Dressed to kill: What do infectious disease agents have in their wardrobes?
One of the few toys I had when I was small child was a plastic ark, which I spent a lot of time sailing over the concrete floors of our house in the Ethiopian town of Harar where we lived at the time. It is unlikely that I would have had any acquaintance with the myth of the Flood. I had run away from the local Maltese missionary school within a few days of being enrolled there, and been granted the freedom never to return. So, I spent my days at home, blissfully alone.
One morning, finding that the deck of my ark had somehow been bent out of shape, I first cried a little and then set about trying to squeeze it back into its frame, and eventually succeeded. I showed my mother and she smiled in delight and congratulated me. Perhaps you will grow up to be engineer, she said.
I did not grow up to be an engineer, and indeed never exhibited any further aptitude for it. But there was a magic in thinking that the rest of my life could be composed of such utterly satisfying experiences as fitting a deck back onto my toy ark – and something of that feeling comes back to me whenever I find a new solution (not necessarily the right one) to a scientific conundrum, and each time I know I should thank my mother for reinforcing the thrill I felt in fixing that little ark and opening my young mind up to the possibility of spending my life solving puzzles and understanding how things work.
I now use mathematical models to make sense of the evolutionary ecology of infectious disease systems. One of the most important questions in medical science is how we can protect ourselves against the cunning bugs that have the capacity to return in disguise against our immune defences. Influenza is a prime example of such a pathogen that regularly re-invades the human population literally by picking a different set of clothes from its wardrobe to fool our immune systems into thinking it is not a threat.
Measles, by contrast, has only a very monochromatic (measly?) wardrobe – and once we have had measles, we are on guard for any further attacks. This is why we have a vaccine for measles but are still flailing around when it comes to protecting ourselves against influenza. Indeed, when it comes to deciding what the influenza virus might do next, we are thrown into a panic of such enormous proportions that the leaching of this kind of panic into the public has actually stimulated the cinema industry to make not just boring scary movies but films of worth such as ‘Contagion’.
But does influenza, or any other pathogen, really have an unlimited wardrobe of disguises with which to haunt us till the end of time? The biological answer must be “no”, since all these accoutrements actually have a vital function to play in the life history of the pathogen. For example, the parts of the influenza virus we recognise are also its machinery for attaching with a human cell and exiting it (having meanwhile made lots of babies): it is clear that this virus can vary these elements but there are strong biological arguments for why this variation must be limited in its scope.
In my research group, we have developed mathematical arguments to show how the influenza virus can use its limited wardrobe to engage in a dance with its host population in which it has to continually select the correct set of accoutrements to outwit us. There are two important public health implication of our work: first, that we might be able to get the measure of this limited wardrobe and put it to use in making a better vaccine for influenza and second, that we can relax about whether influenza is going to show up in a completely new disguise and cause us all to die.
I have been privileged, in my life, to have had parents who made no distinction between men and women in ability and aspiration, and to have grown up in an enlightened middle-class community in Calcutta where women were expected to follow their ambitions. It was a shock to me when I came to the West to find that it was not quite the same here, and for many years I simply regarded this as a curiosity. Indeed, in my 25 years working as a scientist in the UK, the occasions have been rare when I have questioned whether my gender was militating against me.
I think, now, the main impediment that women face in science is not discrimination by men but a form of liberterianism practised by certain senior women and men alike where each person is seen to be out for themselves and to have to ‘play the game’ – those who have neither the energy nor the inclination to do this are bound to be victims of this attitude, and I see younger scientists daily being discouraged by it.Tagged in: Contagion, education, gender, health, infectious diseases, Influenza, maths, Measles, medical science, medicine, nhs, science, women, women in science
Latest from Independent journalists on Twitter