Tuberculosis

Historical Background :
            Tuberculosis (TB) is a disease of great antiquity affecting mankind from very early times. Evidence of existence of tuberculosis has been found in the bones of Prehistoric man, found in  Germany. Those remains date  back to about 8000 B.C. Typical tuberculosis changes have been found in the spines of skeleton of ancient Egyptians dating from  about 2500 to 1000 B.C. In the year of 1882, Robert Koch discovered the tubercle bacilli, the  causative organism.
 

Present Scenario :
            Tuberculosis is by far the  most frequently encountered mycobacterial disease affecting  human beings.     About 1.7 billion or one third of world's  population are, or have  been  infected  with Mycobacterium  tuberculosis.
              In India, 12-13 million  individuals are infected, with 50% of the Indian population, over the  age of  22 years are prone to tuberculosis. World wide an annual  addition of 2.5-3.2 million new  cases and 2.6-2.9 million deaths are reported, while in India an  annual addition of 2.5 millions new  cases and 0.5 million deaths (one  death per minute) are reported  (National Survey, NTI, 1991).  With  the rapid spread of HIV-TB coinfection and multidrug resistance the epidemiology of this  disease is changing very fast. An  upward trend is seen in the developed countries and Africa. Three million people are infected with HIV TB worldwide.

 Global Emergency :

             Although tuberculosis is a  curable and to some extent  preventable disease, its diagnosis  sometimes, especially in  Extrapulmonary tuberculosis, HIV- TB, Childhood TB, Smear Negative  Pulmonary TB becomes difficult.  The WHO declared tuberculosis as a Global Emergency in 1993.  

Clinical Presentation of Tuberculosis :

             The incidence of pulmonary  tuberculosis is more frequent than  extrapulmonary form of  tuberculosis (EPTB). EPTB is increasingly recognized since last  decade because of the emergence  of AIDS. Tuberculosis is an air  borne disease,  being transmitted via respiratory route on inhalation  or ingestion of droplet nuclei  containing  varying    quantities of M tuberculosis bacilli. The man with active disease when coughs, sneezes or spits, aerosolizes  droplet nuclei. The risk of infection  progressing to disease varies with age, the risk being greatest in  children below 3 years, followed by young adult and the elderly people.

Pulmonary tuberculosis :

            This is the most common  form and affects the lung. The onset is usually insidious and  illness remains unnoticed by the patients for some time. It reaches   full extent with in few weeks. The extent of the disease varies from minimal infiltrates that produce no clinical illness to massive involvement with extensive cavitation and debilitating constitutional and respiratory symptoms. In the absence of effective therapy, this pursues a  chronic and progressive course  with growing bacterial colony. With the progression of pulmonary  disease the normal pulmonary  architecture is lost. The over all death rate of  untreated pulmonary tuberculosis approaches 60%.

Extra pulmonary tuberculosis :

             This occurs following haematogenous and lymphatic  dissemination of tubercle bacilli  from  primary pulmonary infection or  a reactivated focus elsewhere in  the body i.e. infected lymph node  etc. Number of tissues or different  organs may be infected such as :  

• Tubercular lymphadenitis

involve the unilateral cervical nodes  especially those high in the neck  are more frequent in children. This  form of tuberculosis is the most  common form of extrapulmonary   tuberculosis constituting towards 30% of the total disease. As the disease progresses, sinus tracts are resulted. These may slowly respond to medication, rarely may require excision.

• Bone & Joint tuberculosis

is more common in elderly,  although seen in all ages. The involvement is usually a late manifestation of haematogenous  spread of this disease. The site  most frequently involved is the vertebral body representing 36- 50% of the total bone and joint tuberculosis cases. Lumbar and low dorsal spines are commonly involved in older; high dorsal in young. The weight bearing bones / joints (knee, 12-15%) are also  involved. However any bone or  joint can be involved. The course of  disease starts from synovial  membrane, then inflammation  followed by demineralization and  caseous necrosis.   

• Abdominal tuberculosis 

includes i) abdominal organ (GIT, liver, spleen etc.) ii) peritoneum iii)  lymphatics. The intestinal  tuberculosis can be related to  swallowing sputum tubercule bacilli  or the disease reactivation in peri  intestinal lymphatic tissue. The  ileocoecal area of small intestine is  the most common site (91%) involved. Peritoneal TB presents  with seeding of tubercles through out the peritoneal surface and occurs in ascitic (exudative) or plastic (adhesive or dry) forms. This form of TB is easily confused with other diseases such as  irritable bowel syndrome, alcoholic  cirrhosis etc. Usually the signs and  symptoms are vague and non specific, increases with age and patient presents with abdominal swelling, vague pain and alternate  diarrhoea and constipation.

•  Meninges-CNS tuberculosis

is most common amongst infants, children with extrapulmonary  tuberculosis. The patient presents in  different stages: early fever,  headache, and malaise; later  confusion, seizures and coma. The  prognosis is related to stage.  

• Genitourinary tuberculosis

is rare in young, more frequent  among females. This may involve  kidneys, ureters, bladder, testes,  epididymis, uterus, fallopian tubes  etc. This may complicate to early or  late obstructive uropathy, infertility  etc.