First infectious disease against which effective method of prevention developed was a _:

Explanation

a. Bacterial disease: Bacterial diseases were among the first for which effective prevention methods were developed. Vaccination, such as the smallpox vaccine developed by Edward Jenner, is a notable example. b. Viral disease: This option is correct. The smallpox vaccine, developed in the late 18th century by Edward Jenner, is a landmark achievement in the prevention of viral diseases. It played a crucial role in the eventual global eradication of smallpox. c. Protozoan disease: Protozoan diseases are caused by single-celled organisms (protozoa). Prevention methods for these diseases often involve medications (antiprotozoal drugs) rather than vaccines. Malaria, caused by the Plasmodium protozoan, is an example of a protozoan disease with preventive measures like antimalarial drugs and bed nets. d. Viroid disease: Viroids are infectious agents consisting of small, circular RNA molecules. They cause diseases in plants. Preventive methods for viroid diseases typically involve plant hygiene and control measures, as there are no widely recognized vaccines for viroids. Correct Answer: b. Viral disease Explanation: The smallpox vaccine is a historic example of the first effective prevention method developed against a viral disease, marking a significant milestone in the history of infectious disease control. Summary: The correct answer is b. Viral disease. The smallpox vaccine, developed for the prevention of smallpox caused by the variola virus, is a groundbreaking achievement in the history of infectious disease prevention. While bacterial diseases also saw early success with vaccination, the smallpox vaccine stood out as a pivotal moment in addressing viral infections and contributed to the eventual global eradication of smallpox.