#28 Book Review: Undeniable: Evolution and the Science of Creation

Undeniable: Evolution and the Science of Creation

By Bill Nye

What is this book about?
This book, despite the title, is actually focused on the basic research, discoveries and theories that support evolution. It discusses the benefits that have come from the study of evolution and the history of the concept.

What I love about this book...

It is written in a very relaxed and informative. It is very easy to read and is written very much like the Bill Nye the Science Guy TV show. The book covers some very in-depth and complex science concepts in a way that anyone can enjoy and understand. It has a lot of humor as well as seriousness. Even as someone who knows the science background there was enough history and related information to keep it interesting.

What could have been better?
This is a book that I read in print and kind of wish I would have listened to the audiobook. I feel like Bill Nye's exuberance that comes through in his voice would have made the book even more enjoyable. I do feel like the title might keep people from reading this book. There isn't much in this book about creationism at all which some people might think given the title.

Question #27 What is the importance of herd immunity?

From Linda on Facebook.

Before we talk about the importance of herd immunity we should define it. Herd immunity is sometimes called community immunity. I think herd immunity is most easily defined through an example.

Let's imagine two communities of 100 individuals. 

Community A Most of the individuals have had vaccinations (90) and there are 10 people who are either too young or too immune compromised to be vaccinated. So in this community 90% of people have vaccinations and 10% cannot receive them.

Community B Few individuals have had vaccinations (10) and there are also 10 people in this community that are either too young or too immune compromised to receive vaccinations. In this community 10% have vaccinations, 10% are unable to get vaccinations and 80% are unvaccinated, meaning they have no immunity.

Now, let's imagine the virus that the vaccination is for comes into contact with these two communities. 

In community A, 90% of people who come into contact with the virus are not effected by it because their immune system has antibodies. These 90% of individuals also do not become carriers, meaning once they come in contact with the virus they do not carry the virus off to infect other people. This means that 9 out of 10 times the virus tries to invade this community it is ineffective because of the immunity. Most of the herd/community is immune to the virus so those who don't have the immunity are unlikely to contract it.

In community B, 10% of the people who come in contact with the virus have immunity and do not become sick or carriers. However, 80%, or 8 out of 10, of individuals do come down with the sickness and carry the virus into the community to infect others. That means the 10% unable to be vaccinated have an 80% chance of catching this virus. Those most susceptible to the virus are highly likely to come in contact with a community member who is carrying the virus.

This is the basis of herd immunity, the more of the herd that is immune the more safeguard there is for those who are unable to receive vaccinations or may be in serious danger from becoming sick, such as the young, those with immunodeficiency diseases, or undergoing chemotherapy. Herd immunity works on small scales; a single family with a new baby or a sick elder; or a community as large as an entire city, state, country or the broader world. Herd immunity is important to stop the spread of a disease from one individual to another and is a major force in preventing epidemics and pandemics.

What percentage (R0) of the population must be vaccinated to provide herd immunity?

This is a very tricky question and involves several variables. One major variable is how contagious the virus or bacteria, or how fast it spreads. The more contagious the disease the higher the percentage of people needed to provide herd immunity. The interaction and travel patterns of the community matters to this as well. With modern travel, such as cars and airplanes, someone carrying a virus can travel much farther in a single day. This means that the herd immunity of the home population and the destination population are both equally important when it comes to a carrier. In general, the higher the percentage who are vaccinated, the better the herd immunity.(Check out the link in the more information section for an article about how this is calculated)

Why are vaccinations important to herd immunity?

Vaccinations provide a few important things. First, immunizations create a record of who has immunity. This information is important during an outbreak and also allows officials to track down patient Zero. (Patient Zero is a term for the person who initially brings a disease into a community. Knowing patient zero can allow officials to track who they have been in contact and who might have contracted the illness.) Secondly, vaccinations allow the individual and the medical professionals to know that an individual, or group of individuals, is immune to a specific strain of a disease. Perhaps the most important aspect of herd immunity through vaccinations is that it allows a large portion of the population to become immune without having to contract the disease. This is a particularly important benefit when the disease is debilitating or has a high rate of death, such as polio. A final importance, at least to those who have and love pets, is that some diseases are zoonotic, meaning they can be transmitted between people and animals. Having a pet and/or person vaccinated against a zoonotic disease protects the human population, the pet population, and in some cases populations of food animals.A great example of a pet vaccination that provides safety to both the pet and the humans who love them is the rabies vaccination.

More information:
Research paper on the benefits of herd immunity in Meningitis
 PBS page that discusses how to calculate percentages required for herd immunity to be effective as well as other related topics.
CDC discussion of herd immunity
Series of interactive animations to show visually the impact of herd immunity vs no herd immunity

Free Courses online that cover immunity and health
An Introduction to Global Health
An Introduction to Population Health
Epidemiology: The Basic Science of Public Health
Epidemics, Pandemics, and Outbreaks

Question #10: Does eating sugar make you more likely to get sick?

A question from email and a complicated one.. the answer is yes... and well no.

One thing we must consider is the health of the person consuming the sugar in question. Those with immune diseases, diabetes, leukemia and digestive disorders (among other conditions) are going to have different experiences on health in this case than the average, healthy individual. Age and body size can also affect the case related to this question, partially, due to the body mass to sugar intake ratio. Of course a 40lbs child will be more effected by the large quantities of sugar than a 150lbs adult.

So, for the sake of this discussion we are going to assume that the individuals consuming the sugar is a healthy, average sized adult with no health conditions that will increase or decrease the effects of the sugar on the body.

The background

The only study discussing sugar and the immune system revolves around the behavior of neutrophils. Neutrophils are one type of immune cell found in the body. They are often in the blood but can also be found at sites of infection or cancer. These cells are usually the first ones to respond to infection or cancer due to their phagocytic nature, i.e. they come in and devour  the foreign or cancerous cells. There are several types of neutrophils that respond to different stimuli. The study does not seem to list which type(s) of neutrophils they are observing. This is problematic for deducing the actual impact of the sugar on the specific parts of the immune system.

The 1973 study I read started with individuals who have fasted. This means that they have not consumed food in 12-24 hours. Their body would be processing stored sugars at this point after exhausting the blood sugar (sugar in the blood). The subjects are then dosed with 20 or more teaspoons of sugar (different sources are used in studies such as honey, fructose, glucose, etc.) are then administered. After a wait time blood is drawn and added to a culture of bacteria. The neutrophil or other white blood cell activity is observed.

What did I find?

Aside from the 1973 study, which by science standards would be considered way out of date, I didn't uncover any scientific papers in peer reviewed journals that discussed humans and sugar intake. I was very disappointed as I searched around many distributors such as PubMed, EBSCOHost and several others and found nothing. I even tried different sugars to see if there would be papers for glucose or fructose instead of just sugar. I had no luck. I did find lots and lots of blogs and unreferenced sources that harken back to the 1973 study or no study at all.

What does that mean? Well there is one, outdated source, that suggest there may be a link. I say outdated because in most fields, particularly medicine, articles over 10 years old are considered sketchy to use and those 20 years or more are considered obsolete. The study suggests that it is the large inflow of sugar into the blood stream after fasting that depresses the immune system. The neutrophils are still working just a little slower.

Does this mean I will get sick from drinking a can of soda? No, probably not. Everything in moderation is how I have always felt. Perhaps with the recent interest in the subject more studies will be done to clarify what the outcome truly is. Below are links to the study and some relevant sources. Sadly, I can't give a better answer to this question until there is more research to read.


Sources:
Information about White Blood Cells
Blog Post about Immune System Cells
1973 Study most often cited
Blog post summarizing the study.
USA Today discussion of the study
Mouse Study - Note that the mice here are give 50g/kg of sugars which is much, much higher sugar to body weight dose than was used in the human study.
Another article that examines the study and raises the fact that no studies have really been conducted since 1973.
Another mouse study but it isn't only high sugar given but also high fat and cholesterol.