Leprosy.

Leprosy* 1. Brief description of the disease Leprosy is a chronic tnfectious discase caused by Al vcobacterium leprae. It usually aftects thc skin anid peripheral nerves but has a wide range of possible clinical manifestattons The disease is classi- fied as paucibacillary or multibacillanr leprosy (i.e. tuberculoid or lepromatous leprosy, respectively). Paucibacillary leprosy is a milder disease clharacter- ized by one or more hypopigmnented, hypoaesthic skin lesions. Multibacillary leprosy is associated with symmetric skin lesions, nodulcs, plaques, thickened dermis, and trequent involvemenit of the nasal mnucosa resulting in nasal congestion and epistaxis. and of peripheral nerve trunks resultine in deformi- ties of the limbs, eves and face. The mode ot transmission of leprosy remains uncertain but most investigators believe M. leprae is usually spread from person to person primarilv as a nasal droplet infection. The Incubation penod is unusually long for a bacterial disease. generally 5-7 years, with the shiortest period beino2 2-3 years and the longesL up to 40 years Peak age ot onset is young adulthood, usuiaHy 20-30 yeais of age: disease is rarely seen in children under 5 years of age Leprosy is usually diagnosed by Its clinical manifestations. wliich are characterized by anaes- thetic skin lesions and inflammation of periphieral nerve trunks. The diagnosis is confirmed by skin bi- opsy and acid-fast staining, whiich are also used to stage disease and judge the response to therapy. Since 1982. WHO has advocated use of multidrug therapy (MDT) regimens to treat paucibacillary lep- rosy (6 months) and multibacillarv leprosy (12 months). This regimen has served as the cornerstone for elimination effoits. 2. Current global burden and rating within the overall burden of disease In 1985, WHO estimated 10-12 million lepi osy cases worldwide; 5.4 million of these were registered in a leprosy programme. At the bcginning of 1998 WHO reported that 883340 were registered and bcing treated. Another 1-2 million people are penna- nently disabled as a result of leprosy but are consid- ered tree of active infection. Contnbuled by Richard A Spiegel and Bradley A. Perkins Centers for Disease Control and Prevention. Atlanta, GA, USA Each year, an estimated 500000 new leprosy cases aie ideintified. Most come fromn 32 countiies where the discase continucs to be considcred a putblic lhealth problem. At the beginniing ot 1998. 16 countries - Bangladesh. Brazil. Cambodia Deniocratic Republic of the Congo, Ethiopia. Guinea, India, Indonesia, Madagascar, Mozam- bique. Myanmar. Nepal. Niger. Nigena, Plilippines, and Sudan - repoited more the 90% of the world's leprosy cases. 3. Feasibility (biological) of elimination/eradication Elimination of leprosy may be feasible. Although other animals (e.g. armadillos) carry Atf. leprcae. humans are believed to be the organismii's major res- ervoir, and MDT is curative. However. prolonged incubation of leprosy mnakes recognition of a disease- free area difficult. Asyznptomatic carriers of M. lep-ae may infect other people, and the trequently chrontc and mild symptom-ns may be difficult to detect without sysLematic screening of populations. 4. Estimated costs and benefits of elimination/eradication The estimated cost to identify and treat 2 million leprosy cases per year for the 3 years 1997-2000 is US$ 250 millioil; drugs account for 10% of the total cost. Prevention of leprosy-associated pain, suffenng, ostracism, and disabilittes (pnmarily de- tornmity and blindness) is the pnmary benefit. In ad- dition, resources now devoted to leprosy (rcatment and rehabilitation programmes could be directed elsewhere. 5. Key strategies to accomplish the objective The strategy las focused piimarily on increasing case-linding and expanding MDT services to all health lacilitics: ensuring that aIl existing and new cases are treated appropriatelv w%itlh MDT: encour- aging all patients to take treatment regulaily and completely promoting leprosy awareness in the communiLt so that people with suspicious lesions will report voluntaily foi diagnosis and treatment. betting targets anid time tables for activities anid mak- ing all efforts to achieve themn and improving Butletn of the World Health Organization. 1 998. 76 (SuppI 2) 133-134 133 Leprosy surveillance and tracking of patients to monitor progress towards elimination. BCG vaccine is effective in preventing leprosy in some populations but its role in leprosy elimina- tion programmcs has yet to be defined. 6. Research needs * Resistance of M. Ieprae to nfampicin, when used alone as monotherapy. has been identified. Since rifampicin is a key drug in the MDT programme, this should be carefully monitored. * New drug regimens requiring shorter treatment times arc needed. Trials of ofloxacin. minocycline, and rifamnpicin in various dosages and time intervals are ongoing. e Validation of supervised intermittent therapy op- tions are needed. These may be useful when patients are living in remote settings. * Better means arc needed to identify AM. leprae in- fection at the subclinical and early clinical stages, either through direct detection of the organism or indirectly by serological response * In the post-elimination phase, surveillance for lep- rosy will need to be maintained because of its long incubation timc. 7. Status of elimination/eradication efforts to date WHO's year 2000 goal for eliminating leprosy is de- fined as a reduction in the number of cases to <1 case per 10000 population. Since 1985, the estimated number of leprosy cases lhas declined from 10L2 million to under 1 mllion registered cases in 1998. During the past I0 years. more than 10 million pa- tients have been cured using MDT. 8. Principal challenges to elimination/eradication The primary challenges to leprosy elimination are: reaching populations that have not yet received MDT services: improving detection of the disease: and providing patients witlh quality services and drugs free ot charge to patients. 1WHO BuIlein OMS Vol 76, Suppi 2 1998134