Tuesday, 24 March 2015

World TB Day

Mycobacterium tuberculosis is one of the biggest infectious killers of people, the other billboard causes of death are malaria and infectious diarrhoea but these are caused by a variety of different bugs.  Deaths from malaria are usually caused by a protozoa parasite Plasmodium falciparum but only because its relatives P. vivax, P. ovale, P. knowlesi and P. malariae cause a milder form of the disease which merely debilitates (makes you feel crap) and destroys economies by lost or inefficient work-days.  Destroying economies may well mean that the bread-winner is laid low so that the children starve.  Infectious diarrhoea is caused by a much wider variety of agents notably rotavirus which kills half a million children every year.  An equal number dehydrate themselves to death from bacteria such as Vibrio cholerae, Campylobacter and Escherichia and also protozoans like  Giardia lamblia, Entamoeba histolytica and Cryptosporidium parva.  The old name for infectious diarrhoea is The Flux or the Bloody Flux which is what happens.

Tuberculosis, is also called consumption romantically associated with dying poets, or phthisis which is more awkward to spell and is a major health problem in the third world although its incidence is increasing among the dispossessed of the West.  World TB Day is the WHO's way of raising awareness and has been running for the last 20 years, each year having a theme which emphasises one aspect of the disease, its treatment or control.  They picked 24th March to remember an extraordinary piece of scientific theatre delivered in Berlin on that day in 1882 by Robert Koch [R nursing a worrying headache].  Koch is famous in science and microbiology for Koch's Postulates which tie particular disease to a particular microbe which becomes the first step in treatment and cure.  If you don't know the cause, you can just mop up the mess, try to make thye patient comfortable and wait.  This is all that Florence Nightingale was able to achieve in the 1860s.  Koch changed all that.  His raree show that day brought his lab to the lecture theatre, as he took his audience through the evidence that a particular rod-shaped bacillus, for which he had invented a specific microscopic staining protocol, caused a spongy destruction of the lung in mammals.  For this he won the Nobel Prize in 1905.  Paul "magic bullet" Ehrlich (Nobel 1908) maintained "I hold that evening to be the most important experience of my scientific life." and reported that at the end of Koch's tour-de-force the audience was stunned into silence - no amount of applause would suffice and Koch had already answered all their questions in his presentation.

If you think that TB is a serious enough problem now, and it is, you should reflect on the fact with which Koch started his lecture - in the 1880s one in every seven people was infected with Mycobacterium.  And also think long and hard about how we use antibiotics because many strains of the bacillus are resistant to everything we have to throw at it. There was no cease upon the midnight with no pain when Keats was hacking up bloody sputum as he composed his Ode to a Nightingale:
Darkling I listen; and for many a time   
I have been half in love with easeful Death,   
Call'd him soft names in many a musèd rhyme,   
To take into the air my quiet breath;   
Now more than ever seems it rich to die,
To cease upon the midnight with no pain . . .

No comments:

Post a Comment