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Author Topic: causes and prevalence of Leprosy.  (Read 2631 times)

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causes and prevalence of Leprosy.
« on: 01/08/2007 22:02:29 »
I only have "experience" of leprosy from the movie "life of Brian". How is leprosy contracted, how common is it, and are there still leper colonies?



  • Guest
causes and prevalence of Leprosy.
« Reply #1 on: 01/08/2007 23:43:08 »
Leprosy is a bacterial (I think - maybe viral - will have to check) infection.

Leprosy is not easy to contract (contrary to common prejudice), and it is no longer considered necessary to quarantine lepers in colonies.

I believe one of the treatments of leprosy now involves thalidomide.

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causes and prevalence of Leprosy.
« Reply #2 on: 02/08/2007 21:23:34 »
Mycobacterium leprae IIRC is related to the bug that causes tuberculosis. They are so closely related that exposure to one can confer immunity to the other. Thalidomide is used in treatment of one of the complications of leprosy. I think the same drugs are used to treat tuberculosis as are used for leprosy.

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causes and prevalence of Leprosy.
« Reply #3 on: 03/08/2007 14:00:01 »
Well, a few hours after i posted this question, Dr Karl goes and does a podcast all about Leprosy. I thought i would post the text of that podcast here, it is not in quotes because it is rather long and the text in quotes can sometimes be too small when the quote is rather long.

I was rereading a favourite article, "A Short History of Leprosy in Postage Stamps", when I suddenly wondered what the average person thought leprosy was. I asked a random passer-by (okay, my daughter) and she said something along the lines of 'their hands and legs fall off, and sometimes even their heads'. I'm sure she meant their noses, rather than their heads. However, like many of us, she believed that leprosy caused bits of your body to fall completely off - but that's not true.

Leprosy is now called Hansen's Disease after Armauer Hansen the Norwegian who discovered the bacterium that caused it (Mycobacterium leprae) in Norway in 1873. In fact, it was the very first bacterium that caused a human disease to be discovered.

Leprosy has afflicted humans for a long time. It existed in ancient China, India and Egypt as far back as 6000 BC. It was probably brought back to Europe by Alexander The Great, around 4 BC. There is evidence of leprosy in Great Britain and France back to at least 500 AD. From Great Britain it is thought to have been spread to Scandinavia by the Vikings. The incidence of leprosy in Europe peaked in the fourteenth century. It was brought to the New World by explorers in the sixteenth century, and then later was introduced to Australia and the Pacific Islands. In fact between 1920 and 1929 on Nauru, 35 % of the entire population was infected with leprosy.

Leprosy rates in Australia are only about one case per million, but are higher in Aboriginal Australians and immigrants from infected areas. Worldwide, leprosy is still endemic mostly in Africa and around India. There is also some leprosy in parts of the USA.

In the past lepers were expected to live in isolated colonies and in Europe they carried a bell to warn others of their presence. Leper colonies do still exist. In West Australia during the 1920's and 1930's, Aboriginal lepers were confined above the 25th Parallel, which became known as the "Leper Line", while white patients with leprosy were sent to the far more salubrious Wooroloo Infectious Diseases Hospital near Perth. It turns out that leprosy does not seem to be as highly contagious as was once thought. In fact, most people who are exposed to the bacterium will never get the disease. While it is still not exactly clear how the disease is spread, it is thought to be from human-to-human by respiratory droplets, but probably not through intact skin.

Leprosy affects the skin, the nerves and the lining of the upper respiratory tract. It can take a long time after exposure to develop leprosy, even up to 50 years. The average incubation period is around 5-10 years.

Leprosy will affect you differently, depending on your genes. If your immune system responds vigorously, you will suffer a milder version of the disease, than if your immune system responds weakly. It can attack skin and nerves, causing areas of skin to lose both pigment and sensation. This is the key point about this myth. The nerve damage results in loss of sensation, and loss of motor function. It is the lack of sensation that results in most tissue damage.  If you don't have feeling in your hands or feet, you are more likely to injure them and then neither notice nor treat the damage. It is this frequent trauma that results from lost sensation that causes the tissue damage, not the bacterium Mycobacterium Leprae rotting the flesh. It does not rot flesh.

Treatment for leprosy first became available with Dapsone in the 1940's. Today's Multi Drug Regimes are effective, and are used to try to avoid the problem of drug resistance. Prolonged treatment courses are needed because leprosy is a chronic infection. Unfortunately, delivery of antibiotics is still a problem in many poor countries where leprosy is a public health issue.

Back in 1991, the World Health Organisation stated its aim of reducing the numbers of people who needed treatment for leprosy to less than one per 10,000 population about 600,000 people in the world. But today the number of people with leprosy is somewhere between 2 and 15 million people. For the World Health Organisation to get anywhere near the figures they want, it's the duty of us to get over the stigma associated with the disease and its sufferers and for us to stop treating them like lepers.

  • Guest
causes and prevalence of Leprosy.
« Reply #4 on: 03/08/2007 14:00:43 »
This is a supplimental about Leprosy in Neplal.

This is a story about today's technology and an ancient disease. It is set in the beautiful but poor Kingdom of Nepal and describes scientists who are sharing their skills and using molecular biology to understand and control leprosy. Jenny Davis tells the story of her visit to the "Forest of Joy" outside Kathmandu.

A road leading up to the Forest of Joy
I am a microbiologist in an Australian public health laboratory. We have modern equipment and use sophisticated methods to investigate infectious disease problems in our community. But I've wondered about how much use this technology would be if I was in a lab in a developing country -basic health needs mean basic lab techniques, right?

Then last year, I heard Australian immunologist Dr Paul Roche speak about his research work with leprosy in Nepal. I thought Paul was great. He was very aware of the ethics of conducting research in a developing country; he was keen to apply cutting-edge techniques to solve complex problems; and best of all, he was enthusiastic about the sharing of skills with his Nepali scientific colleagues. I decided to visit him at the Mycobacterial Research Laboratory at Anandaban Leprosy Hospital, Nepal.


"Anandaban" means "The Forest of Joy" and the hospital is in a beautiful wooded mountainside setting, about 12 kilometres south of Nepal's capital, Kathmandu. I travelled by bus on a particularly bumpy road, with hairpin bends as it climbed from the valley floor. Nepal is one of the poorest countries in the world. On our journey from Kathmandu, the problems were obvious; open drains, a grey haze of pollution over the city, rubbish piled in the narrow streets and trucks, buses and cars belching black fumes over unfortunate pedestrians already coated with dust from the unsealed road. It seemed to me that the needs, such as clean water, clean air and enough food were basic and obvious. I asked myself whether research scientists could make a difference in this country - could their experiments lead to any real benefits for its people? I tried to find an answer to this question during my stay at Anandaban over the next few days.

A leprosy infection can result in disfigurement of the eyelids so that they don't quite close properly.
Anandaban Leprosy Hospital is the main leprosy referral hospital for the Central Region of Nepal. The term "leprosy referral hospital" would be unknown in Australian cities, where leprosy is a rare and feared disease. But leprosy is not rare in Nepal, nor in many other countries, because it is primarily a disease of poverty. There are over 6,000 outpatient visits to Anandaban each year, with over 600 admissions, and this doesn't include the non-leprosy medical services provided by the hospital. So what is leprosy, and what's it like to be affected by it?


Leprosy, or Hansen's Disease, is a disease of skin and nerves, thought to be spread by airborne droplet infection, caused by the bacterium, Mycobacterium leprae. It is mildly infectious (but most people are naturally immune to it); and it's cured by antibiotic treatment (three antibiotics taken concurrently for up to two years). But it's a disease that has been feared throughout human history. It has often meant rejection and isolation for those people unfortunate enough to suffer its effects. Probably the fear stems from myths about fingers dropping off and rotting flesh.

Why have these myths developed? Leprosy is a very visible disease, because M. leprae likes to grow in skin and nerve cells. The signs might start with a visible, numb patch on your skin. They might develop to include paralysed, crooked fingers, or unsightly lumps on your face or eyelids that can't close completely. At this point you feel embarrassed at best or terrified and ashamed at worst. You may well decide that you don't want to hear whatever a doctor or a health worker might tell you and hope it will all go away. But there's worse to come. Your damaged nerves have lost their ability to warn you with pain. So your normal life is full of dangers that you cannot recognise; a thorn in your foot, some grit in your eye, a burn on your hand are all undetected and untreated. The consequences of infection, tissue decay and bone disease are all to come. The longer you go without help, the more severe and irreversible are the effects of this slow, insidious disease.

Testing for feeling on the palm.
The fight against leprosy is one of the medical success stories of the past two decades. The number of people requiring treatment for the active disease has gone down from 11 million in the 1980s to about one million today. This remarkable decrease has resulted from improvements in antibiotic treatment (notably the concurrent therapy with three antibiotics, which greatly reduces treatment time). Yet the effects on nerves and muscles are permanent; this means that many people ( 2-3 million worldwide) cured of their leprosy may still face their future with a disability, such as fingers that cannot grasp, or a foot that cannot feel pain. And the stigma associated with leprosy persists today, so that people who have the condition may be excluded from normal society.


The hospital is a complex of buildings nestled among trees and bushes, with magnificent views of the valley below. I soon realised that the views had a price, as I attempted the near-vertical paths, trying to keep up with the locals as they showed me around. I was able to meet people who were affected by leprosy, and the medical and paramedical staff who work to help them. But I had come to see the work of the scientists in the Mycobacterial Research Laboratory, so it was here that I spent the first day.

Paul Roche, Director of the Mycobacterial Research Laboratory at Anandaban, is from Sydney, Australia. He has lived and worked in Nepal with his family for over six years. He has had three dreams for the laboratory -- that its resources will be used to probe the unanswered questions of leprosy, that it will provide leprosy workers with tools to diagnose and treat leprosy, and that it will serve to train Nepali scientists. Paul will return to Australia later this year and Scottish scientist Dr Murdo MacDonald will take over his role. Paul's research skills and experience have been shared with two young Nepali research scientists, Rakesh Manandhar and Niraj Shrestha. Rakesh graduated from the University of Adelaide, Australia, after studies in molecular microbiology. Niraj has a Master of Science from Mysore University in India and would like to continue his studies towards a PhD. Both Rakesh and Niraj have had opportunities to extend their experience in Europe and America.

Kapil Dev Neupane in the Mouse Footpad Test Laboratory 
As well as the research activities and a basic hospital pathology service, the laboratory offers the skills to detect M. leprae in skin tissue and to determine its sensitivity to antibiotics. Sarah Failbus, with Kapil Dev Neupane, runs the Mouse Footpad Test, which detects antibiotic sensitivity. Dhurba Kumar Mahat and Ishwor Raj Shrestha are also part of the laboratory team.

I always enjoy visiting other laboratories and swapping stories with microbiological colleagues. Soon I was busy looking down a microscope at Mycobacterium leprae and asking Kapil Dev about the technical details of the Mouse Footpad Test. This intriguing title arises from the fact that, unlike many other bacteria involved in human disease, M. leprae does not grow on ordinary laboratory culture medium. It will, however, multiply in some living tissues-human tissue, obviously, but also tissue in the nine-banded armadillo or (more conveniently) in the footpad of a mouse. Samples of human tissue, containing the living bacteria, are injected into the footpad of a mouse. If a particular antibiotic is then fed or administered to the mouse, and the bacteria are susceptible to this antibiotic, they will not grow in its foot. When tissue from the footpad is examined with a specal identifying stain (the Ziehl-Neelsen stain), no bacteria are found. Of course, if they are resistant, they will have grown and be detected. Because the germ grows very slowly, each test takes 6-8 months.


But now I wanted to know about the latest in leprosy research. I already knew that leprosy is a complex disease, because so many of its effects depend on the interaction between the bacterium and the person it infects. Well, here are three questions that Paul and the team at Anandaban are trying to answer:

How do we know if people are being exposed to leprosy? Leprosy has not been eradicated and over half a million new cases of the disease are diagnosed each year. So what is the source of infection for these people? You can't measure exposure to leprosy with a simple blood test for antibodies (like glandular fever or HIV). But you can look at the effect of M. leprae on the activity of T-cells in the blood and assess whether these cells have encountered the germ before. If they have, they will produce a substance called interferon-gamma (IFN). Different portions of material from M. leprae have been tested to see which ones promote the best response from the T-cells. This laboratory test on blood may now be applied to the development of a skin test for leprosy, similar to the skin test already used for tuberculosis. A skin test for leprosy would be a very useful tool, as the relationship between exposure to the germ and occurrence of the disease in communities is explored.

Mukchi holding her daughter Susan at the Anandaban Leprosy Hospital
How can we tell if the antibiotics used to treat leprosy are still effective? We already know that M. leprae can develop resistance to dapsone, the antibiotic first introduced to treat the disease in the 1940s. This is why the recommended treatment since the 1980s has been three antibiotics, usually rifampicin, clofazimine and dapsone, all taken concurrently. But what if this combination loses its effectiveness? The laboratory has not only been monitoring the resistance of M. leprae to dapsone, it has also been using a polymerase chain reaction (PCR) test to detect resistance to rifampicin. This test shows if there has been a mutation in the rpoB gene in the bacteria. Niraj has been exploring the genetic basis of rifampicin resistance and participating in studies which use a technique called a line probe assay (developed at the Institut Pasteur in France).


What's happening when the treatment is worse than the disease? For some people, the antibiotic treatment works with no problems; but for others, it brings even more problems into their lives. Their bodies react badly to the build-up of dead bacteria, as the drugs do their work. These "leprosy reactions" may give rise to a number of symptoms, ranging from unpleasant to painful to life-threatening. The treatment usually involves anti-inflammatory drugs, such as prednisolone or even thalidomide. Niraj is involved in a study to see whether some people are genetically predisposed to suffer reactions to treatment. Rakesh is working on two studies which look at the basic mechanisms of action of the anti-inflammatory drugs. These studies will help to answer the questions: "How does thalidomide work? Could we develop a similar, safer drug? What is the best time to give these drugs? How long should they be administered?"

Outpatient clinic at Patan Hospital
These laboratory studies are of course linked to the clinical histories of real people, so Paul suggested that I go with him to the weekly leprosy outpatient clinic, run by the Anandaban staff at Patan Hospital, Kathmandu. As we walked into the Outpatient area, there were already two rows of seats filled with waiting patients. Once the consultations began, the whole room looked very crowded to me. At the end of each table, there were two doctors sitting on either side, each consulting with their patient at the other end. Australian patients wouldn't think of tolerating this lack of privacy during a visit to the doctor, but it seemed to be quite acceptable here. In fact, it had the added benefit that if the doctor wanted a second opinion from a colleague, it was available across the table!

In another room, Dr Joe LeMaster, an American doctor working at Anandaban, was checking eyes. One of the consequences of leprosy may be an inability to blink or close the eyelids. This means that the unprotected surface of the eye may become irritated and damaged and blindness may develop. Every person newly diagnosed with leprosy has their eyes checked and they are regularly checked at subsequent visits. I watched a young man, who couldn't close his eyes completely. His sight was not yet affected, so he could not really appreciate the risk of blindness. It was very hard to convice him that the benefits of surgery on his eyelid would outweigh the inconvenience and risk.


There are other images that I remember from this day. I watched a young man being told that he had leprosy, after he failed to feel any sensation on a small, hairless patch on his leg. I observed a spirited discussion between a middle-aged woman and her doctor; the woman was (justifiably) complaining that she couldn't rest her ulcerated foot when she had so many daily chores and responsibilities. I chatted with the staff setting up temporary Medical Records and Pharmacy Departments from cupboards and tin trunks in the busy corridors. What impressed me most was the quality of the care offered to each patient under crowded and noisy conditions.

Molecular biologist, Rakesh Manandhar, a graduate of the University of Adelaide
As I left Anandaban, I thought again about whether Western research scientists such as Paul can make a difference to Nepal and its people and whether cutting -edge technology is appropriate in a developing country. My visit had helped me to reach some conclusions.

Like most research, the projects at the Mycobacterial Research Laboratory are not immediately applicable to individual patients. However, the answers to problems such as the spread of leprosy in a community, the antibiotic resistance of M. leprae, and inflammatory reactions to treatment are ones that could give new and better weapons to those fighting this ancient disease. But I believe that the most significant contribution in the long term will be Paul's enthusiasm and generosity in sharing his skills with the young research scientists, Rakesh and Niraj and providing them with opportunities to collaborate with other scientists overseas. My most vivid memories are of the Nepali scientists, both in the general and the research laboratories. These are the people whose skills and commitment will continue to drive the work in the laboratories at "The Forest of Joy".


The Naked Scientists Forum

causes and prevalence of Leprosy.
« Reply #4 on: 03/08/2007 14:00:43 »


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