How does smallpox attacks and spreads?
1. Initial Exposure:- Smallpox is primarily transmitted through close contact with an infected person or by inhaling infectious respiratory droplets.
2. Incubation Period:
- After exposure to the smallpox virus, there is an incubation period of approximately 10-14 days before symptoms develop.
3. Onset of Symptoms:
- The first symptoms of smallpox often resemble a flu or cold:
- High fever
- Headache
- Muscle aches
- Back pain
- Weakness
4. Primary Rash:
- Within 2-4 days of the initial flu-like symptoms, a rash develops, typically beginning on the face and spreading to the rest of the body.
5. Evolution of Rash:
- The rash undergoes distinct stages:
- Macules: Flat, red spots
- Papules: Small, raised bumps
- Vesicles: Clear, fluid-filled blisters
- Pustules: Yellow, pus-filled blisters
6. Maximum Rash:
- The pustular rash becomes most pronounced around 3-4 days after the rash's onset.
7. Secondary Spread:
- Infected individuals are highly contagious from the time the rash develops until all the lesions have crusted over.
8. Lesion Progression:
- The pustules eventually rupture, forming scabs that gradually crust over and dry out.
9. Scabbing and Healing:
- The scabs gradually detach over several weeks, leaving behind scars.
10. Duration:
- The infectious period typically lasts for about 2-3 weeks, from the onset of the rash until all the lesions have crusted over.
11. Transmission:
- Smallpox can spread through:
- Direct contact with the infected person's respiratory droplets or pustules
- Indirect contact with contaminated objects, such as clothing or bedding
- Airborne transmission over short distances
12. Complications:
- In severe cases, smallpox can lead to serious complications, including:
- Bacterial infections
- Pneumonia
- Encephalitis (brain inflammation)
- Blindness
- Death
13. Eradication:
- Smallpox is one of the few infectious diseases eradicated through global vaccination efforts. The last known case of naturally occurring smallpox occurred in Somalia in 1977.