Facts about smallpox

Introduction

Smallpox, commonly known as Variola, is a highly infectious and contagious illness caused by either of two variants of the Variola Virus, Variola Major or Variola Minor, all of which belong to the Orthopoxvirus Genus. Variola major, the most common strain, is lethal, while Variola minor is not. Variola major smallpox comes in four varieties. The most prevalent types are ordinary or classic smallpox, hemorrhagic smallpox, which involves blood leakage from body organs into the mucous membranes, malignant smallpox, which is very moderate, and modified smallpox, which affects individuals who have been vaccinated but still respond to the vaccine (Levine, 2007).

Virus Structure and Replication

The Virus is large, rectangular-shaped, double-stranded, and in an envelope made of the host’s cell membrane. Unlike other DNA viruses that multiply in the nucleus, the Variola virus replicates in the cytoplasm. It cannot survive in the environment for an extended period, but is maximumly stable at low temperatures and humidity. When stained with Eosin and Hematoxylin, the virus looks like pink blobs. In this paper, I will do an in-depth discussion of the epidemiology of the smallpox virus, how it's transmitted, its pathogenicity, diagnosis, Treatment, and prevention.

Transmission

Smallpox only affects human beings with no carrier state and no known natural reservoir for the virus. It is transmitted mainly through droplet inhalation of viral particles or spread onto the mucous membranes of the respiratory and oropharyngeal tracts. The virions are typically found in the mouth and nose secretions of an infected person. There has been documentation of transmission through close personal contact over extended time, fomite transmission, and airborne transmission over long distances (Shors, 2016). The infectious dose is assumed to be very low, but patients in prodromal phase are not considered infectious. However, people should be regarded as infectious from the onset of fever since the virus is already present in the mucous membranes and oral lesions ulcerate before the start of the rash. The virus is presumed to be at the peak of infectiousness during the first week after onset of the rash when large quantities of the virus are released into the saliva from the ulcerating lesion in the mouth. The period of communicability persists till all sores have scabbed over and final scabs have fallen off, though some viable viral particles can still be detected in the crusts.

Pathogenesis

Upon entry, the virus affects the body’s macrophages in the first seventy-two hours. The incubation period, in most cases, lasts from seven to seventeen days, and within this time, the virus is considered not infectious and is asymptomatic. The virus, however, is rapidly multiplying during this period in the lymphoid organs. The virus avoids detection from the immune system by using Complement Regulatory Protein. After the genetic material is inside the cell, it quickly multiplies but does not destroy the cell. After the incubation period, the signs and symptoms start showing, the most prominent being a fever (Craighead, 2000). Early symptoms mirror those of influenza and the common cold, malaise, headache and body aches. Later, the virus multiplies so fast that the cells begin to erupt, and the severity of symptoms increases rapidly. On the skin, a maculopapular rash which later results into fluid-filled blisters spreads on the arms, legs, face and inside the mouth. The blisters then get bigger and fill with pus by the seventh day. By the twelfth day, the pus-filled blisters start deflating and drying up forming crusts (Parija, 2009). At this stage, confusion and stomach pains may also be present. Between the sixteenth and twentieth day, all lesions have formed crusts, which start to flake off, leaving pitted depigmented scars on the skin.

Epidemiology

In October 1977, the last endemic case of smallpox was recorded in Somali, and 1949 in the United States. The World Health Organization declared smallpox eradicated in 1980 after a global immunization campaign. There have not been any reported cases of smallpox since then.

History

The virus is believed to have originated from an African rodent thousands of years ago, before civilization, with initial evidence seen in a mummified body of a Pharaoh of Egypt. In the late years of 18th century, smallpox killed around four hundred thousand Europeans every year and was the cause of blindness in a third of the population (Ian Glynn, 2004). When administered within seven days of exposure, the vaccine prevents the disease or reduces the risk of infection in most people. However, the vaccine is now not available to the public since the eradication of the virus. There are only two facilities in the world where the virus resides, the CDC facility in Atlanta, and in Russia, at the Russian State Centre for Research on Virology and Biotechnology. Presently, the people at risk of getting infected are people working in these facilities.

Diagnosis, Treatment and Prevention

Smallpox can sometimes be confused with chickenpox, but microscopic examination and close observation of the lesions differentiates the two. Smallpox has no known cure, but cidofovir can be given within two days of exposure to prevent infection. The only other option is the smallpox vaccine, which provides protection two days after administration.

Conclusion

Small pox is fatal and claimed lots of lives in the 18th century, the government should always be ready in case of an epidemic in hospitals and government facilities. Despite its eradication in 1980, there have been concerns that the virus does not reside in the stipulated facilities and could be used as a biological weapon of mass destruction (Ian Glynn, 2004). Due to its highly contagious state, protocols should be put in place for isolation of any identified cases, and the mass educated on signs and symptoms of infection, and what to do in case of exposure.

References

Craighead, J. E. (2000). Pathology and Pathogenesis of Human Viral Disease. Academic Press.

Ian Glynn, J. G. (2004). The Life and Death of Smallpox. Cambridge University Press.

Levine, R. (2007). Case Studies in Global Health: Millions Saved. Jones & Bartlett Publishers.

Parija. (2009). Textbook of Microbiology & Immunology. Elsevier India.

Shors, T. (2016). Understanding Viruses. Jones & Bartlett Publishers.