Our Bacterial Selves

 

   

 

 I start many conversations with "There are 10 times more bacterial cells than human cells living in us and on us. We are more bacterial than human." 

 

But as newborns, we come into this world sterile. It is by passing through the vaginal canal that provides our first dose of bacteria, called lactobacillus. Right out of the gates, bacteria gifts us with the ability to digest our mother's milk. 

 

That's day one. How does bacteria help us for the rest of our lives?

 

Scientists have studied bacterial DNA from healthy individuals and found 10,000 DIFFERENT species of bacteria. To put that number into perspective, many probiotics boast on having 10 to 20 species. Lame.

It's time we learn more about our "bacterial selves".

 

Studying our bacterial selves has only recently been possible as a result of the genome revolution (See post below). Cells from our mouth, genitals, gut, nose, skin, and even belly button have been sequenced. Strikingly, for every human gene there are 360 bacterial genes. I find this both exciting and frightening. Imagine going to a mechanic who only knew how 0.2% of a car worked.  Now replace that mechanic with a doctor, and replace that car with you!

 

For better or for worse, funding is largely given to scientists that study what's killing us. Cancer and pathogenic (bad) bacteria or viruses always take center stage and a good chunk of funding. The 10,000 bacteria that make us who we are have been watching from the peanut gallery.

 

Healthy bacteria equals a healthier you, and scientists are studying how to enrich the good guys, while minimizing the impact of bad ones. Imagine a house party where every time a crasher tries to join in, the host uses mustard gas.  The crashers are killed, but so are your invited guests. In later parties, the crashers get wise and bring masks. Now everyone dies, except for the evolved party crashers. When we get an infection, we drop antibiotic bombs on the bacterial party in our guts; killing the good guys that brought the keg, chips, and dip. By learning more about the good bacteria, we can start treating infections with snipers instead of bombs.

 

So what do our bacterial selves do? The easier question might be what don't they? Alterations in our bacteria have been linked to Crohn's and irritable bowel syndrome. That may not come as a surprise, but links are also being made to our behavior, depression, allergies, and many, if not most, inflammation-related diseases.

 

One of the key goals of the study was to find the key bacteria in all healthy individuals. Shockingly, it turns out that different people have different microbial communities, and so do different body parts on the same person! Not a single species was universally present across all volunteers. This suggests different bacteria can do the same jobs. We have to find out what those jobs are. What causes the bacterial diversity? Age, gender, weight, diet, geography, genetics, the tenancy to lick door knobs? These and more likely play a role.

 

Sequencing an individuals bacteria again after several months showed the same bacterial communities. This means our bacterial selves are unique, but stable over time. I can easily imagine a future where a visit to the family doctor will literally involve a "gut check".  When you are young and healthy, your stool sample will be used to grow, dry and store your bacterial selves in pill-form. You'll then be able to rePOOPulate your gut for the rest of your life and whenever you want - after a dose of antibiotics, traveler's diaherra, or any other illness.

The Human Microbiome Project Consortium, “Structure, function and diversity of the healthy human microbiome,” Nature, 486: 207-214, 2012.

Flu 101

Vaccine or no vaccine? That is the question.
Whether 'tis nobler in the mind to suffer the symptoms of flu,
Or to take arms against a sea of viruses,
And by opposing, end them.

We make this decision every winter, but often with misinformation. The number of reported flu cases is exploding and we aren't even near peak flu season.

Let's put the question into context. Last year's flu season was mild for two reasons: (1) The circulating flu strains were the same as the previous two years. That means if you got the flu or the vaccine even in 2009, you were likely still immune from the strains of last season. (2) Scientists do a bit of guess work to decide on which strains to vaccinate against based on the ones currently circulating and the ones expected to circulate in the next season. The degree to which a vaccine matches the circulating strain determines its effectiveness. Last year, the vaccine was an excellent match. Go science!

So what about the 2012-2013 flu season? The strain, H3N2, is new and aggressive. But fortunately, this season's vaccine protects against H3N2. Scientists guessed correctly once again! If you got the flu shot you have a strong chance of not getting the flu. But as with every flu season, false information circulates just as fast as the virus. As a result, conspiracy theories and "vaccine-hesitancy" still looms and they are serious health problems in Canada and the US.

Flu shot myths are rampant, so I thought it would be fun to discuss my favorites: 

"The flu shot gave me the flu!"
Impossible! Sorry, but the science is strong on this one.  You are not given a live virus in the vaccine. You are given dead or attenuated virus that cannot replicate. There are three main reasons why you may still get the flu after the shot: (1) It takes two weeks for the vaccine to become effective.  That means you are still vulnerable to infection for a couple weeks after injection. (2) As I mention above, scientists have to guess at what strains to defend against. Sometimes they are way off the mark and the shot is only 0 to 50% effective. Even when a good guess is made, as they did this season (and last), the vaccine effectiveness is still not 100%. It is more like 60-90% effective. Therefore you may still be vulnerable. (3) There are plenty of other flu strains that are not defended against in the shot and there are other viruses that give flu like symptoms. 

"The flu shot is a government and pharmaceutical conspiracy to make money"
I never understood the logic on this one.  Yes, pharma companies make big money and yes, the government saves big money. But did you ever ask why? Because it works! Kids go to school, thousands of work hours are saved, the few hospital beds we have stay open for those who need them, and most importantly, less people die from a preventable infection.

"The flu shot causes...Autism, Guillian-Barre Syndrome (GBS), Allergic reactions, death, etc."
Millions of research dollars have been put to waste to conclusively show Jenny McCarthy and Jim Carrey that vaccines do not cause autism. There is also no increased risk for GBS. All flu vaccines are made by injecting virus into chicken eggs and the amount of egg protein in the vaccine is extremely low. But those who react to eggs severely should see an allergist before receiving a vaccine. There is less than a 0.1% increased risk of febrile seizures in kids. To put that number into context, 1 in 25 kids normally experience at least one febrile seizure in their lifetime and it is typically not life threatening.

H3N2 is aggressive. It is spreading early and fast, and it is only going to get worse in the coming months. But it's not too late. If not for your own health, think about your co-workers, friends, kids, and family members that have to breathe your air. Think of it as a gesture of courtesy. 18 children have already died in the US and that is just the reported number. The actual number due to complications is actually much larger.

Vaccine or no vaccine? As always, the decision lies with you.

On a personal note, my wife and I got our shots as we do every year. We both had the usual sore arms and drowsiness that lasted the day.

Do you already have the flu? Would you like to see who gave it to you? Or perhaps who you gave the flu to? There's an app for that! "HELP I HAVE THE FLU" app searches the profiles of your friends to see if they have used the terms cough, fever, flu, etc...
Finally a good reason to be on Twitter and Facebook!

HAPPY NEW YEAR!!!!