Tuberculosis

Also known as consumption. TB is caused by an infection of any one of several species of the Mycobacterium, also known as tubercle bacillus. In humans, most TB is caused by M. Tuberculosis, although cases involving the bovine counterpart M. Bovis are not uncommon. Pigs and birds can also get their own variants of the disease. Tuberculosis has been known of for millennia; the ancient Egyptians and Hippocrates both knew of the disease, and pretty much every urban society since then. In the 1800s, TB was practically an epidemic, being the leading cause of death in industrialized countries for all age groups. These days, you hardly hear of it outside of the Third World.

TB can be contracted in two ways: By either breathing M. Tuberculosis from the same air as a TB sufferer, or by drinking milk contaminated with M. Bovis. The parts of the body attacked by the disease are the parts related to how it was contracted. The human type resides in the lungs as pulminary TB. The cattle type affects the bones and joints of the body, kind of like drinking antimilk.

Once in the body, TB will eat and reproduce where it can until the body forms a protective wall around the affected area known as a Tubercle. The tubercle is microscopic in and of itself, but large formations of tubercles can form a cheese-like mass in the affected tissue, hampering proper organ function.

Pulmonary TB occurs in childhood, and is usually exhibits no symptoms when it first infects. If the child is lucky, the bacteria will be destroyed, and all they'll have to show for it is a small scar. If they're not lucky, the bacteria will spread into the blood stream, which is highly fatal if drugs are not properly administered.

Postprimary pulmonary TB is historically known as the disease Consumption. It occurs in adolescents and adults, and is characterized by a lack of energy, weight loss, and coughing. Oddly enough, women with consumption were considered more feminine in Victorian times, due to their unnatural fragility and constant plight, echoed in the goth look today. This attraction probably faded as the disease spread, causing chest pain, sweating, and blood in the saliva. If left unchecked, the patient will begin to cough up blood as the bacteria eat away at the lungs, and soon the lack of proper lung tissue is enough to prove fatal, from either lack of oxygen or exhaustion.

Diagnosing pulmonary TB is easy: Just put some spit under a microscope and look for tubercles. If you don't like spit, you can also check the urine or the stool, or you can avoid touching the patient altogether and take an X-ray of the lungs and look for scars. A skin test is available to determine whether a subject is immune to TB or not.

Avoiding TB is also easy, if you live in a developed country. Keep good hygiene, only drink pateurized milk, and avoid contact with people who have pulmonary TB, and you should be OK. There is also a BCG vaccine composed of weakened tubercles that can be used to immunize against the disease.

Even treatment of TB is easy, these days. Whereas in previous centuries you were prescribed years of bed-time and several surgical procedures to remove tubercles, (and trust me, you didn't want to undergo surgery back then), these days there are several drugs that will kill TB dead.

The fact that diagnosis, prevention, and treatment of TB is so simple makes it even more tragic that children still die from this disease in third-world countries.

Thanks to britannica.com for most of the info, except for the victorian females thing, which came from The Big Book of Death

Overview

Tuberculosis can affect any part of the body. The most common site is the lungs, of course, but anything from lymph nodes (the second most common site) to skin to brain to bone to kidneys to gastro-intestinal tract (and any other part of the human anatomy else I haven't mentioned) can be affected. TB is an old disease. Evidence for Pott's disease - tuberculosis of the spine - has been found in Egyptian mummies.

The cause of tuberculosis, Mycobacterium tuberculosis is an aerobic bacterium that divides every 16-20 hours. This is extremely slow compared to other bacteria which tend to have division times measured in minutes.

TB is the most common infectious disease in the world. It is more common in undeveloped, tropical countries. In Australia, the incidence of TB is currently 6 per 100,000. Of Australians born in Australia, the rate is 1.8 per 100,000.

Primary tuberculosis is a person's first exposure to M. TB. Assuming the infection was not completely cleared by the immune system (which sometimes happens if the bacterial load was small enough), post primary tuberculosis can occur - this is a reactivation of TB following primary tuberculosis (symptomatic or asymptomatic). In 40% of patients with primary TB, this may take more than 10 years.

Primary tuberculosis is more dangerous than post primary tuberculosis because, if the immune system is compromised or deficient, there is the threat of miliary tuberculosis which infiltrates all the organs of the body and carries a high mortality rate. This is why contact tracing is so important whenever someone is diagnosed with tuberculosis. All his/her close contacts should be screened for TB with a Mantoux test and a chest x-ray.

A persistent respiratory illness that does not respond to regular antibiotics (e.g. penicillin, amoxil) in an otherwise healthy individual is tuberculosis until proven otherwise.

Diagnosis

A chest X-ray is essential in all cases of suspected pulmonary tuberculosis. The classical X-ray picture of post-primary tuberculosis is of bilateral, posterior apical, cavitating, caseous lesions.

Sputum smears and cultures should be done for acid-fast bacili if the patient is producing sputum. If no sputum is being produced, bronchoscopy or fine needle aspiration should be considered.

The Mantoux test should be done in all cases of suspected tuberculosis, although the results must be interpreted carefully. Tuberculin units are injected intradermally and read at 48 to 72 hours. An induration of more than 10mm to 10 Mantoux units is considered a positive test. A negative test does not exclude active tuberculosis, especially if the test was done within 6 to 8 weeks of acquiring the infection, if the infection is overwhelming or if the patient is immunocompromised.

Treatment

The first-line drugs currently used for treatment of TB are rifampicin, isoniazid, pyrazinamide and ethambutol. The current treatment regime in Australia calls for two months of directly observed therapy of all four drugs followed by four more months with just rifampicin and isoniazid.

Why four drugs? If only one drug is given, what ends up happening is that you end up killing all the bacteria sensitive to that drug and three months later, you get a bunch of bacteria which were resistant. Rifampicin and isoniazid are bactericidal agents that kill the bacteria, pyrazinamide acts well against the intracellular bacteria which are dormant inside macrophages and other cells and ethambutol is a bacteriostatic agent that inhibits bacterial proliferation while the other drugs kill off the TB.

Adverse drug reactions are expected in 20-25% of patients but only 5% all patients will have a severe enough reaction to warrant a change in their drug regimen. Hepatic damage is the most significant of the drug reactions.

Supervised therapy has a cure rate of about 98%.

Prevention

Bacille Calmette-Guerin vaccine (BCG) immunization gives the receiver between 0-70% resistance to TB. In tropical areas where the incidence of atypical mycobacteria are high (exposure to non-TB mycobacteria give some protection against TB), the effectiveness of BCGs are much lower than in areas where mycobacteria are much less prevalent.

Although tuberculosis was once easily treatable by antibiotics, since the late 1970's, highly drug resistant and highly contagious versions have cropped up.

Worse, it is becoming epidemic in some areas like India and Africa, possibly because it is hitting those whose immune systems are already weakened by AIDS. TB has always been an opportunistic disease, sickening and killing those who were depressed and living in poor conditions.

Tu*ber`cu*lo"sis (?), n. [NL. See Tubercle.] Med.

A constitutional disease characterized by the production of tubercles in the internal organs, and especially in the lungs, where it constitutes the most common variety of pulmonary consumption.

<-- caused by Mycobacterium tuberculosis. See Tubercle bacillus. -->

 

© Webster 1913.