Tuberculosis
History:
Tuberculosis has been known for centuries, with historical records indicating its presence in ancient
Egypt, India, and China. It was first described by the Greek physician Hippocrates around 460 BC.
However, the modern understanding of TB began in the 19th century with the work of Robert Koch, who
identified Mycobacterium tuberculosis as the causative agent in 1882.
Scientific Name:
Mycobacterium tuberculosis a member of the Mycobacteriaceae family.
Common symptoms of tuberculosis include:
- Persistent cough lasting more than three weeks
- Coughing up blood or sputum
- Chest pain
- Unintentional weight loss
- Fatigue
- Fever
- Night sweats
- Chills
If not treated, TB can lead to severe health issues, including:
- Progressive lung damage
- Spread to other parts of the body (extrapulmonary TB), such as the kidneys, liver, bones, and brain
- Increased risk of infections due to weakened immune system
Mode of Transmission:
Tuberculosis is primarily spread through airborne transmission. It occurs when a person with active TB
disease in their lungs coughs, sneezes, speaks, or sings, releasing tiny droplets containing Mycobacterium
tuberculosis into the air. These droplets can be inhaled by others, leading to infection. It is not transmitted
by touching a person or by sharing food or drink. The bacteria typically enter the body through the
respiratory tract.
Cure:
Tuberculosis is treatable and curable with a combination of antibiotics over a period of at least six
months. The standard treatment regimen includes:
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
Preventive measures include vaccination with the Bacillus Calmette-Guérin (BCG) vaccine, especially in
areas where TB is common, and measures to reduce transmission, such as wearing masks and ensuring
proper ventilation in healthcare settings.
Tuberculosis Overview
Stages of Infection:
1. Primary Infection: Initial infection occurs when M. tuberculosis bacilli are inhaled and infect
alveolar macrophages. Most primary infections (95%) are asymptomatic, while a small
percentage progress to clinical disease. Infection is typically not contagious at this stage.
2. Latent Infection: After 3 weeks, the immune system suppresses bacillary growth, leading to a
dormant phase. Bacilli can survive in granulomas for years, with a 5–10% risk of reactivation.
Latent TB is non-contagious.
3. Active Infection: Reactivation of latent TB or reinfection leads to active disease. Symptoms arise
in 5–10% of those infected, often in the lung apices.
Pathophysiology:
•
M. tuberculosis spreads hematogenously during primary infection, seeding various organs.
•
Granulomas form as the immune response contains bacilli, though foci can persist.
Risk Factors for Reactivation:
•
Immunosuppression (e.g., HIV, organ transplantation, TNF inhibitors).
•
Chronic conditions (e.g., diabetes, CKD).
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Lifestyle factors (e.g., tobacco use, significant weight loss).
Manifestations:
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Pulmonary TB: Cavitary lesions, granulomatous necrosis, potential empyema.
•
Extrapulmonary TB: Lymphadenopathy, meningitis, or organ involvement without lung disease.
Progression:
•
Active TB can result from reactivation (common in low-prevalence areas) or reinfection (common
in high-prevalence regions).
•
Disease severity depends on host immunity and organism virulence.
Complications:
•
ARDS, massive hemoptysis, and rapidly fatal TB empyema may occur in severe case
Leprosy
History:
Leprosy, also known as Hansen's disease, has been recognized for centuries. It is believed to have
originated in ancient India and Egypt. The disease was described by the Greek physician Hippocrates
around 460 BC. However, it was not until the 19th century that the bacterium causing leprosy was
identified by Gerhard Armauer Hansen in 1873.
Scientific Name:
Mycobacterium leprae a member of the Mycobacteriaceae family.
Symptoms:
Symptoms of leprosy can vary depending on the type of leprosy (e.g., tuberculoid or lepromatous) and
the individual's immune response. Common symptoms include:
- Skin lesions or patches that may be pale or reddish
- Nerve damage leading to numbness, muscle weakness, and loss of sensation
- Thickened nerves
- Disfiguring sores
- Fever
- Weight loss
If left untreated, leprosy can lead to severe complications, including:
- Permanent nerve damage
- Deformities due to muscle weakness and skin lesions
- Increased risk of infections
- Psychological impact due to disfigurement and stigma
Mode of Transmission:
Leprosy is caused by the bacterium Mycobacterium leprae. It is transmitted through prolonged close
contact with an infected person. The bacteria are believed to enter the body through the respiratory
tract or through breaks in the skin. It is not spread through casual contact, such as touching or sharing
food or drink.
Cure:
Leprosy is treatable with a combination of antibiotics. The standard treatment regimen typically
includes:
- Multi-drug therapy (MDT) with a combination of drugs such as dapsone, rifampin, and clofazimine
- Treatment duration usually lasts from 6 to 12 months
Early diagnosis and treatment are crucial to prevent the progression of the disease and to avoid
complications. Multidisciplinary care, including dermatological, neurological, and psychological support,
is often necessary to manage the various aspects of the disease. Preventive measures include early
detection and isolation of infected individuals, as well as public health initiatives to reduce transmission.
Leprosy Overview
Stages of Infection:
1. Early Infection: Caused by Mycobacterium leprae, leprosy begins when the bacteria infect
peripheral nerves and skin. The incubation period varies from months to years. Early symptoms
include numbness, pale patches, or nodules on the skin.
2. Latent/Intermediate Phase: The infection progresses slowly, with immune response determining
the severity and type of disease. It is not always contagious in this phase.
3. Advanced Disease: Without treatment, leprosy causes nerve damage, skin deformities, and
disability.
Pathophysiology:
•
M. leprae primarily affects cooler parts of the body (e.g., skin, peripheral nerves, mucosa).
•
The bacteria are intracellular and replicate slowly within Schwann cells and macrophages.
Types of Leprosy (based on immunity):
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Tuberculoid Leprosy: Strong immune response limits the disease; few skin lesions and localized
nerve damage.
•
Lepromatous Leprosy: Weak immune response allows widespread bacterial multiplication,
leading to numerous lesions, nerve damage, and systemic involvement.
•
Borderline Forms: Features of both types, with variable severity.
Risk Factors for Disease Progression:
•
Prolonged close contact with untreated patients.
•
Genetic predisposition (specific HLA types).
•
Immunosuppression (e.g., HIV, malnutrition).
Transmission:
•
Spread occurs through prolonged exposure to nasal droplets from untreated cases.
•
Not highly contagious; about 95% of people have natural immunity.
Manifestations:
•
Skin lesions: Hypopigmented or reddish patches, nodules, or thickened dermis.
•
Nerve damage: Numbness, weakness, muscle atrophy, and deformities (e.g., claw hand).
•
Systemic involvement: Eye damage, nose deformities, or secondary infections.
Complications:
•
Permanent nerve damage and disability if untreated.
•
Reactions (Type 1 or Type 2) causing inflammation, fever, or pain, often requiring steroids or
other therapies.
Treatment:
•
Multi-drug therapy (MDT) combining dapsone, rifampin, and clofazimine is highly effective and
prevents transmission. Early treatment reduces complications.