Polio, or poliomyelitis, is an infectious disease caused by the poliovirus. It invades the nervous system and can cause total paralysis in a matter of hours. Polio used to be one of the most feared diseases in the US and around the world, but thanks to vaccination efforts it has been eliminated in most countries. However, because the poliovirus is still circulating in some parts of the world, there is still a risk of infection and the question remains – can polio come on suddenly?
What Is Polio?
Polio is caused by one of three serotypes of poliovirus, which are part of the enterovirus subgroup of the Picornaviridae family. The virus is transmitted through the fecal-oral route, most often by ingesting contaminated food or water. It multiplies inside the intestines and invades local lymphoid tissue, entering the bloodstream and spreading to other sites like the central nervous system.
Once inside the nervous system, poliovirus infects motor neurons in the spinal cord, brain stem, and motor cortex. This leads to swelling and inflammation of nerve cells, damaging and destroying them. When a sufficient number of neurons die, muscles no longer receive signals from the brain and spinal cord, causing paralysis.
Symptoms
The majority of polio infections (about 72%) are asymptomatic, causing no symptoms at all. In symptomatic cases, common symptoms include:
- Fever
- Fatigue
- Headache
- Vomiting
- Stiff neck
- Muscle pain
These flu-like symptoms usually last 2-5 days. In a small proportion of cases, the virus moves into the central nervous system, leading to more serious manifestations:
- Meningitis (infection of the membranes surrounding the brain and spinal cord)
- Loss of reflexes
- Persistent headache and stiff neck
- Increased muscle tone and spasms
- Paresis (slight weakness) or paralysis (complete loss of movement), usually beginning in the legs
Paralytic polio only occurs in 0.5% of infections but is the most severe presentation with symptoms varying from mild weakness to complete paralysis. Without proper treatment up to 40% of paralytic cases can be fatal.
Does Polio Come On Suddenly?
One of the reasons polio strikes fear in the hearts of many is the idea that it can cause sudden onset of paralysis without warning. But does the scientific evidence support this notion?
Sudden Paralysis
The pattern of paralysis seen in polio is described as follows:
- It develops rapidly, reaching its peak within hours to a few days
- It is usually asymmetric – affects one side of the body more than the other
- It largely affects the lower body – legs more than arms
So paralysis is certainly rapid or sudden in its progression. But what about the onset of symptoms leading up to it?
Early Symptoms
For the majority of patients, there are noticeable early symptoms for 1-6 days before the rapid paralysis sets in.
The early symptoms include:
- High fever
- Severe muscle aches
- Neck and back stiffness
- Loss of appetite
- Vomiting
- Increased sensitivity
These indicate that the poliovirus has entered the body and started replicating before attacking the motor neurons. So paralysis does not usually occur completely “out of the blue” but after a short prodrome.
However, in some cases signs like muscle twitching, loss of reflexes, and abnormal crying or screaming may immediately precede flaccid paralysis over a few hours.
Night Paralysis
There are dramatic accounts of people going to sleep able bodied and waking up paralyzed. So it seems polio could occasionally strike during the night.
Some key points about night time paralysis:
- It tended to follow 1-2 days of feeling unwell, so not completely without warning
- It may have been exacerbated by sleeping in a curled position that put pressure on the spine
- Paralysis was likely developing gradually during sleep but only noted upon waking
Missed Prodrome
In some cases, people later recalled having mild early symptoms which they had not paid close attention to. Fatigue, muscle aches, vomiting or fever could have seemed insignificant at first or been mistaken for a common virus.
Also young children may not be able to communicate nonspecific feelings of malaise before sudden paralysis.
So the suddenness may be partly an illusion – some early signs and symptoms were there but overlooked.
Difference Between Adults and Children
The pattern of onset and severity of paralysis can vary between adults and children:
Adults
- More likely to have early minor symptoms
- Paralysis is less severe and complete
- Lower mortality rate
Children
- More abrupt paralysis, less pronounced early symptoms
- More severe and complete paralysis
- Higher mortality rate
So while polio can seem to come on out of nowhere, children appear to be more vulnerable to sudden, severe paralysis compared to adults.
Historical Perceptions
The perception of polio as a terrifying disease that could instantly paralyze previously healthy people peaked in the late 1940s.
Iron Lung Wards
Hospital wards filled with rows of iron lungs (large ventilators) with paralyzed, immobile polio patients made a stark visual impact.
FDR
When President Franklin D. Roosevelt contracted polio in 1921 at age 39, the nation was shocked that such a vigorous person could be abruptly paralyzed.
Post-War Era
In the late 1940s just as the postwar baby boom began, polio outbreaks created panic as parents feared their children could go to bed able bodied and wake up paralyzed. This added to the perception of its sudden onset.
Salk Vaccine
Once Dr. Jonas Salk’s polio vaccine began widespread use in 1955, incidences declined dramatically and the prevailing attitudes shifted as well. Polio was still dreaded but the perception spread that it could be prevented.
Current Risk
Thanks to vaccination, polio has been eliminated from most of the world. Only two countries continue endemic wild poliovirus transmission:
- Pakistan
- Afghanistan
However, rare outbreaks can still occur in under-immunized populations. For example, Malawi and Mozambique both detected imported wild polio cases in 2022.
The USA has been polio-free since 1979 but unvaccinated travelers can bring it back across borders. This occurred in the Rockland County, NY outbreak of 20 people in 2022.
So while polio no longer spontaneously paralyzes children in the middle of the night in the developed world, the risk is still present.
Future Eradication
Public health officials have hope polio could be globally eradicated in the near future, like smallpox in 1980. However, obstacles remain:
- Pakistan and Afghanistan conflict makes access difficult
- Vaccine misinformation and hesitancy reduces coverage
- Rare mutations can cause vaccine-derived polio outbreaks
Continued vaccination and surveillance are needed to finally make polio the second human disease ever fully eradicated worldwide.
Conclusion
In summary, here are the key points on whether polio comes on suddenly:
- Polio paralysis does progress rapidly over hours to days
- It is often but not always preceded by minor symptoms for 1-6 days
- Overnight paralysis can occur but likely reflects progression during sleep
- Children, especially young children, appear more susceptible to abrupt, severe paralysis
- The historical perception focused on sudden paralysis, but this may have partly reflected limited understanding
- Thanks to vaccination, polio is now rare in developed countries though risk remains elsewhere
So while polio can sometimes seem to strike without warning, particularly in children, the onset is usually more gradual than historically portrayed. Continuing vaccination efforts are crucial to eventually eradicate this devastating disease worldwide.