Tuberculosis, TB or Pulmonary tuberculosis is a bacterial contagious disease caused by Mycobacterium tuberculosis. Persons with weakened immune system, infants and elderly people are at higher risk for tuberculosis. You can be at greater risk if you are in frequent contact with persons suffering TB. Poor nutrition and sanitation contribute to the risk factor. Many drug-resistant strains of TB have made it more difficult to treat the disease. Pulmonary tuberculosis shows up with symptoms like fatigue, fever, cough with mucus and blood, chest pain, difficulty in breathing and unexplained weight loss. A person suffering TB will have enlarged lymph nodes and pleural effusion. Bronchoscopy, chest x-ray and sputum culture can aid diagnosis of pulmonary tuberculosis. Pulmonary TB is treated with Isoniazid, Rifampin, Ethambutol, Streptomycin or Moxifloxacin. Treatment usually lasts for 6 months or longer.
Extra pulmonary tuberculosis or Miliary tuberculosis
Tuberculosis can also affect other parts of the body such as bones, lymphatic system, central nervous system and genital or urinary system. Disseminated tuberculosis or Miliary tuberculosis is a contagious bacterial infection that has spread from the lungs to other parts of the body through the blood or lymph system. This type of TB can also affect the larynx, skin and pericardium too.
Though Melioidosis has existed for more than 100 years, health officials and policy makers are paying attention only now. In 2015, Melioidosis killed 53% of infected people. This is almost equal to annual global mortality from Measles and greater than deaths from leptospirosis or dengue. Both measles and leptospirosis or dengue are rated as health priorities for many international health organizations. Furthermore, Melioidosis can become a potential agent for biological warfare and biological terrorism. Naturally Melioidosis is gaining priority attention.
What is Melioidosis?
Pathologist Alfred Whitmore and his assistant C.S. Krishnaswami first described Melioidosis in 1911 in Rangoon. Melioidosis is an infectious disease caused by bacteria. It is also known as Whitmore's disease. Melioidosis is caused by the bacteria Burkholderia Pseudomallei. This is a gram-negative bacterium mostly found in water, soil and on plants. Melioidosis affects humans and animals.
How do people get Melioidosis?
The infection is acquired when an individual comes in direct contact with contaminated soil and surface water. The modes of infection are ingestion, inhalation and inoculation (through local cuts and wounds on the skin). The latter appears to be most common. The disease does not spread from one person to another but may occur through contact with blood fluids of the infected person. Neonatal cases have been reported. It suggests either perinatal transmission or transplacental. Laboratory-acquired infections may rarely occur, especially if procedures produce aerosols.
Is Melioidosis region specific ?
Certain factors, environmental and climate support the microbe to thrive well when introduced. Till recently, the disease was considered to be restricted to Southeast Asia and Northern Australia. Philippines is considered to be endemic country of Melioidosis in Southeast Asia.
In United States, Melioidosis is reported to be rare. But Florida, Louisiana and Texas in United States and Okinawa and Kagoshima prefectures in Japan are rated as Melioidosis compatible based on climate and environmental factors. These regions have similar environmental factors like Caribbean islands and Taiwan. The microbe if introduced in these regions can thrive well.
What is the clear trend about Melioidosis ?
What are the symptoms of Melioidosis ?
Symptoms are site-specific as symptoms vary depending on the site of infection. The infection can form a cavity of pus (abscess). The infection usually starts in the lung or in the skin and then spreads to other parts of the body. As it spreads Melioidosis can affect lungs, kidneys, liver, heart and circulatory system.
The pulmonary form of infection takes place when bacteria in aerosol form enters the respiratory tract. Symptoms of lung infection include shortness of breath, cough, chest pain, high fever, headache or anorexia and abnormal lung sounds.
Localized form of Melioidosis takes place when the bacteria enters the skin through a laceration or abrasion. This can lead to skin wounds with pain and swelling, fever, ulceration or abscess. There can be increased mucus production in the affected areas.
On entering the blood stream, symptoms differ. Associated symptoms include fever, headache, respiratory difficulties, abdominal pain or discomfort, joint pain, muscle tenderness etc. Disseminated infections of Melioidosis include fever, weight loss, stomach or chest pain, muscle or joint pain, headache and seizures.
When are Melioidosis symptoms noticeable ?
The incubation period of the bacterium is not clearly defined. The anticipation established is 1 to 21 days. On the other hand, there is a possibility of remaining asymptomatic from 10 days to many years after contracting the bacterium. But, when the symptoms begin, it can be sudden or gradual.
Being informed about Melioidosis is the key to seeking timely medical attention. Melioidosis can be fatal if not treated promptly. If you suspect Melioidosis infection, seek medical attention immediately.
How is Melioidosis diagnosed ?
Misdiagnosis can result in deaths. Distinguishing Melioidosis from pulmonary TB is challenging. The clinical manifestations are similar. Early diagnosis and effective treatment prevents casualties. Expert micro-biologists supervise Melioidosis diagnosis. Healthcare professionals recommend blood culture, skin-lesion sample, urine or sputum examination aided by microscopic evaluation in a laboratory.
Chances of infection are high if the blood test shows an elevated white blood cell count. In cases involving lung infection, chest x-ray is required to study presence of cavitating lesions resembling tuberculosis.
How is Melioidosis treated ?
Melioidosis is a treatable disease. Hospital admission is required only in severe cases. Treatment is entirely dependent on the location of Melioidosis. Treatment involves administering antibiotic therapy that includes intravenous microbial therapy for 10-14 days followed by oral antimicrobial therapy for 3-6 months. If required, surgical drainage of pus is beneficial.
Are there ways to prevent Melioidosis ?
Prevention through vaccination is not available currently. Preventive measures reduce risk of Melioidosis especially in areas where the risk of infection is high.
The Mantoux test or tuberculin sensitivity test is a diagnostic test for tuberculosis. This test, also known as Piquet Test is endorsed by the American Thoracic Society and Centers for Disease Control and Prevention (CDC). The other diagnostic tests for tuberculosis are Tine test and Heaf test. Since the Mantoux test makes use of purified protein derivatives (PPD), it is also referred to as PPD test. This tuberculosis test does not indicate how long the infection has been festering or if it is in the active stage. This tuberculosis test is prescribed for persons who have abnormal chest x-rays or symptoms such as weight loss and persistent cough for many months. A Mantoux test is not recommended for those suffering from any skin conditions or allergy. Women who are pregnant or breastfeeding must not be subjected to the Mantoux test.
This PPD test involves injecting a dose of TB antigens into the top layer of skin on the forearm. The dose includes 10 Tuberculin units (0.2 ml) as this exposes the person to enough bacteria to mount an immune reaction in the skin. A little bump (wheal) is noticed under the skin. This area is then observed for any reaction in then next 48 - 72 hours. Reactions such as fever or swollen lymph nodes in the armpit must be brought to the notice of health professionals immediately. The results of this test must be interpreted carefully. A positive result indicates tuberculosis. There may be cases of false positives or false negative results. The significance of the Mantoux test on those vaccinated with BCG is still controversial.
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Collection of Pages - Last revised Date: November 22, 2019