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What is Leprosy?
Leprosy, also called Hansen’s disease, is a chronic infectious disease that primarily affects the skin, the peripheral nerves, the mucosa of the upper respiratory tract, and the eyes. Leprosy can lead to progressive permanent damage of these structures, and the resulting devastating disfigurement and disability has led to the historical social stigma and isolation (leper colonies) of those affected by the disease.
Historically speaking, leprosy has existed since at least 4000 BC, and the disease was present and described in the ancient civilizations of China, India, and Egypt. The first known written reference to the disease on Egyptian papyrus dates from about 1550 BC. It is believed that leprosy was brought to Europe by the Romans and the Crusaders and that later the Europeans brought it to the Americas. For centuries, leprosy remained a poorly understood disease characterized by human suffering and social isolation.
read more: Sign of Leprosy
Causes of Leprosy
Leprosy is a contagious, chronic disease caused by Mycobacterium leprae, a rod-shaped bacterium. The disease is also called Hansen’s disease, after a Norwegian doctor, Armauer Hansen. Hansen was the first to discover the bacterium that causes leprosy and published a paper on it in 1873, according to an article in the Indian Journal of Dermatology.
Leprosy affects not just the skin, but also the peripheral nerves, mucosa of the upper respiratory tract and the eyes. If left untreated, the disease can be debilitating and cause muscle weakness, disfigurement, permanent nerve damage in the arms and legs and loss of sensation in the body.
Symptoms of Leprosy
The main symptoms of leprosy include:
- muscle weakness
- numbness in the hands, arms, feet, and legs
- skin lesions
The skin lesions have decreased sensation to touch, temperature, or pain. They don’t heal after several weeks and are lighter than your normal skin tone.
read more: Elephantiasis: Human Diseases and Conditions
What is Psoriasis?
Psoriasis is a noncontagious, chronic skin condition that produces plaques of thickened, scaling skin. The dry flakes of skin scales result from the excessively rapid proliferation of skin cells. The proliferation of skin cells is triggered by inflammatory chemicals produced by specialized white blood cells called lymphocytes. Psoriasis commonly affects the skin of the elbows, knees, and scalp.
The spectrum of disease ranges from mild with limited involvement of small areas of skin to large, thick plaques to red inflamed skin affecting the entire body surface.
Psoriasis is considered an incurable, long-term (chronic) inflammatory skin condition. It has a variable course, periodically improving and worsening. It is not unusual for psoriasis to spontaneously clear for years and stay in remission. Many people note a worsening of their symptoms in the colder winter months.
Causes of Psoriasis
Psoriasis turns your skin cells into Type A overachievers: They grow about five times faster than normal skin cells. And your body can’t keep up. The old ones pile up instead of sloughing off, making thick, flaky, itchy patches.
Why do these cells go a little haywire? There’s more going on under the surface of this skin disease.
Researchers think something sets off your immune system. The exact reason is a mystery. But it’s likely a combination of genetics and triggers.
Your Genes and Your Immune System
Little bits of your DNA, called genes, are instructions for your cells. They control things like your eye and hair color, if you can taste certain things, and other ways your body works. Some genes are only active at certain times.
When you have psoriasis, the genes that control your immune system signals get mixed up. Instead of protecting your body from invaders as it’s designed to do, it promotes inflammation and turns skin cells on overdrive.
Scientists have found about 25 genes that are different in people with psoriasis. They think it takes more than one to cause the disease, and they’re looking for the main ones.
Symptoms of Psoriasis
Psoriasis signs and symptoms can vary from person to person but may include one or more of the following:
- Red patches of skin covered with silvery scales
- Small scaling spots (commonly seen in children)
- Dry, cracked skin that may bleed
- Itching, burning or soreness
- Thickened, pitted or ridged nails
- Swollen and stiff joints
Psoriasis patches can range from a few spots of dandruff-like scaling to major eruptions that cover large areas.
Most types of psoriasis go through cycles, flaring for a few weeks or months, then subsiding for a time or even going into complete remission.
Several types of psoriasis exist. These include:
- Plaque psoriasis. The most common form, plaque psoriasis causes dry, raised, red skin lesions (plaques) covered with silvery scales. The plaques itch or may be painful and can occur anywhere on your body, including your genitals and the soft tissue inside your mouth. You may have just a few plaques or many.
- Nail psoriasis. Psoriasis can affect fingernails and toenails, causing pitting, abnormal nail growth and discoloration. Psoriatic nails may become loose and separate from the nail bed (onycholysis). Severe cases may cause the nail to crumble.
- Scalp psoriasis. Psoriasis on the scalp appears as red, itchy areas with silvery-white scales. The red or scaly areas often extend beyond the hairline. You may notice flakes of dead skin in your hair or on your shoulders, especially after scratching your scalp.
- Guttate psoriasis. This primarily affects young adults and children. It’s usually triggered by a bacterial infection such as strep throat. It’s marked by small, water-drop-shaped sores on your trunk, arms, legs and scalp. The sores are covered by a fine scale and aren’t as thick as typical plaques are. You may have a single outbreak that goes away on its own, or you may have repeated episodes.
- Inverse psoriasis. Mainly affecting the skin in the armpits, in the groin, under the breasts and around the genitals, inverse psoriasis causes smooth patches of red, inflamed skin. It’s worsened by friction and sweating. Fungal infections may trigger this type of psoriasis.
- Pustular psoriasis. This uncommon form of psoriasis can occur in widespread patches (generalized pustular psoriasis) or in smaller areas on your hands, feet or fingertips. It generally develops quickly, with pus-filled blisters appearing just hours after your skin becomes red and tender. The blisters may come and go frequently. Generalized pustular psoriasis can also cause fever, chills, severe itching and diarrhea.
- Erythrodermic psoriasis. The least common type of psoriasis, erythrodermic psoriasis can cover your entire body with a red, peeling rash that can itch or burn intensely.
- Psoriatic arthritis. In addition to inflamed, scaly skin, psoriatic arthritis causes pitted, discolored nails and the swollen, painful joints that are typical of arthritis. Symptoms range from mild to severe, and psoriatic arthritis can affect any joint. Although the disease usually isn’t as crippling as other forms of arthritis, it can cause stiffness and progressive joint damage that in the most serious cases may lead to permanent deformity.
read more: Psoriasis in Children: Causes And Triggering
Difference Between Leprosy and Psoriasis
Leprosy is caused by Mycobacterium leprae, a slow-growing bacterium that cannot live outside its host. It’s difficult to study because it can only be grown in animals and the symptoms take years to develop.
Psoriasis, on the other hand, is an autoimmune disorder. It causes skin cells to grow rapidly, leading to skin lesions and plaques. Psoriasis isn’t contagious. A combination of genetics and environmental triggers is thought to cause psoriasis.