Leprosy (Hansen’s disease) - Frequently Asked Questions for the General Public
What is Leprosy?
Leprosy, also known as Hansen’s disease, is a curable chronic infectious disease caused by a bacterium called Mycobacterium leprae (M. leprae).
Historically, Leprosy was once feared as a highly contagious and devastating disease. However, following an initiative from the World Health Organization (WHO) to eliminate Leprosy, drug treatment was made available free of charge to all patients worldwide since 1995. The elimination of Leprosy as a public health problem was achieved in 2000. Now, the disease is rarely seen; but when seen, it can be easily and effectively treated. It currently has a worldwide prevalence rate of 16.9 per 1 million persons, of which most cases are found in Africa and Asia.
There are 3 main types of Leprosy: lepromatous, tuberculoid, and borderline. Tuberculoid Leprosy is not related to tuberculosis (TB). In lepromatous Leprosy, the immune response is poor, and the infection is more contagious.
What are the symptoms of Leprosy?
Leprosy affects certain parts of the body such as the skin, peripheral nerves (e.g. nervous system outside of the brain and spinal cord), the lining of the upper respiratory tract (e.g.the nose and throat), and the eyes.
The 5 main symptoms of Leprosy are:
- Skin patches that may be red or faded
- Skin patches with diminished or absent sensation
- Numbness or tingling in the hands, feet, arms, and legs
- No pain when wounded or burnt on the hands and feet
- Muscle weakness
Additional symptoms include:
- Thick or stiff skin
- Loss of eyelashes or eyebrows
- Severe pain
- Nasal congestion
- Nose bleeds
Symptoms of advanced disease include:
- Paralysis
- Vision loss
- Nose disfigurement
- Permanent damage to the hands and feet
- Shortening of fingers and toes
- Chronic ulcers on the bottom of the feet that don’t heal
Furthermore, the symptoms are different for the 3 types of Leprosy. In tuberculoid Leprosy, symptoms tend to be milder except for nerve involvement, which is often severe. In lepromatous Leprosy, there is more severe widespread disease involving all systems of the body. Borderline Leprosy presents with a mixture of tuberculoid and lepromatous symptoms.
Because M. leprae grows very slowly, the person who is infected may not have any symptoms for a few months to a few decades. On average, it takes about 5 years for symptoms to occur.
If left untreated, it can lead to progressive and permanent damage to the nerves, leading to loss of sensation and loss of sweating in the hands and feet, and paralysis of muscles in the hands, feet, and face. In women who have been exposed to persons with untreated Leprosy, pregnancy may trigger clinical Leprosy.
How do you get Leprosy?
Leprosy is not highly contagious. However, it can spread from person-to-person due to prolonged close contact with a person who has untreated Leprosy. It is not fully understood how Leprosy spreads, but it is likely through airborne droplets when an infected person coughs or sneezes. If these are inhaled in, you may become sick from the disease. Spread may also occur if these droplets come into contact with broken skin. Untreated pregnant women may pass the infection to the foetus.
Some armadillos in the southern United States of America are naturally infected with Leprosy, however the risk of getting the disease from them is low.
Who is at risk?
Leprosy rarely occurs in Ireland, with most of the diagnosed cases being persons who were infected outside of Ireland. In fact, most adults around the world, face no risk at all. That is because evidence shows that 95% of all adults are naturally unable to get the disease, even if they’re exposed to the bacteria that cause it.
Those at greatest risk of getting Leprosy are:
- Prolonged close contact with someone with untreated Leprosy
- Living in a country where the disease is more common, including
- Angola
- Brazil
- Central African Republic
- Democratic Republic of Congo
- Federated States of Micronesia
- India
- Kiribati
- Madagascar
- Mozambique
- Nepal
- Republic of Marshall Islands
- United Republic of Tanzania.
How is Leprosy diagnosed?
Leprosy is most often diagnosed with a skin biopsy. During this, a healthcare professional will take a small sample of tissue which is then sent to a laboratory for analysis.
How is Leprosy treated?
Leprosy is now curable with multidrug therapy, which means different antibiotics are prescribed. However, these antibiotics can’t treat the nerve damage that occurs, and so early treatment is important to prevent disability.
Medication is administered under the supervision of a medical doctor, usually an Infectious Diseases/Microbiology Consultant. Normally, after 3 months of prescribed treatment by a medical doctor, a person will no longer be able to spread the disease to others.
How can Leprosy be prevented?
Household contacts of a person with Leprosy, especially children, should be examined yearly for at least five years after their last contact with an infectious person. Household contacts of person with lepromatous Leprosy who are less than 25 years of age may be considered for preventive treatment under the care of a medical doctor (usually an Infectious Diseases/Microbiology Consultant).
Is there a vaccine available for Leprosy?
Currently there is no vaccine available for Leprosy. However, there are some vaccines currently undergoing clinical trials.
Further information is available from:
World Health Organization (WHO), 2016. Available URL: https://www.who.int/en/news-room/fact-sheets/detail/leprosy (Accessed: 19th October 2023).
Centre for Disease Control and Prevention (CDC), 2013. Available URL: https://www.cdc.gov/leprosy/ (Accessed: 19th October 2023).
New South Wales (NSW) Australia, 2012. Available URL: https://www.health.nsw.gov.au/Infectious/factsheets/Factsheets/leprosy.PDF (Accessed: 19th October 2023).
Last updated: 19 October 2023