Thursday, February 27, 2014

Why I Immunize: Part III

This is the third of a series of entries about disease prevention and medical treatments.  To understand what has been covered and why some topics are mentioned or not, please be sure to read the previous entries about hygiene practice and healthy diet choices for disease prevention

While no one method is perfect for all people, the next logical step for most parents in prevention of illness is choosing to provide immunity through vaccination.  Not all people will choose to participate in vaccination due to a number of concerns, but it is impossible to make a reasonable decision if valid information is not available.  I am picky about my citations here and want to avoid false information and shoddy sources; this means while I acknowledge that she is considered an authority in the anti-vaccine movement, I will not be quoting material from Jenny McCarthy

In an attempt to understand the benefits of vaccines and why a parent would take the risk of exposure or reaction, we will explore a vaccine recently in the news for achievements in the eradication of a serious problem as well as known and assumed dangers related to it; I am speaking here about Poliomyelitis, often called "Polio".

Why I Immunize: Part III - Polio and Vaccine History

On January 13th of 2014 the announcement came that India, a country known for massive outbreaks of otherwise preventable diseases because of widespread sanitation problems, was declared "Polio Free" for a full three years.  This is still being verified by the World Health Organization and other sources, but marks a huge step along the path of eliminating a disease lethal to children and adults because of the regular practice of vaccination.  Two years free of disease is often the time at which efforts to continue vaccination begin to fail in public view that the risk is already gone.

The CDC defines Polio as "a crippling and potentially deadly infectious disease caused by a virus that spreads from person to person invading the brain and spinal cord and causing paralysis.  Because polio has no cure, vaccination is the best way to protect yourself and the only way to stop the disease from spreading. The spread of polio has never stopped in Afghanistan, Nigeria and Pakistan. Poliovirus has been reintroduced and continues to spread in Chad and Horn of Africa after the spread of the virus was previously stopped.".

The virus is spread by fecal-to-oral contamination, meaning poor hygiene is once again a factor in transmission.  While this means that proper washing of hands and other sanitary practices should be instituted to lower risks, the lack of clean running water can prove problematic.  Fecal contamination in the water supply has already shown in widespread Cholera outbreaks in even the most modernized areas, making sanitation a problem at all levels and thus an ineffective method of prevention in this situation.

The vaccine for Polio was created by Dr. Jonas Salk in 1952 and released for public use in 1955.  By 1957 the American government made their first push into inoculation by starting a well funded campaign to provide vaccines for families with young children.  At the time Polio was such a disturbing epidemic that many medical professionals flatly refused to see patients in those wards or with a suspected case.  According to numbers from the Smithsonian Institute as many as 11%  of nurses and doctors working in Polio wards in Los Angeles would contract the condition while treating those with an outbreak.  The push to use the only viable prevention was so huge that one New York City doctor reported giving an estimated 700 vaccines to children in the course of one week.

Polio Vaccine promotional poster from the Smithsonian Institute.
Unfortunately, no vaccine is without risk and the Oral Polio Vaccine (OPV) had some of the worst.  Children with highly compromised immune systems resulted in cases of Paralytic Polio. This is caused by the type of exposure and the use of an attenuated virus* (sometimes called a Live Virus).  Though the virus is intentionally made weaker through a preparation process it will reproduce and begin the pattern of infection to trigger the body's immune system to respond properly and build an effective protection.  As one might guess the risk lies in how some bodies may not provide timely reaction for any number of reasons and will allow the weak but present virus to spread too quickly, thus leaving an infection too large for natural solution and just as risky.

In more than 95% of the population there is no infection and the body develops the immunity as expected.  4 - 4.5% react with a-symptomatic polio which causes no complication and will be fended off in a slower building of immunities.  In the remaining 0.5 - 1% the outcome is no antigen reaction resulting in paralytic polio which may become permanent.

Much of this risk was removed when the second form of vaccine was released a few years later.  The Inactivated Polio Vaccine (IPV) became the standard form of treatment by 1963 and was credited with the eventual removal of the disease from regular outbreaks in the population.  These vaccines use an "inactivated" strain of the virus which has been treated to prevent infection but can result in allergic reaction to the other components (neomycin, streptomycin, and polymyxin B) which are used to keep the virus in stasis while allowing the body to form antigens. 

By 1979 the widely promoted use of vaccines meant that the number of reported cases was small and reduced mainly to those areas where religious law did not allow for the use of vaccinations.  An estimation of ten confirmed cases of Polio through exposure to the wild form of the virus was given as proof of eradication due to the general population's immunity and began the theory and study of herd immunity as a viable method to control disease spread.  

Antibody: A protein found in the blood that is produced in response to foreign substances (e.g. bacteria or viruses) invading the body. Antibodies protect the body from disease by binding to these organisms and destroying them.  

Foreign substances (e.g. bacteria or viruses) in the body that are capable of causing disease. The presence of antigens in the body triggers an immune response, usually the production of antibodies.

Attenuated Vaccine: A vaccine in which live virus is weakened through chemical or physical processes in order to produce an immune response without causing the severe effects of the disease.  Attenuated vaccines currently licensed in the United States include measles, mumps, rubella, shingles (herpes zoster), varicella (chicken pox), and yellow fever. Also known as a live vaccine.

Booster shots: Additional doses of a vaccine needed periodically to "boost" the immune system. For example, the tetanus and diphtheria (Td) vaccine which is recommended for adults every ten years.

Community immunity: A situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely. Even individuals not vaccinated (such as newborns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community. Also known as herd immunity.

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