Disease Post: Anthrax

Something a little different: our first bacteria!

Background:

Anthrax is a disease caused by a bacteria called Bacillus anthracis.

What is bacteria? A bacterium is a single-celled organism. The cells are a little like ours, but a bit more primitive. They are called "prokaryotes" which means "primitive nucleus." (Our cells are "eukaryotes," meaning "true nucleus.") This means that they do not have a nucleus that holds the DNA like our cells do.

Bacteria come in all different sizes and shapes. Bacillus anthracis is in the shape of a rod and is large (relatively speaking). It is Gram-positive, which refers to the way bacteria are stained before looking at them under a microscope. Gram-positive means that they stain with crystal violet dye because they have a cell wall made of peptidoglycan. I won't go into too much detail about peptidoglycan, but it is made of sugars and amino acids and is important in how the bacteria functions and how the immune system interacts with the bacteria.

Anthrax bacillus. Credit: the Wellcome Collection. The bottom two images show the long, rod-shaped bacteria the best.

Another important thing is that this bacteria forms endospores. Endospores (or just "spores") are dormant bacterial cells that cannot reproduce and are very resistant to anything that would kill a normal bacterium. This means that anthrax can survive in bad conditions and in the environment for a long time (usually a few months to a few years, but some can survive for decades). Once a spore enters a host, it can enter the active phase and start reproducing again. Once they are exposed to the environment again, they can sporulate and wait in the dormant state until they can infect another host.

Anthrax bacteria can contain up to three genes in their DNA that codes for different toxins. It is the toxins that cause symptoms. There are particular ways that these genes can be present and they can be transferred between the bacteria, but I don't want to go into too much detail about that. Just know that there are important toxins that can make an anthrax infection worse if the bacteria have any of those genes.

How is it spread?

There are a few types of infection that anthrax can cause: cutaneous (skin), gastrointestinal (in the digestive tract), inhalational (infected through the lungs), and, rarely, meningitis (infecting the nervous system).

Anthrax is mostly a disease of animals and is naturally present in soil all over most of the world. Human to human transmission is very, very rare. We see it in domestic livestock like cattle and in wild animals. Humans are usually infected through the skin or the lungs, often from animals that have the disease or animal products that are contaminated with anthrax.

Symptoms:

Let's break it down into the different types of infection.

Cutaneous: It takes about 1-7 days (incubation period) until a small papule forms on the skin at the infection site. It may become larger. They are usually painless. They can rupture easily and become ulcers and the base will become black, which is characteristic of cutaneous anthrax infection. As long as there are no complications and treatment is received, the lesions will heal just fine. This form is very rarely fatal and is one of the more common forms humans get.

Meat handler: skin lesion of anthrax. Credit: Royal Veterinary College and the Wellcome Collection

Gastrointestinal: This is often how animals are infected, by ingesting the bacteria, and it is an uncommon infection in humans. The incubation period is abut 1-5 days. There will be a fever and localized symptoms like nausea, vomiting, diarrhea, and/or abdominal pain. From here, it can spread to the blood stream (sepsis) and may cause secondary meningitis if it gets into the central nervous system. The gastrointestinal form can be treated, but is about 40% lethal without treatment.

Inhalational: This is the other infection type that humans get (relatively speaking, inhalational anthrax cases are actually quite rare). It is this form that makes anthrax so scary. Inhalational antrax infection is extremely dangerous and is nearly always fatal without treatment. And treatment needs to happen very quickly and aggressively. This type is about 92% fatal, even with treatment. Usually in this form, spores are inhaled and enter the lungs. They incubate for about 1-6 days. The first symptoms are flu-like (fever, tiredness, aches, headaches). As the disease progresses, there is a high fever, decreased lung function, respiratory distress, chest pain, and more. This form can also cause secondary sepsis and/or meningitis as the bacteria spread. While all forms of human cases of anthrax are rare, this one is the reason it is an agent for bioterrorism.

Meningitis: This form is rare and is mostly associated with gastrointestinal or inhalational infections. This happens when the bacteria infect the central nervous system via the blood stream.

Prevention and Treatment:

There is an anthrax vaccine, but it is not normally available to the public. People who usually have access are laboratory and military personnel and other people who may come in contact with infected animals. The vaccine can also be used after a person has been exposed, much like the rabies vaccine.

There are vaccines available for animals like livestock. Vaccinating these animals significantly reduces human exposure.

There are various antibiotics that can be used to treat the different types of infections. Doxycycline and Ciprofloxacin are commonly used, according to the CDC, but there are others. The treatment with antibiotics is very long and intensive to make sure that the bacteria and any spores are treated.

Sources:
Medical Microbiology 6th Edition by Patrick R. Murray, Ken S. Rosenthal, and Michael A. Pfaller
Centers for Disease Control: Anthrax
WHO: Anthrax

Disease Post: Rabies

Welcome to the Rabies post!

Background:

Rabies is caused by a virus from the rhabdovirus family and is bullet-shaped. The virus has an envelope (a double layer of lipids like those that form our cell membranes). Rabies' genetic material is single-stranded RNA.

Transmisson electron microscopy picture of a rhabdovirus. Image from the Wellcome Collection.

Brief review: in humans, our genetic material is double-stranded DNA (deoxyribonucleic acid) that is kept in the nucleus of our cells. Kind of like the control center. When we need to make a protein, the DNA strands unwind and we have cellular proteins that make a copy of the DNA which is called RNA. Human RNA (ribonucleic acid) is always single-stranded. This strand of RNA then exits the nucleus and into the cytoplasm of the cell where other proteins translate the RNA instructions into a protein.

Since rabies contains single-stranded RNA, it can enter the cytoplasm of our cells and use our cell's machinery to make more viruses.

Rabies is a disease that is present all around the world (except in Antarctica) and has been around for thousands of years (at least). It is thought to have evolved with dogs and wolves as those are usually the most easily affected and infected animals. Most cases in humans occur in Asia and Africa, but it is regularly seen in Europe, Australia, and the Americas, too. In places where dog vaccination is common (like the US), fewer dogs are problems and bats become more likely to spread the disease. There are also vaccination programs in wild animals like foxes and raccoons via food baits, which is great, but there aren't any programs that can easily vaccinate bats, to my knowledge.

How is it spread?

Rabies is often found in wild animals like raccoons, foxes, coyotes, and bats. Domestic animals, like dogs and cats can become infected. And of course, humans. To my knowledge, rabies only infects mammals.

Rabies is spread through the saliva of an infected mammal and enters the new host through broken skin. Infections are usually caused by a bite, but can be transmitted by a scratch.

The virus enters the wound and moves into the local nerve cells or neurons. Once it is in the neurons, it can hide really well from your immune system (obviously your immune system should not normally attack your nervous system because it is so important for all of your normal functions). From the local nerves it makes its way from nerve to nerve to reach the central nervous system (your spinal cord and brain). After that, the virus travels down to the salivary glands where they can shed into the saliva and try to spread further! (Side note: viruses when they multiply are said to be "shed" or released, usually in very large numbers. This is how they enter the environment and spread to other hosts.)

One lucky thing about this virus is that it moves pretty slowly, depending on how far away it is from the central nervous system when it enters the body. For example, if you are bitten on your calf, you will have a lot more time before the virus reaches your brain than someone who is bitten on the neck. Viral load, or how many viruses enter the wound, also plays a role in how quickly it moves. If only a few viruses enter a wound, it will take longer to get to the brain. It's slow movement is important for treatment, which we will discuss later.

Symptoms:

According to the WHO, "incubation period for rabies is typically 2–3 months but may vary from 1 week to 1 year, dependent upon factors such as the location of virus entry and viral load."

Rabid dog. Image from the Wellcome Collection.

Early symptoms are pretty standard: fever, weakness, headache, and body aches. Oftentimes, people will feel tingling, prickling, and/or burning sensations as the virus spreads through the nerve cells. Hydrophobia (fear of water) and sometimes photophobia (fear of light or sensitivity to light) are later symptoms.

There are two forms of the disease: paralytic rabies and furious rabies. Furious rabies is the rabies most of us are familiar with. Furious rabies is a faster moving manifestation of the disease. It is characterized by hyperactivity, excitability, hydrophobia, agitation, confusion, and insomnia.

What is super interesting to me is the hydrophobia. The people who experience this (and not all rabies-infected people/animals do) have pain when they try to swallow. This is a viral strategy (so to speak, they aren't alive) to help spread it. The virus is present in saliva and the virus wants to get out, not be swallowed. Being swallowed defeats the virus' purpose. The virus affects an animal's ability to swallow in order to spread. Much like a cold virus will cause a person to sneeze so that virus can be spread in the air to new hosts.

In paralytic rabies, the disease is slower and not as exciting, so to speak. As the virus spreads, the person becomes paralyzed starting at the site of infection and slowly spreading until the person is completely paralyzed and falls into a coma.

No matter which form you get, the ultimate outcome is almost always death. According to the CDC, "less than 20 cases of human survival from clinical rabies have been documented" and only a few of the survivors had not had any preventative treatment (like the rabies vaccine) or treatment after they were exposed. This shows just how deadly this virus is. It has been noted throughout much of history that if a victim reaches the hydrophobia stage of disease, the outcome will be death.

Prevention and Treatment:

For those of you with dogs, you probably know that rabies vaccines are routine. Generally, they receive the vaccine as puppies and then have a booster every three years, though some areas require a booster every year. Dogs are often vaccinated against rabies, which is good because most cases of human rabies are from domestic dogs. Humans who work closely with animals, like veterinary doctors and staff, or laboratory staff that work with animals may receive the vaccine as prevention. Vaccination against rabies is not standard in humans, though.

If you get bitten or scratched by an animal that can carry rabies, what do you do? Seek care as soon as you can, especially if you do not know the animal or their health state. Cleaning the wound very well can help a person's chances. Normally, people who may have been infected receive the rabies vaccine because the virus moves slowly enough for your body to react to the vaccine and then to react to the actual virus to clear it. Your body just needs a little help from that vaccine. If someone is further along or more at-risk, they may receive rabies immunoglobulin. Immunoglobulin are antibodies specific to a disease, rabies in this case. Antibodies are produced by your immune system to help target and inactivate viruses (or bacteria, and so on). The immunoglobulin is produced in a laboratory and given to people to help their immune system combat the disease until that person's own immune system can catch up and start making its own antibodies.

Miscellaneous Information: 

If you are interested in rabies, I highly recommend the book Rabid: A Cultural History of the World's Most Diabolical Virus by Bill Wasik and Monica Murphy. My favorite parts were about how the rabies virus may have helped inspire the stories of werewolves and vampires. Both horror figures are strongly associated with wolves/dogs. Vampires are also associated with bats. Both involve biting to spread the conditions. Werewolves are often associated with rage and being unpredictable and uncontrollable. And then vampires don't do well (or can't exist at all) in sunlight--photophobia. Many classic vampires also can't cross water--hydrophobia.

The book also goes into the history of the disease, old time treatments (like drinking something containing "the hair of the dog that bit you," which is a common phrase even now) and how it has caused people throughout time to create laws to prevent the spread of rabies.

That is about it for rabies! Please let me know if you have any questions or if I have any information incorrect! Thanks for reading!

And a very special thank you to my friend, Veronica! She edited this post and helped me find things that needed more information or clarification. So thank you for your help!

Sources:
Virology: Principles and Applications by John Carter and Venetia Saunders
World Health Organization
Centers for Disease Control and Prevention
Rabid: A Cultural History of the World's Most Diabolical Virus by Bill Wasik and Monica Murphy
Medical Microbiology 6th Edition by Patrick R. Murray, Ken S. Rosenthal, and Michael A. Pfaller
WebMD Pet Vaccines: Schedules for Cats and Dogs

Disease Post: Smallpox

Greetings and welcome to my first (hopefully of many) science posts.

If you read my last post, I was inspired by the second half of the vaccine episode of the podcast This Podcast Will Kill You (which is an awesome podcast and everyone should listen to it). In the second part of the vaccine episodes, they discussed that people not believing science and scientific research is because scientists don't make information accessible and easy to understand. I agree and think this is a huge shortcoming in the field of science. To that end, I would like to contribute to the scientific knowledge that is available out there.

Let me start with a little introduction and background:

I have my Bachelor's degree in Biology with a minor in Chemistry. I did a decent amount of focus on molecular biology at this time. I have my Master's in Microbiology and infectious diseases are certainly my passion. Currently I am taking steps (slow baby steps, but steps) towards medical school and on to be a doctor who specializes in infectious diseases (fingers crossed). Because that would be the most amazing thing ever. I have a pretty good science background. I have worked in a lab for several years and have background as a tutor. I am hoping that these things will enable me to take on this blog project.

However, my background is almost entirely in Biology and Microbiology. I can get by Chemistry alright, but that is about the extent of what I know. So as much as I wish I could educate on topics like global warming, I can't and don't plan to try unless I get help from someone who knows the field. So that means that I will end up focusing on diseases (at least to start). I do have an older post about vaccination here: Why You Should Vaccinate, and I may do more like that in the future. Right now this is a bit of a pet project and we will see how it goes.

And now for:
Disease Post One: Smallpox!

A tiny bit of background information: what is a virus? The Merriam-Webster dictionary says a virus is
     any of a large group of submicroscopic infective 
     agents that are usually regarded as nonliving 
     extremely complex molecules, that typically 
     contain a protein coat surrounding an RNA or DNA 
     core of genetic material but no semipermeable 
     membrane, that are capable of growth and 
     multiplication only in living cells, and that 
     causes very important diseases in humans, 
     animals, and plants

Basically, this means that there are several different kinds and families and types of viruses. They might have DNA or RNA genetic material which may be single- or double-stranded (which will affect how they use the host cell to make more copies). Some have an envelope around them that is basically the same as our cell's membranes. Some do not have a membrane. These will affect how a virus enters and exits a host cell and provide some level of protection/preservation when the virus is not inside a host. It is up for debate whether viruses are actually alive or not. That's not something we are going to get into here. Viruses are mostly considered non-living because of one important feature: they need another living cell in order to multiply their numbers and spread. 

Viruses are the source of many different diseases, some are lethal and others are minor. Some can even cause cancer. I'm going to underline this next point: viruses cannot be treated with antibiotics! Antibiotics treat bacterial infections, not viral. There are anti-viral medications out there for serious infections, but viruses can be harder to treat because they like to hide in our cells.

Smallpox is a disease caused by a virus, namely Variola major. (There is a less common and less lethal virus that causes smallpox called Variola minor.) The variola viruses are double-stranded DNA viruses so their genetic material is like ours! They are very large viruses because they have to carry a bunch of machinery around due to the fact that they replicate their DNA in the cytoplasm of human cells. Since we, as humans, replicate out DNA in the nucleus of our cells, the virus can't hijack our own machinery to aid them. Therefore, they carry their tools with them!

Smallpox was common around the world for thousands of years. It was officially eradicated in 1980. Smallpox virus only has one host: humans. Which made it a good target for eradication because it cannot be hiding somewhere in the environment or in an animal host, waiting to re-establish itself in the human population. Once the vaccination programs spread, the virus had no where to go, and now its gone! The only smallpox left in the world are in a couple of laboratories (both in the US and in Russia because it is a great pick for bioterrorism and biowarfare--maybe an idea for a future post as I actually took a course on that very thing during my Master's).

While smallpox seems less relevant today, it is a historically important disease that killed loads of people. According to the CDC (Center for Disease Control): "On average, 3 out of every 10 people who got it died. Those who survived were usually left with scars." It is also where vaccines started. I won't get too into all of the history here, but in the late 1700's Edward Jenner used a live vaccinia virus (which causes cowpox, a virus/disease related to smallpox) to inoculate or infect a patient. The reason for this was that he noticed that milkmaids often didn't get smallpox if they had contracted the much milder cowpox. His methods worked (luckily since he used human subjects in the days before scientific ethics was a thing). And the word "vaccine" comes from "vacca," which is latin for "cow!"

Edward Jenner vaccinating a child. Image from Wellcome Collection.

How is it spread? 

Smallpox initially infects the respiratory system and so it is usually transmitted in the air from one person to another. It can also be spread through touch because the scabs and sores contain live virus, but that is less common. Namely, it happened when the infected person sneezed or coughed virus into the air.

Once smallpox is in the body, it incubates (develops, multiplies) for several days, the CDC estimates between 7 and 19 days. During this time, there may not be any symptoms present and the person probably won't know he or she is sick.

Symptoms: 

• First symptoms are pretty common for diseases: fever and body aches. Some patients may experience vomiting. The CDC states that this stage is not usually contagious, but it can be.
• Next the patient will start to develop a rash in the mouth and tongue. This is when patients are most contagious! That is part of why this disease is dangerous and easy to spread: people around you don't know you have smallpox!
• Following this stage, the sores in the mouth will begin to fade to be replaced by the signature skin sores. 
• The sores become pustules (bumps filled with fluid) form that have a characteristic dent in the middle. 
• The pustules will start to scab over and the scabs eventually fall off. This happens after about 3 weeks of obvious disease (from the mouth sores). And remember, the pustules and scabs are also contagious. Once the scabs are all gone, the person is not contagious anymore.

This highlights another reason this disease is important: if you got smallpox (and almost everyone did before vaccines), you were sick and contagious for about a month. If you survived. Remember the mortality rate was about 33%. Meaning that about a third of the people who were infected would die of the disease.

If the virus moved to the eye, the patient could become blind.

According to the WHO, "Between 65–80% of survivors are marked with deep pitted scars (pockmarks), most prominent on the face."

One upside: if you survived, you had life-long immunity! This means you cannot get smallpox twice!

Smallpox rash and pustules. Image from Wellcome Collection.

Prevention and Treatment:
These are not super important now that smallpox is eradicated, but there are still stocks of smallpox vaccine out there. Military personnel are the most common people vaccinated these days, and not even all of them receive the vaccine. I believe it is available to medical professionals in some places, but many never receive it. The main reason for this is that the vaccine is still a live virus (a weaker vaccinia virus that was developed in labs for the vaccine for many generations) and can cause people nearby to become infected by the vaccine strain. When a person gets the vaccine, they are supposed to avoid human contact for a while until the vaccine site heals. (I know the old vaccines gave a pox mark/pock mark and pustule, so you would have to wait for the scab to fall off, just like with smallpox. I'm unsure if the current vaccines are the same, but I know they are still contagious.)


As for treatment, there are a couple options, just in case! None of these antivirals (medication used to treat viruses) have been used to treat smallpox because there are no more cases, but they are: tecovirimat (TPOXX), cidofovir and brincidofovir.

That's about it for smallpox! I hope you liked it and learned something. And if I missed anything or got anything wrong, please, please let me know so that I can correct it! Feel free to reach out with questions or if something needs clarification. Thanks!

Sources:
Centers for Disease Control and Prevention
World Health Organization
Medical Microbiology, 6th edition by Patrick R. Murray, Ken S. Rosenthal, and Michael A. Pfaller
Mayo Clinic

Also, thanks so much to my friend, Veronica, for helping me edit this post!

Why You Should Vaccinate

I have been working on this one for some time, now. I think it is time to share it.

Most of my friends are well aware how pro-vaccine I am.

In the first place, I think that I have the educational background required to make a very well-informed analysis of the topic. (If you don't know, I have a B.S. in Biology [minor in Chemistry and an emphasis in Biotechnology, which both come in handy if we are discussing vaccines] and am completing an M.S. in Microbiology and Immunology.)

Vaccines were a huge development created in order to prevent horrible diseases like small pox, polio, rabies, measles, diphtheria, and so on. The thing about vaccines is, no, they are not perfect. Some of the people vaccinated (out of millions, mind you) will have bad side effects. Some of these, I believe, can be due to an underlying autoimmunity in the vaccinated person (which is there whether you get the vaccines or not—these types of conditions are often genetic. I don't think this has been proven, it's just an idea I've had). Regardless, some just have nasty side-effects that are general and go away. The thing about this is that vaccines prevent diseases that are MUCH worse than the side-effects of vaccination. The risk of you falling into maybe 1% of people who have bad side-effects are out-weighed by the benefit of being protected from these diseases.

I feel that most people who are anti-vaccine do not know enough about the diseases the vaccines prevent. To that end, I will attempt to give an overview of one of these diseases. You can tell me if you think the vaccines are worth it.

MMR vaccine protects against measles, mumps, and rubella. According to the CDC Website (that is, the Centers for Disease Control) "Measles is a highly contagious respiratory disease caused by a virus... Measles causes fever, runny nose, cough and a rash all over the body. About one out of 10 children with measles also gets an ear infection, and up to one out of 20 gets pneumonia. For every 1,000 children who get measles, one or two will die." One in 1,000 is .001% Not very high. However, according to the US Census Bureau, the estimated population in 2013 for the US alone was 316,128,839! .001% of this is 316,128. Over 300,00 people per year would die of measles in the US.

The CDC also states "The virus is highly contagious and can spread rapidly in areas where vaccination is not widespread. It is estimated that in 2008 there were 164,000 measles deaths worldwide—that equals about 450 deaths every day or about 18 deaths every hour." Now that is intense.

Common side effects of the vaccine include: "pain where the vaccine is given, fever, a mild rash, and swollen glands in the cheeks or neck." (CDC)

Also according to the CDC, severe reactions can happen. For example, less than one out of one million have a severe allergic reaction to the vaccine. Here is a direct link to the page: CDC: Side-effects of MMR. And for those of you who don't do well with math (like myself), that is less than .000001%! See? It becomes a numbers game where the benefits out-weigh the risks.

Measles is just one disease. If you are not sure about the symptoms of these various diseases, research! Make sure you know what you might be getting into by choosing not to vaccinate. Half-jokingly, my response is, "Do you know what happens when you get (insert disease here, ie: Tetanus)? Nothing good and then you die." I have various text books and resources easily available to myself. If you have questions about certain diseases, I would be happy to share the information.

Here is another thing that some people do not know/like to acknowledge. There has been absolutely no proof that vaccines cause autism. The CDC states "Because signs of autism may appear around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism."

The guy who first published this study, Wakefield, is pretty notorious in my graduate program. He was the one who first observed this correlation between vaccines and autism (as a side note, correlation is not to be confused with causation. What this means is that vaccination rates rose as well as rates of autism, but that does not follow that vaccinations cause autism. No proof has been found to support Wakefield's claim.) Wakefield's "data" could not be duplicated and was later found to be fraudulent. In the scientific community, this is a huge offense—we call it scientific misconduct and it can get you into all kinds of trouble (which sadly, doesn't prevent it from happening—that is a topic for a different day, but I can answer questions if anyone has any). He was found guilty of misconduct and was forbidden to practice in the UK after that. I think he should have had his PhD revoked, personally (which can and has happened to other data fabricators and falsifiers). But alas, he didn't. Every time we talk about dropping vaccination rates and outbreaks of measles (or what have you) in the US, it is usually accompanied by a sarcastic, "Thanks, Wakefield" from someone in class.

Despite all of this, preservatives in vaccines were changed to help people not be so scared. People still harp on use of mercury in vaccines. For your information (and verified by the FDA), the mercury-containing compound that was used has been removed from many vaccines and reduced to the barest (we say "trace") amounts in the rest. I imagine that you get much more mercury from eating fish than you do from all the vaccines you get over your life-time.

And here, in my opinion, is the most important thing about vaccination: it creates a herd immunity. This means that enough people get vaccinated to block the infection in the general population. If most people are vaccinated, that helps protect the few that are not. This does not give you license to not vaccinate yourself or your children; that's not the point. The point is that some people are allergic to vaccines and some people don't have healthy immune systems. These people CANNOT get vaccinated, even if they want to. These individuals rely on the herd immunity to protect them. They rely on the people who CAN get vaccines to do so.

Lastly, say vaccines cause autism (I know they don't, but lets pretend). There is a chance that your child, following vaccines, will get autism. People, apparently, would rather not have a child who is autistic (and therefore a little different) than to have a sick/dead child. Not only that, but by not vaccinating their own child (at the horrible, life-threatening risk of autism<—this is sarcasm) endanger the life of their child AND the children around them who are relying on herd vaccination to protect them. To me, that is just selfish. The choice is death or autism and you are going to choose death? And the deaths of others? This is just sad, actually.

Here are a few resources and personal accounts for your purusal:
New York Times: Autism and the Agitator by Frank Bruni
Voices for Vaccines: Growing Up Unvaccinated
Violent metaphors: Dear parents, you are being lied to by Jennifer Raff

And here is a video that a friend posted on Facebook in response to a mutual friend posting the NYT article above. I am so glad this was made. It really hits exactly the point I was trying to make. There is some swearing, just so you know: Penn and Teller on Vaccinations

If there are points that I didn't address here (I'm sure there are) that you want me to address, please let me know and I will do my best.

When in doubt, you can always talk to a doctor or nurse, or, if you have the opportunity, a Medical Microbiologist or Immunologist!