Lecture delivered to 1st year medical students at Kuantan, Pahang on January 24, 1998 by Prof Dr Omar Hasan Kasule, Sr. Deputy Dean for Research and Post-graduate Affairs, Kulliyah of Medicine


            Definition of Disease

            Relativity in Disease Definition


            Disease in the Qur’an

            Superstition and Disease






            Acute & chronic

            Amradh al qalb & amradh al badan

            Physical Causes

            Mental Disease



            Reaction and Adjustment

            Attitude to Disease


            Excuse from Obligations



            Sufficient Cause

            Necessary Cause

            Multi-factorial Causation

            Endogenous & Exogenous       

Intrinsic & Extrinsic

            Environmental Causes

            Genetic Causes

            Immunological Causes







            Disease as Qadar

            Treatment of Disease as Qadar

Definition of disease: Health is a condition in which all of the body functions are integrated and are being maintained within the limits of optimal design (Bowman p. 4.2). Disease is divergence from the normal (Gaussian mean) but not all deviation is disease because of the reserve capacity and ability of the body to adjust. In most cases, a deviation must also be related to other adverse changes to be able to constitute disease. The demarcation between pathology and normal physiological variation can be fine. Hunger and thirst for example are psychological warning signs and are not pathological conditions. A hungry person is not in immediate danger to any part of the body. When the situation of food deprivation persists over a long time then pathological changes appear.


Relativity in Disease Definition: The definition of disease is very relative. A high blood pressure in an elderly person does not have the same implication as the same level in a younger person. Temperature levels have different interpretations in neonatal and adult infections. Adolescent behavior that may be normal would be considered illness in adults. There are changes in the body that should be accepted as normal processes of aging and not as diseases. There is a space-time variation in definition and perception of disease depending on the culture, beliefs, attitudes, and prevalence of diseases. In localities where the burden of major diseases is high, some minor ailments may be ignored whereas in other places they are taken as serious diseases. There are diseases that may be associated with social status. Some diseases become reclassified with changing public opinion for example homosexuality was considered a mental disorder half a century ago but is now accepted as normal sexual expression. New diseases continue to be defined  due to changes in the causative agents, host factors, or new scientific knowledge. Some old diseases like small-pox have disappeared.


Multi-dimensional definition of disease: Definition of disease considers several dimensions that may operate singly or in combination: moral/spiritual, biological/pathological (khuruuj al badan ‘an al i’itidaal), psycho-social, or  normative/statistical. Loss of spiritual equilibrium is a disease in itself and soon leads to physical disease. Most diseases involve disturbances in the equilibrium of the normal body physiology. These biological disturbances may be within the range of normal physiological variation or may be clearly pathological. The psycho-social dimension of disease is associated with loss of equilibrium and may precede or follow physical disturbances. The normative or statistical dimension is the most confusing. Sometimes people are branded ill because they fall at the extreme end of the health-illness spectrum. In the final analysis it is the perception of disease by the victim, the family or the health care givers that defines disease. The underlying pathology need not correspond with the victim’s disease complaint; perception operates in between.


Disease in the Qur’an: The Qur’an has used several terms to refer to disease. In the subject form the word maradh has been employed. In the adjective form the words maridh and saqim have been used (27:89, 37:145). The Qur’an being primarily a book of moral guidance, spends more time discussing the causes and treatments of moral diseases and gives relatively little space to physical diseases. Humans are argued to undertake the necessary research to understand the physical diseases


Superstitions and disease: The growth of scientific knowledge about the pathology of disease has contributed to a marked decrease in superstitious beliefs that have plagued mankind for centuries. Superstition is an attempt to understand and come to terms with frightening and dangerous disease phenomena that afflict humans. In the absence of true knowledge there is resort to superstitious beliefs and explanations. Despite much progress in scientific medicine, the majority of humans still suffer from the consequences of superstitious beliefs.


Pathology: Pathology is concerned with abnormalities of structure and function which result from disease or are produced by disease (Bowman p. 4.3). It seeks to explain the why of a disease which includes: etiology, pathogenesis, morphological changes, and the functional impairment. Most of pathology is about the reactions of the body and its adjustment to insults.


Manifestations of disease: Disease manifests as symptoms or signs. Symptoms are subjective patient complaints or description of disease. Signs are objectively verifiable disorders. A syndrome is a combination of symptoms and signs associated with a disease condition. Symptomatology is perhaps a better indication of disease severity because it includes the personality of the patient and reactions. Thus the same pathology does not produce the same symptomatology in all patients. Those with strong iman may complain less about pain than others. Fear of death also affects worry and complaint about disease.


Diagnosis: Diagnosis are measures including history, physical examination, and logical deduction or induction that lead to definition of a disease. There is a role for istikharat in the diagnostic process. Allah can guide a believing and diligent physician to the correct conclusion from available more often than the non-believing one. A definitive diagnosis need not be made before treatment starts. Treatment is started using a tentative diagnosis. The true diagnosis may be deduced from the response to treatment. One of the strengths of empirical science is that a disease can be treated successfully without fully understanding its pathogenesis or even how the treatment works at the molecular level. This occurs for example in cases when a new unknown chemical compound is tried on animals and then on humans with good results. It is then adopted as a treatment. The mechanism of action is established only later or may never be established definitely. However this strength has a back-side to it. Using treatments whose mechanisms of action are not well understood can lead to side effects and adverse effects later.


Prognosis: Prognosis is an empirical estimate of the future course of the disease. From the Islamic view-point, prognosis is part of the knowledge of the unseen (‘ilm al ghaib). The physician does not have the privilege to say anything definitive about the future prognosis. He or she can only extrapolate based on available data and must always have the humility to say ‘Allah Knows Best’ (Allah  a’lam).


Relation between diseases of the heart (amradh al qalb) and diseases of the body (amradh al badan): There is a 2-way interaction between physical and spiritual maladies. Disbelief (kufr) leads to a lot of human cruelty like psychological or physical torture because of lack of moral restraint. Diseases of the heart such as jealousy lead to violence and even death. Lack of spiritual equilibrium leads to inability to handle the normal stresses of life such that the victims become addicted to alcohol and psycho-active substances with consequent physical illness. Addiction to power and sex leads to violence. Physical diseases may cause so much depression and loss of hope that they develop into diseases of the heart.



Duration: Diseases may be classified by their duration as acute or chronic. Acute disease is a temporary disturbance of homeostasis. Chronic disease may establish a new level of homeostasis.


Moral Criteria: Diseases may also be classified by cause as diseases of the heart (amradh al qalb) and diseases of the body (amradh al badan). These two categories have been mentioned by the Qur’an. Diseases of the heart include: doubt(shakk), passion (shahwat), and …. (ghil) (2:10, 5:52, 8:49, 9:125, 22:53, 24:50, 33:12, 33:32, 33:60, 47:20, 47:29, 74:31, 2:16). Diseases of the body mentioned in the Qur’an include:  blindness (ama) (p 851 2:2:17-18 … 80:2, 3:49 … 12:96), akma (congenital blindness 4:49), deafness(sum) (2:18, 2:171, 6:39, 8:22, 10:42, 21:45, 27:80, 30:52, 43:40), lameness (araj) (p 807 24:11 … 48:17), leprosy (baras) (p 189 3:49, 5:110),  dumbness (bukm) (p 204 2:18 …17:97). 


Physical cause: Disease can also be classified by physical cause: infectious (viral, bacterial, fungal, protozoal), neoplastic, allergic, genetic, congenital, nutritional, environmental, mental, degenerative, metabolic, circulatory, or hormonal. The Prophet (PBUH) talked about the contagiousness of leprosy (Ibn al Qayim p. 154). The inflammatory process is a reaction to the original disease pathology in both its acute and chronic forms and is essentially a defensive measure. It is sometimes also harmful to the body on its own. Most disease processes are actually attempts by the body to repair damage.


Site: Disease can also be classified as local or systemic. Fever is a systemic condition whereas a local wound is a local condition. However local conditions become systemic with time and systemic conditions may have particular effects on some local tissues. The Prophet (PBUH) described the human body as one physiological entity such that if any part is afflicted the whole body suffers. Thus the local-systemic dichotomy is not important.


Mental cause: Disease can be classified as physical or mental. This classification is not valid all the time because in many instances mental conditions have a physical basis. Mental disorders are either neuroses (anxiety, phobia, hysteria, obsessive-compulsive disorders, or depression) or psychoses. Psychoses are more serious than neuroses. Psychoses normally require drug treatment whereas the preferred management for neuroses is psychotherapy. Psychoses can be organic or functional. Some types of epilepsy have an organic basis. The functional psychoses are either affective disorders or schizophrenia. Examples of affective disorders are: (manic-depressive disorders, endogenous depression, reactive depression. Schizophrenia involves disorders of thought, emotions, will, body movements, delusions, and hallucinations. The Qur’an uses the term madness (junuun) to refer to the major disorders like psychoses. Neuroses are described as sadness (huzn), worry and anxiety (hamm and ghamm). The Qur’an also explains how the label of madness is used to refer to righteous people like prophets who are abused because they differ from the general public that is bent on evil.



Reaction and adjustment: a patho-physiological disturbance is normally a response to a biological, physical, or chemical insult or injury to the body. Thus most disease manifestations including their symptoms and signs are a reaction to injury and an attempt to re-adjust. From this point of view the disease process is a benefit and not a harm. Most disease processes operate at the cellular level. The causes of cell injury are: hypoxia, physical agents, chemical agents, infectious agents, immunological anomalies, genetic, and nutritional disorders. Cells respond to injury in two ways: (a) adaptation: atrophy, hypertrophy, and  hyperplasia. (b) Acute injury which could terminate in death or could be reversed. 


Attitude to Disease: In an Islamic context, disease does not always connote a negative or bad event. There are indeed many situations when what is a disease situation is actually beneficial. Falling ill may be Allah’s way of forcing the person to take a desired rest or care for the body before it can deteriorate further. Death from some diseases was said by the Prophet to be martyrdom (shahadat). Patience in the face of severe illness is a reason for entering paradise (jannat). The pain due to disease is a reminder of the punishment and suffering that the evil-doers will suffer from. Disease can be an opportunity for personal redemption by expiation/atonement for previous sins. The trials that one goes through and the eventual patience can be rewarded by Allah’s forgiveness. Disease may enable a person return to the due equilibrium in life. Falling sick may at times be Allah’s blessing in disguise that a person is incapacitated and thus is prevented from pursuits that could prove more dangerous for him. While a person is sick and is not busy with the routines of life he may have time to reflect and remember Allah.


Punishment: Some diseases are due to disobedience. Acts of disobedience may be followed by epidemic disease or by disease in an individual. The disease may be directly related to the sin such as liver cirrhosis due to chronic alcohol consumption or there may be no direct relationship.


Disease as an excuse from obligations: Allah in recognition of the burden of disease and the need to give the body a chance to recuperate excused the sick from some physical religious obligations (2:10, 48:17, 2:184, 2:185, 2:196, 4:43, 4:102, 5:6, 9:9, 73:20).



Sufficient Cause of Disease: When all the factors that produce a certain pathological condition are existing, we say that there is a sufficient cause of disease. However humans can never know for sure that there is a sufficient cause because Allah’s divine will (qadar) is involved. There are many cases when all the humanly-known factors of a disease exist but the disease does not occur. This is because of the unknown factor attributable to Allah alone.


Necessary cause: There are empirical factors that must operate for a certain pathological condition to occur. These are referred to as necessary causes. For example the tubercle bacillus is a necessary cause for the disease of tuberculosis. Humans must know the necessary causes of diseases. Denying their existence is denying the cardinal principle of sunan Allah fi al kawn and is akin to superstitious belief.


Multi-factorial Causation of Disease: Human diseases, like the human organism, are complicated and usually several factors are involved in their causation. Humans may know some of the factors and ignore others. It is not necessary to know all the factors in order to treat a disease. Since the factors usually act in sequence, knowledge of only one may be sufficient to interrupt the causal pathway.


Endogenous and exogenous causes of disease: Endogenous diseases are caused by factors from within the human body or the internal environment. Exogenous diseases are caused by factors in the external environment.


Intrinsic and extrinsic diseases: Intrinsic diseases are genetic or in-born. Extrinsic diseases are those acquired after birth. Some diseases are in infancy and may be an extension of intra-uterine problems or are acquired early in life. These include: intra-uterine growth retardation, prematurity, congenital birth injuries, and inborn errors of metabolism.


Environmental causes of disease: heat, cold, radiation, water, smoke, and high altitude can lead to patho-physiological disturbances and disease. Extreme heat can cause heat-stroke and dehydration. Water kills drowning people. Humans on the average inhale many liters of air a day that bring in smoke and other air-pollutants. Inhalation of smoke and other atmospheric pollutants causes respiratory diseases including lung cancer. The low levels of oxygen at high altitudes can cause hypoxia. Extreme cold causes frotbite or death from endothermia. Irradiation causes neoplasia and chromosomal damage. Humans on their own free will ingest chemicals as drugs that have many adverse reactions. Natural and man-made toxins are ingested with food. The Qur’an anticipated space travel (    ). Prolonged life under zero gravity may have long-term effects on the human organism that are not yet known. 


Genetic: Genetic diseases could be a single gene disorder or they may be multi-factorial involving more than one gene even other non-genetic environmental factors. Single-gene disorders could be autosomal or X-linked. As part of the parity principle of human creation, each gene is in pairs one from each parent with the possibility of a dominant or recessive combination. Mutations and chromosomal damage can alter the body’s growth metabolic processes resulting in disease. These operate through disturbances of protein and enzyme synthesis or function. Molecular diagnosis and gene therapy are growing fields and will give rise to a different understanding of pathology. Islamically speaking we can not say that there was a genetic or chromosomal mistake. It is all part of Allah’s grand design.


Immunological: Disease arises from disorders of cells of the immune system: T and B cells, macrophages, dendritic cells, Langhan’s cells, and natural killer cells. Disease could arise in all three conditions of immunological disturbance: a hypo-active immune system cannot protect the body against invading organisms, a hyperactive immune system may destroy parts of the body such as occurs in auto-immune diseases,  and some immune reactions are abnormal or paradoxical causing tissue damage.


Malnutrition: Under-nutrition causes disease by depriving the body of essential nutrients. Protein energy malnutrition of children in poor countries is due to lack of protein and calories. Vitamin and mineral deficiencies disturb normal metabolism. Over-nutrition results in obesity, diseases such as heart disease and various types of cancer. Excessive intake of necessary nutrients like vitamins causes various hyper-vitaminosis syndromes.


Infection (al ad’wah): Infection of the human body by other organisms is part of Allah’s plan especially in fulfilling the food chain. It is part of the balance of the eco-system. This does not however mean that such diseases should be left alone. There has been some confusion about hadiths of the Prophet (PBUH) dealing with infection and contagiousness of disease. There is actually no contradiction between hadiths that indicate that disease is contagious and those that indicate the opposite. The Prophet was speaking about different diseases on different occasions. Even with one disease like leprosy there are contagious and non-contagious forms (Ibn al Qayim p. 154).


Neoplasms: loss of control over cell multiplication results in cancer. This is violation of a basic law in biology that equilibrium and homeostasis will be maintained. The molecular basis of cancer has been elucidated in detail recently. Oncogenes are thought to be the basis for neoplastic growth. Carcinogens as initiators or promoters interact with the oncogenes to lead to neoplastic proliferation. Age and heredity play a role in cancer etiology. Malignant neoplasm differs from the benign one in being less differentiated, being anaplastic, high growth rate, invasion of local tissues, and distant metastases. Normally the immune system is able to detect the neoplastic cells and eliminate them. In situation of relative immune deficiency it is not possible to eliminate the neoplastic cells.


Degeneration: in old age phenomena of growth and decay are more that repair and growth and degenerative diseases could result. These are strictly speaking part of Allah’s design and not an anomaly.



Occurrence of disease as qadar: It is Allah’s pre-destination that a person falls sick. Treatment/prevention of disease not against qadar. Medical treatment is subsumed under the principle that qadar can reverse another qadar (radd al qadar bi al qadar). In the end all cure is from Allah and not the human (26:80).



1. Illness is expiarion of sin: ‘ No fatigue, nor disease, nor sorrow, nor sadness, nor hurt, nor distress befalls a Muslim, even if it were a prick he receives from a thorn, but Allah expiates some of his sins for that’ MB hadith # 1949. ‘The example of a believer is that of a fresh tender plant; from whatever direction the wind comes, it bends it, but when the wind becomes quiet, it becomes straight again. Similarly a believer is afflicted with calamities (but he remains patient till Allah removes his difficulties. The fajir is like a pine tree which keeps hard and straight till Allah cuts it down when He wishes’ MB# 1950. ‘If Allah wants to do good to somebody He afflicts him with trials’ MB#1951


Blessings of fever: Muslim reported on the authority of Jabir that a man abused fever in the presence of the Prophet (PBUH). The Prophet responded: ‘Do not abuse it. It wipes away sins as fire wipes away the khubth of iron’.


2. Blessings of plague: Bukhari and Muslim reported on the authority of Anas Bin Malik that the Prophet (PBUH) said: ‘plague is martyrdom for any Muslim’.


3. Heat of fever: Bukhari and Muslim reported on the authority of Nafi bin Ibn Omar that the Prophet (PBUH) said: Fever is an air-current (faih) from hell cool it down with water (ibn al Qayyim).


4. Fever is systemic: Abu Hurairah said: The best-loved among diseases that afflict me is fever because it enters every organ of mine and Allah the almighty gives each organ its due share of reward (Ibn al Qayim)


5. Suicide: ‘… Whoever commits suicide with a piece of iron will be punished with the same piece of iron in the hell-fire’ MB hadith # 683


6. Infectious disease: ‘ There is no contagiousness (adwa) ……..and one should run away from the leper as one runs away from a lion’ MB hadith # 1969 Loss of sight: ‘Allah said: If I deprive my servant of his two beloved eyes and he remains patient, I will let him enter paradise in compensation for them’ MB hadith # 1955

Professor Omar Hasan Kasule January 1998