World Leprosy Day is celebrated on the last Sunday of January each year and aims to raise awareness about a disease that many believe to be extinct. Currently, not only the disease is overlooked, but also those affected by it.

Leprosy is an infectious disease caused by the bacteria Mycobacterium leprae, also known as Hansen's bacillus (in honor of Gerhard Hansen, a Norwegian physician and bacteriologist who discovered the disease in 1873). The bacillus reproduces very slowly and the average incubation period and appearance of the signs and symptoms is approximately five years.

Contagion between people is the proven source, but there are also very similar mycobacteria that infect wild animals, and their role in the disease transmission is still unknown, specialists emphasize. It is transmitted through the upper respiratory tract, from one untreated person to another, through direct and frequent contact. It is worth clarifying that a person cannot become ill simply by contact with someone who has the infection.

Factors that increase the contagion risk:

• Living for a long time with someone who has untreated leprosy.
• People with compromised immune systems are more susceptible.
• Poverty and overcrowding conditions: These facilitate close and prolonged contact between people.

One of the oldest diseases in the world

The first indications of the existence of leprosy date back to several centuries before Christ. For centuries, people with leprosy were stigmatized and the disease was associated with promiscuity and even with a “divine punishment” for sins committed.

The initial symptoms are spots on the skin with decreased or loss of sensitivity, hair and/or perspiration. Depending on the clinical form, nodules and thickening of the skin and/or peripheral nerves with spontaneous pain or pain on compression may appear. Generally, a disorder of sensitivity occurs, ranging from mild hypoesthesia (numbness and tingling) to total anesthesia in the hands and feet. Thus, little by little, due to lack of care and timely treatment, the wounds become infected, causing damage that over time produces the disabilities that we all know in relation to this disease.

When cases are not treated at the onset of signs and symptoms, the disease can cause progressive and permanent sequelae, including deformities and mutilations - it is sometimes necessary to resort to amputation - reduced mobility of the extremities and even blindness.

The disease mainly affects the skin, nerves, the mucosa of the upper respiratory tract and the eyes. In some cases, symptoms may appear around 9 months after infection, and in other cases, it may take up to 20 years.

Leprosy is diagnosed clinically and is based on 3 cardinal signs that were proposed by the WHO Expert Committee on Leprosy.A case of leprosy is defined when an individual has one or more of the following cardinal signs:

1. Hypopigmented or erythematous dermatological lesions on the skin with loss of sensitivity.
2. Thickening of peripheral nerves.
3. Positive bacilloscopy or bacilli in the biopsy.

Leprosy is curable and the treatment offered considerably reduces the chances of disability::

There is an effective treatment that kills the bacteria that causes the infection, cures the patient and stops transmission. However, there are still people who have leprosy - around 4 million live with disabilities caused by the disease - and do not have access to the therapy that is free through the World Health Organization (WHO).

The distribution of cases globally is uneven and the latest data on infections indicated:

• 71.4% in South-East Asia
• 2.2% in the Eastern Mediterranean
• 12.3% in the Americas
• 1.4% in the Western Pacific
• 12.6% in Africa and, residually, in Europe with 55 new cases

The 23 priority countries worldwide accounted for 95.1% (165,628) of all new cases worldwide. In these 23 countries, the number of new cases increased by 24.5% compared to 2021 (133,008). Brazil (19,635), India (103,819) and Indonesia (12,441) accounted for 78.1% of new cases of leprosy detected worldwide in 2022/23.

Childhood leprosy

The age at which symptoms first appear in children is between 10 and 14 years

• First, the pathogen is elusive and has an extremely long incubation period: it can take from 5 to 20 years from infection to symptoms.
• It is difficult to reach all people who suffer from the disease. Most live in very poor communities without health services, so many cases go undiagnosed.
• End the stigma that makes people hide and not ask for help even if they suspect they have the disease.
• Prevent the disabilities that can develop as a consequence of the disease.
• Help people who already have disabilities with reconstructive surgery and rehabilitation.

If we want to achieve a world without leprosy, it is necessary to mobilize resources and establish alliances with affected people, donors, organizations, governments and international entities.