Week 4 ~ Diseases Jumping Species

Diseases that can jump from one species to another is a pretty freaky topic to think about, especially when the disease is transmitted from an animal to a human (this is known as zoonoses). According to an article by Robert Roy Britt (2011), there are more than 3,000 zoonoses we can catch directly through touch and more than 4,000 from bites. It's weird to think that these tiny, "invisible" agents can do so much damage to living things. "The cross-species infection can originate on farms or markets, where conditions foster mixing of pathogens, giving them opportunities to swap genes and gear up to kill previously foreign hosts (i.e. you)" (Britt, 2011). It's a bit scary but also very fascinating how bacteria and viruses deadly to one species can evolve to infect a completely different species. When these types of diseases start causing outbreaks, things can get pretty difficult and hectic (especially when there is no vaccine for the disease).

One major example of this type of disease is the group of influenza A viruses, which are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). The CDC's website (2012) says there are 17 different hemagglutinin subtypes and 10 different neuraminidase subtypes. Interestingly, all of these subtypes but one have been found among birds; H17N10 has only been found in bats. I also found it intriguing that most influenza viruses either cause asymptomatic or mild infection in birds, but when they transfer over to humans they can be much harsher.

I was also reading on the CDC website about pigs and influenza because I was curious how pigs, birds, and humans can all be connected when it comes to certain influenza viruses. Pigs are an interesting species because they can be infected with human and avian influenza viruses as well as their own (swine influenza viruses), and it's possible for them to be infected with two different species' influenza viruses at the same time. In this sort of situation, the creation of a new virus is possible by the mixing of genes among the two existing viruses. 

This could possibly lead to a change in the influenza A viruses known as antigenic shift: "if a pig were infected with a human influenza virus and an avian influenza virus at the same time, the viruses could mix (reassort) and produce a new virus that had most of the genes from the human virus, but a hemagglutinin and/or neuraminidase from the avian virus. The resulting new virus would likely be able to infect humans and spread from person to preson, but it would have surface proteins (hemagglutinin and/or neuraminidase) not previously seen in influenza viruses that infect humans" (CDC, 2012).

As seen from the above example, antigenic shift occurs when a new influenza A subtype infects humans. Due to the new surface proteins not previously seen in human flu viruses, people would have little to no immune protection against this new virus. This foreign virus could have the potential to cause illness and also be easily transmitted from person to person. If this were the case, then an influenza pandemic could easily occur. Fortunately, influenza infections transmitted directly from animals to humans is unusual, but of course it is still possible. Being aware of the possibilities and knowledgeable about these viruses is essential, even if the chances are low.

Life cycle of the parasitic microbe T. gondii

While doing some reading on zoonoses, I came across a few articles about a parasitic microbe that is commonly found in cats and can be transmitted to humans (Toxoplasma gondii). I have heard that cat litter is unsafe for pregnant women but never knew exactly why, so I was curious to learn more about this parasitic microbe. According to Ker Than's article "Study: Cat Parasite Affects Human Culture" (2006), infection by T. gondii could cause some people to become more prone to some forms of neuroticism, which could lead to differences among cultures if enough people were to become infected. This article also stated a finding by a U.S. Geological Survey scientist, Kevin Lafferty, that people living in countries with higher rates of T. gondii infection scored higher on average for neuroticism. I found this information about T. gondii very interesting because psychology is fascinating to me, especially mental disorders and possible causes.

T. gondii tissue cyst in mouse brain

This parasite is excreted by cats in their feces and causes toxoplasmosis. Pregnant women who become infected can end up transmitting the disease to the fetus, and in some cases severe brain damage or even death can occur to the baby. Another article I found also discusses the possibility of T. gondii affecting the human brain: it "may be changing connections between our neurons, altering how we act and feel" (Mcauliffe, 2012). In the early 1990s, a Czech scientist, Jaroslav Flegr, began to suspect that a single-celled parasite had invaded his brain and was subtly manipulating his personality. Flegr discovered in 1990 that he had T. gondii, and from then on he started researching more and more about the parasite. He learned that it can only sexually reproduce inside cats, so once the parasite is inside another animal or human host it starts working to return back to a cat. Flegr believes T. gondii may be able to manipulate behavior in other species in order for it to make its way back to the body of a cat so it can reproduce.

Reading about this parasitic microbe got me pretty interested in the possible affects it can have on the human brain. I'm glad it can't reproduce in species other than cats because who knows what it could do to our population if the neuroticism theory is true. Learning about new disease-causing organisms really gets me thinking about how many there are out there that we haven't even discovered yet. There could be some that function in ways we can't really even imagine right now, and maybe others could be beneficial to our health in some significant way rather than threatening. There is so much to learn and discover about diseases and their factors. I'm excited to continue growing my knowledge with this subject and encountering new and fascinating information.


References
1. Britt, R. R. (2011). 10 deadly diseases that hopped across species. Live Science. Retrieved from http://www.livescience.com/12951-10-infectious-diseases-ebola-plague-influenza.html 
2. CDC. (2012). Transmission of influenza viruses from animals to people. Retrieved from http://www.cdc.gov/flu/about/viruses/transmission.htm   
3. Mcauliffe, K. (2012). How your cat is making you crazy. The Atlantic. Retrieved from http://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/
4. Than, K. (2006). Study: cat parasite affects human culture. Live Science. Retrieved from http://www.livescience.com/933-study-cat-parasite-affects-human-culture.html
5. Photo (top): http://www.colourbox.com/preview/4326388-26830-swine-flu.jpg
6. Photo (middle): http://www.intechopen.com/source/html/44112/media/image6.jpeg
7. Photo: (bottom): http://upload.wikimedia.org/wikipedia/commons/3/3c/Toxoplasma_gondii_tissue_cyst
_in_mouse_brain.jpg

Week 3 ~ Could Lyme Disease Be Sexually Transmitted?

Deer tick on the right

Last spring it was recommended by my doctor that I have some blood tests done because I was feeling very fatigued all the time, as well as other symptoms that caused me to feel out of it most of the day. I have come across the term "brain fog" many times, which is definitely what I was experiencing. After reviewing the results, my physician highly suspected that I had Lyme. I don't ever remember being bitten by a deer tick, but since they are so small many people never realize they've been bitten. I have been camping every year since I was in elementary school and enjoy working outside during the summer, so the possibility that I had at one time or another been bitten by a deer tick was very likely. Lyme disease is becoming more and more common (or at least more people are being diagnosed with it). I have heard of many people around my town who have it and are being treated for it. This past summer I had a Lyme test done. My blood was taken and cultured for a certain amount of days. The results came back inconclusive, but my doctor was still leaning toward Lyme (apparently the Lyme tests are not very accurate). Then near the end of 2013 my sister ended up having her blood taken to be tested. Just like for me, our physician thinks she has Lyme as well. After meeting with our doctor many times, my family has noticed that she seems to focus a lot on Lyme disease and feels that it is the cause of many people's unknown symptoms. I was planning on starting treatment with antibiotics this month, but now my mom thinks we should get a second opinion first before moving forward.

I just recently came across an article discussing how Lyme disease could possibly be sexually transmitted. I have never heard this before or even thought about it, so it really peaked my interest. I have done quite a bit of research on Lyme disease ever since my doctor first suggested it, but I have never read or heard about this possibility. I decided to search for other articles to see what other information I could find. There was a study done recently that suggests that Lyme disease may be sexually transmitted. An abstract of the research was published in the January issue of the Journal of Investigative Medicine. According to the CDC, though, Lyme disease can only be transmitted through the bite of an infected tick.

Causative agent: B. burgdorferi

Lyme disease is a tickborne infection caused by the Borrelia burgdorferi bacteria. This corkscrew-shaped bacteria is known as a spirochete, and it ironically resembles the agent of syphilis. The study that was done tested semen samples and vaginal secretions from three groups of patients: "control subjects without evidence of Lyme disease, random subjects who tested positive for Lyme disease, and married heterosexual couples engaging in unprotected sex who tested positive for the disease" (The Dispatch, 2014). All of the control subjects tested negative for B. burgdorferi in the semen samples and vaginal secretions. All the women with Lyme disease tested positive for the bacteria in vaginal secretions; however, only about half of the men with the disease tested positive for the spirochete in semen samples. One of the heterosexual couples with Lyme disease showed identical strains of B. burgdorferi in their genital secretions.

Since we just discussed last class about disease transmission, I thought this was an interesting topic to talk about. Even if the CDC is right and people cannot contract Lyme through sexual contact, it is an interesting idea to think about. If Lyme disease is in fact able to be transmitted sexually, that would explain why the disease is becoming more and more prevalent. In 2013, the CDC announced that Lyme disease is more common than previously thought, and there are over 300,000 new cases diagnosed each year in the United States.

I thought it was very interesting that one of the married couples had identical strains of the bacteria. Of course this could just be a coincidence or they could have been bitten around the same time in an area with ticks carrying the same strain, but this definitely supports the prediction. But this brings up the question why the other married couples did not have identical strains. They could have possibly both contracted the disease before they met or before they started having unprotected sex, but it doesn't seem like the study took into consideration when each person was diagnosed with Lyme.

I think there should definitely be more studies to research this Lyme STD theory. Even if it most likely seems that Lyme disease can only be transmitted by infected ticks, I believe it would be very beneficial for more research and studies to be done not only on this specific Lyme disease topic but on Lyme disease in general. Many people are being misdiagnosed and may never know they have Lyme disease (or may not find out for years), and others may be diagnosed with Lyme but not actually have it. From what I have learned about this disease over the past year, it seems that Lyme disease is not as researched as it should and could be. The more information we know, the better protected against it we can be. Reading about this STD prediction also got me thinking about other insect-borne diseases and if any of them have the possibility of being sexually transmitted. There is a lot to think about and consider when researching how diseases can be transmitted, but the more we learn about each disease and how they work the better we can be at preventing, treating, or managing them.


References
1. Borreli, L. (2014). Is Lyme Disease Contagious? Clues Hint That It May Be A Sexually Transmitted Disease. Medical Daily. Retrieved from http://www.medicaldaily.com/lyme-disease-contagious-clues-hint-it-may-be-sexually-transmitted-disease-267964
2. The Dispatch. (2014). Is There A Risk Of Getting Lyme Disease In The Bedroom? Yes, According To One Study. Retrieved from http://www.theglobaldispatch.com/is-there-a-risk-of-getting-lyme-disease-in-the-bedroom-yes-according-to-one-study-73842/
3. Photo (top): http://fyi.uwex.edu/news/files/2013/04/Deer-tick-on-right.jpg
4. Photo (bottom): http://cvmdl.uconn.edu/images/borrelia.jpg

Week 2 ~ History of People and Their Discoveries

In my last epidemiology class we discussed the basic principles of epidemiology and learned about a few very important epidemiologists throughout history. These people included John Snow, Myron Wegman, and George Comstock. Disease origins, causes, preventions, and treatments have been discovered because of these and many other epidemiologists. It was interesting learning about these people and how they contributed their time, effort, and brains in order to break past the unknown and make important discoveries, which in turn ended up positively affecting the public health. After learning about some of the greatest people of epidemiology, I thought I would share what I have learned outside of class about some other epidemiologists and their work. 

James Lind was a surgeon in the English navy, and in 1747 he noticed that many sailors were suffering from scurvy (a condition that causes swollen and bleeding gums, loss of teeth, spots on the skin, and exhaustion). Dr. Lind was determined to find a cure for scurvy, so while he was at sea he decided to perform a simple experiment among some of the sick sailors. He divided twelve of the men into six groups, changing the diets of each group: "For example, one drank a quart of apple juice a day, while another received two spoonfuls of vinegar three times a day" (Asher, p. 14-15). By performing this experiment, Lind discovered that the men who ate two oranges and one lemon a day recovered right away. From then on, the British navy made sure to supply citrus fruits to all the sailors for their voyages.

Another important discovery was made by Dr. Joseph Goldberger, a physician in the U.S. government's hygienic laboratory, in the early 1900s. Pellagra (a disease caused by a lack of vitamin B) was killing many poor southerners around this time. At this point no one knew the cause of pellagra, but most doctors thought it originated from some type of bacteria or virus. Dr. Goldberger performed a series of research experiments, and the results of his tests showed that it was nutrients missing from people's diets rather than germs that caused the condition. He wanted to prove that his results were definitely correct, so on April 26, 1916, Dr. Goldberger injected the blood of a pellagra sufferer into his assistant's arm and his assistant did the same to him. They even wiped their noses with tissues already used by people with the disease. Both Dr. Goldberger and his assistant remained healthy, which seemed to prove their argument about the disease.

These discoveries are just two of many that have been made by epidemiologists throughout history. If these types of people didn't exist it would be hard to imagine what the world would be like today, but it would definitely be very different. In class we learned that epidemiology is the core science of public health, and I definitely agree with that. It contributes so much and impacts public health in such a big way.


References 
1. Asher, D. (2003). Epidemiologists: Life tracking deadly diseases. New York, NY: The Rosen Publishing Group, Inc.
2. Photo (top): http://commons.wikimedia.org/wiki/File:Michael_Zeno_Diemer_-_Ship_at_Sea.jpg
3. Photo (bottom): https://www.healthtap.com/user_questions/209132-what-are-health-benefits-of-getting-a-vitamin-b-shot 

Week 1 ~ Intro to Epidemiology

Welcome to my first blog post :)

http://www.agencypost.com/2012-communications
-trends-for-nonprofits/

Since this is my first post for HTH 450 (as well as my first blog post ever) I am having a bit of trouble thinking of what to write, but I know it will become easier as I go. I have never had to make a blog for a class before, so I'm excited for this new type of assignment! As of right now I have some knowledge about epidemiology, but I know there will be so much more to learn and discover throughout this course. 

http://kintalk.org/discussion

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syndrome-still-a-quandary

Last class (our first class of the semester) something was brought up that I had never really thought about before, and I found it very interesting. Our professor (Dr. Wallis) asked the class if we thought breast cancer is more prevalent now than in the past. It seems like more people are getting breast cancer nowadays, but in actuality this is most likely not the case. Dr. Wallis went on to explain that breast cancer only appears to be more prevalent today because of the new and advanced technology and testing being used. Because of this, more people are being tested resulting in more people being accurately diagnosed with cancer. There is also more awareness now about breast cancer than in the past, so this is another reason why it may seem more prevalent. As breast cancer research continues and more diagnoses are made because of today's better technology, awareness about this cancer grows and grows.

Just learning about that gave me a new perspective about epidemiology and what we will be learning. Not only is it the study of health, disease, and the population, but within that is so much more to learn, recognize, consider, analyze, compare, etc. When it comes to studying trends, correlations, or anything else it seems that there is a lot more than meets the eye, which I'm sure can be very challenging at times. I feel that this course will require a good amount of critical thinking which we can also use in other areas of our lives as well.