Smallpox – Carajás Mail

Smallpox – Carajás Mail

Smallpox was a highly contagious disease characterized by fever, blisters, and pustules with a high mortality rate. A milder form (smallpox) will be caused by the same virus.

The official global eradication of smallpox in 1989 was one of the greatest feats of modern medicine. In the 1980s, smallpox did not reappear. If this pattern continues, the disease that once caused 10% of all deaths in the world will become a disease of major historical significance.

Although smallpox is no longer a subject in medical textbook editions, if it becomes endemic, epidemic or pandemic again, it is wise to continue to prepare to recognize it and prevent its spread. A number of cases are currently being reported around the world, which is worrying public health authorities.

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The oropharynx of an infected person is the main source of virus transmission. Contacts become infected by inhaling the virus, which enters the respiratory tract and multiplies there, possibly in macrophages. The virus is carried into the circulatory system in macrophages and from there to regional lymph nodes. Proliferation occurs in organ lymphoid organs and secondary viremia is present.

The virus localizes to small blood vessels in the dermis, causing telangiectasia, endothelial swelling, and mononuclear cell infiltration. Epidermal cells increase in size and form intraepidermal vesicles on the skin and mucous membranes. The vesicles rupture, forming shallow ulcers, while the epidermal cells enlarge and extend into the chorion.

Viral infection stimulates cytotoxic T cell responses, neutralizing antibodies, and the production of interferons. If the patient recovers, this response limits viral replication and induces prolonged immunity. Smallpox may be more severe in immunocompromised patients, especially those with T-cell deficiencies.

Smallpox was described in Asia in the 1st century AD and in Europe and Africa around 700 AD. The infection spread to Central, South and North America in the 16th and 17th centuries. Endemic smallpox was eradicated in the United States in 1926, and smallpox was eradicated in the 1940s, with a slower rate of eradication in some parts of Asia, Africa, and the Americas. The last natural case of smallpox occurred in Somalia (Africa) in October 1987.

The last known case occurred a year later in September 1979 in Birmingham (England), caused by a laboratory accident. In the 1980s, there was no resurgence of smallpox. The ability to eradicate the disease through an effective global vaccination program appears to have an important relationship with the fact that humans are the only known reservoir of variola virus.

No asymptomatic carriers, easy to control. By rapidly vaccinating contacts, early diagnosis and prevention of disease or its evolution can be altered.

In temperate climates, endemic smallpox occurs in winter and spring. It is basically a disease of children and young adults. Transmission to unvaccinated household contacts was about 58%, compared to 4% for vaccinated people. Overall, patients were severely ill and bedridden, which limited transmission to immediate family members.

Index cases rarely infect more than five patients, more often those who share the same room. Transmission intervals are two to three weeks, with new cases appearing in a community or geographic area for months. That theme will continue in next Tuesday’s edition.

*The author specializes in general surgery and digestive health.

NOTE: The views in this box do not necessarily reflect the views of CORREIO DE CARAJÁS.

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