Leprosy: An Overview of This Historic Yet Present Disease

Leprosy, also called Hansen's disease in honor of the Norwegian doctor Gerhard Armauer Hansen, who discovered the causative agent of the disease in 1874, is a chronic infection caused by the bacterium Mycobacterium leprae, and which, despite being a treatable disease, has been for centuries a pathology stigmatized by society.

History of the disease

Leprosy is a disease that has been known since ancient times and the first written reference that exists of it dates from some Indian texts from around 2000 BC. For many centuries, out of ignorance and fear of contagion, those affected by leprosy were condemned to live isolated in communes (leprosaria).

Today leprosy is eradicated in the vast majority of countries in the world, but there are still pockets of persistence of the disease in India, Indonesia, the Philippines, Brazil, Madagascar, Mozambique, Tanzania or the Democratic Republic of the Congo.

About twenty years ago, the World Health Organization (WHO) set itself the objective of reducing the prevalence of the disease as much as possible, installing detection programs in endemic countries and providing patients with free access to treatment.

Thanks to these campaigns, in 20 years, around 14 million people have been cured and the global prevalence of the disease has been reduced by 90%, accounting for 181,940 cases worldwide in 2011. Thanks to the campaigns of WHO has eradicated leprosy in 119 of the 122 countries where it was still an endemic disease and a serious community health problem.

How is it produced?

Leprosy, as explained at the beginning of the text, is caused by Mycobacterium leprae, a bacterium that is transmitted from an infected patient to a healthy person through microscopic droplets of saliva (Flügge drops) that are emitted when speaking or sneezing, as well as with nasal secretions.

Recently, in 2008, another bacterium was isolated, Mycobacterium lepromatosis, which is also capable of causing this disease in a serious form and which is basically found in Mexico and the Caribbean area.

Despite the stigma of contact with these patients due to the risk of contagion, 95% of people who have been in contact with a person with leprosy do not develop the disease. To begin the contagion requires repeated and close contact with the infected person and, secondly, most people have an immune system capable of dealing with the bacteria if they become infected.

The causative bacterium reproduces slowly, so that after infection the average appearance of symptoms is between 5 and 7 years, and the exuberance of symptoms will depend on the immune system of the patient.

Although it can affect any age, it is more frequent between 20 and 30 years of age, affecting men and women equally in its mild form, but with a predominance of men in its severe form.

Symptoms

Only 5% of people who are infected with leprosy develop the disease and in these it can manifest itself in two ways, tuberculoid leprosy, which is the mild form, or lepromatous leprosy, which is the best known and most serious. .

• In tuberculoid leprosy, patients present whitish skin lesions, especially at the level of the extremities, that are flattened and frequently present with decreased sensitivity due to the involvement of the peripheral nerves caused by mycobacteria. In general, the malformations typical of the severe form of the disease do not usually occur.

• Lepromatous leprosy, the most common form in the collective imagination, is characterized by the presence of bulging skin nodules of different sizes and shapes, which can initially be painful but in which sensitivity is later lost due to the involvement of the system peripheral nervous system, making patients insensitive to pain, temperature or pressure in these areas.

The central, that is, the brain and spinal cord, is not affected, only the sensitivity of the peripheral nerves. Such loss of sensation often causes patients to suffer unaware injuries that can lead to tissue destruction and require limb amputation. The same alteration of the nerves compromises the muscular innervation, so that these undergo atrophy that can cause deformities, such as claw toes or drooping feet.

Mycobacterium leprae also affects other parts of the body, such as the nasal and ear cartilages, causing deformities characteristic of lepromatous leprosy, known as leonine facies or lion's face. Likewise, there is a loss of body hair, losing the eyebrows and eyelashes. Plantar ulcers and nasal mucosa can also lead to significant malformations.

The eyes can also be affected by this infection, which can lead to blindness. On the other hand, testicular involvement is a cause of impotence and infertility by decreasing both testosterone levels and sperm production.

As with many other infectious diseases, an immune reaction is triggered in lepromatous leprosy that can cause fever, joint pain, and inflammation of various chains of nodes.

Diagnosis

The diagnosis of leprosy will be basically clinical, with the observation of the characteristic lesions and the existence of a possible contact with someone affected by the disease. A certain diagnosis will be made by observing a sample of affected tissue under the microscope obtained either by biopsy or by scraping the skin lesions. Bacterial cultures are not useful for the detection of this disease, so they are not carried out.

There is a reactive skin test that allows to differentiate the form of leprosy that the patient suffers. A small number of attenuated mycobacteria are inoculated subcutaneously and observed for reaction. In the tuberculous form, in which the immune system creates antibodies against Mycobacterium leprae, a skin reaction will occur, while in the severe form, the lepromatous, no type of reaction will be appreciated, since the organism is not capable of create defense antibodies against disease-causing bacteria.

Treatment

Despite the common belief, leprosy is an easily treatable disease through the use of antibiotics. Early treatment of the disease can prevent and correct most of the deformities caused by this disease.

Without treatment for a long time, in the 1940s, dapsone, an antibiotic that worked very well in the treatment of leprosy, was developed. Later, in the mid-1960s, other antibiotics also useful for the treatment of this disease were discovered, such as rifampicin or clofazimine.

Initially, a single antibiotic was given, generally dapsone, but when cases of resistance to it began to appear, the combined treatment of three antibiotics was established and so far no resistance to combined antibiotic therapy has been detected. Other therapeutic options are clarithromycin, quinolones, or minocycline. antibiotic treatment must be carried out for a long time, since the mycobacterium is difficult to eradicate due to its slow reproduction cycle, so the medication must be taken between six months and years, sometimes being necessary treatment for life.

General symptoms caused by the inflammatory reaction can be treated with non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, or immunosuppressants.

Precautionary measures

The main preventive measure is to avoid continuous and close exposure to patients affected by leprosy. However, the isolation of these patients is not medically justified, since only the lepromatous form is contagious and, despite everything, contagion to healthy and immunocompetent people is difficult.

• Leprosy or Hansen's disease is caused by bacteria that affect the skin and peripheral nerves.
• It can manifest as tuberculoid leprosy (mild form) or as lepromatous leprosy (severe and better known form).
• It can affect the nasal and ear cartilages, causing facial deformities known as leonine facies.