Tuberculosis (TB), a disease which man has been fighting for centuries and even had hopes of irradicating in the year 2000 is back in full swing. TB kills more adults than any other infectious disease. According to Internet source What is TB? "The World Health Organization (WHO) estimates that 8 million new cases and 3 million deaths are attributed to TB each year." The paper goes on to explain there are 26,000 new active cases reported yearly and is estimated that each person with untreated, active TB will infect 10 to 15 others every year (2). In March of 1998, there was an article in the Arizona Republic telling of a current TB case here in the Phoenix area. A portion of the article read, "The physician held up Madeleine Weekley’s chest x-ray and pointed to the quarter-size hole on the 32-year-old’s lung. The cavity could be caused by one of four things: lung cancer, pneumonia, valley fever or tuberculosis. "I don’t smoke, so I didn’t think it was lung cancer. I was praying for pneumonia. I never thought of TB," said Weekley, a communications specialist who went home and spent an anxious weekend waiting for test results. A sputum test narrowed in down to one culprit: tuberculosis" (1).

TB is an airborne bacterial disease and according to author Julliana Newman, today’s tuberculosis afflicts people of all ages, nationalities, and income levels and is more threatening and stronger than ever with its new antibiotic resistant mutations (392). Therefore, in order to gain some control on this re-appearance and prevent tuberculosis from exploding to epidemic proportions, we must increase public awareness and education to include early detection, proper treatment plans, and preventative measures.

Micobacterium TB

TB is caused by rod-shaped bacillus (germs) called Mycobacterium tuberculosis (Mtb). Mycobacterium is believed to be among the oldest bacteria on earth and are found as free-living organisms in the environment. These bacteria can be infectious to many animals including cattle and pigs as well as humans.

Mycobacterium TB is approximately 1 to 5 um in length and "has an unusual cell wall, a waxy coat comprised of fatty molecules whose structure and function are not well known (Tuberculosis (TB), a chronic bacterial infection 4). Not only does this cell wall make the bacteria more challenging for the human immune system; it also makes Mtb difficult to study in a laboratory setting. To the biologist, this bacterium is called "acid-fast" because this waxy coating on the walls keeps the cell from being decolorized during testing. They also multiply very slowly and tend to form clumps instead of colonies, making them microscopically harder to count and examine. Lastly, since Micobacteria are airborne, they must be studied in laboratories with special equipment to handle airborne contaminants.

Transmission and Infection

FIGURE 1: TB germs spread through the air
 

What you Need to Know About Tuberculosis,

According to Newman, tuberculosis bacteria are not spread through touch or handling of personal items, but rather by inhalation. Tuberculosis is "spread when an infected person sneezes, coughs, speaks, or sings" (see figure 1) (383). When these actions occur, tiny particles known as droplets nuclei, which are basically microscopic drops of phlegm, are released into the air. If these droplets are expelled from an infected person, they will contain Mtb bacteria.

Most of the bacilli that do become airborne die before reaching a potential victim. However experiments under controlled temperature settings have shown airborne tubercles surviving for about six hours. "The probability of infection is proportional to the concentration of infectious droplets in the air and the volume of air breathed during exposure" (383). The Internet article titled Tuberculosis (TB), a chronic bacterial infection explains, "adequate ventilation is the most important measure to prevent the transmission of the disease" (4). Only the droplets expelled from an infected person with active TB contain bacilli. "Because most infected people expel relatively few bacilli, transmission of TB usually occurs only after prolonged exposure to someone with active TB. Researchers have estimated on average, people have a 50 percent chance of becoming infected with TB if they spend eight hours a day for 6 months or 24 hours a day for two months working or living with someone with active TB" (4). Most of these droplets die in transit. Only if the bacillus happens to survive long enough to be inhaled by a susceptible person can it then pass to the upper respiratory system. Nose hair and bronchial tube linings are designed to filter out bacterial pathogens. Therefore, "infection begins only if the bacilli make it deep inside the lungs to tiny air sacs known as alveoli, where they multiply within macrophages" (5). Once in the alveoli of the lung, the bacteria are ingested by alveolar macrophages, which are then modified to become epithelioid cells. Within two weeks, necrosis begins within the tissue containing these epithelioid cells, a process referred to as caseation (Newman, 383). The end result is a fully formed tubercle or small, rounded mass. These tubercles grow and fuse as the caseation process continues and wide areas of tissues are destroyed, which is indicative of active TB disease.
 
 

FIGURE 2:      Inactive TB                                                            Active TB
 
 

What You Need to Know about Tuberculosis

This process, however, in a healthy immune system, is usually kept in check. The bacteria aren’t allowed to proliferate and, although the germ exists in the patient’s body, it doesn’t make the person sick. "The immune system ‘walls off’ the TB bacilli which, protected by a thick waxy coat, can lie dormant for years and years" (Tuberculosis Fact Sheet 1). These ‘walled off’ inactive bacilli aren’t considered damaging or contagious, although these patient’s will have a positive tuberculin skin test (see figure 2).

People infected with the TB germ are at a greater risk of developing the active disease during the first two years post infection, but can develop TB many years after exposure, especially if the immune system should become weakened. "On average, people infected with M. Tuberculosis have a 10 percent chance of developing active TB at some time in their lives" (Tuberculosis (TB), a chronic bacterial infection 6).

FIGURE 3:

What you Need to Know About Tuberculosis

We always think of TB as a lung disease only since the lungs are the most common site for infection, however, TB can infect other parts of the body as well. Active bacilli can travel from the alveoli via the blood or lymph system to other parts of the body and start the same destructive process. The kidney is probably the most common site for extrapulmonary TB, but infection can also occur in the bones, urinary and reproductive systems and the skin (see figure 3).

History of the disease

Tuberculosis has been around forever plaguing mankind. In fact, Newman states, "evidence of tuberculosis can be traced back as far as 10000 B.C." (329). Tubercular lesions have been found in both soft tissue and skeletal remains of Egyptian and pre-Columbian mummies. "Aristotle (384-322 B.C.) Generally is acknowledged as the first person to recognize the contagiousness of the disease, known for thousands of years as "consumption or phthisis" (379). In addition to skeletal remains, evidence of tuberculosis can also be found in ancient art and literature. Artwork found in ancient Egyptian tombs depicts hunchback figures reflective of a form of skeletal tuberculosis known as Pott’s diseases. "Chinese writings dating from 2700 B.C. describe lung fever and cough in conjunction with the expectoration of blood and sputum and general wasting syndrome that are strongly suggestive of tuberculosis, and Greek literature also contains numerous references to tuberculosis" (379).

Although tuberculosis has been present for thousands of years, it did not become a major health threat until the industrial revolution when crowded living conditions created perfect conditions for spreading TB. Newman relates that "In the 17^th and 18^th centuries, tuberculosis caused one-fourth of adult deaths in Europe. The disease was the leading cause of death in the United States from the 1800s until the early 1900s, with mortality rates of 1 per 100" (381).

Cattle are considered to be the original source of human infection. It was discovered that drinking contaminated milk was spreading TB. As a result, development and implementation of pasteurization practices began, and soon afterwards there was a noticeable decrease in the number of outbreaks of tuberculosis in children. "Outbreaks of M. bovis (acquired from cattle) infection in children and adults is still a health problem in developing countries where pasteurization of milk is not practiced" (380).

The clinical symptoms of tuberculosis were recognized by everyone—cough, prolonged fevers, bloody sputum and wasting. However, not everyone agreed on the cause of the disease. Some believed it was a contagious process while others thought it was an inherited disease. In 1865 "Francoise Villemin demonstrated that the disease could be transmitted by injecting infected tissue into guinea pigs and in 1882 Robert Koch identified the tubercle bacillus and documented its pathogenicity," according to Newman (381). The discovery of x-rays in 1895 provided yet another way to document the progress and severity of a patient’s disease (Brief History of TB 2).

Since rest in the open air seemed to help combat the disease process, early treatment programs led to the development of institutions known as sanitariums. It was in these settings a controlled approach to combating the disease was developed by providing a place to isolate the sick and enforce a well-regulated hospital life that promoted the healing process (Brief History of TB 2). Some of the "more fortunate" patients were offered surgical treatments that were designed to rest the patient’s affected lung by preventing the patient from taking in a full breath. Author Frank Ryan, M.D. describes many of the invasive and debilitating procedures used in these treatments, such as an operation called phrenic crush where the nerves leading to the diaphragm were actually crushed. Some other patients had to endure repeated injections of air into the pleural space (space between the chest wall and the lung) which created an artificial pneumothorax. Other patients were subject to having synthetic balls placed in the chest cavity through an incision in the chest wall. Lastly, the most severe and permanently deforming procedure of all, a thoracoplasty which involved excision of all or parts of the ribcage allowing the chest wall to collapse on the diseased lung leaving the patient with deficient breathing ability and physical deformities. "Such, however, were the experiences of the "lucky ones" (Ryan 28). An average length-of-stay could be anywhere from 6 months to a year, or more.

Finally, in 1944, the first seriously ill patient was successfully treated with the newly developed antibiotic, Streptomycin (Brief History of TB 2). Many anti-TB drugs were developed in the following years and the sanitarium along with the invasive surgical treatments were, for the most part, no longer required. However, within months of the antibiotic development, drug resistant mutants began to appear.

Resurgence

From the l950’s through the 1970’s, continued development of anti-TB drugs such as isonizad and rifampin seemed to stabilize the spread and helped gain control of the disease in the United States (Seymour 585, Newman 381). Conditions have improved so that "in 1987 the Centers for Disease Control set a goal of eradicating tuberculosis by the year 2010" (Seymour, 585). However, after a decade-long decrease in the number of TB cases reported in the US, TB has reemerged as a serious national problem. "From 1985 through 1993, the number of new TB cases increased by 14%--from 22,201 to 25,313" (CDC/DTBE – Core Curriculum on Tuberculosis, 1). Eight million new cases of TB occur worldwide every year. Of these, 20,000 to 25,000 occur in the U.S., and about 300 new cases were reported in Arizona last year (Snyder, 1).

Complex social factors such as poor nutrition, homelessness, drug addiction and the AIDS epidemic seem to be the major causes of its re-appearance. Also, there has been an increase in air travel and immigration to and from countries where TB is common (Brief History of Tuberculosis 4). Many of these immigrants live in crowded housing and have limited access to health care and may not get the treatment they need. Another contributing factor is the increase in the number of congregational settings like long-term care facilities such as nursing homes, correctional facilities, and homeless shelters. The AIDS epidemic and the emergence of multi-drug resistant strains has also had a significant influence.

Since the AIDS virus greatly compromises the immune system, reducing the body’s ability to fight off infection, it provides a favorable host environment for TB. A healthy person infected with TB has a one in ten chance of developing the active disease, while one in two or three AIDS patients will become actively ill (Brief History of TB, 4). "Developing from infection to active tuberculosis is extremely virulent and rapid in HIV-infected individuals, occurring within weeks or months of infection," according to Newman. Tuberculosis often occurs early in the course of Aids, presenting several months or years before pneumocystis (382). Further problems associated with the disease include the fact that AIDS provides an easy pathway for organisms to mutate without repercussion which may contribute to large amounts of drug resistant strains that have developed among AIDS patients.

By far the most threatening influence on the resurgence of TB today is the developing multi-drug resistant strains (MDR-TB). "Drug resistance in TB occurs as a result of tubercle bacillus mutations" (Brief History of Tuberculosis, 4). The bacilli subjected to an anti-TB in which they are sensitive to will be killed. However, there may be a few drug resistant mutations that will survive and continue to proliferate.

There are two types of clinical drug resistance, primary and acquired or secondary. Primary occurs when a person who has never been treated for TB in the past becomes infected with resistant organisms. Acquired or secondary develops due to either improper treatment with the wrong antibiotics or combination thereof, or the patient did not follow the prescription regimen correctly. Many patients stop taking their medications when they start to feel better, which leads to the mutation and proliferation of drug resistant strains. When dealing with TB, improper treatment or incomplete treatment is really worse than no treatment at all. Internet source, Tuberculosis Fact Sheet states, "drug resistant TB is more difficult and more expensive to treat, and more likely to be fatal." In an attempt to counteract this problem, the Center for disease Control and Prevention (CDC) along with the World Health Organization (WHO) have recommended a new TB control strategy called DOTS (Directly Observed Treatment, Short-course). DOTS plan requires a health care worker to physically observe and record the patient taking the proper medications on a daily basis (2,3).

CLINICAL ASSESMENT

A prompt and accurate diagnosis is a key component to limiting the spread of TB. Newman explains that "prolonged exposure to undiagnosed patients with MDR-TB is directly related to the present proliferation in reported cases" (388). Anyone who experiences a combination of fever, night sweats, unexplained weight loss, a loss of appetite, a chronic cough, or coughs up blood, could be actively infected and should be tested (Treatment of Tuberculosis Infection/AAFP Pa, 1). Also, anyone who has close day-to-day contact with someone who has active TB disease (i.e. a family member, friend or co-worker) should be tested. Individuals with HIV infection or other immunosuppressive disorders as well as workers who might be in frequent contact with TB patients, such as correctional officers and health care employees, should also be periodically tested.

Testing usually always begins with the Mantoux (PPD) skin test. "A substance called purified protein derivative (PPD) is injected just under the skin of the forearm and examined about 48 to 72 hours later." A positive test is indicated when this area appears red and hardened (Tuberculosis (TB), a chronic bacterial infection 6,7). However, a positive skin test does not mean the patient has active TB disease. In most cases, just being exposed to micobacterium will produce a positive reaction. Remember that you can be exposed to the bacteria without developing active TB disease. Therefore, a positive test reading should be followed with an additional Mantoux test and a standard chest x-ray. If these initial test results continue to produce positive results, sputum and other samples are usually requested as a laboratory culture is necessary to confirm the TB diagnosis and to determine which anti-TB drugs will be most effective. "Since M. tuberculosis is slow-growing, it takes approximately a month to get the sputum culture results. An additional two to three weeks usually are needed to determine the drug susceptibility of the organism, making treatment decisions difficult." (Tuberculosis (TB) a chronic bacterial infection 7).

Recently, advances have been made in research, which has led to the development of new laboratory culture tests capable of producing results in two days by using "nucleic acid amplification." "Another test in development uses luminescent chemicals from the firefly to determine, in 24 to 48 hours, which drugs can kill the TB strain a patient caries" (Tuberculosis (TB), a chronic bacterial infection 7).

If treatment of active TB is indicated, it normally involves a combination of three anti-TB drugs, isoniazid, rafampin, and pyrazinamide. These drug combinations are usually prescribed for a minimum of 6 months, what is referred to as a short course chemotherapy. At this point, patient education is crucial to the success of the treatment plan, and it is extremely important that the medications be taken as long as is prescribed. Again, stopping the medication early is what leads to the development of multi-drug resistant strains (MDR-TB) Consequently; "treatment for MDR-TB often requires the use of a second line of drugs, all of which can produce serious side effects. Drug therapy for 18 months to 2 years may be necessary" (Tuberculosis (TB), a chronic bacterial infection 2, 8). Prevention of TB begins with the diagnosis. Newman writes that "prompt and accurate diagnosis is key to controlling the spread of tuberculosis" (384). Extra attention should be given to those at highest risk of developing the disease and treatment plans utilizing DOTS should be initiated.

In the workplace, prevention for health care workers who care for high-risk patients, or who might be involved in procedures, which could increase the risk of exposure, should have a Mantoux skin tests every six months. Hospitals and clinics can further protect the population by teaching patients to cover their nose and mouth when coughing or sneezing. They can also make use of "Ultraviolet light to sterilize the air along with negative pressure rooms and special room air filters" (Tuberculosis (TB), a chronic bacterial infection 9). Special MTB masks that filter out the droplets nuclei should be provided along with proper use instructions.
 

Conclusion

The dramatic resurgence of tuberculosis is a public health emergency that will continue to have profound effects on our society. The social and economic toll produced by tuberculosis is tremendous, especially with the proliferation of AIDS and multi-drug resistant strains. Early detection and treatment are the keys to controlling this disease. Strategic treatment plans such as the WHO-recommended DOTS plan need to be implemented worldwide along with the development of effective public and occupational awareness programs.

As we continue to research and learn more about tuberculosis, the closer we become to preventing another epidemic. In today’s society, every medical worker should be aware that his or her next patient might have tuberculosis.