Viruses are pathogens of the following diseases except

Step 1: Analyze the question We need the disease that is NOT caused by a virus. Three options are viral, and one is caused by something else.

Step 2: Recall the causes of each disease

| Disease | Causative agent | Type | |---|---|---| | Tuberculosis | Mycobacterium tuberculosis | Bacterium | | Measles | Measles virus (Morbillivirus) | Virus | | Small pox | Variola virus | Virus | | Poliomyelitis | Poliovirus | Virus |

Step 3: Eliminate the options

• B. Measles is viral, so it is not the answer.
• C. Small pox is viral (variola virus), so it is not the answer.
• D. Poliomyelitis is viral (poliovirus attacks the nervous system), so it is not the answer.
• A. Tuberculosis is bacterial, caused by Mycobacterium tuberculosis, so it is the exception.

Step 4: Answer The correct option is A. Tuberculosis.

Tip: Group diseases by their pathogen type to remember them.

• Bacterial: Tuberculosis, Cholera, Typhoid, Tetanus, Leprosy, Gonorrhoea
• Viral: Measles, Small pox, Polio, Mumps, Chicken pox, HIV/AIDS, Rabies, Yellow fever

A useful memory hook is "TB = Bacteria." Also, antibiotics work on bacterial diseases like TB, but not on viral ones.