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The Journal Gazette

Tuesday, September 03, 2019 1:00 am

A science triumph

Polio eradication in sight worldwide

Christer Watson

A couple of weeks ago, the World Health Organization announced a successful three-year anniversary. No wild polio cases have been discovered in Nigeria in the past three years.

The only countries in the world with active, wild polio cases are now Afghanistan and Pakistan. Africa may be polio-free. That is obviously great news for public health. Just like smallpox before it, we are aiming to eliminate this disease from our planet so no one suffers from it ever again.

As recently as 2012, Nigeria had 200 cases of polio, which represented half of all worldwide cases. Since that time, there was been a strong push for vaccinations across Nigeria, which has caused this recent good news.

There is a bit of a qualification here. Polio, broadly speaking, comes in a few varieties. Standard polio, the kind that can be crippling or deadly, is sometimes called the wild type. The polio vaccine, which is typically a liquid drop taken by mouth, contains a weakened version of this virus. This weakened version is the second version.

As is true of many vaccines, the body's immune system learns what the virus looks like from this weakened version and develops antibodies. The antibodies are then able to kill any type of polio virus that later enters the body.

The qualification comes in there being a third type of polio. When people are given the vaccine, some of the weakened polio is excreted by the body. This weakened polio then usually dies. If the surrounding population hasn't been fully immunized, however, this weakened polio, after being excreted, can sometimes infect a second person.

That second person would then also become immunized, which by itself is a good thing. However, the weakened virus can sometimes mutate during this process and, very rarely, become strong again. This virus, after becoming strong, is called a circulating, vaccine-derived poliovirus and can be deadly.

Such a virus requires significant time to develop; typically the weakened virus has to circulate among a population for at least 12 months before it will happen upon the mutation to become strong again. Thus, circulating, vaccine-derived poliovirus occurs when a single round of the vaccine is administered, but then not followed up with further rounds. It is not a problem in areas where a full vaccination campaign of two to three rounds is completed.

So the qualification is that Africa is close to being declared free of the wild type of polio. The vaccine-derived type, however, is still present in several countries: Democratic Republic of Congo, Central African Republic, Angola, Niger and Somalia.

This latest effort in Nigeria required vigilance and trust between health care workers and those people accepting the vaccine. Unfortunately, the group Boko Haram, which has fought for control of Nigeria, has claimed the vaccinations secretly sterilize people. Although this is false, the rumor can cause some people to be hesitant to take the vaccine.

That hesitancy then creates the environment where polio can survive. Combating this rumor requires trust between health care workers and those accepting the vaccine.

To help establish this trust, in 2015 the president of Nigeria, Muhammadu Buhari, gave the vaccine to his grandchildren on television.

This story is one of science working. It is common in issues of public health for success to require almost everyone to cooperate. That requires, among other things, strong leadership that describes a problem and a solution as clearly as possible. It is wonderful to see all of that happen and that the process making people's lives better.

 

Christer Watson, of Fort Wayne, is a professor of physics at Manchester University. Opinions expressed are his own. He wrote this column for The Journal Gazette, where his columns normally appear the first and third Tuesday of each month.