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Tuberculosis is a threatening infectious disease that kills two million people each year and threatens the lives of billions that are left infected (Tuberculosis: What is TB, 2009). In the 17th and 18th century, this ruthless disease was nicknamed the “White Plague” in Europe because nearly 100% contracted it. This disease in its active stage attacks the lungs, kidneys, bones, joints, and even the brain. In the 1940s, the first antibiotics were used to combat against it, but misuse led to drug resistance, which is even worse. Our immune system, which produces macrophages to surround the tubercle bacilli to keep the mycobacterium tuberculosis under control, along with the help of antibiotics have been proven successful in most cases but not all. There are several treatments that have enabled success, such as tablets for common cases and chemotherapy for extensively- drug resistant ones, in addition, the DOTS strategy and the BCG vaccine have aided to control TB from spreading; treatments are needed in order to aid our immune system because there are factors that allow the TB bacteria to infect and cause disease. We have found these treatments through the testing on animals and research done within animal science. Without the contribution and research from this department we would not know what we know today about the disease TB. TB and all of its research connects human and animal science because it helps us find new treatments and possible cures for not only humans but animals who also suffer from this disease. Tuberculosis is an infectious disease caused by a bacterium known as mycobacterium tuberculosis.
Although our bodies are equipped to prevent it from entering and taking over our bodies, our bodies can only do so much before we become ill. Our body has lines of defenses, from the mucus in our nasal cavity to the acidity in our stomach to kill the bacteria. In addition, it walls off the microbes of tuberculosis in “tiny capsules”, but the down part is that they aren’t killed, they are just captured “until some event triggers the disease’s emergence” (Tuberculosis, 2013). This is why although “as much as 1/3 of the world’s population, two billion people, carry TB bacteria, most never develop active Tuberculosis disease” (Tuberculosis: What is TB, 2009). This leads to another point, the difference between active and inactive tuberculosis.
Inactive tuberculosis refers to resulting in a positive Tuberculin (PPD) skin test, which means having TB infection, but not being ill or contagious, in other words, having the mycobacterium captured. The mycobacterium gets released when the infected person becomes weak, ill, and/or undernourished, basically, when he/she gets a weak immune system and/or he/she is highly exposed to the mycobacterium again. It isn’t unordinary to be completely fine and then develop active TB. According to studies, “half of the people who go from having an infection to developing active TB develop it in the first 5 years after the infection” (What is the BCG, 2012). First, it is important to know that our body has barriers and responses to keep out, destroy, and keep under control bacteria. Our immune system’s attempt to protect us from the disease is one of the reasons why there are many people left only infected with tuberculosis and never develop the disease. The bacteria in them stays “dormant”, meaning that as long as they don’t develop a weak immune system and/or are exposed to a higher exposure, they’ll be completely fine, but if they do, then the mycobacterium will “reactivate and cause the disease.
The way a person can be infected is if it were an overwhelming number of mycobacterium that survived from being captured by the macrophages, if they evaded being destroyed by the acidity in our stomach and the other lines of defenses. It is a path that the bacteria go through before they can infect an individual. First, the person has to be exposed to the bacteria, which come in droplet nuclei. ‘Each droplet nuclei inhaled contains no more than three bacilli, which someone can have released by coughing, sneezing, laughing, talking and even singing. Talking for five minutes generates 3000 droplet nuclei, which is the same as coughing, but the most astonishing is that singing generates 3000 droplet nuclei in one minute and sneezing can spread to individuals up to ten feet away’ (Tuberculosis, 2013). The fact that they are tiny particles allows them to stay in the air for several hours, meaning that even if a person weren’t present at the time the infected person sneezed or such, a passerby could as easily be infected. In addition, contact with infected blood leads to transmission of tuberculosis. “So after inhaling the droplets, the alveolar macrophages take up the bacteria but aren’t activated and so don’t destroy the organisms and that’s not good because once the droplet nuclei reach the alveoli, the larger droplets become stuck in the nose and the throat, where infection is unlikely to develop.
On the other hand, the smaller droplet nuclei sometimes reach the small air sacs of the lungs, which are known as the alveoli, where the infection begins (Tuberculosis, 2013). Treatments vary depending on the type of tuberculosis, whether it’s active or inactive. The treatment for inactive tuberculosis is taking an antibiotic known as Isoniazid (INH) for about 6 to 9 months, sometimes a year. It is very crucial that although the person with inactive tuberculosis has no symptoms and is not ill, that he/she goes through with the full medication in order to prevent developing active tuberculosis. The patient also needs to go to periodic checkups so the doctor can be sure that the patient is taking their medication. If the active tuberculosis is caught at the beginning, then the patient will need to take several tablets for several months, of which the most commonly used are isoniazid (INH), rifampin, pyrazinamide, and ethambutol, sometimes they even receive streptomycin, an injection. It’s usually a combination of INH and three others listed above, so it’s a four-drug treatment. The patient takes those for at least six to nine months. Tablets known as fixed-dose combinations have been created, which “the World Health Organization recommends” because they “combine several medications into a single tablet” (Tuberculosis: What is TB, 2009). Even though they are effective, “these medicines usually have side effects, such as an upset stomach and liver problems. But on the brighter side, the patient usually sees improvements only a few weeks after starting to take the drugs” (Tuberculosis: What is TB, 2009).
The good news, however, is that the patient can be cured. Even if the patient were drug-resistant, according to the CDC “when adherence with the treatment is assured, this four-drug treatment is highly effective. Based on the commonness and characteristics of drug-resistant organisms, at least 95% of patients will receive adequate treatment if this four-drug regimen is used at the beginning of therapy (Tuberculosis, 2013). So that means that the person must take their full medication so that the drugs taken simultaneously can help “prevent the emergence of tubercle bacilli resistant to the others,” (Tuberculosis, 2013). In other words, if some tubercle bacilli are resistant to one, another can kill it, so that no tubercle bacilli survive and can’t reproduce and make the disease affect the patient even more. Drug-resistance has become an issue due to the fact that millions die each year due to it. “The CDC reported that in 2004, there were 128 cases of multiple-drug resistance TB, which was an increase from the 113 in 2003. In addition, there was a rise from 3.9% to 4.5% in the extensively-drug resistance TB. The treatment for extensively-drug resistant TB patients is extremely painful because it’s chemotherapy for over two years. According to the World Health Organization, 1 out of 30 cases of tuberculosis are resistant to primary and secondary antibiotic treatments, this means that the TB is resistant to the first two commonly used antibiotics, Isoniazid and Rifampin. These TB strains are known as “multiple-drug resistant”.
There are even more resistant strains known as extensively-drug resistant (XDR) TB, which have barely emerged. They can withstand the most toxic and expensive antibiotics. In the 1960s, it had become “standard for patients to get 2 or 3 antibiotics in tandem to combat the ineffectiveness of some drugs”. It wasn’t until the 1990s strains became resistant to stronger antibiotics. The reason why drug resistance is such a big issue is because “about 400,000 of the new cases are drug resistant strains, while fewer than 1 in 50 people who develop it have access to effective treatment and most die” (Tuberculosis, 2013). A preventative strategy is the Bacillus of Calmette and Guerin vaccine. It’s derived from a strain of Mycobacterium bovis. It is an injection given to young infants and neonates because it prevents severe childhood tuberculosis. The two possible are TB meningitis and military TB (Tuberculosis, 2013). In a study in schoolchildren, it was shown that immunity lasts to at least fifteen years. “It has been calculated that every year about 100 million doses of BCG vaccine are given to children” (Tuberculosis: What is TB, 2009). “Studies suggest a 60-80% effective rate in children” (Tuberculosis, 2013). However, it is important to note that the United States doesn’t use this vaccine because “only about 1 in 10 people infected with TB go on to develop the disease. So 9 out of 10 people given a course of drugs to prevent it from developing will have been given the drugs unnecessarily. Instead of giving the BCG, the United States administers regular skin tests to check up on people who are at high risk” (What is the BCG, 2012). The U.S. also doesn’t use it because it doesn’t prevent infection, only the disease and because it complicates the way the tuberculin skin test is administered because people who have this vaccine test positive because they have the antibodies.
There is a world-wide strategy known as DOTS being practiced all over the world. It is the internationally recommended approach to TB control”; “it is an inexpensive and highly effective means of treating patients already infected with TB and preventing new infections and the development of drug resistance.” (Tuberculosis: What is TB, 2009). It was seen to be so effective because “by 2004, 183 countries had implemented [it],” with “the average success rate turning out to be 82 %”( Tuberculosis: What is TB, 2009). DOTS is composed of five parts: ”political commitment to sustained TB control, access to quality-assured TB sputum microscopy, standardized short-course drug treatment, including direct observation of therapy, an uninterrupted supply of quality-assured drugs, and a standardized recording and reporting system enabling assessment of outcome in all patients” (Tuberculosis: What is TB, 2009). In shorter words, it is “where a health care worker ensures that patients are taking their treatment regimens properly,” whether they are being treated for inactive or active TB (Tuberculosis: What is TB, 2009). In conclusion Tuberculosis can be treated and prevented. Tuberculosis is important in animal science because without the testing that has been done on and with animals we would not have the treatments that we have today. That is why it is very important in human medicine and animal, because we can continue to learn and produce treatments and prevention methods not only for humans but for the animals that become infected as well with a very similar case called bovine TB.
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