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- Smallpox facts
- What is smallpox?
- What is the history of smallpox?
- What causes smallpox?
- What are the risk factors for smallpox?
- Is smallpox contagious, and how long is it contagious?
- What is the incubation period for smallpox?
- How is smallpox transmitted?
- What are smallpox symptoms and signs?
- How do health-care professionals diagnose smallpox?
- What specialists treat smallpox?
- What is the treatment for smallpox?
- Can smallpox be prevented with a vaccine?
- What is the prognosis for smallpox, and what are complications of smallpox?
- Where can people find more information on smallpox?
What are smallpox symptoms and signs?
Fever is the most common initial symptom and can be quite high. This is accompanied by body aches, chills, and headache. Often, the patient is too unwell to get out of bed (malaise). Within 24-48 hours, a rash begins to appear everywhere on the body but especially on the legs, arms, mouth, and face. Pharyngitis (sore throat), abdominal pain, back pain, and occasionally vomiting may also develop. The eyes may also be affected, leading to potential blindness among survivors. Symptoms in children are similar to those in adults. The rash also appears on the palms and soles and goes through stages as the disease progresses. At the beginning, the rash consists of red dots that become raised. The lesions (see Figure 1) rapidly fill with fluid and may turn yellow, resembling pus. Rarely, the rash may start to fill with blood (hemorrhagic smallpox), which is a poor prognostic sign. After one to two weeks, the lesions scab over and eventually fall off, leaving deep scars. One of the defining features of smallpox is that all the lesions on the body are always at the same stage of development. This is in contrast to chickenpox where new lesions form while old ones are healing.
Approximately one-third of people with smallpox died from the infection. People who had an extensive rash were at higher risk of death. People who had only a few lesions or a milder rash had a lower risk of death. Infections caused by the variola minor strain were less severe and death occurred in only approximately 1% of cases.