vaccine against poliomyelitis. The oral vaccine (a pink liquid administered on a sugar cube when I was a child) was developed by Albert Sabin in 1988, leading to the establishment of the Global Polio Eradication Initiative in 1998. This initiative reduced polio worldwide by 99 percent.
Polio is caused by a virus, is highly contagious and occurs naturally only in humans. Most people who contract the virus never have symptoms. It is spread by fecal-oral transmission (as are some other infectious diseases), from poor hygiene or from ingesting food or water contaminated by human feces. It can also be spread orally. The disease dates back thousands of years.
There are three types of polio, two of which cause a minor illness that does not affect the nervous system. The milder forms cause sore throat and fever that resolve within a week or two. One percent of the virus can migrate from the gastrointestinal tract to the central nervous system (brain and/or spinal cord) which can produce meningitis. About 1-5 in 1,000 cases progress to paralytic disease where the muscles become weak, floppy and, finally, paralyzed. ("Flaccid paralysis" can occur in other neurologic diseases, such as Guillain-Barre syndrome.) In polio, the weakness usually involves the legs, but severe cases can affect the muscles of the head, neck or diaphragm. When it affects the diaphragm, it impairs breathing and up to 10% of people with this form die.
The virus causing polio (the official name is poliomyelitis) is caused by RNA viruses (we are all now experts on those, thanks to COVID-19) that infect and reproduce in the gastrointestinal tract. The virus is highly destructive, and three types exist, named for wild poliovirus: WPV1, WPV2 and WPV3. WPV1 is the most common and is associated with paralysis. WBV2 was eradicated in 2015 (the last reported case was in India in 1999) and WPV3 was eradicated in 2019 (the last reported case was in Nigeria in 2012). So, we are two-thirds of the way there, but the worst type is still with us.
Wild poliovirus is still widespread in Afghanistan (9 cases in 2025) and Pakistan (29 cases in 2025). This has been attributed to interruption of funding support ($200 million USD in donor funding) for vaccinations and outreach, partly from the USAID (U.S. Agency for International Development). However, other challenges include unstable security environments, misinformation, religious and political opposition to vaccination and weak health infrastructure in these countries. Other countries with immediate risk of international spread of polio are Mozambique, the Democratic Republic of Congo and Guinea.
The virus enters the body through the mouth and starts to replicate, spreading to the tonsils and the lymphatic tissue in the intestine, then to the blood stream which is how it gains access to the central nervous system. It is diagnosed by detecting the virus in a stool sample or in the throat. Anyone who is exposed to the virus, either by infection or immunization, develops immunity to that specific type of poliovirus.
The first vaccine, developed by Jonas Salk in 1952 was inactivated polio that was grown in monkey kidney cultures. It was given in 2 injections and 99% of people are immune following 3 doses. Albert Sabin developed an oral vaccine of live, attenuated virus. It can reproduce in the gut but cannot replicate well in nervous tissue. A single dose provides immunity to all 3 types of polio in 50% of people, and 3 doses protect more than 95% of people. It was licensed in 1962 and is used worldwide. It's inexpensive, easy to administer and protects large groups of people where polio is commonly found. It rarely causes paralysis.
Polio conjures up images of children in the "iron lung" back in the day. It was a negative pressure ventilator that is now obsolete. If ventilation is needed, portable ventilators are used to support breathing. Fortunately, this rarely occurs now. Most cases of paralytic polio recover in 6-8 months but paralysis lingering for more than a year is likely to be permanent. Between 25-50% of those who have recovered from paralytic polio develop new weakness decades after the acute infection, known as the post-polio syndrome. It slowly progresses, is not infectious, and there is no specific treatment.
How to observe World Polio Day? Donate! Rotary International has a special fund to carry on their life-saving work (and the Gates foundation is tripling every donation). Every little bit helps.
Have a good weekend and do good. Seven days and counting until Halloween!
Deb
Enjoy some cool autumn jazz by the masters: https://www.youtube.com/watch?v=IwQVRQeXCSc