Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by the bacterium Mycobacterium leprae. It primarily affects the skin and peripheral nerves and can lead to severe deformities and disabilities if left untreated. The exact mechanism of how leprosy starts is not fully understood, but here's a general overview of the process:
1. Exposure to the Bacterium: Leprosy is thought to be transmitted from person to person through respiratory droplets, similar to how the common cold is spread. Prolonged close contact with an untreated leprosy patient is considered the main mode of transmission. However, not everyone who is exposed to the bacterium will develop the disease. The exact reasons why some individuals become infected while others do not remain a topic of research.
2. Incubation Period: After exposure to Mycobacterium leprae, there is an incubation period that can vary widely, ranging from a few months to several years. During this time, the bacterium multiplies within the body without causing any noticeable symptoms.
3. Immune Response: The development of leprosy is influenced by the individual's immune response to the bacterium. Some people are able to mount an effective immune response that prevents the bacterium from causing disease, while others are more susceptible to infection.
4. Clinical Presentation: When leprosy does manifest clinically, it typically starts with skin lesions or patches that may be discolored and numb. Numbness is a characteristic feature of leprosy because the bacterium has a predilection for peripheral nerves, which can lead to nerve damage and sensory loss.
5. Spectrum of Disease: Leprosy presents as a spectrum of clinical forms, with the two main types being paucibacillary and multibacillary leprosy. Paucibacillary leprosy has fewer bacteria in the body and milder symptoms, while multibacillary leprosy has a higher bacterial load and more severe symptoms. The exact manifestations and progression of the disease can vary from person to person.
It's important to note that early detection and treatment with antibiotics, such as dapsone, rifampicin, and clofazimine, can effectively cure leprosy and prevent its progression to more severe stages. Additionally, public health efforts have been successful in reducing the prevalence of leprosy in many parts of the world. Early diagnosis and prompt treatment are critical in preventing disability and deformities associated with the disease.