Tuberculin

Tuberculin, also known as purified protein derivative, is a combination of proteins that are used in the diagnosis of tuberculosis. This use is referred to as the tuberculin skin test and is recommended only for those at high risk. Injection is done into the skin. After 48 to 72 hours if there is more than a five to ten millimeter area of swelling the test is considered positive. Tuberculin, also known as purified protein derivative, is a combination of proteins that are used in the diagnosis of tuberculosis. This use is referred to as the tuberculin skin test and is recommended only for those at high risk. Injection is done into the skin. After 48 to 72 hours if there is more than a five to ten millimeter area of swelling the test is considered positive. Common side effects include redness, itchiness, and pain at the site of injection. Allergic reactions may occasionally occur. The test may be falsely positive in those who have been previously vaccinated with BCG or have been infected by other types of mycobacteria. The test may be falsely negative within 10 weeks of infection, in those less than 6 months old, and in those who have been infected for many years. Use is safe in pregnancy. Tuberculin is made out of an extract of Mycobacterium tuberculosis. Tuberculin was discovered in 1890 by Robert Koch. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 0.22 USD per dose. In the United States testing costs less than 25 USD. The test used in the United States at present is referred to as the Mantoux test. An alternative test called the Heaf test was used in the United Kingdom until 2005, although the UK now uses the Mantoux test in line with the rest of the world. Both of these tests use the tuberculin derivative PPD (purified protein derivative). Tuberculin was discovered by German scientist and physician Robert Koch in 1890. The original tuberculin discovered by Koch was a glycerine extract of the tubercle bacilli and was developed as a remedy for tuberculosis, but reductions in deaths did not meet those expected of the treatment. British efforts to set up 'dispensaries' for the examination, diagnosis and treatment of the poor achieved better results as the Edinburgh System structure encompassed treatment of the homes and entire contacts of the TB sufferers. The example of Dr Hilda Clark's dispensary at Street, Somerset was especially marked for its efficacious treatment of the less severe cases. Clemens von Pirquet, an Austrian physician, discovered that patients who had previously received injections of horse serum or smallpox vaccine had quicker, more severe reactions to a second injection, and he coined the word allergy to describe this hypersensitivity reaction. Soon thereafter von Pirquet discovered the same type of reaction took place in those infected with tuberculosis, and he thus found the utility of what would become the tuberculin skin test. Individuals with active tuberculosis were usually tuberculin positive, but many of those with disseminated and rapidly progressive of disease were negative. This led to the widespread but erroneous belief that tuberculin reactivity is an indicator of immunity to tuberculosis. In Koch's time, close to one in seven Germans died of tuberculosis. For that reason, the public reacted euphorically to the discovery of the pathogen since it aroused hopes for a cure. Until that time, the only effective remedy for an infectious disease was quinine (for malaria). At the Tenth International Medical Congress held 1890 in Berlin, Koch unexpectedly introduced a cure for tuberculosis, which he called tuberculin. He did not reveal its composition, which is understandable as it was not then customary to patent medicine; Phenazone being the only exception. The public trusted the famous physician and reacted enthusiastically. Koch was awarded the Grand Cross of the Order of the Red Eagle. The social hygienist Alfred Grotjahn described the arrival of tuberculin in Greifswald: “Finally the great day also arrived for Greifswald on which the Clinic for Internal Medicine was to carry out the first inoculations with tuberculin. It was celebrated like the laying of a foundation stone or the unveiling of a monument. Doctors, nurses and patients dressed in snowy white and the director garbed in a black frock coat stood out against a background of laurel trees: ceremonial address by the internist, execution of the vaccination on selected patients, a thunderous cheer for Robert Koch!“ Koch attempted to make money from his discovery, which was held against him since he had conducted his research at a public institution with public money. He demanded that the Ministry of Culture finance an institute exclusively to produce tuberculin, and estimated the annual profit at 4.5 million marks. He also hinted that he had received offers from the USA.