Specific diseases

Pulmonary tuberculosis (TB):

• caused by the bacterium Mycobacterium tuberculosis

  
  

• transmission by infected airborne droplets released when a patient coughs: also carried on infected dust particles

  
  

• symptoms include coughing, swollen neck glands, and later exhaustion and weight loss

  
  

• prevention is by vaccination of young children and teenagers at risk. The vaccine used is BCG (Bacille Calmette-Guérin) developed by the French workers Calmette & Guérin. The vaccine contains attenuated bacteria and induces active immunity (Core syllabus content).

  
  Sufferers may be treated with antibiotics such as streptomycin, though many antibiotic-resistant strains of the bacterium are appearing. It is now usual to prescribe at least three antibiotics simultaneously for the initial phase of treatment, which may last 8 weeks and is designed to achieve a very rapid reduction in the initial population of bacteria. The second phase of treatment, which may last for 9 months, employs one or more antibiotics different from those used in the first phase. Sometimes, for community protection, populations are screened for the disease by means of chest X-ray.

  
  

• the disease continues to rage around the world at an increasing pace, currently with 8 million new cases and 3 million deaths being reported annually.