Question

Describe one of the worst infectious disease outbreaks in history. Identify the causative microorganism. Using the resources available on the Internet, describe in detail how this organism would be identified in a modern laboratory today. Please specify the type of specimen to be studied and the exact tests that would be used for preliminary and final identification. Please describe the appropriate treatments that are available today .

Note: Initial answers to the discussion question have to be substantive and in the range of 250 to 400 words. Any references used should be properly cited following APA formatting guidelines.

Answer 1

Smallpox, which was considered as one of the brutal killers in human history, has killed between 300-500 million people in its 12,000 year existence. Thousands of years ago, variola virus (smallpox virus) emerged and began causing illness and deaths in human populations, with smallpox outbreaks occurring from time to time.

Smallpox was a serious infectious disease caused by the variola virus. It was contagious, it spread from one person to another. People who had smallpox had a fever and a distinctive, progressive skin rash. Most people with smallpox recovered, but about 3 out of every 10 people with the disease died. Many smallpox survivors have permanent scars over large areas of their body, especially their faces.

Before smallpox was eradicated, it was mainly spread by direct and fairly prolonged face-to-face contact between people. Smallpox patients became contagious once the first sores appeared in their mouth and throat (early rash stage). They spread the virus when they coughed or sneezed and droplets from their nose or mouth spread to other people. They remained contagious until their last smallpox scab fell off. These scabs and the fluid found in the patient’s sores also contained the variola virus. The virus can spread through these materials or through the objects contaminated by them, such as bedding or clothing. People who cared for smallpox patients and washed their bedding or clothing had to wear gloves and take care to not get infected. Rarely, smallpox has spread through the air in enclosed settings, such as a building (airborne route).

Diagnosis

• A simple, rapid, reliable and sensitive diagnostic assay would be essential for effective medical and public health countermeasures in the event of a variola virus release. The first genetic techniques used to specifically identify variola virus used RFLP analysis of viral genomic DNA, but this approach is slow to perform.
• PCR based methods offer an alternative for rapid diagnosis, and RFLP assays of PCR amplicons from the A-type inclusion protein or the haemagglutinin protein genes have been described. Orthopoxvirus (OPV) whole genome sequences are now available for the principle species of the genus including ectromelia, camelpox, monkeypox, cowpox, vaccinia and variola viruses, an important resource for designing new PCR based assays.
• Definitive laboratory identification of variola virus involves growing the virus on chorioallantoic membrane (part of a chicken embryo) and examining the resulting pock lesions under defined temperature conditions. Strains may be characterized by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Serologic tests and enzyme linked immunosorbent assays (ELISA), which measure variola virus-specific immunoglobulin and antigen have also been developed to assist in the diagnosis of infection.

Prevention and Treatment

There is no proven treatment for smallpox disease, but some antiviral drugs may help treat it or prevent it from getting worse. There also is a vaccine to protect people from smallpox. If there were a smallpox outbreak, health officials would use the smallpox vaccine to control it.

• Smallpox Vaccine

​The smallpox vaccine protects people from smallpox by helping their bodies develop immunity to smallpox. The vaccine is made from a virus called vaccinia, which is a poxvirus similar to smallpox, but less harmful. The smallpox vaccine contains live vaccinia virus, not a killed or weakened virus like many other vaccines. For that reason, people who are vaccinated must take precautionswhen caring for the place on their arm where they were vaccinated, so they can prevent the vaccinia virus from spreading.

Smallpox can be prevented by the smallpox vaccine. If you get the vaccine before contact with the virus, the vaccine can protect you from getting sick. Within 3 days of being exposed to the virus, the vaccine might protect you from getting the disease. If you still get the disease, you might get much less sick than an unvaccinated person would. Within 4 to 7 days of being exposed to the virus, the vaccine likely gives you some protection from the disease. If you still get the disease, you might not get as sick as an unvaccinated person would. Once you have developed the smallpox rash, the vaccine will not protect you. Currently, the smallpox vaccine is not available to the general public because smallpox has been eradicated, and the virus no longer exists in nature.

• Antiviral Drugs

In laboratory tests, Tecovirimat has been shown to be effective against the virus that causes smallpox. In laboratory settings this drug was effective in treating animals which had diseases similar to smallpox. Tecovirimat has not been tested in people who are sick with smallpox, but it has been given to healthy people. Test results showed that it is safe and causes only minor side effects.
In laboratory tests, Cidofovir and Brincidofovir have been shown to be effective against the virus that causes smallpox. In laboratory settings this drug was effective in treating animals which had diseases similar to smallpox. Cidofovir and Brincidofovir have not been tested in people who are sick with smallpox, but they have been tested in healthy people and in those with other viral illnesses. Test results indicate that Brincidofovir may cause fewer side effects than Cidofovir, which can be toxic to kidneys.