Anatomy and Physiology - Tuberculosis: June 2010

Sunday, June 20, 2010

DEFINITION

Tuberculosis or TB (short form for Tubercles Bacillus) is a common and often deadly infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis in humans.

There are also other ways of contracting tuberculosis. As shown in this picture, pulmonary tuberculosis is contracted from inhaling infected droplets (of cough or sneeze).

Here's a short video on Tuberculosis.

CAUSES

Tuberculosis is caused by an organism called Mycobacterium tuberculosis (picture on the left). The bacteria spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings. Although tuberculosis is contagious, it's not especially easy to catch. You're much likely to get tuberculosis from a family member or close co-worker than from a stranger. Most people with active TB who've had appropriate drug treatment for at least two weeks are no longer contagious.

When a person becomes infected with tuberculosis, the bacteria in the lungs multiply and cause pneumonia along with chest pain, coughing up blood, and a prolonged cough. In addition, lymph nodes near the heart and lungs become enlarged. As the TB tries to spread to other parts of the body, it is often interrupted by the body's immune system is unable to fight TB or if the bacteria break through the scar tissue, the disease returns to an active state with pneumonia and damage to kidneys, bones and the meninges that line the spinal cord and brain.

This picture shows the damage pnuemonia can cause.

Due to tuberculosis, pneumonia occurs. Lungs are inflammed and this causes breathing difficulties. More complications caused by tuberculosis will be covered in the following post, POSSIBLE COMPLICATIONS.

Here is a song on Tuberculosis we found on Youtube.

Tips and Precautions to avoid Tuberculosis...

-Avoid people who you know are sick or have the flu. You would not know if they have the bacteria that causes tuberculosis.

-Get vaccinated.

-DO NOT share items such as utensils, towels etc.

PREVALENCE

According to the World Health Organization (WHO), nearly 2 billion people, one-third of the world's population, have TB and new infections occur at a rate of about one second. The proportion of people who become sick with tuberculosis each year is stable or falling worldwide but, because of population growth, the absolute number of new cases is still increasing. In 2007, there were an estimated 13.7 million chronic active cases, 9.3 million new cases, and 1.8 million deaths, mostly in developing countries.

In addition, more people in the developed world are contracting tuberculosis because their immune systems are compromised by immunosuppressive drugs, substance abuse or AIDS. The distribution of tuberculosis is not uniform across the globe; about 80% of the population in many Asian and African countries test positive in tuberculin tests, while only 5-10% of the US population test positive.

This is a case study with statistics we found on the Internet (this dates back to 2008).

Global and regional incidence

WHO estimates that the largest number of new TB cases in 2008 occurred in the South-East Asia Region, which accounted for 34% of incident cases globally. However, the estimated incidence rate in sub-Saharan Africa is nearly twice that of the South-East Asia Region with over 350 cases per 100 000 population.

An estimated 1.3 million people died from TB in 2008. The highest number of deaths was in the South-East Asia Region, while the highest mortality per capita was in the Africa Region.

In 2008, the estimated per capita TB incidence was stable or falling in all six WHO regions. However, the slow decline in incidence rates per capita is offset by population growth. Consequently, the number of new cases arising each year is still increasing globally in the WHO regions of Africa, the Eastern Mediterranean and South-East Asia.

visit this link for the full statistics and review.

http://www.who.int/mediacentre/factsheets/fs104/en/

Here are also some facts we found from the link.

Did you know that...

-Someone in the world is newly infected with TB bacilli every second.

-Overall, one-third of the world's population is currently infected with the TB bacillus.

-5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB.

Finally, here is a pie chart showing the prevalence of Tuberculosis by age.

Based on the pie chart shown...

Ages 15 or less - 6%
Ages 15 ~ 24 - 12%
Ages 25 ~ 44 - 32%
Ages 45 ~ 64 - 30%
Ages > or = 65 - 19%

Hence, we can conclude that people in the age range of 25~44 and 45~64 contract tuberculosis at a higher rate then the other age ranges.

SYMPTOMS

Most people who become infected with the bacteria that cause tuberculosis actually do not present symptoms of the disease. However, when symptoms are present, they include:
-Cough
-Fever
-Chills
-Sweating
-Night sweats
-Flu-like symptoms
-Gastrointestinal symptoms
-Weight loss
-No appetite
-Weakness
-Fatigue

The following are symptoms of early stage TB.

The most common symptom is cough.

The disease develops slowly, infected people at first may blame the cough on smoking, a recent episode of flu, the common cold, or asthma. The cough may produce a small amount of green or yellow sputum in the morning. Eventually, the sputum may be streaked with blood, although large amounts of blood are rare.

Other obvious symptoms include cold/night sweat and fatigue.

People may awaken in the night and be drenched with a cold sweat, with or without fever. Sometimes there is so much sweat that people have to change nightclothes or even the bed sheets. However, tuberculosis does not always cause night sweats, and many other conditions can cause night sweats.
People also feel generally unwell, with decreased energy and appetite. Weight loss often occurs after they have been ill for a while.

Fatigue is a general term for an abnormal condition in which a person feels a sensation of tiredness, weariness, exhaustion, weakness, or low energy. Fatigue is a symptom of a wide variety of mild to serious diseases, disorders and conditions. It can result from infection, inflammation, trauma, malignancy, chronic diseases, autoimmune diseases, mental illnesses and other abnormal processes.

The following are symptoms of pulmonary tuberculosis:

-Persistent cough
-Chest pain
-Coughing up bloody sputum
-Shortness of breath
-Breathing difficulty
-Recurring bouts of fever
-Weight loss
-Progressive shortness of breath
-Urine discoloration
-Cloudy urine
-Reddish urine

Rapidly developing shortness of breath plus chest pain may signal the presence of air or fluid (pleural effusion) in the space between the lungs and the chest wall. About one third of tuberculosis infections first show up as pleural effusion. Eventually, many people with untreated tuberculosis develop shortness of breath as the infection spreads in the lungs.

Urine discoloration may occur when one has contracted TB. The colour may vary, depending on the stage of tuberculosis.

Saturday, June 19, 2010

DIAGNOSIS

Tuberculosis diagnosis usually occurs after a combination of skin, blood and imaging tests. The most common diagnostic test is a simple skin test called the Mantoux test.

-The Mantoux test consists of a small amount of purified protein derivative (PPD) tuberculin that is injected into the forearm. After 48 to 72 hours, a doctor or nurse looks for a reaction at the injection site; a hard, raised red bump usually indicates a positive test for TB. Blood tests may also be used to determine whether TB is active or latent (inactive), and a microscopic sputum analyses or cultures can find TB bacteria in the sputum.

This picture shows a person that is tested to be positive for TB. A swell or bump develops at point in which the PPD is injected into the forearm.

While in this picture, this person underwent the mantoux test and was tested negative for TB. As shown, the bump is not so obvious.

-Chest X-rays and computer tomography (CT) scans are also used to diagnose TB. If the immune system traps the TB bacteria and creates scar tissue, this tissue and the lymph nodes may harden like stone in a calcification process. This results in granuloma (rounded marble-like scars) that often appears on x-rays and CT scans. However, if these scars do not show any evidence of calcium on an x-ray, they can be difficult to distinguish from cancer.

These two pictures above shows X-ray scans of the ribcage at different stages of tuberculosis.

The one on the top shows tuberculosis at an early stage while the one on the bottom shows tuberculosis at a late stage.

Friday, June 18, 2010

TREATMENT

Treatment for TB depends on the whether the disease is active or latent. For inactive TB, an antibiotic called isoniazid (INH) is prescribed for six to twelve months.

Active TB is treated with INH as well as drugs such as rifampin, ethambutol and pyrazinamide. It is also not uncommon for TB patients to receive streptomycin if the disease is extensive. Drug therapies for TB may last many months or even years.

If a patient has a drug-resistant strain of TB, several drugs in addition to the main four are usually required. In addition, threatment is generally much longer and can require surgery to remove damaged lung tissue.

Today, doctors treat most people with TB outside the hospital. Gone are the days of going to the mountains for long periods of bed rest. Doctors seldom use surgery.
Doctors will prescribe several special medications that one must take for six to nine months.
Standard therapy for active TB consists of a six-month regimen:

-two months with Rifater (isoniazid, rifampin, and pyrazinamide)

-four months of isoniazid and rifampin (Rifamate, Rimactane)

-ethambutol (Myambutol) or streptomycin is added until your drug sensitivity is known (from the results of bacterial cultures)

Rifater is given to patients for the first few months of treatment. The above picture shows us the chemical structure of Rifater. Research has also shown that this medication can cause

severe liver problems.

-The picture on the left shows how both isoniazid and rifampin work together to get rid of the mycobacterium tuberculosis.

-Both are antibiotics that help to prevent the tuberculous bacteria from spreading in the body.

This is the chemical structure of ethambutol.
It is used as antibiotic to prevent the growth of tuberculous bacteria.

Ethambutol, as mentioned earlier, is also used in combination with the other current medication to identify one's drug sensitivity.

Finally, surgical methods are also used to help cure tuberculosis. However, it is not common today as there is a variety of medication that can help to prevent and/or cure tuberculosis.

If needed, surgery is used to:

-Repair lung damage, such as serious bleeding that cannot be stopped any other way, or repeated lung infections other than TB.

-Remove a pocket of bacteria that cannot be killed with long-term medicine treatment.

Thursday, June 17, 2010

PROGNOSIS (OUTLOOK)

The prognosis for recovery from TB is good for most patients, if the disease is diagnosed early and given prompt treatment with appropriate medications on a long-term regimen. Modern surgical methods have a good outcome in most cases in which they are needed.

The following information are obtained from the following link:

http://www.wrongdiagnosis.com/t/tuberculosis/prognosis.htm

The estimated mortality rate from tuberculosis.

-Deaths: 930 (USA annual deaths calculated from this data: 930 reported deaths in USA 1999 (NVSR Sep 2001))

-Incidence: 18,360 (USA annual incidence calculated from this data: 18,361 cases annually in the USA (1998); 8 million people worldwide develop active TB and 3 million die; 17,531 annual cases notified in USA 1999 (MMWR 1999); 5.50 per 100,000 in Canada 2000

-5.1% (ratio of deaths to incidence).

Here is a death rate extrapolation for tuberculosis:

930 per year,

77 per month,

17 per week,

2 per day,

0 per hour,

0 per minute,

0 per second.

Here are some facts from the following website:

http://www.wrongdiagnosis.com/t/tuberculosis/deaths.htm

These rates are three of the highest amongst 23 countries as observed from the link. (We would like to apologize for not using recent statistics. The ones we used dated a few years back.)

-About 599,000 deaths from tuberculosis in South East Asia 2002 (The World Health Report, WHO, 2004)

-About 366,000 deaths from tuberculosis in Western Pacific 2002 (The World Health Report, WHO, 2004)

-About 348,000 deaths from tuberculosis in Africa 2002 (The World Health Report, WHO, 2004)

While these are the three lowest ones among the range of countries.

-17 deaths in Puerto Rico 2000 (Regional Core Health Data Initiative, Pan American Health Organisation, 2003)

-9 deaths in Belize 2000 (Regional Core Health Data Initiative, Pan American Health Organisation, 2003)

-6 deaths in Bahamas 2000 (Regional Core Health Data Initiative, Pan American Health Organisation, 2003)

For more information, visit the link above.

Wednesday, June 16, 2010

POSSIBLE COMPLICATIONS

The list of complications that have been mentioned in various sources for Tuberculosis includes :

-Progressive shortness of breath,
-pneumothorax,
-pleural effusion,
-military tuberculosis,
-spine TB,
-meningitis,
-tuberculosis meningitis,
-kidney TB,
-kidney disease,
-peritonitis,
-pericardities,
-lymph node infection,
-bone complications,
-joint complications,
-fallopian tube infection (salpingitis),
-bowel infection,

-Addison's disease and death (the high death rate of 40-60% if untreated).

We will touch on 3 of the complications which we have chosen randomly. (Those that are highlighted in red above.)

Tuberculous meningitis: Tuberculous meningitis is an infection of the membranes covering the brain and spinal cord caused by Koch's bacillus.

The picture on the left shows Koch's bacillus.

The picture below shows screenings of the brain being infected by the bacteria.

The several symptoms of Tuberculous meningitis include:

-Fever
-Headache
-Stiff Neck
-Aching Muscle
-Nausea
-Vomitting
-Listlessness
-Loss of Appetite
-Loss of Conciousness
-Seizures
-Sensitivity to light

Complications that arise from tuberculous meningitis are:

-Abnormal Behavior

-Mental Impairment

-Motor paralysis

-Seizures

Fallopian Tube infection (also known as Salpingitis):

This picture shows an inflammed fallopian tube. Symptoms of salpingitis include:

-Abnormal smell and colour of vaginal discharge.
-Pain during ovulation
-Pain during sexual intercourse
-Pain coming and going in periods
-Abdominal pain
-Lower back pain
-Fever
-Nausea
-Vomiting

These are the various complications that arise from salpingitis:

-Infection to nearby structures, such as the ovaries or uterus
-Infection of sex partners (leading to AIDS and HIV)
-An abscess on the ovary
-Ectopic pregnancy
-Infertility

Addison's Disease

Addison's disease is a rare endocrine, or hormonal disorder that affects about 1 in 100,000 people. It occurs in all age groups and afflicts men and women equally.

Symtoms of Addison's disease:
The disease is characterized by weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin in both exposed and nonexposed parts of the body.

Addison's disease occurs when the adrenal glands do not produce enough of the hormone cortisol and in some cases, the hormone aldosterone. For this reason, the disease is sometimes called chronic adrenal insufficiency, or hypocortisolism.