Q.The substance produced by a cell in viral infection that can protect other cells from further infection is:

Biology Disease Control — A First Look

Think of your body as a city. Every day, germs (bacteria, viruses, fungi, parasites) try to enter — through the air you breathe, the food you eat, a cut on your skin. Most of the time, your body's defence systems stop them before you even notice. That's immunity, your natural security force.

But sometimes the invaders break through. You get a fever, a cough, an infection. Now you need disease control — the set of actions that stop the illness from spreading and help you recover.

What exactly is disease control?

In biology, disease control means reducing the incidence (new cases), prevalence (total cases), or transmission of a disease. It's not about wiping out every germ — that's impossible. It's about keeping the disease at a level where it no longer threatens public health.

The NCERT textbook divides disease control into two broad approaches:

1. Preventive measures — stopping the disease before it starts

These are actions taken by individuals, communities, and governments to block the entry of pathogens.

• Vaccination — training your immune system to recognise a germ before it attacks. This is the single most powerful tool in disease control.
• Sanitation and hygiene — clean drinking water, proper sewage disposal, handwashing. Many diseases (cholera, typhoid, hepatitis A) spread through contaminated water or food.
• Vector control — killing or avoiding the organisms that carry disease. Mosquito nets, insect repellents, draining stagnant water — these control malaria, dengue, chikungunya.
• Quarantine and isolation — separating sick people from healthy ones during outbreaks. You saw this during COVID-19.

2. Curative measures — treating the disease once it occurs

Even with the best prevention, some people will fall ill. Curative measures aim to:

• Reduce the severity of the illness (e.g., antibiotics for bacterial infections, antiviral drugs for flu)
• Shorten the duration of the illness
• Prevent complications and death
• Stop the patient from infecting others

The key point: treatment alone cannot control a disease in a population. If you only treat sick people without preventing new infections, the disease keeps circulating.

Why does disease control matter for society?

A single outbreak can paralyse a city. Schools close, hospitals overflow, businesses shut down. The economic cost is enormous. That's why disease control is not just a medical issue — it's a public health issue.

The NCERT textbook emphasises that disease control requires community participation. No matter how good the doctors or vaccines are, if people refuse to vaccinate their children or ignore hygiene, the disease will keep spreading. …