Leprosy is caused by a bacteria, Mycobacterium leprae, and transmitted via droplets from the nose and mouth during close and frequent contacts with untreated cases. Leprosy is most prevalent in underserved and marginalized communities, often among the poorest of the poor. Untreated, leprosy can cause progressive and permanent damage to the skin, peripheral nerves, limbs and eyes.
Signs and Symptoms
Mycobacterium leprae multiplies very slowly and the incubation period of the disease varies from 9 months to 20 years, with an average of about five years. Initial symptoms are that of patchy skin discoloration, then turning into skin lesions that are lighter than normal skin color and with loss of sensation. Other symptoms include muscle weakness and numbness. Leprosy mainly affects the skin, the peripheral nerves, the eyes, the mucosa of the upper respiratory tract, apart from other structures. Early diagnosis and treatment with multidrug therapy (MDT) are key elements in eliminating the disease as a public health concern.
Because the diagnosis of leprosy might have adverse social consequences for the patient and his family, a reasonable degree of certainty is required before making the diagnosis of leprosy. Leprosy is diagnosed when at least one of the following cardinal signs ocurrs:
- Definite loss of sensation in a pale (hypopigmented) or reddish skin patch.
- A thickened or enlarged peripheral nerve, with loss of sensation and/or weakness of the muscles supplied by that nerve.
- The presence of acid-fast bacilli in a slit skin smear.
Globally, according to the official reports of 130 countries and territories during 2013 the number of new cases detected during 2012 was of 232,587, which implied a reduction of approximately 7% with respect to the number of new cases detected in 2008. By 2013, with only one exception, all the countries of the Region had reached the national goal of elimination (<1 case per 10 000 population), while at first subnational administrative level five countries had still not reached the goal. Between 2010 and 2013, 18 countries and territories have not reported cases of leprosy, 17 countries and territories reported less than 100 new cases and 10 countries reported 100 or more new cases.
In the early 1960s, when M. leprae started to develop resistance to dapsone, the world’s only known anti-leprosy drug at the time, rifampicin and clofazimine were discovered. In 1981, the World Health Organization (WHO) recommended multidrug therapy (MDT). MDT consists of 3 drugs (dapsone, rifampicin and clofazimine), a combination that kills the pathogen, cures the patient and stops transmission.
In the Region of the Americas, the implementation of MDT began in 1985. Its coverage in 1990 reached 42%. By 2013, coverage is almost universal for newly diagnosed patients. Its impact on reducing the disease burden during the period the period between 1992 and 1999 was dramatic: an 83% reduction in incidence was observed, from 8.1 per 10,000 inhabitants in 1992 to 1.4 in 1999.
Continued efforts are being made to consolidate elimination and further reduce the burden of disease. WHO provides free MDT for all patients in the world, initially through the drug fund provided by the Nippon Foundation and since 2000, through the MDT donation provided by Novartis and the Novartis Foundation for Sustainable Development.
Globally, according to the official reports of 130 countries and territories during 2013, the number of new cases detected during 2012 was of 232,587, which implied a reduction of approximately 7% with respect to the number of new cases detected in 2008. By 2013, with only one exception, all the countries of the Region had reached the national goal of elimination (<1 case per 10,000 inhabitants), while at first subnational administrative level five countries had still not reached the goal. Between 2010 and 2013, 18 countries and territories have not reported cases of leprosy, 17 countries and territories reported less than 100 new cases and 10 countries reported 100 or more new cases.
Prevention and Control
In 1991 WHO's governing body, the World Health Assembly (WHA) passed a resolution to eliminate leprosy as a public health problem by the year 2000. Elimination of leprosy as a public health problem is defined as a prevalence rate of less than 1 case per 10 000 people. The target was achieved at the global level in the year 2000 time and the widespread use of MDT reduced the disease burden dramatically. Efforts currently focus on eliminating leprosy at a national level in the remaining endemic countries and at a sub-national level from the others. Over the past 20 years, more than 15 million persons were diagnosed and cured with MDT, with very few relapses reported.
In order to reach all patients, leprosy treatment needs to be fully integrated into general health services at all levels. Moreover, political commitment needs to be sustained in countries where leprosy remains a public health problem. Partners in leprosy elimination also need to continue to ensure that human and financial resources are available. The age-old stigma associated with the disease remains an obstacle to self-reporting and early treatment. The image of leprosy has to be changed at the global, national and local levels. A new environment, in which patients will not hesitate to come forward for diagnosis and treatment at any health facility, must be created.
PAHO´s role in leprosy elimination
With the Regional Plan of Action for the Elimination of Leprosy in the Americas promoted by PAHO in 1992, the coverage with multidrug therapy (MDT) since 2001 until the present time has been steadily increasing and is currently almost universal. Since 1995, PAHO through WHO provides MDT free of charge to all the people that need it, initially through the funds for medications from The Nippon Foundation and since the year 2000 through the donations of MDT provided by Novartis and currently by the Novartis Foundation for Sustainable Development.
In Resolution CD49.R19, adopted on October 2, 2009 by PAHO´s Member States, leprosy was included as one of the neglected infectious diseases (NIDs), for which the goal of elimination of leprosy at first subnational level by 2015 was defined.
In 2010 WHO´s Global Leprosy Program issued the “Enhanced Global Strategy for Further Reducing the Disease Burden due to Leprosy: 2011-2015” and its operational guidelines. The goal of the Enhanced Global Strategy is to further reduce the disease burden due to leprosy and sustain the provision of high-quality leprosy services for all affected communities, ensuring that the principles of equity and social justice are followed. While the main principles of leprosy control, based on timely detection of new cases and their treatment with effective chemotherapy in the form of multidrug therapy, remain unchanged, emphasis is given to sustaining the provisions for quality patient care that are equitably distributed, affordable and easily accessible. The strategy also highlights the need for decisive and innovative changes to the organization of leprosy control and the working arrangements among all partners, as well as to influence the attitude of health-care providers, persons affected by leprosy and their families, and the general public.
Based both on Resolution CD49.R19 as well as on the WHO “Enhanced Global Strategy for Further Reducing the Disease Burden due to Leprosy: 2011-2015”, in 2012 PAHO formulated a "Plan of Action in order to Accelerate the Achievement of the Elimination of Leprosy in Latin America and the Caribbean" which presents the lines of action with the objective of maintaining the achievements reached in the elimination of leprosy in the Region and further advancing towards the elimination of leprosy as a public health problem at first sub-national political-administrative level (less than 1 case per 10 000 population) by 2015.