MCQ Detailed View

Diseases are caused by different types of microorganisms such as viruses, bacteria, protozoa, and fungi. Understanding which microorganism is responsible for a disease helps in choosing the right treatment and preventive measures.

Among the given options, smallpox is the disease caused by a virus. Smallpox is caused by the variola virus, which belongs to the family Poxviridae. It was a highly contagious disease that affected humans for centuries before being completely eradicated worldwide through vaccination programs. Symptoms of smallpox included fever, fatigue, and a distinctive skin rash that developed into fluid-filled pustules. The smallpox virus spread mainly through airborne droplets or direct contact with infected individuals or contaminated objects.

The other diseases listed are not caused by viruses:

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  Tuberculosis (TB): This is caused by a bacterium named Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other parts of the body.

  
  


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  Malaria: This is caused by a protozoan parasite called Plasmodium, transmitted to humans through the bite of infected female Anopheles mosquitoes.

  
  


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  Cholera: This is caused by a bacterium called Vibrio cholerae. It infects the small intestine and leads to severe diarrhea and dehydration.

  
  

Viruses are very different from bacteria or protozoa because they are non-cellular infectious agents that cannot reproduce on their own. They invade living cells of the host and use the host’s cellular machinery to replicate. Vaccination is one of the most effective ways to prevent viral infections like smallpox, measles, polio, and influenza.

In conclusion, smallpox is the correct answer because it is the only disease among the options that is caused by a virus.