What happens if you get a tetanus shot with a rusty needle?

It's one of those paradoxes of life. In order to answer this question, we have to know how tetanus the bacteria works inside our body (and how the vaccine prevents it).

Tetanus is caused by the bacterium Clostridium tetani. Spores of it are found all over the place, especially in the soil. We usually associate tetanus with rusty nails mainly because it's easy to puncture yourself with a nail and a rusty one is most likely to have all sorts of germs on it. But rust is nothing special... its not necessary for the bacteria's survival.
Once inside the body, the bacteria start to multiply and establish an infection. C. tetani produces two exotoxins, tetanolysin and tetanospasmin. We don't really know what tetanolysin does, but tetanospasmin is a neurotoxin and is super lethal. Once inside you, it travels through your blood vessels and lymphatics, where it gains access to certain parts of the nervous system: peripheral nerve terminals (nerve endings found all over the body), the spinal cord, and the brain. The toxin is absorbed by the nerve axon and transported across synaptic junctions until it reaches the central nervous system, where it attaches to gangliosides (certain proteins that serve in cell signaling) at the ends of inhibitory motor nerve endings. Here, the toxin cleaves other proteins that are involved in nerve signaling, and thus prevents any electrical movement between synapses.

Once you have no communication between motor neurons, this causes problems for the muscles that they attach to. Remember that tetanus affects inhibitory neurons, so if one neuron cannot inhibit the next motor neuron, that motor neuron will continue sending signals to a muscle fiber, putting it in a state of permanent contraction, which causes muscle rigidity and spasms. This is why tetanus is called "lockjaw".




So now you know how tetanus is caused. What does the vaccine do?


The tetanus vaccine is a toxoid. Toxoid vaccines are made by treating the toxins with heat or chemicals such as formalin. Doing this alters the toxin slightly, destroying the ability of the toxin to cause illness (in this case, to bind to the components of the nervous system) but it doesn't alter the toxin too much--the immune system will still produce antibodies against it and these antibodies can also bind to the potent unaltered form of the toxin. Once the toxin molecule (the antigen) is bound by antibodies, it can be destroyed a number of ways by cells of the immune system. Over a period of time, we get tetanus boosters so that we can increase the proliferation of the memory B and T lymphocytes that are responsive to the neurospasmin antigen, which is basically like refreshing our immune system's "memory".


Just FYI, there is another tetanus shot you can get which, technically speaking, is not a vaccine. It is tetanus immunoglobulin, and is essentially the serum from someone else who has antibodies against tetanus. Injecting yourself with this will give you temporary immunity in case you might have just been infected. This is called passive immunization because unlike active immunization (what is described above) the body doesn't produce its own antibodies.



Now, you know how the vaccine (and vaccines in general) work. So, now we can ask:
What happens if you get a tetanus shot with a rusty needle? (Assuming that: you have no prior immunity to tetanus and you are receiving the tetanus vaccine, not the immunoglobulins)

Essentially, we are asking: what happens if you get hit with the tetanoplasmin producing bacteria and the the weakened form of the tetanoplasmin toxin at the same time? The short answer is: you will still get sick.
This is because when you administer a vaccine, you need to give your immune system enough time to develop the antibodies via B lymphocytes, the cells that make the antibodies. B and T lymphocytes are part of your body's adaptive immune system, which typically kicks in 6-7 days after the innate immune system (which acts immediately upon invasion by pathogens). By the time a B cell recognizes the antigen, replicates, and creates antibodies to the weakened form of the tetanoplasmin, the bacteria from the rusty needle could have proliferated and produced enough toxin to cause damage.

So there you have it. Don't get a shot with a rusty needle, even if it's a tetanus shot :)
Thanks for reading

An intriguing question

In this post (which I plan on finishing later), I will attempt to answer a question that I have wondered about since I was about 11 years old.

What happens if you get a tetanus shot with a rusty needle?

I know very little immunology at this point, but I will venture an educated guess.

Let's talk about Lookback Time

Ok. Time to shake things up. As we all know, the quality of this blog has rapidly gone downhill, so the content around here is going to be changed. Instead of rambling on self-centeredly about my own life, I will enlighten you all with the wonderful knowledge I am daily acquiring at school. And no, there is no sarcasm here. I really like most of my classes, as is evidenced by the fact that I attend lectures. My two favorites are Astronomy and Indian History, and Immunology is rather engaging as well. And now that I have decided to share my knowledge of these three subjects with you, you will know which way is north just by looking at the stars (useful if you're ever stranded at sea), you will know what a Swastika originally meant, and if you happen to get sick with the flu virus, you will understand how exactly H1N1 is wreaking havoc inside your body.

And if you really want an update on my own life, here's what happened the past few weeks: I went to class. I came home. I did homework. I went to meetings. I watched TV. I went to parties. Oh and I passed the MCAT.

Soooo lets get to some interesting stuff, like some of the things I learned in Astronomy. By the way, the class itself is painfully boring because its an intro level non-science major class. However, some of the topics are nevertheless intriguing, such as the concept of lookback time. Lookback time is the idea that whatever you see with your eyes is actually old information. Allow me to explain. Say that you are standing about twenty yards in front of me and I wave to you. The moment I wave to you, you see it because the light reflects off me and reaches your eyes. However, because light has a finite speed (3 x 10^8 meters per second), it takes a certain amount of time for the light to get from me to you. In this case, it is far less than even a thousandth of a second. In normal earthly situations, nobody cares about lookback time because the distances we deal with are so small and so whatever we see is almost exactly what is happening.

Lookback time actually matters when we consider astronomical distances, such as that between galaxies, between stars, or even between the earth and the sun. The sun is so far away from the earth that it takes a full 8 minutes for the sun's light to reach us. So if you ever watch a sunrise, know that the first rays of sun you are seeing are a little bit late. The sun has already "risen" 8 minutes ago but you're just finding out about it now. Lookback time is even more dramatic when we talk about objects that are much farther away, such as stars and galaxies. Take for example the star Vega, which is 25 light years away from the earth. That is, it takes 25 years for the light from Vega to reach us. When we look up at Vega, we are seeing how it was 25 years ago. We don't really know the present state of matters. Vega could have exploded and died 10 years ago and we wouldn't know for another 15 years. Crazy, huh? And for galaxies that are ridiculously far away, such as those that are billions of light years away, it gets even cooler. When we see light that is more than 5 billion years old, we are looking well into the past, into a time before the earth and the solar system even existed. Imagine that.

The age of our universe is thought to be about 13.73 billion years. Get a load of this: the top circled galaxy in this picture is 13 billion years away.

Tell me this is not cool. What, now? Yeah. That's what I thought.

Take this Astronomy quiz from the New York Times if you're interested.

New post

I have decided this is an apt time for a new post, as it is right before the long weekend and if I don't post now, I probably won't ever again.

This is it--my final year in college. Senior year, if you will. I've been here for less than two weeks and I already feel like I've lived here forever. Summer? Did that even happen? It's so weird what a change in location does to you. So anyway, I've been having a good time so far. I and all the other progs live in Simmons Hall on the same two floors (we planned it this way). We have nice rooms with high ceilings, vast closets, and lots of shelf space. And we're a good distance to classes, downtown, and other places of interest. I have a new roommate, Anita, who brought many wonderful things to the room such as neatness, vast amounts of food, and a TV. Right now, I am watching a Hindi sitcom that is running on TV Asia. It's a good life.

Not to say that I haven't been keeping busy. I actually attend some of my classes this year, especially the interesting ones such as HIST 176 (A Survey of Indian History). The other class I like is ASTRO 001 (Astronomy). Lectures are a bit slow sometimes, but its still pretty cool stuff. Apart from those, I have PHYS 212 (Electricity and Magnetism) and MICRB 410 (Immunology) which both promise to be challenging enough. There's also MATH 140 (Calc). Oh! And hip hop dance too.

Which reminds me. I am running late for hip hop, so I will resume this post after I return.

yeah...

This is bad, I know, sorry. But I'll have a new post soon.

In the meantime, look at the following pictures inspired by my ASTRO 001 class. They put things into perspective. Thank you, Professor Kregenow.

Pretty sick, eh?