36. Darwin to Hugh Falconer, 5 January, Cor. 11, p.11.
37. Darwin to Fox, 23 March, Cor.11, p.255.
38. Darwin to Hooker, 26, Cor.11, p.265.
39. Cor.11, p.603, note 6 and p.655 note 3.
40. Cor.11, p.643, note 5.
41. Darwin to Hooker, Cor.12, p.31.
42. Darwin to Gray, 25 February, Cor.12, p.60.
43. Emma to Fox, Cor.12, pp.168–69.
44. Darwin to Buckland, 15 December, Cor.12, p.471.
45. Cor. 13, p.147, note 3.
46. Darwin to John Chapman, 7 June 1865, Cor.13, p.179.
47. Cor.7, p.482.
48. Darwin to Gray, 15 August, Cor. 13, p.223, and note 12.
49. Darwin to Edward Cresy, 7 September, Cor.13, pp.229–30.
50. Darwin to Hooker, 27, Cor.13, pp.245–46.
51. Darwin to Fox, 25/26 October, Cor.13, p.284.
52. Darwin to Bence Jones, 3 January, Cor. 14, p.4.
53. Darwin to Hooker, 3 February, Cor.16, p.65.
54. Darwin to J.J. Moulinié, 22 February, Cor.17, p.93.
55. Darwin to W.C. Tait, 18 April, Cor.17, p.183.
56. Darwin to Hooker, 22 June, Cor.17, p.279.
57. Darwin to H.B. Jones, 3 August, Cor.18, p.224.
58. Darwin to W.S. Dallas, 27 January, Cor.19, p.44.
59. Darwin to Matthew, 15 March, Cor.19, p.182.
60. Darwin to F.E. Abbot, 16 November, Cor.19, p.686.
61. Hayman, Professor John A., ‘Darwin’s Illness Revisited’, British Medical Journal 2009:339:b4968. 13 December 2009.
62. Berg, Tymoczko, Stryer, and Clarke, Biochemistry, p.442.
63. http://barryjmarshall.blogspot.com/2009/02/darwins-illness-was-helicobacter-pylori.html
64. Mandell, Bennett, and Dolin, Principles and Practice of Infectious Diseases, p.2286.
65. Ibid, p.2288.
66. Ibid, pp.2288–9.
67. Oxford Dictionaries Online.
68. Warrell, Cox, Firth, and Benz Jr, Oxford Textbook of Medicine, p.561.
69. Ibid, p.562.
70. Ibid, p.563.
Chapter 29
Dr Ralph Colp: Professor Saul Adler: Chagas’ Disease
In his exhaustive study entitled ‘Darwin’s Illness’, published in 2008, US psychiatrist Ralph Colp Jr, assesses the validity of the numerous tentative diagnoses which have been made, over the years, in respect of Darwin’s condition. Apart from the ones already mentioned, they include toxicity from the taking of snuff and/or from the imbibing of alcohol; gout; chronic neurasthaenia; refractive anomaly of the eyes; pyorrhea of the gums; mental overwork; mild (hereditary) depression; serious anxiety neurosis; chronic brucellosis; malaria; chronic appendicitis; cholecystitis; diaphragmatic hernia; hypoglycaemia; arsenic poisoning; mercury poisoning from the ingestion of medicines containing mercuric chloride; severe allergy, possibly to pigeons, which Darwin studied and bred; hyperventilation syndrome; panic disorder; agoraphobia; dysfunction of the immune system; hypoadrenalism; and systemic lupus erythematosis. However, the only candidates to which Colp gives any credence in respect of Darwin, are psychoneurosis and Chagas’ disease.1
‘Psychoneurosis’ is defined as a relatively mild mental illness that is not caused by organic disease, involving symptoms of stress (depression, anxiety, obsessive behaviour, hypochondria) but not a radical loss of touch with reality.2 To anyone familiar with Darwin, it is obvious that he was a driven man whose overwhelming desire was to explore, discover, and theorize about the natural world. And he became positively morose and depressed at anything that stood in his way in this respect. Work, to him, was not only a tonic, but also a therapy. Said he, in November 1863:
My chief enjoyment and sole employment throughout life has been scientific work, and the excitement [derived] from such work makes me for the time forget, or drives quite away my daily discomfort.3
I have been so steadily going down hill, I cannot help doubting whether I can ever crawl a little up hill again. Unless I can, enough to work a little, I hope my life may be very short; for to lie on [the] sofa all day & do nothing, but give trouble to the best & kindest of wives & good dear children is dreadful.4
To journalist, translator, and poet Charles Boner, in early 1870, Darwin wrote, ‘You describe the grand scenery of the [Austrian] Tyrol most graphically, and it makes me long to be strong and young again to ramble over the mountains.’ This was in reference to Boner’s book Chamois Hunting in the Mountains of Bavaria and in the Tyrol, published in 1860.5 These words are hardly those of a psychoneurotic.
Darwin, in his younger days at Cambridge, had not been averse to enjoying himself. However, because of his illness, he said,
I have therefore been compelled for many years to give up all dinner-parties; and this has been somewhat of a deprivation to me, as parties always put me into high spirits.6
Given that psychoneurosis is defined as ‘a relatively mild mental illness’, then surely Darwin, with his tremendous willpower, would have been able to overcome it. Clearly, there was something far more seriously amiss with Darwin’s health.
The time has come, therefore, to consider Dr Colp’s other possible diagnosis in respect of Darwin’s illness, namely Chagas’ disease.
Professor Saul Adler
It was Professor Saul Adler of the Department of Parasitology, Hebrew University, Jerusalem, who first pointed out, in October 1959, the likely cause of the ill health which Darwin experienced all his adult life when he wrote that:
Darwin’s illness, which practically amounted to forty years of invalidism, has given rise to considerable speculation. The doctors who treated him could find no physical explanation for his distressing symptoms and apparently concluded that he was a hypochondriac.7
‘Hypochondria’ is an abnormal anxiety about one’s health, especially with an unwarranted fear that one has a serious disease,8 and even Darwin himself, in a letter to Hooker dated 31 March 1845, stated that ‘many of my friends I believe think me a hypochondriac’.9 Adler, however, introduces a note of caution when he states that ‘A purely psychological aetiology for Darwin’s illness cannot be accepted as conclusive until all other factors have been eliminated’.10
Referring to the voyage of HMS Beagle, Adler opined that ‘there is nothing of any medical significance prior to the voyage which could throw light on his subsequent illness’. And he quotes Lady Nora Barlow, daughter of Darwin’s son Horace, who contrasted Darwin’s ‘forty years of invalid existence’ with his ‘youthful vigour … strength and endurance [which were] were well above the average …’.11 Adler himself noted that
Darwin was a dedicated geologist and throughout his whole life maintained the keenest interest in this subject. Nevertheless, at the age of thirty-three, he was compelled to abandon field work in a favourite subject because he found by experience that the physical effort it entailed exhausted him.12
Adler now proceeds to quote from Darwin’s Voyage of the Beagle, and in particular the March 1835 episode at Luxan in the Argentinian province of Mendoza, where Darwin, by his own admission, was attacked by the ‘great black bug of the Pampas’. In Darwin’s own words:
It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body. Before sucking they are quite thin, but afterwards they become round and bloated with blood … . One which I caught at Iquique [Chile] (for they are found in Chile and Peru) was empty. When placed on a table, and though surrounded by people, if a finger was presented, the bold insect would immediately protrude its sucker, make a charge, and if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the act of sucking, as in less than ten minutes it changed from being as flat as a wafer to a globular form. This one feast, for which the Benchuca [triatome bug – see below] was indebted to one of the officers, kept it fat during four whole months; but after the first fortnight, it was quite ready to have another suck.13
Adler identifies the ‘bug’ as Triato
ma infestans which, in turn, is the ‘most important vector [carrier] of Trypanosoma cruzi [a single-celled parasitic protozoan with a trailing flagellum – tail],14 the causative agent of Chagas’ disease in the Argentine, Chile and parts of Brazil’.15 He continued,
The province of Mendoza has a relatively high incidence of Chagas’ disease, and according to South American colleagues with whom I discussed this problem at the recent congress on Chagas’ disease held in Rio de Janeiro during July 5–12 [1959] as many as 60 per cent of the population in parts of Mendoza give a positive complement-fixation test for T. [Trypanosoma] cruzi … .
The complement fixation test was used, at that time, to diagnose infectious diseases by detecting the presence of a specific antibody or antigen in the patient’s blood serum.
[Also] … as many as 70 per cent of specimens of Triatoma infestans are infected with the trypanosome. Darwin was therefore definitely exposed to infection on at least one occasion. It is highly probable that he was also exposed on other occasions … .
We must also bear in mind that Chagas’ disease has a very wide distribution in South America from Chile to Mexico (recently a few cases have been recorded in Texas) and the province of Mendoza is an area of relatively high infestation.
The incident in Luxan cannot, however, explain Darwin’s previous seven weeks severe illness during September and October 1834 which confined him to bed in Valparaiso and commenced during the last week of a six weeks journey. Unfortunately, no clinical details of this episode are available.
However, said Adler, according to Scottish anatomist and anthropologist Sir Arthur Keith, typhoid fever was ‘a very probable diagnosis’ for this unexplained illness.16 Adler continued:
The complications and sequelae of Chagas’s disease have been studied in detail by some of the ablest South American pathologists and clinicians, particularly in Brazil, the Argentine, Chile and Uruguay, and considerable literature on this subject is now available. Particular attention has been paid to the clinical and pathological aspects of the myocarditis [inflammation of the heart muscle] which appears in some victims of the disease. Darwin’s exhaustion after physical effort can well be explained on the basis of an infection with T. cruzi.
Adler concludes that
It is obviously impossible to prove that Darwin was a victim of Chagas’ disease but two points cannot be overlooked: (1) his symptoms can be fitted into the framework of Chagas’ disease at least as well as into any psychogenic [having a psychological origin or cause rather than a physical one]17 theory for their origin; (2) it is possible to pin-point with certainty a definite incident on March 25, 1835, during which he was exposed to optimal conditions for infection with T. cruzi.18
Chagas’ disease
Chagas’ disease, otherwise known as New World or South American trypanosomiasis, is a disease principally of northern, north-western and central-south America, and it was Carlos Chagas (1879–1934) who discovered the disease that now bears his name. The son of a Brazilian coffee grower, Chagas graduated from the school of medicine at Rio de Janeiro in 1902 and was awarded his doctorate in medicine the following year whilst working at the new Medical Research Institute founded by physician, bacteriologist, epidemiologist and public health officer Oswaldo Cruz. Having left the institute for the port of Santos, São Paulo (200 miles to the south-west), to help combat a malaria epidemic, he returned in 1906, and the following year was sent to the city of Lassance (450 miles to the north) to combat another malaria outbreak. It was during his two-year sojourn at Lassance that he studied the behaviour of blood-sucking insects, known as triatomines. These ‘bugs’ are commonly found in the cracks and crevices of the walls and ceilings of primitive rural dwellings in which they hide by day, and emerge at night to suck the blood of those sleeping in the house, whether human beings or domestic animals.
When Chagas examined the intestinal contents of the triatomes he discovered that they harboured a new species of the Trypanosoma genre.19 Suspecting that the triatome ‘bugs’ might be instrumental in transmitting their trypanosome parasites to man and other vertebrates, Chagas
therefore sent [a collection of] bugs to our Institute where the director, Dr Oswaldo Cruz, tried to infect a monkey of the species Callithrixpenicillata, by having it bitten by several examples of the hemipteran [triatomes]. Twenty or thirty days after the bite, large numbers of trypanosomes were found in the peripheral blood of the monkey, with morphology that was entirely distinct from any known species of the genus Trypanosoma.20
Chagas named this new parasite Trypanosoma cruzi, in honour of Oswaldo Cruz.
In 1912 E. J. Alexander Brumpt, Professor at the Faculty of Medicine and Director of the Parasitology Laboratory in Paris, challenged Chagas’ view that the disease was transmitted by the bite of the triatomine. He suggested, instead, that in most cases it was the faeces of infected bugs which transmitted the disease via the mucous membranes of humans (or animals). In other words, a bug lands on a person, deposits its faeces on the skin, the person then touches or scratches the spot, his hands become contaminated, he then touches his mouth, which gives the trypanosome easy access to the body via the mouth’s lining. (That this was the usual mode of transmission was later confirmed by Chagas’ disciple at the Oswaldo Cruz Institute, Dr Emmanuel Dias.)21 It has since been discovered that the disease can also be spread by consuming the uncooked meat of animals infected with the trypanosome, or by consuming food contaminated by the faeces of infected bugs.
The course of the disease
Between the time of a person contracting Chagas’ disease and the onset of its clinical symptoms, a delay of between four and forty years is possible.
The early or acute phase of Chagas’ disease is frequently without symptoms, but is occasionally fatal: there may be an initial lesion at the site where T. cruzi has entered the body. The acute phase may resolve in a symptomless, indeterminate period, which can be life-long, but can progress into chronic Chagas’ disease with heart abnormalities or intestinal malfunction and enlargement, especially of the oesophagus and colon, with damage to the nerve supply of these organs.22
The pathology of the disease
In 1968 Austrian-born Fritz Köberle, Chairman (from 1953) of the Department of Pathology at the Medical School of Ribeirao Preto, Brazil, described how, in patients with Chagas’ disease, there was a significant loss of ganglion (assemblage of nerve) cells from the parasympathetic autonomic nervous system (the so-called Auerbach’s plexus of nerve fibres and ganglia, which acts upon the muscle of the gastrointestinal tract and controls its motility). This explains why the oesophagus and/or colon of patients infected with Trypanosoma cruzi may lose their normal muscle tone, fail to perform peristalsis, and become dilated. (This is of particular significance as far as Darwin’s illness is concerned, as will be seen.) The colon may be affected in a similar way and also the heart, leading to chronic heart disease, heart failure, cardiomegaly (enlargement of the heart), arrhythmias (irregularities of the pulse) and thromboembolism; all of which are potentially life-threatening conditions.23
Arguments against the Chagas’ disease hypothesis
i. Wikipedia
The online website Wikipedia, under the heading ‘Evidences against the Chagas hypothesis’, lists the following objections to Professor Saul Adler’s theory in respect of Darwin.24
(The author of this volume’s comments appear, in italics, after each entry):
‘Darwin died at a relatively old age for his time (seventy-three years old)’.
The modern consensus of opinion is that the presence of chronic Chagas’ disease (in the absence of other factors) reduces the patient’s lifespan by up to one decade only. Darwin’s father Robert, lived to be eighty-two.
‘The symptoms abated as he aged, which is not typical for the disease, where age exacerbates the symptoms.’
Untrue. His symptoms did not abate as he aged.
‘He did not seem to have several of the pathological damages present at [i.e. in
patients with] chronic Chagas’ disease, such as megacolon and megaesophagus.’
As the technique of clinical biopsy was not available in Darwin’s time, and in the absence of post-mortem evidence, this statement is impossible to verify. What is true is that Darwin’s digestive symptoms were typical ofmegaoesophagus.
‘Some of the symptoms, such as tachycardia, fatigue and tremors, were already present before the Beagle voyage.’
Possibly, but not to the extent that they impeded Darwin in any significant way. Had they done so, he would have been unable to undertake the rigours of the Beagle voyage.
‘The numerous partial exacerbations and remissions [experienced by Darwin] are unusual in Chagas’ disease.’
This is not true, at any rate as far as Darwin’s digestive symptoms are concerned, for according to Professor Antonio R. L. Teixeira (Director of the Chagas’ Disease Multidisciplinary Research Laboratory, Faculty of Medicine, University of Brasilia, Brazil) and others, the digestive symptoms of the disease ‘evolve during periods of dysphagia [difficulty or discomfort in swallowing25 and are], followed by long periods during which symptoms are absent’, and so on in a continual cycle.26
‘The incidence of trypanosome-infected benchucas [triatome bugs] in Mendoza, Argentina (which had a colder climate) where Darwin reported the bite, is very low.’
It is true, according to data provided by the World Health Organization, that the Andes Mountains are a trypanosome-free zone27 (presumably because here, there are few animals or beasts for the triatomes to feed off), but the same is not true of the foothills of the Andes, where Luxan is situated and where Darwin had personally encountered the bugs.
‘No other members of Beagle’s crew who accompanied Darwin in his land trip showed signs of a similar disease.’
This cannot be said with certainty. Darwin lost touch with the majority of the Beagle’s crew members; so if they had become ill, he would not necessarily have known about it. Also, it is unlikely that any physician of the time would have recognized the significance of the symptoms as it would be another seven decades before the nature of the disease was elucidated. However, it is possible that one or more of the small proportion of the members of the Beagle’s crew who ventured into the interior, did become infected with trypanosomes. (Recent estimations of Chagas’ disease prevalence in the rural populations of Argentina, for example, show values ranging from 25 per cent to 45 per cent.)28
Charles Darwin Page 25
