Pneumonia - An infectious disease

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List of contents

Introduction
Report
- Background on infectious diseases
- Background on pneumonia
- Bacterial pneumonias
- Viral pneumonias
- Pneumonia now and then
- My personal experiences of pneumonia
Conclusion
List of references
Critical review of references

Introduction
This report is about infectious diseases and pneumonia in particular. I chose to work with pneumonia, because I have had the disease once, and hoped that my memories from that time would help me understand how pneumonia affected people, but also to get a general picture of all infectious diseases, by learning about one of them. Another reason for choosing pneumonia, was because it is quite a common disease, which is likely for me to get again, or someone in my immediate surroundings, so perhaps my future knowledge could help me prevent me from getting the disease, or at least make me discover the symptoms quickly, to receive the right treatment as fast as possible.
When I started reading about pneumonia, I realised that there were too many sorts of them to write about them all, so I chose to write about two particular bacterial pneumonias, but only about viral pneumonias in general, because they are not as common as bacterial pneumonias.


Background on infectious diseases

Why do you get sick?
There are many different reasons to why people get sick, but infectious diseases are caused by a micro organism called pathogen. A pathogen is virulent, meaning that it causes diseases. Pathogens are always searching for a place to live and a place where they can reproduce. Some pathogens reproduce easily inside humans, and some reproduce more easily in for example animals. There are many different sorts of pathogens, but the most common are bacteria, viruses, worms, fungi and protists. They do not always have to be dangerous, humans have many organisms from these groups in their natural flora, but it is when they start damaging individual cells, that they can cause diseases.
Bacteria damage cells by reproducing rapidly anywhere in the body, or by invading cells or tissues and then produce a highly poisonous toxin. Viruses, on the other hand, can only reproduce inside living cells, so they enter cells, take over them and direct them to reproduce new viruses. This process eventually kills the host cell, and releases new harmful viruses.

Transmission
To get an infectious disease, you have to be exposed to human pathogens. Those pathogens could be transmitted to you from another person, through both direct contact, such as touching or kissing, but also through indirect contact, e.g. when a person sneezes, and pathogens shoot into the air. Another way of transmission is contaminated objects, because some pathogens are able to survive outside the human body. Food or water can also be contaminated. Animal bites are yet another way of disease-spreading, if the biting animal has a disease. Pathogens can also exist naturally in the environment, for example in water.

Defence
To fight harmful organisms, the body has a lot of different techniques. Firstly, the body’s physical structure makes it very difficult for pathogens to enter the body at all. If entering through the skin, the infectious agents first have to survive the destructive chemicals in the oils or sweat produced by the skin, and then go through the thick barrier of skin. If they choose to enter through the mouth, they could easily get destroyed by dangerous chemicals in the saliva, or else by the acid produced in the stomach. The breathing passages use cilia and mucus to trap and remove dangerous organisms, by coughing or sneezing.
If the pathogens would get through anyway, the inflammatory response would kick in. An inflammation would occur, which would make an infected area turn red and swell, causing an increased pressure, which could hurt. The area swells because the blood flow must increase so that white blood cells, phagocytes in this case, could demolish the pathogens.
If the inflammatory response fails in its mission to remove the harmful agents, the immune system would send immune system cells to fight the pathogens. That is called the immune response. The immune system cells know the differences between different pathogens, and can therefore send cells especially good at fighting the particular pathogens. The white blood cells doing this are called lymphocytes and there are two sorts of them, T cells and B cells. The T cells’ job is to make a distinction between the pathogens, and they do that by recognizing the antigens on the pathogens. They alert the B cells, which produce antibodies that can bind to the antigens and cluster the pathogens together, so that the phagocytes, and also the T cells can destroy the pathogens.
Disease occurs when some cells in the body are damaged, and when the body starts fighting the disease, the body can react with for example fever, coughing and sneezing.

Immunity and vaccine
The state of not being susceptible to different diseases is called immunity. Immunity is divided into active and passive immunity. Active immunity occurs when the body has produced antibodies against an invading pathogen’s antigens, and next time recognizes the antigens so fast, that disease not is needed. Another way to gain active immunity is by vaccination. Harmless antigens are released, mostly by injections, in a person’s body. The body will answer to the treatment by producing antibodies that can kill or remove the pathogens, and if the body later get invaded by the same sorts of pathogens, it will remember what it has to do. Some vaccinations last for a lifetime, but others have to be retaken.
Passive immunity is gained when antibodies to a pathogen are not produced by the body itself, but given to it. Some diseases stay in mind of the immune system only for a few months after the body was infected, so some diseases give you a passive immunity.

Background on pneumonia
Pneumonia is a common designation of different infections in the lower breathing passages. There are more than 50 different sorts of pneumonia and they can be caused by bacteria, viruses, fungi or other pathogens. In 25% of the cases, is it viruses that are the main cause, and in 50% of the cases, is it bacteria, that are the main cause. The infections could eventually cause an inflammation of the lungs.
Pneumonias could be divided into three groups according to anatomy, and these are lobar pneumonia, bronchi pneumonia and interstitial pneumonia. Lobar pneumonia affects at least one lobe in the lung, while bronchi pneumonia on the other hand only affects parts of lobes or bronchi. Both of them are often caused by bacteria. Interstitial pneumonia is caused by virus and strikes at the alveoli and the lungs’ connective tissue. Lobar pneumonia is the most common one. The most common bacteria causing pneumonia are called pneumococci and mycoplasma. Pneumococci can cause both lobar and bronchi pneumonia, whereas mycoplasma only can cause lobar pneumonia.
A passive immunity is given to many sorts of pneumonias, after a surveyed sickness, but it only lasts for a couple of weeks or months.

Pneumococcal pneumonia
Most pneumonias are caused by a bacterium called pneumococcus. Pneumococci are bacteria that many people usually have in the nose, and are parts of their normal flora. Up to 50% of the population may be carriers of the bacteria, in the throat or pharynx without showing any symptoms at all. It is when the bacteria start moving down to the trachea that disease may arise. The bacteria move downwards if the host get infected by something in the upper breathing passages, such as an ordinary cold or influenza, which weakens the immune system. They travel into the alveoli, where gas exchange takes place. When the pneumococci have got inside the air sacs, they start to reproduce, making the alveoli fail in their job of exchanging oxygen. The air sacs get filled with fluid, and when that has happened, you have pneumonia. To keep giving the blood the needed oxygen, the capillary net directs the oxygen-poor blood to the healthy parts of the lungs.

Transmission
The carriers of pneumococci can transmit the bacteria to other persons, when they sneeze or cough, and because of this, pneumococcal pneumonia is an airborne droplet infection. If the pathogens get inside the person, the person can get sick within a week, but if that does not happen, the person will only be carrier of the bacteria. Children are carriers of the bacteria for one to several months, whereas adults only carry the bacteria for one to several weeks. The pathogens are infectious all the time while being inside a human and can therefore make other people sick as well.

Symptoms and diagnosis
The incubation period for pneumococcal pneumonia is rather short and varies from one to three days. The symptoms come quite suddenly and hastily and they could be high fever, 40ºC or higher, chills, stitch when breathing and suppressed coughs. The breathing frequency also increases, which is called tachypnoea. Sometimes, if the inflammation area is larger, the skin might get bluish, a state called cyanosis, because there are not many healthy parts to reroute the blood flow to, and the blood does not get as much oxygen as it needs.
The diagnosis is based on mentioned symptoms, and an x-ray of the lungs, which will show condensations in the alveoli. A culture of the bacteria can also be taken on sputum and in the trachea, but the result of these is often hard to interpret as pneumococci from the normal flora in the pharynx can be shown, which are not dangerous. About 15% of those infected by pneumococci have the bacteria in the blood to, so a culture of the blood is sometimes necessary. If you listened to the lungs with a stethoscope, you would hear rattles and weakened breathing sounds, which are signs of fluid in the lungs. To get the diagnosis pneumococcal pneumonia, you should also have more white blood cells than normal and an intensified sedimentation rate. The sedimentation rate shows if the red blood cells’ tendency to clump, a behaviour which increases while having an inflammation.

Treatment and recovery
A person with pneumococcal pneumonia can be treated at home, as well as at the hospital, depending on the general condition of the infected, the places available at the hospital, if the infected belongs to any specific risk group and of course the severity of the disease. Pneumococcal pneumonia is treated with antibiotics, penicillin in almost all cases, which prevents the bacteria from building cell walls, which is needed for maintaining their initial shape. The osmotic pressure within the cell increases, and eventually the cell explodes and dies. The penicillin is to be taken for one to two weeks, a certain amount of times per day, depending again, on the severity of the disease. If the penicillin has not helped at all after three to four days, the first diagnosis might be incorrect, and a new x-ray of the lungs is at interest. Some people, especially children under the age of two, might need respirator care or oxygen treatment if the respiration is troublesome. If this does not help, yet again, something else might be the cause, for example lung cancer.
Furthermore should the sickness be treated as an ordinary cold or flu, with much rest, a balanced diet, plentiful of water and fresh air. To reduce fever symptoms and aches, analgesic could be eaten and also cough medicine which can alleviate the coughing. It is important to remember though, that these medicines can’t fight diseases, only ease the symptoms.
If there are no complicating factors, most of the people recovers and have no injuries at all left when the disease is over, which normally is after two to three weeks. It can take a while, though, for the pathogens to leave the body, and the disease can be passed on several weeks after the person feels healthy and does not show any symptoms. Death occurs almost only when the infected are weakened by something else.

Mycoplasma pneumonia
The second most common bacterium causing pneumonia is mycoplasma pneumoniae, responsible for about 20% of the disease cases. Mycoplasma are the smallest of the cell organisms, but differs a bit from ordinary cells, because they do not have a cell wall, and can change their looks a lot, depending on the surrounding environment. There are about hundred different sorts of mycoplasma, but only four is known to cause human diseases and one of them are, as mentioned, mycoplasma pneumoniae, causing mycoplasma pneumonia.
Mycoplasma strikes at epithelial cells in the breathing passages, by multiplying inside of them. The function of the cilia is abolished and the epithelial cells are damaged and pushed away, and the area under the infected cells may swell. This may lead to secondary infections in the breathing passages, showing the way for example pneumococci.

Transmission
The mycoplasma pneumoniae bacterium is highly contagious and infects via the air as droplets of sneezing and coughing substances. It is transmitted from human to human. There are carriers of the bacterium, who show no signs of illness, but no one is a carrier a whole lifetime, but only for a couple of weeks or months. After the active part of the disease, and all the values are back to normal, mycoplasma can still live inside the body and infect other people.

Symptoms and diagnosis
In comparison with pneumococci, the mycoplasma strikes quite slowly, and the incubation period vary from 10-20 days, and the symptoms are insidious. The first signs could be headache and a dry cough, and then ascending fever and chills. Later, a hacking cough with sputum may occur. The symptoms get more severe the older one is.
The diagnosis for mycoplasma pneumonia is not set by culture of sputum, as it takes too long time to get the results, and because it is tough to carry out. The diagnosis is instead based on an x-ray of the lungs or blood tests showing antibodies for mycoplasma in the blood. The history of the sickness (anamnesis), the early symptoms, how long one has had them and how one has felt, are also an important factor in the diagnosis, and also a high sedimentation rate.

Treatment and recovery
Mycoplasma can not be treated with penicillin, because they do not have any cell walls, and the cell walls are the penicillin’s target to destroy. Other antibiotics must be used, and mostly erythromycin or tetracycline are used. Both tetracycline and erythromycin attack the build up of proteins in the bacteria, which prevent the cell growth and could cause death of the pathogens. The remaining treatment is the same as for pneumococcal pneumonia.
Mycoplasma pneumonia is a fatal disease, but as with the pneumococcal pneumonia, almost only people in particular risk groups die. Unlike pneumococcal pneumonia, mycoplasma pneumonia might give permanent injuries, such as diffusion problems, but many people get perfectly healthy after a few weeks. This disease can get healed by itself, without any treatment, but it is preferable to find a hospital to get an orderly investigation.

Viral pneumonias
There are many different sorts of viral pneumonias, and they are not as common as the bacterial pneumonias. Viral pneumonias can be bronchi, lobar or interstitial pneumonia. Interstitial pneumonia is called pneumonitis, appearing anywhere in the alveoli or the lungs’ connective tissue. Another common sort of pneumonia is called bronchiolitis, which causes inflammations in the bronchioles. Some of the viruses causing lower breathing passages infections are flu virus, adenovirus, chicken pox or RS-virus (respiratory syncitial virus). Viral pneumonias are often more severe and lead to death more often than bacterial pneumonias. To get under the right treatment fast can often be crucial when having a viral pneumonia. Viral pneumonias can also get complicated by secondary bacterial pneumonias.

Symptoms, diagnosis and transmission
The symptoms for viral pneumonias are very similar to those of bacterial pneumonias, such as coughs, fever, chills, head- and muscular ache. A difficult in breathing can also arise; it can come very suddenly and lead to cyanosis. Both bronchiolitis and pneumonitis can release reactions in the body, which remind of allergy. These symptoms, along with x-rays of the lungs, and sometimes an increased sedimentation rate, are the basis for pneumonia diagnosis.
The viruses causing pneumonia are transmitted as mycoplasma and pneumococci, by airborne infected substances inhaled after someone has sneezed or coughed. The airborne viruses can also enter through other people’s eyes, mouths or noses.

Treatment and recovery
Antibiotics do not work on viruses, but in case of pneumonia, antibiotics can be used to prevent a secondary bacterial pneumonia. Depending on the infective virus, different drugs can be used, for example anti-flu medicine. Most of the prescribed drugs are taken orally, but if you are lying in a hospital, the medicines could be given intravenously. As mentioned, some viral pneumonias can be severe, and these must be treated in hospital, but many pneumonias can be treated as home, in the same ways as bacterial pneumonias. The recovery from viral pneumonias is about the same as from bacterial pneumonias, and there are no permanent injuries.

Pneumonia now and then
About a hundred years ago, pneumonia was a very serious disease, and no treatment existed, and therefore many people died from it. A state called “The Crisis” occurred after nine days, and after that, the person would either start to recover, or die. In the beginning of the 20th century, however, penicillin and antibiotics had been discovered, and nowadays, pneumonia only kills about 1-2% of the Swedes who has the disease.

Vaccine in the 70’s
When the vaccine for pneumococci was invented in the seventies, pneumonia cases decreased a bit. The vaccine gives immunity to 80% of the vaccinated for about 5 to 10 years. It is only given to adults, as it does not work on children. All people over 65 years are recommended to take the vaccine, and also person in particular risk groups such as people with severe heart and lung diseases or people with impaired immune system, their relatives and people working with people in risk groups.
Development of vaccine for children is going on, and the best method is to conjugate the vaccine with protein. This process is quite expensive though, and for the developing countries, where the need is the biggest, because pneumonia still kills many children there, it is not an alternative.

Problems with vaccine
The vaccine is not only a good thing, and neither are antibiotics. In the eighties and nineties, more and more bacteria became resistant. This is the result of overuse of antibiotics and vaccine. Those penicillin resistant pneumococci (PRP) are an increasing problem, which makes it harder to treat sick patients, and can also cause a bigger spreading of a more dangerous disease, because it is harder to recover from. Because of this, people infected with pneumococci with reduced sensitivity for penicillin are obliged by Swedish law to report this to The Swedish Institute for Infectious Disease Control (SMI). This is to prevent the PRPs from spreading, and causing a big epidemic.

My personal experience of pneumonia
In May of 2002 I had my first and so far only experience of pneumonia. I will compare what I have learnt about pneumonias with this experience, to learn more about my sickness period, and also if it can affect me now, a few years later.

Symptoms and diagnosis
It all started one day when I was feeling really tired, and went to sleep in the middle of the day and slept for hours, which at that time were quite unusual for me. The following day I had about 38ºC in body temperature, but stupid as I was, went to my football training anyway. When I came home I felt worse than ever and went to sleep. The coming week, the temperature just kept rising, but eventually landing on about 41ºC and stayed there for a couple of days. I went to the hospital and took some tests after about four days or so, and then went back home to continue sleeping, which was probably everything I did for about one and a half week. At first, the hospital gave me medicine for ordinary flu, but when that didn’t help I went there again, a couple of days later. At this point, I had started to cough too, and had quite a hard to time when I breathed. Now, they understood that I hade pneumonia, so I did a culture of sputum, which showed pneumococci, and got penicillin. This penicillin did not help either and we started to get a bit worried. When we went to the hospital for the third time, they finally discovered the mycoplasma.

Treatment and recovery
When they discovered the mycoplasma, I finally got the antibiotics I needed, and could be treated at home, because the fever had eventually decreased a bit. I started to get better quite fast, and after a few days, I could go to school again. I felt quite weak for two weeks or so though, and it was not until then that I could play football again, and start doing all the things that I had done before I got sick.

Transmission
Both pneumococci and mycoplasma are common bacteria, so I could have got infected from any public place or even my own home, because someone in my family could have carried it. My on theory on which I got first is however, that the mycoplasma came first, probably sometime in the middle of April. Then, I got the first symptoms in the beginning of May, because of the long incubation period. The symptoms were insidious, with first the tiredness, and then quite low fever, but when I went training, when my body already was weak, pneumococci from perhaps myself or someone of my team mates could easily attack me. As the pneumococci symptoms come more hastily, the fever rapidly increased, and other symptoms, such as headache occurred. I guess that the mycoplasma would have shown in the culture of the sputum, but a few weeks later. The reason why the penicillin didn’t help is quite simple: penicillin can not kill mycoplasma, because mycoplasma doesn’t have cell walls.
Although mycoplasma is quite contagious, no one in my family or immediate surroundings got pneumonia.
I think that I have recovered completely from the sickness, and I do not have any diffusion problems that I know of.


Conclusion
Pneumonias are a very common infectious disease, caused by both bacteria and viruses. Pneumonias are divided in groups; bronchi, lobar or interstitial pneumonia. The most common bacteria causing pneumonia are pneumococci and mycoplasma.
Before the penicillin was discovered, pneumonia was a highly fatal disease, because there was no treatment. Nowadays, people who normally are healthy should not die from pneumonia. There are also vaccine for pneumococci, which helped when it first came, and is still helping, but more and more pneumococci get resistant because of overuse of this and antibiotics, which could lead to more severe cases of pneumonia in the future, but the authorities seems to have realised the danger, and are taking desirable actions.

The report was quite interesting, and it was rather fascinating to learn about what the bacteria actually hade done to my body while I was sick. My sickness seems like quite a typical case, which made it all easier to understand, as I could compare many things in the books with myself. I think that I have learned a lot, and it feels like the knowledge can be necessary in real life, and not just for school.


Critical review of references
Medicinsk mikrobiologi and Klinisk mikrobiologi were both written as education books for students studying microbiology at higher institutuions, but also for nurses and doctors wanting to refresh their memories on infectious diseases. Dan Danielsson is a docent in microbiology and also a senior physician. Elsy Ericsson is a subject teacher in immunology at a university. Both of the books contain a lot of facts, and when there is something which are not 100% certain, both of the authors are very careful with telling that the facts are not facts, but theories. I guess that the authors want the reader to learn things from the books, so that they could treat their coming patients in the right way.
Human biology and health is also written as an educational book, but for younger people. The purpose of this book is to learn students things about their health, not for becoming doctors or nurses later, but to use the knowledge to be able to take care of themselves later. So the purpose is not only to educate but also to raise youngsters to become responsible humans. The book contains lots of facts, but the raising parts are quite influenced by the current society ideals.
Nya Familjeläkarboken was written in the purpose that people should diagnose themselves at home, with different pictures or schemes. I get the feeling that the author would want the reader to find a hospital as fast as possible, because you get the feeling that you have almost every diseases described in it. The symptoms described are very universal and could occur even if you...