V. Read the following text and answer the questions in the Discusion section

SHOULD WE DESTROY THE LAST SMALLPOX VIRUS?

In two freezers, one at the Center for Disease Control and Prevention in Atlanta and another at the Research Institute for Viral Preparations in Moscow, lie the last smallpox viruses on the planet. Infectious disease experts and virologists are debating whether or not to destroy the remaining smallpox virus, called Variola.

Smallpox is the deadliest infectious disease known to strike humans, in terms of numbers of people killed. Smallpox ravaged the Roman Empire and enabled the Spaniards to defeat the Aztecs in Mexico, whose immune systems could not handle the foreign virus. Survivors of smallpox often are left with severe scars. Luckiest were those few individuals who had mild cases and were left with relatively smooth skin plus immunity against reinfection.

English physician Edward Jenner's invention of the first vaccine in 1796, against Variola, was the beginning of the end of the scourge. It took many decades before the vaccine was improved and distributed widely enough to impact upon the disease's prevalence. By 1967, when the World Health Organization (WHO) began its eradication campaign, some 10 million people in 40 nations still contracted smallpox each year.

The WHO campaign was remarkably successful, and in October 1977, the last victim in the general population, a Somali man, died of smallpox. A year later, though, a shocking case prompted public health officials and scientists to question the wisdom of maintaining samples of the virus. A photographer, Janet Parker, acquired smallpox while visiting a laboratory in England that kept the virus, obviously not sufficiently contained. Parker developed smallpox and died. The head of the laboratory, overcome with guilt, killed himself.

In 1979, the world was declared free of smallpox. The Global Commission for the Certification of Smallpox Eradication formed and requested that all Variola samples be destroyed or sent to appropriate facilities. In 1986, WHO raised the idea of destroying all samples, if the scientific and public health communities approved. In 1990, scientists request that the decision be postponed until they could learn the virus’s DNA sequence, so that they could continue to study it. Researches in the United States and the former Soviet Union collaborated and sequenced all 200,000 DNA bases that constitute Variola virus by 1993.

The remaining Variola samples are tentatively scheduled to be destroyed in the following years, though the debate over their fate continues. The "destroy" arguments tend to be political and practical; the "do not destroy" arguments are scientific in tone. The reasoning is as follows:

Destroy!

1. A terrorist could use the stored virus for biological warfare.

2. Damage to the freezers storing the virus — such as from a bomb, earthquake, or other disaster —could unleash a deadly smallpox epidemic.

3. Knowledge of the DNA sequence of Variola will enable researchers to continue studying the virus, without needing the actual virus.

Do Not Destroy!

1. Learning how the smallpox virus evades the human immune system will provide clues on how to combat HIV. Both Variola and HIV seem to infect only humans, and in many cases they defeat the human immune system.

2. Knowing the DNA sequence of a virus is not sufficient to understand how it causes symptoms and evades the immune system.

3. Viral infections reemerge. Should a new virus evolve to fit the niche that Variola occupied, or an existing virus (such as monkeypox) expand and change to affect humans, the lack of supplies of smallpox virus could hamper research.

4. Smallpox could reappear even if we destroy the frozen samples. Variola may have been stored in other laboratories, and smallpox victims buried in Soviet permafrost could some day thaw and release active virus.

A final note is more philosophical. Even though a virus is not technically alive, do we have the right to destroy it? In the words of one researcher, "It's taken millions of years for nature to make the Variola virus, and why should 10 guys sitting around a table say: 'Let's destroy it'?"

Читайте також:

<== попередня сторінка	\|	наступна сторінка ==>
IV. Read the passage below and fill in the blanks with the words from the box	\|	Discussion

Не знайшли потрібну інформацію? Скористайтесь пошуком google:

Генерація сторінки за: 0.003 сек.