Epidemic: causes, transmission, and public health response

Epidemic

Polio Epidemic of the 1950s

The concept of epidemic regarding infectious diseases is a rather simple concept to understand: over a period of time, an infectious disease spreads within a population -- local or otherwise -- causing, in excess, results that far surpass human expectation of said disease. In the case of poliomyelitis, nobody expected the outbreak to have caused such massive impact on society, let alone the fact that there is now a unionized global fight against further spreading of the virus. Polio was a highly feared disease at its beginning phases. The aftermath of such an epidemic outbreak even went so far as to have become a national problem, and prior to the release of a vaccine, many families cowered in the onslaught of the virus. Thankfully, however, this fear has significantly subsided by 1955.

History of Poliomyelitis

Poliomyelitis (known as polio) is named appropriately due to the fact that the disease causes the "inflammation of the gray matter in the spinal cord" (Dalakas). Though it took around the 1840s for doctors and medical researchers to further delve into the symptoms and theory of the disease, signs of polio can be seen from as far back as ancient Egypt, around 1580 BC to 1350 BC. In 1789, British physician Dr. Michael Underwood began a further study of what he called the "debility of the lower extremities," the earlier description of what would later be called polio ("History of Polio"). Over a century later, in 1894, it became a feared outbreak of infantile paralysis in the United States.

The biggest global outbreak of polio was perhaps during the 1940s to the mid-1950s; close to 100 countries were endemic to the outbreak of what most people believed to be an infant-paralyzing disorder, because it affected many children under the age of 5. Because of the easy way that the virus is spread between people, exposure to someone who had been infected with polio might prove to be enough to infect a person. The virus can quickly spread by direct person-to-person contact, physical contact with feces, or contact with infected mucus or phlegm ("Poliomyelitis"). Cases were observed to be particularly heavy during the summer and fall.

2. Symptoms and Geographic Spread

The polio virus is highly infectious, once called "infantile paralysis" for its attacks on young children (Dalakas). The virus commonly enters the mouth and then proceeds to multiply in the intestines ("WHO"). Usually, the time that it takes for the virus to infect and develop symptoms takes between 5 to 35 days, with an average of 7 to 14 ("Poliomyelitis") for most people. After the virus invades the nervous system, however, total paralysis can be achieved in a matter of hours.

Various non-specific symptoms can be attributed to polio; among them are fever, sore throat, vomiting, headache, abdominal pain, lack of appetite, and stiffness in the neck (Dalakas). For more severe cases, fever intensity increases, meningitis is evident, and there is a prolonged sense of pain in the neck and the back. In a rare and fatal case, paralysis increases, and muscle wasting becomes an apparent cause for distress within a matter of seven days after the illness (Dalakas).

The spread of polio has reached levels of over 100 countries, with at least 125 by 1988 ("WHO"). In Israel alone, the disease carried a 10%-12% mortality rate, and a 30% rate of child paralysis once infected (Blum). While there is clearly a significant decline in the viral infection, polio is still endemic in Afghanistan, Pakistan, Nigeria, and India (Dobriansky). According to World Health Organization data, 23 may be re-infected.

3. Mortality Rate and Societal Impact

Figure

1

. Poliomyelitis in the United States during 1951-1959. Provided by the National Vital Statistics System. Fortunately for 90% of those infected with acute polio, the onslaught of the disease is mild, and in most cases the patient makes a full recovery (Dalakas). Of those infected, 10% suffer more severe symptoms, and usually illness develops (Dalakas). Paralytic extremes develop in 1% of those infected with polio, and of those who contract paralytic polio, 5% of children and 15%-30% of the adults die in the process. According to the WHO, about one in 200 cases usually leads to paralysis, usually in the legs. Of those who are paralyzed, around 5%-10% die due to breathing muscles becoming immobilized ("WHO"). Figure 1 compares the severity of paralytic and non-paralytic polio regarding the passage of time. There is clearly a distinct drop of polio cases in the United States, and due to the global prevention of WHO and UNICEF, the drop has been consistent worldwide.

Polio "terrified Americans in the 1940s and 1950s, much as AIDS does today" (Dalakas). This can be further seen through images of children strapped into braces or posters of a child waving from a wheelchair. In another extreme, adult polio victims were seen lying helplessly in ads about the virus (Dalakas). The fear of such a polio outbreak caused schools to close and swimming pools to shut down across the country (Dobriansky). The reaction in the present world has not been so dramatic, though even today, survivors of the polio epidemic that infected the country during the 1940s and 1950s still suffer from memories of infection (Gevirtz).

4. Treatment and Eradication of Polio

Figure

2

. Reported cases of poliomyelitis in the United States in a 30-year period. Provided by the National Vital Statistics System. There is a clear decrease of polio once Jonas E. Salk produced an injectable vaccine in 1955 (Dalakas). Only six years later, Albert B. Sabin introduced the oral vaccine, which enabled the dispensation of mass immunizations (Dalakas). Cases in the United States dropped to a huge low; by 2009, there was a 99% decrease from 350,000 reported cases to 1604 ("WHO"). Figure 2 illustrates the huge decline of reported cases of paralytic polio in the United States from 1966 to 1996.