Leprosy

Other name :  Hansen’s disease

Description:
Leprosy is a chronic infection caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Initially, infections are without symptoms and typically remain this way for 5 to as long as 20 years. Symptoms that develop include granulomas of the nerves, respiratory tract, skin, and eyes. This may result in a lack of ability to feel pain and thus loss of parts of extremities due to repeated injuries. Weakness and poor eyesight may also be present.

Leprosy is spread between people. This is believed to occur through a cough or contact with fluid from the nose of an infected person. Leprosy occurs more commonly among those living in poverty and is believed to be transmitted by respiratory droplets. It is not very contagious. The two main types of disease are based on the number of bacteria present: paucibacillary and multibacillary. The two types are differentiated by the number of poorly pigmented, numb skin patches present, with paucibacillary having five or fewer and multibacillary having more than five. The diagnosis is confirmed by finding acid-fast bacilli in a biopsy of the skin or via detecting the DNA by polymerase chain reaction.

Leprosy is curable with treatment.  Treatment for paucibacillary leprosy is with the medications dapsone and rifampicin for 6 months.Treatment for multibacillary leprosy consists of rifampicin, dapsone, and clofazimine for 12 months.  These treatments are provided for free by the World Health Organization.  A number of other antibiotics may also be used.  Globally in 2012, the number of chronic cases of leprosy was 189,000 and the number of new cases was 230,000.  The number of chronic cases has decreased from some 5.2 million in the 1980s.  Most new cases occur in 16 countries, with India accounting for more than half.  In the past 20 years, 16 million people worldwide have been cured of leprosy.  About 200 cases are reported per year in the United States.

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Leprosy has affected humanity for thousands of years.  The disease takes its name from the Latin word lepra, which means “scaly”, while the term “Hansen’s disease” is named after the physician Gerhard Armauer Hansen.  Separating people by placing them in leper colonies still occurs in places such as India,  China,   and Africa.   However, most colonies have closed since leprosy is not very contagious.   Leprosy has been associated with social stigma for much of history, which is a barrier to self-reporting and early treatment.  The word “leper” is considered insulting with the term leprosy being preferred.   World Leprosy Day was started in 1954 to draw awareness to those affected by leprosy.

Forms of Leprosy:
Leprosy may also be divided into the following forms:

*Early and indeterminate leprosy
*Tuberculoid leprosy
*Borderline tuberculoid leprosy
*Borderline leprosy
*Borderline lepromatous leprosy
*Lepromatous leprosy
*Histoid leprosy
*Diffuse leprosy of Lucio and Latapí
This disease may also occur with only neural involvement, without skin lesions

Symptoms:
Leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions (light or dark patches) are the primary external sign. It first affects the skin and the nerves outside the brain and spinal cord, called the peripheral nerves. It may also strike the eyes and the thin tissue lining the inside of the nose.

The main symptom of leprosy is disfiguring skin sores, lumps, or bumps that do not go away after several weeks or months. The skin sores are pale-colored.

Nerve damage can lead to:
*Loss of feeling in the arms and legs
*Muscle weakness

It usually takes about 3 to 5 years for symptoms to appear after coming into contact with the leprosy-causing bacteria. Some people do not develop symptoms until 20 years later. The time between contact with the bacteria and the appearance of symptoms is called the incubation period. Leprosy’s long incubation period makes it very difficult for doctors to determine when and where a person with leprosy got infected.

If untreated, leprosy can progress and cause permanent damage to the skin, nerves, limbs, and eyes. Contrary to folklore, leprosy does not cause body parts to fall off, although they can become numb or diseased as a result of secondary infections; these occur as a result of the body’s defenses being compromised by the primary disease.  Secondary infections, in turn, can result in tissue loss.
How the infection produces the symptoms of the disease is not known.

Causes:
Leprosy is caused by a slow-growing type of bacteria called Mycobacterium leprae (M. leprae). Leprosy is also known as Hansen’s disease, after the scientist who discovered M. leprae in 1873.
M. leprae and M. lepromatosis are the causative agents of leprosy. M. lepromatosis is a relatively newly identified mycobacterium isolated from a fatal case of diffuse lepromatous leprosy in 2008.

An intracellular, acid-fast bacterium, M. leprae is aerobic and rod-shaped, and is surrounded by the waxy cell membrane coating characteristic of the Mycobacterium genus.

Due to extensive loss of genes necessary for independent growth, M. leprae and M. lepromatosis are obligate intracellular pathogens, and unculturable in the laboratory, a factor that leads to difficulty in definitively identifying the organism under a strict interpretation of Koch’s postulates. The use of nonculture-based techniques such as molecular genetics has allowed for alternative establishment of causation.

While the causative organisms have to date been impossible to culture in vitro, it has been possible to grow them in animals such as mice and armadillos.

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Naturally occurring infection also has been reported in nonhuman primates, including the African chimpanzee, sooty mangabey, and cynomolgus macaque, as well as in armadillos and red squirrels.

Risk factors:
At highest risk are those living in areas with polluted water and poor diet or people suffering from diseases that compromise immune function. There appears to be little interaction between HIV and the risk of leprosy. Genetic predisposition appears to play a role in susceptibility.

Transmission:
Transmission of leprosy occurs during close contact with those who are infected.  Transmission is believed to be by nasal droplets.

Leprosy is not known to be either sexually transmitted or highly infectious. People are no longer infectious after as little as two weeks of treatment.

Leprosy may also be transmitted to humans by armadillos  and may be present in three species of non-human primates.

Two exit routes of M. leprae from the human body often described are the skin and the nasal mucosa, although their relative importance is not  very clear. Lepromatous cases show large numbers of organisms deep in the dermis, but whether they reach the skin surface in sufficient numbers is doubtful.

The skin and the upper respiratory tract are most likely entry route. While older research dealt with the skin route, recent research has increasingly favored the respiratory route. Experimental transmission of leprosy through aerosols containing M. leprae in immune-suppressed mice was accomplished, suggesting a similar possibility in humans

Diagnosis:
Endemic areas:
Per the World Health Organization, diagnosis in an endemic area is based on one of these cardinal signs:

*Skin lesion consistent with leprosy and with definite sensory loss
*Positive skin smears
*Skin lesions can be single or multiple, usually hypopigmented, although occasionally reddish or copper-colored. The lesions may be macules (flat), papules (raised), or nodular. Sensory loss at the skin lesion is important because this feature can help differentiate from other causes of skin lesions such as tinea versicolor.

*Thickened nerves are associated with leprosy and can be accompanied by loss of sensation or muscle weakness. However, without the characteristic skin lesion and sensory loss, muscle weakness is not considered a reliable sign of leprosy.

*Positive skin smears: In some case, acid-fast leprosy bacilli are considered diagnostic; however, the diagnosis is clinical.

Treatment:
A number of leprostatic agents are available for treatment. For paucibacillary (PB or tuberculoid) cases, treatment with daily dapsone and monthly rifampicin for six months is recommended. While for multibacillary (MB or lepromatous) cases, treatment with daily dapsone and clofazimine along with monthly rifampicin for twelve months is recommended.

Multidrug therapy (MDT) remains highly effective, and people are no longer infectious after the first monthly dose.  It is safe and easy to use under field conditions due to its presentation in calendar blister packs.  Relapse rates remain low, and no resistance to the combined drugs is seen.

Prevention:
Early detection of the disease is important, since physical and neurological damage maybe irreversible even if cured. Medications can decrease the risk of those living with people with leprosy from acquiring the disease and likely those with whom people with leprosy come into contact outside the home. However, concerns are known of resistance, cost, and disclosure of a person’s infection status when doing follow-up of contacts. Therefore, the WHO recommends that people who live in the same household be examined for leprosy and only be treated if symptoms are present.

The Bacillus Calmette–Guérin (BCG) vaccine offers a variable amount of protection against leprosy in addition to tuberculosis. It appears to be 26 to 41% effective (based on controlled trials) and about 60% effective based on observational studies with two doses possibly working better than one.  Development of a more effective vaccine is ongoing as of 2011

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Leprosy
http://www.webmd.com/skin-problems-and-treatments/guide/leprosy-symptoms-treatments-history#1

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