But the poliovirus is typically transmitted just one way: through human waste. Eradicating polio is not an easy task, but the way polio is transmitted simplifies our ability to tackle the disease. There used to be three strains of poliovirus that regularly infected humans.
The wild poliovirus cannot survive for long periods outside of the human body. If the virus cannot find an unvaccinated person to infect, it will die out. This is why we have to keep every single child vaccinated—so the virus cannot find any humans to infect.
The length of poliovirus survival varies according to conditions like temperature, and the poliovirus infectivity decreases over time. People are the only reservoir Hundreds of diseases can be transmitted between insects, animals and humans. One of the things that makes polio eradicable is the fact that humans are the only reservoir. No poliovirus has been found to exist and spread among animals despite repeated attempts to document this.
Immunization with polio vaccine interrupts virus transmission Not only are there two safe and effective polio vaccines, but vaccination against polio generates herd immunity, which increases the percentage of the population that is immune to the disease. Mass campaigns using oral polio vaccine, where all children in a specified geographic area are immunized simultaneously, interrupts wild poliovirus circulation by boosting population immunity to the point that transmission of polio cannot be sustained.
But what truly drives our conviction in numbers results. There are now only 3 countries that have never stopped polio transmission. This marathon of a public health endeavour is in the last mile. Who we are Our Mission. In the late s, polio outbreaks in the U. Parents were frightened to let their children go outside, especially in the summer when the virus seemed to peak.
Travel and commerce between affected cities were sometimes restricted. Public health officials imposed quarantines used to separate and restrict the movement of well people who may have been exposed to a contagious disease to see if they become ill on homes and towns where polio cases were diagnosed. Introduction of the polio vaccine dropped polio paralysis cases in the U. Polio was once one of the most feared diseases in the U. In the early s, before polio vaccines were available, polio outbreaks caused more than 15, cases of paralysis each year.
Following introduction of vaccines—specifically, trivalent inactivated poliovirus vaccine IPV in and trivalent oral poliovirus vaccine OPV in —the number of polio cases fell rapidly to less than in the s and fewer than 10 in the s. Thanks to the polio vaccine, dedicated health care professionals, and parents who vaccinate their children on schedule, polio has been eliminated in this country for more than 30 years.
This means that there is no year-round transmission of poliovirus in the United States. It takes only one traveler with polio to bring the disease into the United States. People most at risk are:. The best way to keep the United States polio-free is to maintain high immunity protection against polio in the population through vaccination. PPS is rarely life-threatening, but the symptoms can significantly interfere with an individual's ability to function independently. Respiratory muscle weakness, for instance, can result in trouble with proper breathing, affecting daytime functions and sleep.
Weakness in swallowing muscles can result in aspiration of food and liquids into the lungs and lead to pneumonia. The cause of PPS is unknown. The new weakness of PPS appears to be related to the degeneration of individual nerve terminals in the motor units. A motor unit is formed by a nerve cell or motor neuron in the spinal cord or brain stem and the muscle fibers it activates.
The polio virus attacks specific neurons in the brain stem and spinal cord. Surviving cells sprout new nerve-end terminals and connect with other muscle fibers. These new connections may result in recovery of movement and gradual gain in power in the affected limbs. Years of high use of these recovered but overly extended motor units add stress to the motor neurons, which over time results in the slow deterioration of the neurons and leads to loss of muscle strength.
Restoration of nerve function may occur in some fibers a second time, but eventually nerve terminals malfunction and permanent weakness occurs. This may be why PPS occurs after a delay and has periods of relative stability combined with periods of decline with progressive weakness. There are no laboratory or diagnostic tests specific for PPS. Physicians diagnose the condition after completing a comprehensive medical history and physical examination, and by excluding other disorders that could explain the symptoms.
Physicians look for the following criteria when diagnosing PPS:. Diagnostic tests include:. There are currently no effective treatments that can stop deterioration or reverse the deficits caused by the syndrome itself, but there are recommended management strategies. Individuals with PPS should seek medical advice from a physician experienced in treating neuromuscular disorders.
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