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Leprosy. Nadine Chase & Priyanka Patel. Taxonomy. Genus: Mycobacterium Family: Mycobacteriaceae Mycobacterium Leprae Acid-fast Bacillus Gram Positive Bacillus shape Single arrangement Aerobic Optimum growth temperature is 30° Trivia Can not be grown in culture.
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Leprosy Nadine Chase & Priyanka Patel
Taxonomy • Genus: Mycobacterium • Family: Mycobacteriaceae • Mycobacterium Leprae • Acid-fast Bacillus • Gram Positive • Bacillus shape • Single arrangement • Aerobic • Optimum growth temperature is 30° • Trivia • Can not be grown in culture http://asylumeclectica.com/asylum/malady/archives/leprosy/leprosy4.jpg
Sehgal, Alfica. Leprosy, Deadly Diseases and Epidemics. Philadelphia, PA, 2006.
Sehgal, Alfica. Leprosy, Deadly Diseases and Epidemics. Philadelphia, PA, 2006.
Types • Tuberculoid Leprosy • Pauci-bacillary (PB) Leprosy • Well defined skin lesions that are numb • 1-5 skin lesions • Lepromatous Leprosy • Multi-bacillary (MB) Leprosy • Chronically stuffy nose • Many skin lesions and nodules • >5 skin lesions
Target Tissues • Skin tissue • Peripheral nerves • Mucus membranes • Bacteria prefers outer cooler parts of the body Sehgal, Alfica. Leprosy, Deadly Diseases and Epidemics. Philadelphia, PA, 2006.
Ecology • Widespread organism living in water and food sources • Obligate Parasites (cannot live independently) • Fish • Insects
Infection Process • Not very contagious • Air born disease • Droplets discharged from the respiratory tract • Nasal secretions • Prolonged contact with excretions from lesions • Slow replication time • Long incubation period
Infection process cont. • Affinity for macrophages and Schwann cells • In Schwann cell • Mycobacterium binds to the G domain of alpha chain of laminin 2 in the basal lamina • Stimulates cell mediated immune response which causes swelling, chronic inflammatory response • Ultimately leads to axonal (nerve) death http://www.med.nyu.edu/news_and_views/images/leprosy.jpg
Nerve cell Normal Nerve Cell Nerve Cell enlargement Arnold, Harry. Modern Concepts of Leprosy. Springfield, IL, 1953.
Preventative Measures • Avoid contact with infected persons • 99% of the population have natural immunity http://www.ruggedelegantliving.com/journal/images/2003/05/01/sars.mask.jpg
Symptoms • Long incubation period • Skin lesions with decreased sensitivity • Numbness • Muscle weakness • Cosmetic Disfiguration • Death is usually caused by a secondary opportunistic disease http://www.wrongdiagnosis.com/l/leprosy/deaths.htm
Diagnostic Test • Leprosy Skin Test • Inactive Leprosy-causing bacteria injected into skin • Body will react to the Leprosy antigens • Check injection 3 days and 28 days later • Positive skin reaction is seen in Tuberculoid Leprosy only • Normal result: little to no skin irritation around injection site http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm
Diagnostic Test: Skin Biopsy • Shave Biopsy • Least invasive • Superficial layers of lesion scraped off • No stitches required • Bacteria can be identified on a slide http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm
Diagnostic Test: Skin Biopsy • Punch Biopsy • Small cylinder of skin removed • Sizes vary depending on size of lesion • May require stitches http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm
Diagnostic Test: Skin Biopsy • Excisional Biopsy • Local anesthetic applied • Entire lesion is removed • Stitches are usually needed http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm
Diagnostic Test: • Methacholine sweat testing • An intradermal injection of methacholine demonstrates the absence of sweating in leprous lesions. • Helpful to identify diagnosis when lesions are not visible on dark skin individuals Arnold, Harry. Modern Concepts of Leprosy. Springfield, IL, 1953.
Treatments • Multi-drug therapy • PB Leprosy • Two Drugs: Rifampicin and Dapsone for 6 months • MB Leprosy • Three Drugs: Rifampicin, Dapsone, Clofazimine for 12 months http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm
Sehgal, Alfica. Leprosy, Deadly Diseases and Epidemics. Philadelphia, PA, 2006.
Treatments cont. • Special Footwear to prevent foot ulcers Grunberg, E., Babger, LF, et al. Leprosy. New York, 1951.
Epidemiology • Age • Children are more susceptible • Bimodal age distribution with peaks at ages 10-14 and 35-44 with higher susceptibilities in younger years • Sex • Higher infection rate in males compare to females • Ratio of infection is 2:1
Epidemiology cont. • Race • African blacks are highly susceptible to the tuberculoid form of leprosy • Caucasians and Chinese are more susceptible to the lepromatous type of Leprosy • Its more rural than urban disease in Asia and Pacific Basin
Morbidity and Mortality • 2002 Data • 1,000 deaths in North and South America • 96 cases in the U.S • 3,000 deaths in South East Asia • 1,000 death in Eastern Mediterranean • 1,000 deaths Western Pacific • 2005 Data • 166 new cases were reported in U.S. • 60% of these cases occurred in: • California • Louisiana • Massachusetts • New York • Texas
HANSEN DISEASE (LEPROSY) Number of reported cases, by year United States, 1973-2003 www.cdc.gov/epo/dphsi/annsum/2003/slides/hansgraf.ppt
Research • Attempt to identify new drugs that can stop the neural damage caused by the bacteria • Bacteria needs to recognize certain type glycoprotein on the cell surface to bind with and subsequently enter the cell • If these glycoprotein can be identified and a drug can interfere with the binding between the bacterium and the protein, this could potentially prevent entry of the bacteria and stop neural damage
A Twin Study • Leprosy has been found to NOT be hereditary • If twin siblings become infected, the disease is passed from one to the other solely because of the proximity in which they live • Twin A acquired the disease at age 15 • Twin B at age 19 • The disease effects the twins differently
Twin Study Twin A Twin B Chakravartti, M.R. and Vogel, F. A Twin Study on Leprosy. Germany, 1973.
References Arnold, Harry. Modern Concepts of Leprosy. Springfield, IL, 1953. Chakravartti, M.R. and Vogel, F. A Twin Study on Leprosy. Germany, 1973. Grunberg, E., Babger, LF, et al. Leprosy. New York, 1951. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/hansens_t.htm http://www.nlm.nih.gov/medlineplus/ency/article/003383.htm http://tmcr.usuhs.mil/tmcr/chapter34/large34/34-01.jpg http://www.wrongdiagnosis.com/l/leprosy/deaths.htm “Leprosy. “eMedicine from webmed. http://www.sunysccc.edu/academic/mst/microbes/16mlepr.htm 21 July 2007. “Leprosy, The Disease” World Health Organization; Regional Office for Southeast Asia.www.searo.who.int/En/Section10/section20/section57_8963.htm. 22 December 2006. Sehgal, Alfica. Leprosy, Deadly Diseases and Epidemics. Philadelphia, PA, 2006.