Francis of Assisi’s Illness
Francis of Assisi’s Illness: Stigmata, Leprosy, Trachoma and Psychosis
Francis of Assisi’s Illness: Stigmata, Leprosy, Trachoma and Psychosis
DESCRIPTION: Marking the 800th anniversary of his death: Did Francis of Assisi suffer from leprosy and trachoma, and were the stigmata reinterpreted as symptoms of illness? A pathography based on sources ranging from Thomas of Celano to Thomas of Spalato.
Francis of Assisi: Leprosy, trachoma and the psychosis of a saint
Francis of Assisi returned from Egypt in 1220 seriously ill, relinquished leadership of his order, concealed his hands and feet from almost all his brothers, and died in 1226 as the first person in the history of the Church to receive the stigmata. The Church is marking the 800th anniversary of his death with a jubilee year lasting until 10 January 2027. His feast day is 4 October. The descriptions of his stigmata come exclusively from the circle that campaigned for his canonisation. Reading the sources from a medical perspective reveals further medical interpretations. Leprosy can account for changes to the eyes, hands, feet and skin as a result of a single condition. Trachoma (also known as Egyptian grain disease, a highly contagious, chronic form of conjunctivitis) remains the alternative explanation for the eye condition, whilst his youth and conversion can be interpreted as bipolar disorder with psychotic episodes. Hagiography has interpreted each of these signs as signs of holiness.
What illnesses did Francis of Assisi suffer from?
Early accounts of Francis’s life are strikingly rich in references to illness. Thomas of Celano wrote the first hagiography in 1228 and 1229 on behalf of Gregory IX, who had known and supported Francis personally. He reports a prolonged fever following Francis’s imprisonment in Perugia, an eye condition that left him almost blind upon his return from the East, a prolonged stomach and liver ailment during which he vomited large amounts of blood, and, in his final months, a distended abdomen and swollen legs and feet.
The treatments of the time can also be verified. In 1225, at the urging of his vicar Elias, Francis had his temples cauterised with a red-hot iron at Fonte Colombo near Rieti, the standard treatment for chronic eye infections. On 3 October 1226, he died at the Portiuncula Chapel at the age of about 45. On 16 July 1228, Gregory IX canonised him.
This wealth of detail regarding illnesses is unusual for a hagiography. Thomas needed it because suffering was an integral part of the programme. For a pathography, it is a stroke of luck, for anyone wishing to interpret illness theologically must first describe it.
Which details provided by the hagiographers can be trusted
All early hagiographies originate from within the Order or its immediate circle. Anyone reading them from a medical perspective therefore needs a guideline as to which details may be regarded as observations. Historical scholarship recognises the ‘embarrassment’ criterion for this: the author is unlikely to have invented anything that runs counter to his own interests. The prodigal youth, the mockery and stone-throwing from his own town, his confinement by his father, and the dirty robe mentioned in an outsider’s account all fall into this category. They do not serve the cause of sanctity, so they are presumably included in the text for the sake of historical record.
Conversely, details that fit precisely the pattern demanded by theology lose their weight. Nail-shaped marks, a wound in the side and a crucifix that speaks fulfil the typology of the Second Christ. Here, the hagiographer has good reason to embellish the details. This distinction determines, in what follows, which details are to be read as symptoms and which as interpretations.
The eye ailment from Egypt: trachoma or leprosy?
In 1219 and 1220, Francis was in the Nile Delta, with the Crusader army at Damietta, and met Sultan al-Kamil. Egypt was the classic endemic region for trachoma, the chronic chlamydial infection of the eye, which was still known in Europe in the 19th century as the ‘Egyptian eye disease’. The description in the sources fits this picture: a course lasting many years, pain, excessive tearing, marked sensitivity to light and progressive blindness.
However, trachoma is a diagnosis based on geographical origin. The clinical picture described in the sources is equally consistent with eye involvement in leprosy. Lepromatous leprosy affects the cornea and iris; it causes photophobia and pain and can lead to blindness. The ability to close the eyelids may be lost if the facial nerve is affected. Cauterisation of the temples would have been of no benefit in either disease.
This shifts the question. Did Francis suffer from two diseases – one from Egypt and one from Umbria – or a single one, the ocular manifestations of which were retrospectively attributed to his journey to the East? The second interpretation requires only one disease. The question could only be resolved by investigations which, to date, no one has carried out.
The stigmata and the leprosy hypothesis
The leprosy theory was put forward by the Franciscan nun and nurse Joanne Schatzlein and the internist Daniel Sulmasy, who set it out in 1987 in *Franciscan Studies*. Their starting point was his biography: from the time of his conversion around 1205, Francis cared for lepers; he kissed and washed them, and at times lived amongst them. In his will, he himself describes his encounter with the lepers as a turning point in his life.
The incubation period for leprosy ranges from years to decades. An infection dating from 1205 and symptoms manifesting around 1220 fall precisely within this timeframe. Lepromatous leprosy primarily affects the cooler parts of the body – namely the hands, feet, nose and ears – causing nodules, ulcers and numbness. It explains the eye and foot lesions as resulting from a single disease. At a clinical-pathological conference at the University of Maryland in 2019, both the expert discussion and two computer-assisted diagnostic systems reached the same conclusion: leprosy. All three assessments are based on the same source material; they therefore do not count as independent confirmations.
The theology of the crucifixion provided the reinterpretation at the same time. Isaiah 53:4 reads in the Vulgate: ‘Et nos putavimus eum quasi leprosum’ – ‘we regarded him as a leper’. The Middle Ages interpreted the Servant of God as Christ. Anyone wishing to make a leprous saint in the image of Christ had little difficulty bridging the gap between leprosy and the Passion.
Hands concealed, the sick man shielded
Thomas of Celano and, later, Bonaventure both report that Francis kept his hands inside his sleeves, wore stockings and shoes, and showed his stigmata to only a few brothers. Elias saw them; Rufinus is said to have touched the wound in his side only by means of a ruse. This behaviour has nothing in common with the theatrical display of stigmata seen in later centuries.
The hagiographers interpreted this concealment as humility and as the preservation of a secret between Francis and Christ. A leper had a more tangible reason. Anyone recognised as a leper in the 13th century lost their place in the community and was set apart. For the founder of an order whose reputation depended on him, such a discovery would have spelled the end. Concealing the marks is not proof of leprosy. It is compatible with leprosy and would have had a very practical reason if he had had it.
The chronology reinforces this suspicion. In 1220, Francis stepped down from the leadership of the Order, first in favour of Peter of Catania, then of Elias. He spent his final years in the closest circle with Leo, Rufinus, Angelus and Masseo, often in hermitages. These companions controlled access to him, and they are also the main witnesses to the marks. Disappointment at the direction the Order was taking is independently documented as the reason for his withdrawal. A progressive, shameful illness and institutional humiliation reinforced one another.
Who described the stigmata
Immediately after his death, Elias, as Vicar General, announced a new miracle in a circular letter: Francis had borne the stigmata of the Crucified One on his body. Thomas wrote the first hagiography on behalf of the Pope, who pursued the canonisation and carried it out less than two years after his death. All descriptions of the stigmata come from interested parties.
This also weakens the strongest argument against leprosy. Thomas describes fleshy growths in the shape of nails, with round heads on one side and bent tips on the other. This is precisely the form required by the typology of the crucifixion. An ulcerated leprous nodule on the palm of the hand or the sole of the foot could just as easily be interpreted in this way from a devout perspective. Whilst there is no evidence of such nodules, the description does not rule them out either.
The contemporary reaction shows just how controversial the marks were. The canonisation bull *Mira circa nos* of 1228 makes no mention of them at all. It was not until 1237 that Gregory IX defended them in several bulls against sceptics, including Bishop Robert of Olomouc, who taught that only the wounds of Christ should be venerated. The Church subsequently established the stigmata as orthodox doctrine.
The wound in the side and the soiled habit
The wound in the side is regarded as the mark that cannot be explained by leprosy. On closer reading, little is actually documented: blood and discharge on the tunic and trousers, observed and secretly washed away by his companions. The notion that they originated from a single wound is itself an interpretation.
Thomas of Celano mentions the right side, whilst the Gospel of John makes no mention of a specific side during the crucifixion. The origin of this localisation is likely to be the antiphon ‘Vidi aquam’, which, based on Ezekiel 47, sings of the water flowing from the right side of the temple and which the liturgy applied to Christ. This line of transmission cannot be substantiated. However, a hagiographer who saw bloodstains on a habit knew exactly where the wound must have been.
There was no shortage of material for such stains. Thomas of Spalato, a student from Split, heard Francis preach in Bologna in 1222 and recorded: ‘Sordidus erat habitus, persona contemptibilis et facies indecora’ – his robe was filthy, his appearance contemptible, his face unsightly. An ascetic who called his body ‘Brother Donkey’, refused care, scarcely washed himself and did not change his clothes was, given the everyday conditions of the time, in all likelihood infested with lice, fleas and scabies, suffering from scratch wounds, boils and secondary infections. Lepromatous skin ulcerates and becomes infected easily. Added to this, in the final stages, were vomiting blood and the incontinence typical of the seriously ill. It would therefore be more surprising to find this patient wearing a clean habit.
Brother Donkey: Fasting as anorexia
Francis called his body ‘Brother Donkey’. Bonaventure records him addressing it thus: ‘So, Brother Donkey, you must remain as you are.’ The donkey is the work animal that is driven, laden and fed sparingly. In 1224, Francis fasted beyond the requirements of the Rule of St Francis, on the remote rock of La Verna in Tuscany, some forty days before the Feast of St Michael. According to Bonaventure, he rarely ate cooked food at all, and when he did allow himself some, he mixed ash into it.
If one removes this behaviour from its religious context, it meets the criteria for anorexia nervosa as defined by the DSM-5. The criteria require a significantly low body weight resulting from restricted food intake, a fear of weight gain or persistent behaviour that prevents weight gain, and a disturbance in body image or a persistent failure to recognise the seriousness of being underweight. Weight phobia is therefore not a prerequisite. Fasting beyond the requirements of church rules and mixing ash into food prevent weight gain. ‘Brother Donkey’ is the disguise of the eating disorder in a formula of self-hatred.
In 1995, the psychiatrist Sing Lee, writing from Hong Kong, described female patients who starved themselves without fear of being fat and who gave different reasons for their starvation. He concluded that weight phobia was a cultural manifestation of the disorder. Ten years earlier, in *Holy Anorexia*, the historian Rudolph Bell had interpreted the self-starvation of holy women of the late Middle Ages – foremost among them Catherine of Siena – as anorexia. In 1987, Caroline Walker Bynum countered this in *Holy Feast and Holy Fast*, arguing that food and abstinence had held religious significance for these women and that * * had given them agency. The two interpretations are not mutually exclusive. What applies to delusion applies to Francis: the disorder makes use of the material provided by the culture.
According to Franciscan tradition, shortly before his death Francis asked Brother Leib for forgiveness for his harsh treatment. Clinically, this constitutes a late realisation of the illness, as is also seen in chronic cases of eating disorders.
The end: vomiting blood, ascites, oedema
Thomas of Celano describes the final months in greater detail than any other phase of the illness. In the spring of 1226 in Siena, after a long bout of stomach and liver problems, Francis vomited a great deal of blood. Afterwards, his abdomen, legs and feet swelled up. Vomiting blood, ascites and oedema of the legs together paint a picture of portal hypertension: the pressure in the portal vein rises, varicose veins in the oesophagus rupture and bleed, and fluid accumulates in the abdominal cavity. The most common cause is cirrhosis of the liver, and Thomas explicitly mentions the liver.
Alcohol as a cause can be ruled out in the case of this ascetic. Once again, Egypt is a more likely explanation. Schistosomiasis has been widespread in the Nile Delta since ancient times; traces of it have even been found in mummies. The eggs of Schistosoma mansoni become embedded in the liver; the tissue around the branches of the portal vein becomes scarred, leading to varices and bleeding, whilst the liver continues to function for a long time. However, one year in the Delta and six years until death seem too short a timeframe for such severe scarring.
The leprosy hypothesis offers a second explanation. Lepromatous leprosy frequently leads to secondary amyloidosis, which affects the kidneys and liver. Through nephrotic syndrome, it causes oedema and ascites. In this interpretation, a single underlying condition would account for the eyes, hands, feet, skin and the fatal outcome. However, in this interpretation, the vomiting of blood would require a separate cause, such as a stomach ulcer.
A third interpretation does not require liver disease. Malnutrition leads to protein deficiency over the years, and protein deficiency causes oedema and ascites. A stomach ulcer explains the blood. In their 2021 case conference, Manesh, Schatzlein, Mackowiak and colleagues list the ulcer amongst the possible causes and interpret the swelling as nephrosis.
The clinical picture is clear. Thomas describes a man with a diseased stomach and liver who is vomiting blood and becoming swollen. This outcome needed no explanation from on high.
The remains of Assisi: selectively examined
In 1230, during the transfer to the new basilica, Elias had the body concealed so deeply that it remained lost until 1818. There was never an independent examination of the soft tissues. In 1978, a papal commission opened the sarcophagus, with the participation of the anatomist Nicolò Miani from the Università Cattolica del Sacro Cuore. It described the bone fragments found individually, along with coins and grains from the period, and confirmed their authenticity. Since then, the remains have been kept in a nitrogen-filled container. A further examination followed in 2015, again with the aim of authentication.
There is no record of a published palaeopathological assessment for leprosy. The search would need to focus on the typical bone changes: deterioration of the upper jaw and nasal cavity, loss of the anterior nasal concha, and dissolution of the distal phalanges of the fingers and toes. On both occasions, the investigators were appointed by the church itself. From 22 February to 22 March 2026, to mark the 800th anniversary of his death, the remains were displayed to the public for the first time in the lower church. The spokesperson for the Sacro Convento interpreted their damaged and worn condition as a sign that Francis had given his all. Pious interpretation rather than forensic examination: this has been the approach since Thomas of Celano.
A second approach would be even simpler. In Assisi and Cortona there are tunics attributed to Francis. Textiles can be tested for traces of blood, lice and nits, and for pathogen DNA; indeed, Mycobacterium leprae can even be detected in archaeological material. However, there is no published study of the tunics addressing this very question either.
The dream of knighthood
The story begins long before Egypt. Francis was born in 1181 or 1182, the son of the wealthy cloth merchant Pietro di Bernardone, and was baptised Giovanni. His father was on a trading voyage in France at the time of his birth and, upon his return, named him Francesco. According to Thomas’s own account, his son was a spendthrift leader of the youth of Assisi. He wanted to become a knight. In the Italian communes around 1200, this was conceivable for a merchant’s son, for anyone who could provide a horse served the commune on horseback. In 1202, Francis rode with the Assisi cavalry against Perugia at Collestrada.
The military training of the nobility, however, began in childhood, as a page and squire in a noble household. The merchant’s son bought his own armour and horse and had never learnt to fight on horseback. Fencing schools outside noble households only became common later; London banned them in 1285. The Battle of Collestrada ended in defeat and, for Francis, with about a year in captivity.
His behaviour whilst in captivity is remarkable. The legend of the three companions depicts him as cheerful there, telling his lamenting fellow prisoners that the whole world would one day revere him. In 1205 came his second attempt: a campaign to Apulia in magnificent armour, which he, however, gave to an impoverished knight shortly before setting out. In Spoleto, he dreamt of a hall full of weapons intended for him and his knights, and turned back the very next day. Extravagant expenditure, impulsive generosity, a grandiose undertaking and its abrupt abandonment paint a picture of an expansive phase of mania.
The Speaking Cross of San Damiano
This expansive phase was followed by a crisis of conversion. Francis withdrew, spent weeks in a cave and returned emaciated and unkempt. The people of Assisi thought him mad and pelted him with dirt and stones. His father locked him up. Francis squandered his father’s precious fabrics in Foligno to pay for a dilapidated church, and when his father brought him before the bishop’s court in 1206, Francis stripped naked and returned the clothes to him.
It was during this period that the most famous scene took place: the crucifix at San Damiano is said to have called him by name and instructed him to rebuild his house. Francis took the instruction literally, begged for stones and rebuilt San Damiano, San Pietro and the Portiuncula with his own hands. The interpretation of this as a reform of the entire Church is a later construction by the hagiographers. However, the ‘speaking cross’ does not appear until the second *Vita* by Thomas, dating from the 1240s, and in the Legend of the Three Companions. It is absent from the first *Vita* and from Francis’s will.
If the scene is genuine, there is much to suggest it was an auditory hallucination. The organic contributing factors mentioned in the next section remain a likely cause. And even the cultural congruence of religious content does not preclude this interpretation. Delusional content always stems from the material provided by the culture: those who do not grow up in a religious environment do not hear the voice of Christ. In the 13th century, the belief that God could speak was widely held. The conviction that a painted wooden cross was speaking to one and commissioning a building project was idiosyncratic, and one’s own town saw it that way too.
Bipolar disorder, schizophrenia or organic brain disease?
The crisis occurred during the prime age of onset for psychotic disorders; Francis was 23 or 24 years old. Organic contributing causes cannot be ruled out. A year in captivity, followed by months of feverish illness and later excessive fasting, make an organic brain-related psychotic syndrome resulting from infection or malnutrition a serious differential diagnosis.
Paranoid-hallucinatory schizophrenia is supported by his age and the presence of hallucinations. However, Francis’s own writings speak against this diagnosis: the two Rules, his Testament, letters, the Canticle of the Sun and the Chartula for Leo in his own handwriting. They show no formal thought disorders. Delusions of persecution are absent from all sources. A so-called ‘residuum’ is also absent. Francis led an order comprising thousands of brothers for twenty years and negotiated with the Curia and the Sultan.
As a hypothesis, bipolar disorder with psychotic features fits best. Delusions of grandeur and extravagance in his youth, delusions of grandeur already whilst in prison, the expansive phase prior to Spoleto, a manic-psychotic crisis of conversion with mood-congruent religious content and disinhibition extending to public exposure, followed by long phases of withdrawal, despair and a sense of illness after 1220. The later visions, up to the seraph at La Verna in 1224, occurred during periods of fasting, sleep deprivation, fever and, presumably, advanced physical illness. The duration of the episodes and their distinction from the baseline state cannot be reconstructed from 13th-century sources. The diagnosis therefore remains, like any retrospective diagnosis, a well-founded hypothesis.
A pathography in dates
· c. 1200 to 1202: extravagant lifestyle, the desire to rise above knighthood
· 1202 to 1203: defeat at Collestrada, approximately one year’s imprisonment in Perugia, expressions of grandeur
· 1204: protracted feverish illness, retreat
· 1205: a lavishly equipped procession to Apulia, the dream of Spoleto, immediate return
· 1205 to 1206: crisis of conversion, voice of the Crucifix (late source), embezzlement of his father’s goods, public exposure, social exclusion
· from around 1205: caring for lepers
· 1206 to 1220: Stabilisation within a religious framework, high level of productivity
· 1219 to 1220: Egypt and the Holy Land, onset of eye ailment
· from 1220: Resignation, retreat, veiled hands and feet
· 1224: Visions at La Verna, first instances
· 1225: Cauterisation at Fonte Colombo
· 1226: In Siena, vomiting blood following a long illness of the stomach and liver, followed by ascites and oedema of the legs; death on 3 October; the Epistle of Elijah
· 1228: Canonisation, papal bull without mention of the stigmata
· 1237: Papal bulls against the sceptics
The data can be pieced together to form a medical history: a bipolar disorder with psychotic episodes as the baseline, organic contributing factors during the crisis of 1204 to 1206 and in the final phase, and possible leprosy as the underlying physical condition in his final years. Hagiography has turned the delusions of grandeur into a calling, the hallucinations into a revelation, and the sores of a leper into the stigmata of Christ. The physical aspect could be examined by analysing the remains and the tunics. The psychiatric hypothesis remains unaffected by this; it can only be tested against the texts. No one has yet initiated such an investigation, and the custodians of the relics have little incentive to begin one. For eight centuries, they have thrived on the fact that illness in this body is regarded as a blessing.
Key points in brief
• Information that runs counter to the interests of hagiographers carries greater evidential weight than that which conforms to the Christ-type.
• Francis returned from Egypt in 1220 suffering from an eye condition. Trachoma is the geographically most likely diagnosis, though the involvement of the eyes in leprosy also explains the symptoms.
• Schatzlein and Sulmasy put forward the leprosy hypothesis in 1987. Infection whilst caring for lepers from 1205 onwards and the onset of symptoms around 1220 are consistent with the long incubation period.
• St Francis concealed his hands and feet and allowed only a few companions to come near him. This is consistent with leprosy; for a leper, it served as protection against isolation.
• All descriptions of the stigmata originate from the circle that pursued his canonisation. The bull of canonisation from 1228 makes no mention of stigmata; it was not until 1237 that Gregory IX established them as fact against the sceptics.
• The position of the wound in his side on the right presumably follows liturgical practice. Bloodstains on a soiled habit can be explained by vermin, skin infections and vomiting blood, without the need for a miracle.
• The remains were examined for authenticity in 1978 and 2015. No findings regarding leprosy have been published, nor has any analysis of the tunics for blood, lice or pathogen DNA.
• His youth and conversion reveal delusions of grandeur, extravagance, a period of expansiveness, auditory hallucinations and a loss of inhibitions. The hypothesis that fits best is bipolar disorder with psychotic features.
• In the final stage, Thomas of Celano describes a liver condition characterised by vomiting blood, ascites and oedema of the legs. This corresponds to portal hypertension. Possible causes include cirrhosis, schistosomiasis from the Nile Delta or amyloidosis associated with leprosy; in the absence of liver disease, gastric ulcers and starvation oedema are also possible.
• Regardless of the religious context, Francis’s fasting fulfils the DSM-5 criteria for anorexia nervosa. The DSM-5 does not require a phobia of weight. ‘Brother Donkey’ refers to the failure to recognise one’s own underweight condition.
• Cultural congruence does not exonerate religious content. Every delusion draws on the material of its own culture.
Sources
· Gregory IX, *Mira circa nos*, bull of canonisation, 1228 (EWTN)
· Thomas of Celano, First and Second Lives of Saint Francis (Medieval Sourcebook, Fordham)
· Thomas of Celano, The Crucifix of San Damiano, Vita secunda 10 ff. (Vatican)
· Rudolph M. Bell, *Holy Anorexia*, Chicago: University of Chicago Press 1985
· Caroline Walker Bynum, *Holy Feast and Holy Fast. The Religious Significance of Food to Medieval Women*, Berkeley: University of California Press 1987
· Thomas of Spalato and his account of Francis in Bologna in 1222
· Joanne Schatzlein and Daniel P. Sulmasy, *Francis the Leper*, new edition of the 1987 study
· Historical Clinicopathological Conference 2019: Francis of Assisi, University of Maryland
· Circular letter from the four Franciscan Ministers General regarding the 1978 investigation (EWTN)
· The relics of Francis of Assisi on public display for the first time (ORF, 2026)
· The remains of Saint Francis of Assisi, examinations in 1978 and 2015 (Agerpres, 2026)
· Santuario Francescano Fonte Colombo, cauterisation 1225 (FAI)
· Gallenga et al., ‘Why the SAFE-S Strategy for Trachoma?’, Pathogens 12 (2023)
· Statuta Civitatis London, 13 Edw. I (1285), ban on fencing schools
Related
DESCRIPTION: Marking the 800th anniversary of his death: Did Francis of Assisi suffer from leprosy and trachoma, and were the stigmata reinterpreted as symptoms of illness? A pathography based on sources ranging from Thomas of Celano to Thomas of Spalato.
Francis of Assisi: Leprosy, trachoma and the psychosis of a saint
Francis of Assisi returned from Egypt in 1220 seriously ill, relinquished leadership of his order, concealed his hands and feet from almost all his brothers, and died in 1226 as the first person in the history of the Church to receive the stigmata. The Church is marking the 800th anniversary of his death with a jubilee year lasting until 10 January 2027. His feast day is 4 October. The descriptions of his stigmata come exclusively from the circle that campaigned for his canonisation. Reading the sources from a medical perspective reveals further medical interpretations. Leprosy can account for changes to the eyes, hands, feet and skin as a result of a single condition. Trachoma (also known as Egyptian grain disease, a highly contagious, chronic form of conjunctivitis) remains the alternative explanation for the eye condition, whilst his youth and conversion can be interpreted as bipolar disorder with psychotic episodes. Hagiography has interpreted each of these signs as signs of holiness.
What illnesses did Francis of Assisi suffer from?
Early accounts of Francis’s life are strikingly rich in references to illness. Thomas of Celano wrote the first hagiography in 1228 and 1229 on behalf of Gregory IX, who had known and supported Francis personally. He reports a prolonged fever following Francis’s imprisonment in Perugia, an eye condition that left him almost blind upon his return from the East, a prolonged stomach and liver ailment during which he vomited large amounts of blood, and, in his final months, a distended abdomen and swollen legs and feet.
The treatments of the time can also be verified. In 1225, at the urging of his vicar Elias, Francis had his temples cauterised with a red-hot iron at Fonte Colombo near Rieti, the standard treatment for chronic eye infections. On 3 October 1226, he died at the Portiuncula Chapel at the age of about 45. On 16 July 1228, Gregory IX canonised him.
This wealth of detail regarding illnesses is unusual for a hagiography. Thomas needed it because suffering was an integral part of the programme. For a pathography, it is a stroke of luck, for anyone wishing to interpret illness theologically must first describe it.
Which details provided by the hagiographers can be trusted
All early hagiographies originate from within the Order or its immediate circle. Anyone reading them from a medical perspective therefore needs a guideline as to which details may be regarded as observations. Historical scholarship recognises the ‘embarrassment’ criterion for this: the author is unlikely to have invented anything that runs counter to his own interests. The prodigal youth, the mockery and stone-throwing from his own town, his confinement by his father, and the dirty robe mentioned in an outsider’s account all fall into this category. They do not serve the cause of sanctity, so they are presumably included in the text for the sake of historical record.
Conversely, details that fit precisely the pattern demanded by theology lose their weight. Nail-shaped marks, a wound in the side and a crucifix that speaks fulfil the typology of the Second Christ. Here, the hagiographer has good reason to embellish the details. This distinction determines, in what follows, which details are to be read as symptoms and which as interpretations.
The eye ailment from Egypt: trachoma or leprosy?
In 1219 and 1220, Francis was in the Nile Delta, with the Crusader army at Damietta, and met Sultan al-Kamil. Egypt was the classic endemic region for trachoma, the chronic chlamydial infection of the eye, which was still known in Europe in the 19th century as the ‘Egyptian eye disease’. The description in the sources fits this picture: a course lasting many years, pain, excessive tearing, marked sensitivity to light and progressive blindness.
However, trachoma is a diagnosis based on geographical origin. The clinical picture described in the sources is equally consistent with eye involvement in leprosy. Lepromatous leprosy affects the cornea and iris; it causes photophobia and pain and can lead to blindness. The ability to close the eyelids may be lost if the facial nerve is affected. Cauterisation of the temples would have been of no benefit in either disease.
This shifts the question. Did Francis suffer from two diseases – one from Egypt and one from Umbria – or a single one, the ocular manifestations of which were retrospectively attributed to his journey to the East? The second interpretation requires only one disease. The question could only be resolved by investigations which, to date, no one has carried out.
The stigmata and the leprosy hypothesis
The leprosy theory was put forward by the Franciscan nun and nurse Joanne Schatzlein and the internist Daniel Sulmasy, who set it out in 1987 in *Franciscan Studies*. Their starting point was his biography: from the time of his conversion around 1205, Francis cared for lepers; he kissed and washed them, and at times lived amongst them. In his will, he himself describes his encounter with the lepers as a turning point in his life.
The incubation period for leprosy ranges from years to decades. An infection dating from 1205 and symptoms manifesting around 1220 fall precisely within this timeframe. Lepromatous leprosy primarily affects the cooler parts of the body – namely the hands, feet, nose and ears – causing nodules, ulcers and numbness. It explains the eye and foot lesions as resulting from a single disease. At a clinical-pathological conference at the University of Maryland in 2019, both the expert discussion and two computer-assisted diagnostic systems reached the same conclusion: leprosy. All three assessments are based on the same source material; they therefore do not count as independent confirmations.
The theology of the crucifixion provided the reinterpretation at the same time. Isaiah 53:4 reads in the Vulgate: ‘Et nos putavimus eum quasi leprosum’ – ‘we regarded him as a leper’. The Middle Ages interpreted the Servant of God as Christ. Anyone wishing to make a leprous saint in the image of Christ had little difficulty bridging the gap between leprosy and the Passion.
Hands concealed, the sick man shielded
Thomas of Celano and, later, Bonaventure both report that Francis kept his hands inside his sleeves, wore stockings and shoes, and showed his stigmata to only a few brothers. Elias saw them; Rufinus is said to have touched the wound in his side only by means of a ruse. This behaviour has nothing in common with the theatrical display of stigmata seen in later centuries.
The hagiographers interpreted this concealment as humility and as the preservation of a secret between Francis and Christ. A leper had a more tangible reason. Anyone recognised as a leper in the 13th century lost their place in the community and was set apart. For the founder of an order whose reputation depended on him, such a discovery would have spelled the end. Concealing the marks is not proof of leprosy. It is compatible with leprosy and would have had a very practical reason if he had had it.
The chronology reinforces this suspicion. In 1220, Francis stepped down from the leadership of the Order, first in favour of Peter of Catania, then of Elias. He spent his final years in the closest circle with Leo, Rufinus, Angelus and Masseo, often in hermitages. These companions controlled access to him, and they are also the main witnesses to the marks. Disappointment at the direction the Order was taking is independently documented as the reason for his withdrawal. A progressive, shameful illness and institutional humiliation reinforced one another.
Who described the stigmata
Immediately after his death, Elias, as Vicar General, announced a new miracle in a circular letter: Francis had borne the stigmata of the Crucified One on his body. Thomas wrote the first hagiography on behalf of the Pope, who pursued the canonisation and carried it out less than two years after his death. All descriptions of the stigmata come from interested parties.
This also weakens the strongest argument against leprosy. Thomas describes fleshy growths in the shape of nails, with round heads on one side and bent tips on the other. This is precisely the form required by the typology of the crucifixion. An ulcerated leprous nodule on the palm of the hand or the sole of the foot could just as easily be interpreted in this way from a devout perspective. Whilst there is no evidence of such nodules, the description does not rule them out either.
The contemporary reaction shows just how controversial the marks were. The canonisation bull *Mira circa nos* of 1228 makes no mention of them at all. It was not until 1237 that Gregory IX defended them in several bulls against sceptics, including Bishop Robert of Olomouc, who taught that only the wounds of Christ should be venerated. The Church subsequently established the stigmata as orthodox doctrine.
The wound in the side and the soiled habit
The wound in the side is regarded as the mark that cannot be explained by leprosy. On closer reading, little is actually documented: blood and discharge on the tunic and trousers, observed and secretly washed away by his companions. The notion that they originated from a single wound is itself an interpretation.
Thomas of Celano mentions the right side, whilst the Gospel of John makes no mention of a specific side during the crucifixion. The origin of this localisation is likely to be the antiphon ‘Vidi aquam’, which, based on Ezekiel 47, sings of the water flowing from the right side of the temple and which the liturgy applied to Christ. This line of transmission cannot be substantiated. However, a hagiographer who saw bloodstains on a habit knew exactly where the wound must have been.
There was no shortage of material for such stains. Thomas of Spalato, a student from Split, heard Francis preach in Bologna in 1222 and recorded: ‘Sordidus erat habitus, persona contemptibilis et facies indecora’ – his robe was filthy, his appearance contemptible, his face unsightly. An ascetic who called his body ‘Brother Donkey’, refused care, scarcely washed himself and did not change his clothes was, given the everyday conditions of the time, in all likelihood infested with lice, fleas and scabies, suffering from scratch wounds, boils and secondary infections. Lepromatous skin ulcerates and becomes infected easily. Added to this, in the final stages, were vomiting blood and the incontinence typical of the seriously ill. It would therefore be more surprising to find this patient wearing a clean habit.
Brother Donkey: Fasting as anorexia
Francis called his body ‘Brother Donkey’. Bonaventure records him addressing it thus: ‘So, Brother Donkey, you must remain as you are.’ The donkey is the work animal that is driven, laden and fed sparingly. In 1224, Francis fasted beyond the requirements of the Rule of St Francis, on the remote rock of La Verna in Tuscany, some forty days before the Feast of St Michael. According to Bonaventure, he rarely ate cooked food at all, and when he did allow himself some, he mixed ash into it.
If one removes this behaviour from its religious context, it meets the criteria for anorexia nervosa as defined by the DSM-5. The criteria require a significantly low body weight resulting from restricted food intake, a fear of weight gain or persistent behaviour that prevents weight gain, and a disturbance in body image or a persistent failure to recognise the seriousness of being underweight. Weight phobia is therefore not a prerequisite. Fasting beyond the requirements of church rules and mixing ash into food prevent weight gain. ‘Brother Donkey’ is the disguise of the eating disorder in a formula of self-hatred.
In 1995, the psychiatrist Sing Lee, writing from Hong Kong, described female patients who starved themselves without fear of being fat and who gave different reasons for their starvation. He concluded that weight phobia was a cultural manifestation of the disorder. Ten years earlier, in *Holy Anorexia*, the historian Rudolph Bell had interpreted the self-starvation of holy women of the late Middle Ages – foremost among them Catherine of Siena – as anorexia. In 1987, Caroline Walker Bynum countered this in *Holy Feast and Holy Fast*, arguing that food and abstinence had held religious significance for these women and that * * had given them agency. The two interpretations are not mutually exclusive. What applies to delusion applies to Francis: the disorder makes use of the material provided by the culture.
According to Franciscan tradition, shortly before his death Francis asked Brother Leib for forgiveness for his harsh treatment. Clinically, this constitutes a late realisation of the illness, as is also seen in chronic cases of eating disorders.
The end: vomiting blood, ascites, oedema
Thomas of Celano describes the final months in greater detail than any other phase of the illness. In the spring of 1226 in Siena, after a long bout of stomach and liver problems, Francis vomited a great deal of blood. Afterwards, his abdomen, legs and feet swelled up. Vomiting blood, ascites and oedema of the legs together paint a picture of portal hypertension: the pressure in the portal vein rises, varicose veins in the oesophagus rupture and bleed, and fluid accumulates in the abdominal cavity. The most common cause is cirrhosis of the liver, and Thomas explicitly mentions the liver.
Alcohol as a cause can be ruled out in the case of this ascetic. Once again, Egypt is a more likely explanation. Schistosomiasis has been widespread in the Nile Delta since ancient times; traces of it have even been found in mummies. The eggs of Schistosoma mansoni become embedded in the liver; the tissue around the branches of the portal vein becomes scarred, leading to varices and bleeding, whilst the liver continues to function for a long time. However, one year in the Delta and six years until death seem too short a timeframe for such severe scarring.
The leprosy hypothesis offers a second explanation. Lepromatous leprosy frequently leads to secondary amyloidosis, which affects the kidneys and liver. Through nephrotic syndrome, it causes oedema and ascites. In this interpretation, a single underlying condition would account for the eyes, hands, feet, skin and the fatal outcome. However, in this interpretation, the vomiting of blood would require a separate cause, such as a stomach ulcer.
A third interpretation does not require liver disease. Malnutrition leads to protein deficiency over the years, and protein deficiency causes oedema and ascites. A stomach ulcer explains the blood. In their 2021 case conference, Manesh, Schatzlein, Mackowiak and colleagues list the ulcer amongst the possible causes and interpret the swelling as nephrosis.
The clinical picture is clear. Thomas describes a man with a diseased stomach and liver who is vomiting blood and becoming swollen. This outcome needed no explanation from on high.
The remains of Assisi: selectively examined
In 1230, during the transfer to the new basilica, Elias had the body concealed so deeply that it remained lost until 1818. There was never an independent examination of the soft tissues. In 1978, a papal commission opened the sarcophagus, with the participation of the anatomist Nicolò Miani from the Università Cattolica del Sacro Cuore. It described the bone fragments found individually, along with coins and grains from the period, and confirmed their authenticity. Since then, the remains have been kept in a nitrogen-filled container. A further examination followed in 2015, again with the aim of authentication.
There is no record of a published palaeopathological assessment for leprosy. The search would need to focus on the typical bone changes: deterioration of the upper jaw and nasal cavity, loss of the anterior nasal concha, and dissolution of the distal phalanges of the fingers and toes. On both occasions, the investigators were appointed by the church itself. From 22 February to 22 March 2026, to mark the 800th anniversary of his death, the remains were displayed to the public for the first time in the lower church. The spokesperson for the Sacro Convento interpreted their damaged and worn condition as a sign that Francis had given his all. Pious interpretation rather than forensic examination: this has been the approach since Thomas of Celano.
A second approach would be even simpler. In Assisi and Cortona there are tunics attributed to Francis. Textiles can be tested for traces of blood, lice and nits, and for pathogen DNA; indeed, Mycobacterium leprae can even be detected in archaeological material. However, there is no published study of the tunics addressing this very question either.
The dream of knighthood
The story begins long before Egypt. Francis was born in 1181 or 1182, the son of the wealthy cloth merchant Pietro di Bernardone, and was baptised Giovanni. His father was on a trading voyage in France at the time of his birth and, upon his return, named him Francesco. According to Thomas’s own account, his son was a spendthrift leader of the youth of Assisi. He wanted to become a knight. In the Italian communes around 1200, this was conceivable for a merchant’s son, for anyone who could provide a horse served the commune on horseback. In 1202, Francis rode with the Assisi cavalry against Perugia at Collestrada.
The military training of the nobility, however, began in childhood, as a page and squire in a noble household. The merchant’s son bought his own armour and horse and had never learnt to fight on horseback. Fencing schools outside noble households only became common later; London banned them in 1285. The Battle of Collestrada ended in defeat and, for Francis, with about a year in captivity.
His behaviour whilst in captivity is remarkable. The legend of the three companions depicts him as cheerful there, telling his lamenting fellow prisoners that the whole world would one day revere him. In 1205 came his second attempt: a campaign to Apulia in magnificent armour, which he, however, gave to an impoverished knight shortly before setting out. In Spoleto, he dreamt of a hall full of weapons intended for him and his knights, and turned back the very next day. Extravagant expenditure, impulsive generosity, a grandiose undertaking and its abrupt abandonment paint a picture of an expansive phase of mania.
The Speaking Cross of San Damiano
This expansive phase was followed by a crisis of conversion. Francis withdrew, spent weeks in a cave and returned emaciated and unkempt. The people of Assisi thought him mad and pelted him with dirt and stones. His father locked him up. Francis squandered his father’s precious fabrics in Foligno to pay for a dilapidated church, and when his father brought him before the bishop’s court in 1206, Francis stripped naked and returned the clothes to him.
It was during this period that the most famous scene took place: the crucifix at San Damiano is said to have called him by name and instructed him to rebuild his house. Francis took the instruction literally, begged for stones and rebuilt San Damiano, San Pietro and the Portiuncula with his own hands. The interpretation of this as a reform of the entire Church is a later construction by the hagiographers. However, the ‘speaking cross’ does not appear until the second *Vita* by Thomas, dating from the 1240s, and in the Legend of the Three Companions. It is absent from the first *Vita* and from Francis’s will.
If the scene is genuine, there is much to suggest it was an auditory hallucination. The organic contributing factors mentioned in the next section remain a likely cause. And even the cultural congruence of religious content does not preclude this interpretation. Delusional content always stems from the material provided by the culture: those who do not grow up in a religious environment do not hear the voice of Christ. In the 13th century, the belief that God could speak was widely held. The conviction that a painted wooden cross was speaking to one and commissioning a building project was idiosyncratic, and one’s own town saw it that way too.
Bipolar disorder, schizophrenia or organic brain disease?
The crisis occurred during the prime age of onset for psychotic disorders; Francis was 23 or 24 years old. Organic contributing causes cannot be ruled out. A year in captivity, followed by months of feverish illness and later excessive fasting, make an organic brain-related psychotic syndrome resulting from infection or malnutrition a serious differential diagnosis.
Paranoid-hallucinatory schizophrenia is supported by his age and the presence of hallucinations. However, Francis’s own writings speak against this diagnosis: the two Rules, his Testament, letters, the Canticle of the Sun and the Chartula for Leo in his own handwriting. They show no formal thought disorders. Delusions of persecution are absent from all sources. A so-called ‘residuum’ is also absent. Francis led an order comprising thousands of brothers for twenty years and negotiated with the Curia and the Sultan.
As a hypothesis, bipolar disorder with psychotic features fits best. Delusions of grandeur and extravagance in his youth, delusions of grandeur already whilst in prison, the expansive phase prior to Spoleto, a manic-psychotic crisis of conversion with mood-congruent religious content and disinhibition extending to public exposure, followed by long phases of withdrawal, despair and a sense of illness after 1220. The later visions, up to the seraph at La Verna in 1224, occurred during periods of fasting, sleep deprivation, fever and, presumably, advanced physical illness. The duration of the episodes and their distinction from the baseline state cannot be reconstructed from 13th-century sources. The diagnosis therefore remains, like any retrospective diagnosis, a well-founded hypothesis.
A pathography in dates
· c. 1200 to 1202: extravagant lifestyle, the desire to rise above knighthood
· 1202 to 1203: defeat at Collestrada, approximately one year’s imprisonment in Perugia, expressions of grandeur
· 1204: protracted feverish illness, retreat
· 1205: a lavishly equipped procession to Apulia, the dream of Spoleto, immediate return
· 1205 to 1206: crisis of conversion, voice of the Crucifix (late source), embezzlement of his father’s goods, public exposure, social exclusion
· from around 1205: caring for lepers
· 1206 to 1220: Stabilisation within a religious framework, high level of productivity
· 1219 to 1220: Egypt and the Holy Land, onset of eye ailment
· from 1220: Resignation, retreat, veiled hands and feet
· 1224: Visions at La Verna, first instances
· 1225: Cauterisation at Fonte Colombo
· 1226: In Siena, vomiting blood following a long illness of the stomach and liver, followed by ascites and oedema of the legs; death on 3 October; the Epistle of Elijah
· 1228: Canonisation, papal bull without mention of the stigmata
· 1237: Papal bulls against the sceptics
The data can be pieced together to form a medical history: a bipolar disorder with psychotic episodes as the baseline, organic contributing factors during the crisis of 1204 to 1206 and in the final phase, and possible leprosy as the underlying physical condition in his final years. Hagiography has turned the delusions of grandeur into a calling, the hallucinations into a revelation, and the sores of a leper into the stigmata of Christ. The physical aspect could be examined by analysing the remains and the tunics. The psychiatric hypothesis remains unaffected by this; it can only be tested against the texts. No one has yet initiated such an investigation, and the custodians of the relics have little incentive to begin one. For eight centuries, they have thrived on the fact that illness in this body is regarded as a blessing.
Key points in brief
• Information that runs counter to the interests of hagiographers carries greater evidential weight than that which conforms to the Christ-type.
• Francis returned from Egypt in 1220 suffering from an eye condition. Trachoma is the geographically most likely diagnosis, though the involvement of the eyes in leprosy also explains the symptoms.
• Schatzlein and Sulmasy put forward the leprosy hypothesis in 1987. Infection whilst caring for lepers from 1205 onwards and the onset of symptoms around 1220 are consistent with the long incubation period.
• St Francis concealed his hands and feet and allowed only a few companions to come near him. This is consistent with leprosy; for a leper, it served as protection against isolation.
• All descriptions of the stigmata originate from the circle that pursued his canonisation. The bull of canonisation from 1228 makes no mention of stigmata; it was not until 1237 that Gregory IX established them as fact against the sceptics.
• The position of the wound in his side on the right presumably follows liturgical practice. Bloodstains on a soiled habit can be explained by vermin, skin infections and vomiting blood, without the need for a miracle.
• The remains were examined for authenticity in 1978 and 2015. No findings regarding leprosy have been published, nor has any analysis of the tunics for blood, lice or pathogen DNA.
• His youth and conversion reveal delusions of grandeur, extravagance, a period of expansiveness, auditory hallucinations and a loss of inhibitions. The hypothesis that fits best is bipolar disorder with psychotic features.
• In the final stage, Thomas of Celano describes a liver condition characterised by vomiting blood, ascites and oedema of the legs. This corresponds to portal hypertension. Possible causes include cirrhosis, schistosomiasis from the Nile Delta or amyloidosis associated with leprosy; in the absence of liver disease, gastric ulcers and starvation oedema are also possible.
• Regardless of the religious context, Francis’s fasting fulfils the DSM-5 criteria for anorexia nervosa. The DSM-5 does not require a phobia of weight. ‘Brother Donkey’ refers to the failure to recognise one’s own underweight condition.
• Cultural congruence does not exonerate religious content. Every delusion draws on the material of its own culture.
Sources
· Gregory IX, *Mira circa nos*, bull of canonisation, 1228 (EWTN)
· Thomas of Celano, First and Second Lives of Saint Francis (Medieval Sourcebook, Fordham)
· Thomas of Celano, The Crucifix of San Damiano, Vita secunda 10 ff. (Vatican)
· Rudolph M. Bell, *Holy Anorexia*, Chicago: University of Chicago Press 1985
· Caroline Walker Bynum, *Holy Feast and Holy Fast. The Religious Significance of Food to Medieval Women*, Berkeley: University of California Press 1987
· Thomas of Spalato and his account of Francis in Bologna in 1222
· Joanne Schatzlein and Daniel P. Sulmasy, *Francis the Leper*, new edition of the 1987 study
· Historical Clinicopathological Conference 2019: Francis of Assisi, University of Maryland
· Circular letter from the four Franciscan Ministers General regarding the 1978 investigation (EWTN)
· The relics of Francis of Assisi on public display for the first time (ORF, 2026)
· The remains of Saint Francis of Assisi, examinations in 1978 and 2015 (Agerpres, 2026)
· Santuario Francescano Fonte Colombo, cauterisation 1225 (FAI)
· Gallenga et al., ‘Why the SAFE-S Strategy for Trachoma?’, Pathogens 12 (2023)
· Statuta Civitatis London, 13 Edw. I (1285), ban on fencing schools
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