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DIFFERENCE BETWEEN SMALLPOX AND CHICKENPOX?

Chickenpox and smallpox are viral infections, which share some of the common characteristics and causes diagnostic confusion.
Chickenpox
Varicella zoster, which belongs to the herpes virus family, is responsible for the disease. It is a DNA virus and has an ability to cause latent infections. The disease transmission is by respiratory droplets and direct contact with the lesions. It is highly infectious and more severe in adults, pregnant women and immune compromised people. Immunity following the disease is a lifelong.
Following an incubation period of 14-21 days vesicular eruption begins, often on the mucosal surfaces first and then rapid dissemination in a centripetal distribution mostly involving the trunk. The rash progresses from small pink macules to vesicles and pustules within 24 hours and then crust. The lesions appear to be in different stages of development. The pocks are more superficial, and the vesicles collapse on puncture.

The lesions are itchy, and scratching can lead to secondary bacterial infection, which is the most common complication. Rare complications involve self-limiting cerebella ataxia, varicella pneumonia, encephalitis and reye’s syndrome specially in children who are on aspirin.
Small pox

It is a severe deadly disease caused by a pox virus. It has a single stable serotype, which is the key to successful eradication. Human is the only reservoir. The disease transmission is by respiratory droplets or direct contact with virus either in the skin lesions or on fomites as bedding. Immunity following the disease is a lifelong.

Following an incubation period of 7-14 days, sudden onset of prodromal symptoms occur such as fever and malaise followed by rash. The lesions are typically deep seated centrifugal vesicular pustular rash worst on the face and the extremities with no cropping. The lesions appear to be in the same stage of development. Vesicles do not collapse on puncture.

The diagnosis is by growing the virus in cell culture or chick embryo or by detecting viral antigen in vesicular fluid.


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