Early in his career, the well-known scourge of psychiatry and psychiatrists, Thomas Szasz, suggested that male baldness was a psychosomatic condition. It was brought about, he said, by the increased muscular tension in the scalp interfering with the hair's blood supply when men forced themselves to smile even when they were feeling low and depressed.
I hesitate to join Prof Szasz, but I have long felt there was a psychological component to travellers' diarrhoea (the subject of an interesting article in last week's Lancet): that it was not all in the bowel, as it were. Surely everyone must have noticed that it is precisely the people who are most afraid of contracting it who get it worst? The nervous types who assiduously avoid every culinary hazard are struck low, while the (relatively) insouciant types get away with it. There is no justice in the world, that is for sure.
For myself, I haven't had travellers' diarrhoea for 20 years, despite disobeying the rules in places where cholera epidemics were raging, and where no food was ever served without its halo of attendant flies. Back in 1960, though, when Italy was still a country where travellers might suffer intestinal disturbances, and my brother and I were under strict instructions to drink only acqua minerale, I watched my brother pass out in a Naples shop from weakness brought about by constant diarrhoea. I was shortly to suffer similarly, and had to be evacuated to Switzerland.
The authors of the article in the Lancet conducted an enquiry among 67,231 visitors to various holiday destinations - Goa, Mombasa, Montego Bay and Fortaleza (in Brazil). Attack rates were highest in Kenya and India (54.6 and 53.9% respectively), lowest in Fortaleza (13.6%), with Montego Bay in between (23.6%). Where people stayed made a lot of difference: the attack rate in the worst hotel in Montego Bay was nearly five times greater than that in the best hotel.
The authors found that British visitors were by far the worst afflicted. In Indian and Kenya their attack rates were nearly 50% higher than those among other Europeans, while their attack rate in Jamaica was more than double. The authors of the article found no evidence that the British visitors were less careful about what they ate than other visitors, and were at a loss to explain the difference.
Several possible explanations offer themselves, of course. Perhaps the British visitors were merely more truthful in their answers than the others, or were more sensitive to any changes in their bowel habit. Recollection, even in tranquillity, is notoriously unreliable, after all.
But if the differences were real, what do they mean? That British food hygiene is so superior that the British have become super-sensitive to any bacteriological impurity? Hardly. Perhaps they drank vastly more beer than others - not a hypothesis to be dismissed lightly.
What of my idea that travellers' diarrhoea is partly psychosomatic? Nothing in the data presented contradicts the hypothesis. The difference in attack rates in hotels in Jamaica might be due as much to psychological contagion as to physical contagion. And the fact that toxic organisms were found in the stool samples of some of the people who suffered from diarrhoea is not decisive evidence against the contribution of the psyche to the condition: many people who did not suffer from diarrhoea were infected by such organisms also. Perhaps the difference between the British and the others was in their expectations - abroad being considered dangerous and uncivilised - rather than in what they consumed.
Interestingly, the attack rate was inversely proportional to the percentage of visitors who were not tourists. Business visitors would be too busy to be ill, perhaps, just as the self-employed suffer fewer backaches than employees who work for others. On the other hand, it is likely that most business visitors go to where there is most business to be done - places developed enough to have a clean water supply and to pay some attention to food hygiene.
If I were asked by a patient what he should do to avoid travellers' diarrhoea, however, I would repeat the mantra for voyagers to exotic places contained in the Lancet article: boil it, cook it, peel it - or forget it. This is not advice I follow very closely myself, but then, as la Rochefoucauld so wisely remarked, it is easier to give good advice than to take it.