WARNING: confronting images
It is the world's oldest and most reviled disease with evidence it may have existed in India in 4000BC, more than 6000 years ago.
It has been referred to in ancient texts, such as the sacred Sanskrit work the Arthavaveda in 2000BC.
And a form of leprosy called "tzara'aat" in Hebrew is mentioned in the Old Testament's Book of Leviticus, written about 500BC.
Leprosy is a dreaded affliction which mutilates and causes horrible disfigurement and was believed to be highly contagious.
The name of those afflicted with the disease — lepers — is associated with social outcasts, the "unclean" and those who must be shunned from society and disowned by their ashamed relatives.
It carries such a stigma that it was known as the "living death," its victims given funeral services to declare them "dead" to society, and relatives allowed to claim their inheritance.
Leprosy is a disease with a long history of misery, as University of Cambridge social anthropologist Gilbert Lewis puts it.
In Medieval times, sufferers were banished to leper colonies, condemned to wander the roads wearing a sign or ringing bells to warn healthy people of their approach.
In the modern era leper colonies were set up on islands which became known as "islands of death" from which lepers often never returned.
Many people believe that leprosy is an ancient disease long eradicated from the face of the earth.
Nothing could be farther from the truth.
Every two minutes, one more person is diagnosed with leprosy, international leprosy awareness charity lepra.org.uk says.
"Millions more go undiagnosed each year and around four million are permanently disabled by the disease," the charity, which has Queen Elizabeth as its patron, says.
Each day, 600 new lepers, including 50 children, are diagnosed.
But "due to fear and lack of knowledge" more than three million people around the world live with undiagnosed leprosy.
Memories of the world's infamous leper colonies from the more recent past inspire revulsion and a desire to keep leprosy behind closed doors, locked away.
WHAT IS LEPROSY?
People think of leprosy as a disease of the tropics.
That is not true.
In the second half of the 19th century, Europe was hit by the breakout of a large-scale leprosy epidemic with its epicentre in Norway where 3000 cases were reported
In 1873, in his job at a leprosy hospital in Bergen in southern Norwegian, physician Dr Gerhard Armauer Hansen identified the disease.
Examining a patient's nasal biopsy specimen under the microscope, Hansen saw the rod-shaped bacillae of Mycobacterium leprae.
The bacteria, which closely resembles its relative Mycobacterium tuberculosis, has waxy cell walls which make them difficult to destroy.
The condition was renamed Hansen's disease which, apart from humans, only occurs naturally in chimpanzees and mangabey monkeys, and nine-banded armadillos which carry it in their lungs, liver and spleen.
Even so, much about leprosy remains mysterious, and despite its fearful history the infection is difficult to contract.
Most people, even under repeated exposure, will never develop the disease.
Leprosy can be a slow grower, taking anything from between nine months and 20 years to manifest.
It has two forms.
• Tubercloid, the more common representing 80 per cent of cases worldwide, results in firm, dry patches with pale, hairless centres that are insensitive to heat, cold, touch or pain.
Nerve damage occurs in muscles and bones, leading to claw hands and gross deformity of the feet.
Paralysis of muscles of the face, eye, and neck may also occur, and as a result of the anaesthetised patches of skin, patients can accidentally mutilate their own limbs.
Large eroding ulcers can form, causing loss of fingers and toes; sometimes the condition of the limb is so bad that amputation is necessary
• The less common lepromatus leprosy presents as skin lesions over the body, with facial skin thickening, and "rotting away" of bones, fingers, and toes.
It causes skin corrugation and a "lion face".
Soft nodules appear on the ears, nose, and cheeks and sometimes erode into discharging sores. The nose often is teeming with bacilli, and this sometimes leads to destruction of the septum of the nose and the palate.
HISTORY OF LEPROSY
Leprosy derives from the Ancient Greek word "lepra", meaning scaly.
A 4000-year-old skeleton found in India in 2009 bore erosion patterns similar to those found in skeletons of lepers in Europe dating to the Middle Ages.
An illness that fits the description of leprosy appears in the Sushruta-samhita, an Indian medical work from India dating back to about 600BC.
A 400BC Chinese medical text describes a similar ailment and Greek texts from 300BC describe a similar ailment.
The armies of Alexander the Great were said to contract the disease when they invaded India in the 4th century BC and carried it back to the Middle East and the Mediterranean.
The "leprosy" referred to in the Bible, the "tzara'aat" of Leviticus and "lepra" of the Greek New Testament, may represent a number of severe chronic skin diseases.
But according to Leviticus, anyone pronounced unclean due to tzara'aat should be put outside the Israelite camp, marked and exiled as a polluter.
That person must wear torn clothes, leave his hair unkempt, cover the lower part of his face, and cry out, "Unclean! Unclean!"
Rabbinic lore traced the cause of leprosy to various transgressions, ranging from murder to slander, and from arrogance to cohabiting with a menstruating woman.
Roman soldiers in the army of Pompey reportedly took leprosy from Egypt to Italy in the 1st century BC, and Roman legionnaires took it on to the British Isles.
In many traditional cultures, lepers were confined to a secluded place at the outskirts of the settlement as a way of preventing the spread of the disease.
In 1200AD an estimated 19,000 leprosy hospitals existed all over Europe.
Leper colonies, also known as leprosaria and Lazaret, were established to house sufferers.
Outside these hospices they were feared and ostracised.
The stigma endures in places like India, for example, where only in February did parliament pass a bill seeking to remove leprosy as a grounds for divorce.
In various Indian states, lepers are banned from contesting elections.
India declared in 2004 leprosy had been eliminated as a public health concern, but in 2017 135,485 new cases were detected.
INFAMOUS LEPER COLONIES
One of the most famous colonies was at Kalaupapa, on the island of Molokai, Hawaii, where Belgian priest Father Damien served leprosy patients forcibly relocated there by law.
Another famed leper's home was at Carville, on the Mississippi River near New Orleans in southern Louisiana.
One hundred years ago, US law required all citizens diagnosed with leprosy to be quarantined there,
Thousands of leprosy sufferers lived out their lives at this national leprosarium.
In its early years, Carville was more a prison than a hospital.
Horrified by the stigma of leprosy, families often just left their infected relatives there and never returned.
Culion Island in the Philippines with 500 lepers, one doctor, four nuns and one priest, was called the "Isle of Sorrow".
Lepers grew their own food, formed their own leper police and lived in squalor with a dearth of supplies or medicine.
Australia had several leper colonies, most notoriously Peel Island Lazaret which lay in Moreton Bay between Brisbane and Stradbroke Island.
Primitive and remote, its establishment allowed health authorities to arbitrarily remove without notice people even only vaguely suspect of having leprosy.
It was previously used as a quarantine station and an asylum for vagrants and inebriates, before operating as a leper colony between 1907 and 1959.
Queensland's Leprosy Act of 1892 legislated to isolate leprosy patients from the mainland.
Transported to Peel Island, mothers, fathers and children didn't see their families again for years, if ever.
Like Carville, Peel Island was prison-like, with dirt floors, bark huts and patients locked in or chained up.
Three compounds separated patients according to gender and ethnicity.
People of white European background were kept apart from those of Aboriginal, Torres Strait Island, South Sea Island or Chinese origin.
Escape was unlikely over the 2.5m fences or across the 5km of shark-infested water back to the mainland.
Other Australian leper colonies were on Channel Island off Darwin and Fantome island in the Palm Island group in northern Queensland.
Though feared throughout much of history, leprosy is not a highly contagious disease and is curable.
Transmission of the infection requires prolonged and close contact.
The bacteria appear to spread from the skin and nasal mucosa of those suffering from leprosy, but the exact portal of entry is not known.
By the 1940s, doctors were treating leprosy successfully with an antibiotic known as dapsone, but the microbacteria developed a resistance to this drug.
A multi-drug treatment was developed, combining dapsone with rifampicin, an antibiotic used to treat tuberculosis and Legionnaires' Disease, and clofazimine, said to work by interfering with DNA.
But there is no vaccine and killing the bacillus has no effect on body tissues that have already been damaged or destroyed.
The World Health Assembly, which governs the WHO, passed a resolution in 1991 to eliminate the disease by 2000.
It was unsuccessful, although prevalence of leprosy has decreased by 90 per cent since the early 1990s.
The disease has disappeared from most temperate countries, but still occurs in Brazil, in parts of Africa and southern Asia.
But more than seven million people are currently affected by leprosy throughout the world.
To donate money to help reduce the occurrence of leprosy, contact lepra.org.uk.