Smallpox

Definition

Smallpox is a highly contagious disease which can cause severe symptoms along with disfiguring scars on the skin. The disease was common before the advent of the vaccine but has been eradicated. This is a result of an extensive immunization program throughout the world. Smallpox is a self limiting viral disease though it can cause widespread scaring on the skin which is more extensive in unvaccinated individuals. It has come to light in recent years as a possible agent in bioterrorism.

Symptoms

Symptoms of smallpox usually appear about 12 days after contracting the infection. The disease can be divided into four phases namely prodromal, eruptive, vesicular and pustular phases. Fever associated with backache, headache and myalgia with abdominal pain and vomiting and/or diarrhea is present in the prodromal phase.

An erythematous rash is seen on the third day of fever which initially appears as flat red spots on the face, hands, forearms and lateral on the trunk. This rash further progresses to small blisters filled with clear fluid and then later fills up with pus (pustular phase). In 10 to 14 days dry crusts form on the lesion which shed off in the next few days leaving deep and disfiguring pitted scars. Such lesion can develop in the mucous membranes of mouth or nose which may break open contaminating the saliva with the virus.

Causes

Smallpox is a viral disease which spreads through respiratory droplets through coughs, sneezes or when a person talks. The virus can spread rarely through contact with contaminated clothing and bedding. Certain strands of smallpox are life threatening whereas others produce mild symptoms. The infection reaches the lungs through droplets and then spreads to the spleen and liver through the bloodstream. This in turn spreads to the skin and produces the skin rash as well as other symptoms.

Treatment

Smallpox is a self limiting viral disease which usually does not require any specific treatment. Only symptomatic treatment is provided along with supportive measures. Antibiotics are given to prevent secondary infections. The infection is rarely fatal. The disease usually affects people with weak immunity or pregnant woman. There is no cure for smallpox.

A vaccine is available but vaccination of smallpox is not carried out routinely or in individuals who are at a low risk of smallpox. Serious complications such as infections of the brain and heart are seen with vaccination so a general vaccination program for smallpox is not indicated. Symptomatic treatment includes providing good nutrition and preventing dehydration. The patients infected with smallpox are kept isolated in a hospital setting to prevent spread of disease.

People who had come in contact with the infected person receive smallpox vaccines which may if not prevent disease then at least reduce its severity. The type of the vaccine used and the method of its administration determines the duration of immunity provided though the vaccine does provide immunity for a period of three to five years and immunity is found to decrease after that. Partial immunity is present for a longer duration.

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