Disease

Leprosy (Hansen's disease, Hanseniasis) is a chronic mycobacterial disease caused by Mycobacterium leprae primarily affecting the peripheral nervous system and secondarily involving skin and certain other tissues.

	Leprosy is a chronic infectious disease caused by Mycobacterium leprae affecting mainly peripheral nerves & skin, known for its potential to cause permanent and progressive physical disability.
	Leprosy has predominant psycho-social aspects / Social Stigma due to misconceptions/misbeliefs /Taboos /Ignorance.
	Man is the only host reservoir.
	Incubation period ranges from 6 months to 30 years with average of 2 to 5 years.
	It is transmitted from untreated MB patient to healthy person via respiratory tract.
	The major sites from which bacilli escape from the body of an infectious patient are nose and mouth.
	Wide spectrum of host resistance, ranging from effective immunity to absence of resistance leads to varied presentation of the disease manifestations.
	Extremely slow generation time of the organisms results in:  a) Long incubation period,  b) A very slow development of pathology, c) A slow and insidious clinical evolution,  d) An unclear epidemiological pattern,  e) Low infectivity.
	There is no potent anti leprosy vaccine

INTRODUCTION

Leprosy, once considered to be a dreadful disease especially because of the disfigurement & deformities associated with it, has lost its dreadful nature, thanks to the wonders of Multi Drug Therapy (MDT). The number of leprosy cases that was in millions has now come down to few thousands and the day is not far away when leprosy, like smallpox would be a disease of history. But this is possible only when people discard the apprehension and come forward to report the disease on their own and start the treatment early, as early diagnosis and prompt MDT is the key to leprosy elimination.

The target of elimination has been fixed at 1 or less than 1 case per 10,000 population as the scientific studies indicate that leprosy as a disease gets naturally eliminated at such a low prevalence. 

It is therefore necessary that concepts of isolation and discrimination associated with leprosy are removed from the social milleau and leprosy is regarded as an ordinary disease like any other diseases afflicting mankind.

History

From the old records, it is evident that LEPROSY is a very ancient disease dating back many centuries. In India, leprosy was referred to as "KUSHTHA" in the ancient vedic literature as far back as 1400 B.C. The laws of Manu mention the instructions for the prevention of leprosy. A good description of this disease and its treatment is given in "SUSHRUTA SAMHITA" a book on surgery written in 600 B.C. by the eminent Indian surgeon SUSHRUTA. He regarded this disease as a contagious disease carried from a person suffering from this disease to a healthy person. There is strong evidence to show that leprosy was common as far back as 1400 B.C.

The word Leprosy is a translation of the Hebrew word "ZARAATH" and is mentioned in the Bible. The term included not only leprosy but also a number of other skin diseases. In ' LEVITICUS' clear instructions are given to the priests about the preventive measures against the spread of disease from persons suffering from leprosy. Some reference is made to Leprosy in Chinese literature dating back to 600 B.C. But there is no conclusive evidence to prove that it existed before. 

The earliest description of the disease in Europe was given by Aractus a contemporary of Galen. Galen also referred to Leprosy as Elephantiasis Graecorum. Galen lived about A.D. 150. Hippocrates who lived in 450 B.C. did not mention Leprosy. The returning Greek and Roman armies probably introduced the disease into Europe. Prof. Moller Christensen through his studies of cranial bones found evidence of Leprosy in Great Britanin, France, and Egypt during the period A.D. 500-700. The disease was at its height in Europe between 1000 A.D and 1400A.D. Anderson in his thesis (1969) reviewed all the literature available about the spread and decline of Leprosy in Europe. The literature reveals that the authors believed Leprosy to be highly contagious. This known fact was probably responsible for the inhuman measures taken to contain the disease during that period.

During the 18th and early 19th century, before Hansen discovered the leprosy bacillus, the hereditary theory of leprosy became very popular in Europe. It was strongly supported by the Norwegian scientists but in view of the new epidemiological evidence in favour of the contagiousness of the disease, the hereditary theory lost its ground. Few authentic outbreaks of leprosy in Nuaru, Cape Breton, Louisiana and other places confirmed the contagiousness of the disease.

The patients during that time were confined in Lazar houses. Leprosy declined form this period and was completely eradicated during the 19th century in Europe due to : 1.Isolation of the patients & 2.Improvement of the socio-economic conditions in the continent, better housing, improved economic conditions, good nutrition, better sanitation have reduced the other factors responsible for the transmission of the disease.

Literature on the origin and spread of Leprosy in Africa is inadequate but the prevalence of disease in states like Nigeria, Uganda, Zaire was very high.

Leprosy was introduced into the Americas by the soldiers of Columbus first & later through the slave trade from the endemic areas of West Africa. Immigrants from Europe & China also introduced the disease into the continent. 

The germ causing Leprosy is called Mycobacterium leprae and was discovered by G.H. Armauer Hansen (1841-1912) from Norway in 1873. Therefore, the organism is commonly known as Hansen's bacillus.