Acute – A disease or medical condition may be referred to as acute if the onset of symptoms is sudden. Symptoms are usually severe, but may not last very long.

Age-standardised rate – A measure of the rate (of disease) that a population would have, assuming a standard age structure. This standardisation is necessary when comparing populations of different ages as age is a potential factor in the incidence and progress of most diseases.

Allergen – A natural or synthetic, chemical or non-chemical substance that triggers an allergic response in the body.

Antibodies – Proteins produced by the immune system in the event of pathogenic invasion of the body, in order to fight off the pathogen and either prevent infection or help recovery. They may also be referred to as immunoglobulin (Ig).

Antihistamines – Drugs that are taken to alleviate the symptoms of an allergic reaction by blocking the effect of histamines (see definition below). Some antihistamines such as chlorphenamine, hydroxyzine and promethazine can make the user feel drowsy, while others such as cetirizine, loratadine and fexofenadine are non-drowsy.

Autoimmune – Autoimmune diseases are caused by the body’s own immune system which, faultily, attacks its own cells, often causing a considerable amount of pain and damage.

Biopsy – A medical procedure that involves obtaining a small sample of body tissue to examine for abnormalities.

Cancer – A state of disease caused by the uncontrolled growth of abnormal cells, leading to the formation of a tumour. Cancers are caused by malignant tumours which, in contrast to benign tumours, have the potential to spread to and invade other parts of the body.

Carrier – A carrier for a genetic disorder refers to a person who has inherited a mutated gene in the form of a recessive allele from a parent, but does not express any physical symptom. They can, however, pass the mutation on to the next generation, in which it may be expressed.

Chronic – A disease or medical condition may be referred to as chronic if it has developed over time. Symptoms, which may be severe, are usually persistent, often requiring long-term medication or care.

Communicable – This refers to a disease being contagious and hence possibly being transmitted from person to person. All communicable diseases are infectious.

Droplet transmission – When a person coughs, sneezes or talks, tiny respiratory droplets are expelled into the atmosphere, eventually settling on surrounding surfaces. In the case of infected individuals, these droplets may contain infectious microorganisms which may in turn be inhaled or ingested by other individuals, thereby potentially spreading the disease to them.

Drug dependence – An adaptive state of the body wherein repeated use of a substance leads to withdrawal symptoms being experienced upon cessation of use.

Elimination – Elimination of an infectious disease refers to the reduction of incidence to zero or to a defined target value in a defined geographical area. Control measures still need to be taken in order to prevent re-establishment of the disease within those areas.

Eradication – Eradication of an infectious disease refers to the complete reduction of the said disease to a zero-incidence rate globally. No further control measures are required against the disease.

Fomite – A non-living object or material (e.g. towels, linen, table tops) which, if contaminated, can temporarily harbour and transfer pathogenic bacteria, viruses, fungi to a new host by contact.

Gait – The pattern of limb movements that are made during a person’s locomotion (movement from one point to another), that either occur naturally or are a result of specialised training. In simple terms, this may be defined as a person’s manner of walking.

Gastrointestinal (GI) tract – This is the pathway that leads from the entry of food into the body to the eventual expulsion of solid waste. It involves the mouth, pharynx, oesophagus, stomach, small intestine, large intestine and anus. It may alternatively be referred to as ‘digestive tract’ or ‘alimentary canal’.

Hereditary – Hereditary diseases or disorders are those that are passed on genetically from parent to child. In some instances, symptoms may skip a generation and show up in the next.

Histamines – Organic chemical compounds released by the body during a local immune response, resulting in symptoms such as inflammation, itching, etc.

In vitro fertilisation (IVF) – This is a method of assisted reproductive technology (ART) where mature ova (eggs) are retrieved from a woman’s ovaries and fertilised with sperm in a laboratory, resulting in the formation of an embryo/s) These embryos may then be frozen for later use or implanted in the woman’s uterus for pregnancy.

Incidence rate – The frequency with which a disease occurs within a specific time period, defined as the number of new cases per people at risk for that disease within a population, within said time period.

Incubation period – The time elapsed between infection of a host by a pathogen and observation of first symptoms.

Infectious – A disease is referred to as infectious if it is caused due to infection by a microorganism (bacteria, viruses, fungi). Not all infectious diseases are communicable (e.g. tetanus is caused by a bacterium but is not contagious).

Insulin resistance – Insulin is a regulatory hormone produced by the pancreas in response to the presence of glucose in blood in order to regulate blood glucose levels. In insulin resistance, body cells (in muscles, liver, etc.) do not use up this insulin effectively, leading to a build-up of unused insulin in the blood and, possibly, causing diabetes over time.

Laparoscopy – Also known as keyhole surgery, this is a minimally invasive surgical diagnostic procedure where a small tube with a camera and light at the end of it is inserted through a small incision to observe the abdominal or pelvic cavity while the surgery is carried out through another small incision.

Malignant – Tumour cells are said to be malignant if they spread to other parts of the body, invading cells and potentially killing tissue. Malignant tumours lead to cancer.

Morbidity – The number of symptomatic cases of a given disease as a fraction or percentage of a population or cluster.

Mortality – The percentage or ratio of deaths in comparison to the number of infected/symptomatic cases.

Mucus – A thick, wet excretion produced by several glands in the body (nose, throat, stomach, intestines) to maintain a moist environment in the respective tract or cavity, and to help trap and destroy dust and microorganisms that may otherwise cause infection.

Mutation – A spontaneous change which occurs in the genetic sequence of an organism during duplication, usually giving rise to a change in some expressed characteristic. This can be due to erroneous copying of genetic material during duplication, or in response to exposure to an unfavourable external factor.

Neuron – Nerve cells which make up the nerve tissue of the nervous system. They are classified into three types – sensory neurons (which carry signals from the rest of the body to the central nervous system), motor neurons (which carry signals from the CNS to the rest of the body), inter-neurons (which transmit signals between neurons).

Non-communicable – This refers to a disease not being contagious and hence not being transmitted from person to person.

NSAIDS – Non-steroidal anti-inflammatory drugs are a class of drugs that helps to alleviate symptoms of fever, pain, inflammation and blood clotting.

Palliative care – Also referred to as ‘end of life care’, this involves the administration of care, pain management and support for patients with incurable diseases in their last months or years of life. The idea is to make the patient feel as comfortable as possible with a more holistic approach.

Pathogen – An organism that can cause disease in its host following infection. They are broadly classified into bacteria, viruses, fungi, protozoa and worms (infectious proteins called prions are also sometimes included as another category).

Post-nasal drip – The noticeable passage of excessive mucus from the back of the nose to the throat. Common triggers include sinusitis, allergic rhinitis, cold, flu, some foods (e.g. spicy), inhalants (e.g. perfume, smoke).

Tumour – An abnormal mass of tissue, arising from the abnormal and uncontrolled multiplication of (usually mutated) cells.

Type 2 diabetes – A condition that causes an increase in blood glucose levels due to an insufficient production of insulin or due to the body resisting the action of the insulin produced.

Virulence – The ability of a pathogen to infect, and usually cause damage to, a host.

-itis­ (suffix) – This implies the presence of an inflammation in whatever organ or tissue of the body its prefix refers to. For example, rhinitis is the inflammation of the nose, sinusitis is the inflammation of the sinus membranes.