LEPROSY [SYMPTOMS AND SINGS / PATHOGENESIS / RISK FACTOR / COMPLICATIONS ] 


             Leprosy currently affects approximately a quarter of a million people throughout the world, with the majority of these cases being reported from India. India is currently running one of the largest leprosy eradication programs in the world. Despite this, 120,000 to 130,000 new cases of leprosy are reported every year in India. This is 58.8% of the global total of new cases. Leprosy colonies exist throughout India. These are typically made up of patients that have moved to the colony often from a significant distance away, along with their children and grandchildren. Leprosy is a curable disease.

        Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by Mycobacteria leprae. The disease mainly affects the skin, the peripheral nerves, mucosal surfaces of the upper respiratory tract and the eyes. Leprosy is known to occur at all ages ranging from early infancy to very old age. Leprosy is curable and early treatment averts most disabilities.


Transmission

         The exact mechanism of transmission of leprosy is not known. At least until recently, the most widely held belief was that the disease was transmitted by contact between cases of leprosy and healthy persons. More recently the possibility of transmission by the respiratory route is gaining ground.




Symptoms and signs

         The skin lesion is a characteristic feature of leprosy. The skin lesion can be single or multiple, usually less pigmented then the surrounding normal skin. Sometimes the lesion is reddish or copper-coloured. A variety of skin lesions may be seen but macules (flat), papules (raised), or nodules are common. Sensory loss is a typical feature of leprosy. The skin lesion may show loss of sensation to pin pick and or light touch. Thickened nerves, mainly peripheral nerve trunks, constitute another feature of leprosy. A thickened nerve is often accompanied by other signs as a result of damage to the nerve. These may be loss of sensation in the skin and weakness of muscles supplied by the affected nerve.




Pathogenesis

        Leprosy bacilli multiply in macrophages in the skin and Schwann cells of the nerves, Two forms of leprosy are known;

        One form is "tuberculoid type which is a mild form. M. leprae multiplies at the site of entry, usually the skin, invading and colonizing Schwann cells. The microbe then induces T-helper lymphocytes, epithelioid cells, and giant cell infiltration of the skin, causing infected individuals to exhibit large flattened patches with raised and elevated red edges on their skin. These patches have dry, pale, hairless centers, accompanied by a loss of sensation on the skin. The loss of sensation may develop as a result of invasion of the peripheral sensory nerves.

      The second from of leprosy, the "lepromatous type", causes serious disfigurement is more virulent. In this form, the microbes proliferate within the macrophages as well as within the epithelial tissues of the face and ear lobes. Extensive penetration of this microbe may lead to severe body damage; for example, the loss of bones, fingers, and toes, nose.


Risk factor

       prolonged contact with a patient of leprosy.  



Complications

  👉The most severe complications result from the peripheral neuropathy, Which causes deterioration of the sense of touch and a corresponding inability to feel pain and temperature.

  👉Patients may unknowingly burn, cut, or otherwise harm themselves. Repeated damage may lead to loss of digits.

  👉Muscle weakness can result in deformities (e.g. clawing of the 4th and 5th fingers caused by ulnar nerve involvement, foot drop caused by peroneal nerve involvement).

  👉Papules and nodules can be particularly disfiguring on the face.

  👉Feet; Plantar ulcers with secondary infection are a major cause of morbidity, making walking painful.

  👉Nose; Damage to the nasal mucosa can result in chronic nasal congestion and nosebleeds and, if untreated, erosion and collapse of the nasal septum.

  👉Eyes; Iritis may lead to glaucoma, and corneal insensitivity may lead to scarring and blindness.

  👉Sexual function; Men with lepromatous leprosy may have erectile dysfunction and infertility. The infection can reduce testosterone and sperm production by the tests.

  👉Kidneys; Amyloidosis and consequent renal failure occasionally occur in lepromatous leprosy.