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DIAGNOSIS OF LEPROSY (Hansen's Disease or H.D. )
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I would like to make an appeal to all public health workers who have had no specific training in the Diagnosis of Hansen’s Disease (H.D. Leprosy). At the turn of this century all WHO-funded leprosy projects in areas where the prevalence of H.D. has fallen below 1 case per 10,000 population, will come under general public health. It is of vital importance, therefore, that all medical personnel be adequately equipped to properly diagnose a case of H.D. both in the early and late stages of the disease. These brief notes are designed to whet the appetite and stimulate an awareness of this need.
Leprosy is a disease with so many various manifestations that it needs to be diagnosed in relation to approx. 30 other conditions which can be confused with early and late leprosy.
Basically, leprosy is a disease of the nervous system but not all nerves are affected. The central nervous system is spared but the peripheral and cutaneous nervous systems can be infiltrated by M.leprae bacilli and then, secondarily, the skin is affected.
NERVES:
1. There may be an area of anaesthesia or numbness with/or “pins and needles, “ants crawling” or tingling in any area.
2. In the hands or feet, there may be a weakening of the small muscles and/or the presence of disability in those areas.
3. Thickening and/or tenderness of the peripheral and cutaneous nerves
4. Weakening or loss of function of the sweating mechanism in those areas
SKIN:
1. Erythematous or Hypo-pigmented patch of skin with loss of sensation to either/or/and touch, pain, temperature.
2. Smooth, oily, shiny and oedematous appearance of the skin
3. Diffuse erythema of the skin
4. On a shiny, erythematous and oedematous skin, there may be nodules or papules
5. There may be a sudden onset of painful erythematous nodules as above.
6. There may be a thickening of the earlobes
7. The eyebrows may become thin or even disappear, beginninng from the outerside.
These various manifestations are not seen in all cases so it is essential to know the SALIENT points which will assist you to reach a diagnosis of Hansen’s Disease. Without a knowledge of these, it is possible to confuse leprosy with about 30 other conditions which may appear to be leprosy. If a person has one of these other conditions such as Psoriasis, Various Fungal Infections, Carpal Tunnel Syndrome, Diabetic Ulcers, Burgeir’s Disease, Bell’s Palsy, Syphillis, Vitiligo etc., etc., and is “diagnosed” as having leprosy, the psychological damage (because of the stigma) can be devastating. The two important diagnostic clinical signs are :-
1. Thickening / tenderness of the peripheral nerve trunks and/or cutaneous branches.
2. The majority of H.D. cases can be diagnosed on the basis of these above two signs. These forms are the “Paucibacilliary” types and are generally non-infectious.
However, there are a few cases (Multibacilliary or infectious) who do not manifest any of these signs. Their skin may be oily, shiny, smooth and erythematous with or without nerve thickening/tenderness. Although this is the more serious form of H.D., in the early stages there may not be any serious nerve involvement or damage. This is because damage to the nerves is not due directly to the leprosy bacillus but rather to the body’s immune system violently reacting to the antigens liberated from the dying and dead M.leprae. In this regard, a study of “Immunity” in H.D. would be helpful. To make a proper diagnosis, therefore, we need to examine the patient bacteriologically by taking skin smears (not of the blood but rather the skin tissue and serum). A proper diagnosis, therefore, will require the presence of the following three CARDINAL SIGNS:-
1 Loss or impairment of sensations
2. Thickening of the above-mentioned nerves
3. The presence of M.leprosy bacilli in smears from skin and/or nasal mucosa
In some of the VERY EARLY lesions suggestive of leprosy, where none of the above-mentioned cardinal signs are present, it may be necessary to conduct three other tests:-
1. Skin Examination by Histo-Pathology. If the tissue is stained for acid-alcohol-fast M.leprae, the bacilli may be seen in the nerve. The need for such examination is rare
2. Histamine Test. This also is rarely needed. Histamine Phosphate in one drop (1:1000) is placed on an area of normal skin of the patient and pricked with a needle. If the nerve is intact, there will be a weal and an erythematous flare showing that the nerve is intact. This same test is then performed on the area of skin suspected of being leprous. There will be a weal as in the first test but NO erythematous flare IF the nerve is damaged, indicating a case of H.D. This test is rarely needed and is performed only as a “last resort”.
3. Sweat Test: In most cases, this is done by feeling with the back of the fingers for coolness of the normal, moist skin, in comparison with the warmness of dry skin affected by M.leprae. In some rare cases, it may be necessary to inject Pilocarpine Nitrate (1:1000) intradermally both in normal skin and skin with a suspected lesion of H.D. . If the lesion is affected by M.leprae, sweating is absent. This can be determined by applying Tr. Iodine on the skin, allowing to dry and then covering the area with starch before injecting . A positive sweat response will turn the starch blue, indicating that the sweating mechanism is intact.
After a diagnosis has been made, “Classification” is necessary to determine the TYPE of leprosy and this will vary according to the patient’s degree of Cell Mediated Immunity The course and duration of treatment will vary, depending on the degree of Immunity. Please advise me by email at :- keithskilli@ozemail.com.au
if you are interested in notes of “Classification” or any other aspect of the disease, please see the following sites:-
1. WORLD HEALTH ORGANISATION ( W.H.O.)- ON LEPROSY
2. INTERNATIONAL FEDERATION OF ANTI-LEPROSY ASSOCIATIONS (ILEP)
3. THE LEPROSY MISSION
P.S.
Hansen’s Disease (Leprosy) is not the highly contageous disease it once was thought to be. It is infectious, but only mildly so, when compared with other diseases. Within 48 hours of starting Multi-Drug-Therapy (MDT), it is now believed nearly all the M.leprae bacilli are rendered non-viable, so there is no need to isolate such patients. It is important that MDT be initiated as soon as possible to prevent nerve damage.
If you are interested in knowing about the various types of leprosy - treatment, health education, differential diagnosis etc. please email me at :- keithskilli@ozemail.com.au
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HOW YOU MAY HELP LEPROSY SUFFERERS PRACTICALLY
THE CHALLENGE OF LEPROSY
THE LEPROSY MISSION INTERNATIONAL
LEPROSY AND WOMEN WHO ARE AFFECTED
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