Despite the disease having been known about for thousands of years -- many people will have first heard about it through references in the Bible -- very little is understood about its biology.
This is in part because the bacteria are difficult to grow in culture and there are no good animal models: M. Zebrafish are already used to study another species of mycobacteria, to help understand tuberculosis TB. Scientists have previously shown that the nerve damage in leprosy is caused by a stripping away of the protective insulation, the myelin sheath, that protects nerve fibres, but it was thought that this process occurred because the bacteria got inside Schwann cells, specialist cells that produce myelin.
In new research published today in the journal Cell , researchers used zebrafish that had been genetically modified so that their myelin is fluorescent green; young zebrafish are themselves transparent, and so the researchers could more easily observe what was happening to the nerve cells.
When they injected bacteria close to the nerve cells of the zebrafish, they observed that the bacteria settled on the nerve, developing donut-like 'bubbles' of myelin that had dissociated from the myelin sheath. When they examined these bubbles more closely, they found that they were caused by M. But, as is also often the case with TB, the M. Professor Ramakrishnan working with Dr Cressida Madigan, Professor Alvaro Sagasti, and other colleagues confirmed that this was the case by knocking out the macrophages and showing that when the bacteria sit directly on the nerves, they do not damage the myelin sheath.
The team further demonstrated how this damage occurs. This uniqueness led researchers to speculate that PGL-1 plays an essential role in functions that are specific to the leprosy bacterium—such as infecting peripheral nerve cells—but they had no proof.
A micrograph illustrating that same interaction being reproduced in vitro in nerve tissue culture; M. Now the researchers have demonstrated that PGL-1 binds specifically to native laminin-2 but not to other proteins in the basal lamina of the Schwann cell-axon unit. It turns out that invasion of the Schwann cell is ultimately controlled by the neural target, not the invading microbe.
The basal lamina is a dynamic action zone that functions to instruct neural cell phenotypes and activation. Modulation of the basal lamina has profound effects both on its function and the consequent behavior of cells residing within it. Therefore, it is not surprising that the basal lamina and Schwann cells respond to PGL-1 upon contact with the bacterium by opening the pathway to allow the intruder to enter. A schematic showing the chemical structure of PGL-1, a unique M. Leprosy is a chronic bacterial infection that damages nerves, mainly in the limbs and facial area, and also leads to skin lesions.
The disease can be treated with multidrug therapy that kills most of the M. However, nerve function loss caused by M. Leprosy is transmitted via droplets, from the nose and mouth. Prolonged, close contact with someone with untreated leprosy over many months is needed to catch the disease.
You cannot get leprosy from a casual contact with a person who has Hansen's disease. Leprosy is curable with multidrug therapy dapsone, rifampicin, and clofazimine , a combination that kills the pathogen, cures the patient, and halts transmission.
This therapy is free of cost in all the countries of the Americas. If untreated, the disease can cause progressive lesions, leading to disability and blindness. The bacteria attack nerve endings and destroy the body's ability to feel pain and injury. Without feeling pain, people don't realize when they injure themselves their injuries are often severe and can become infected. Changes to the skin also leave the person susceptible to ulcers, which if left untreated, can cause further damage, wounds and visible disfigurements to the face and limbs.
If the facial nerve is affected, this can interfere with a person's ability to blink, which can eventually cause blindness.
In , 23 countries in the Americas reported leprosy cases and children were diagnosed with this disease. Of those, 38 had visible impairments. Each year, about people in the United States and , around the world External get the illness. Still, a lot of stigma and prejudice remains about the disease, and those suffering from it are isolated and discriminated against in many places where the disease is seen.
Continued commitment to fighting the stigma through education and improving access to treatment will lead to a world free of this completely treatable disease. Hansen's Disease Leprosy. Section Navigation.
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