Biology · Human Health and Diseases · NEET
| Cause | Caused by a pathogen (bacteria, virus, fungus, protozoan, worm) | No pathogen; caused by internal/genetic/lifestyle factors |
| Spread | Can spread person to person (communicable) | Cannot spread (non-communicable) |
| Prevention | Hygiene, vaccination, vector control | Cannot be prevented by hygiene or vaccines |
| Example | Typhoid, malaria, common cold, ringworm | Cancer, diabetes, genetic disorders |
An infectious disease is caused by a pathogen (a disease-causing organism) and can spread from one person to another. A non-infectious disease is not caused by a pathogen and cannot spread. This is the single test NEET wants you to apply: ask 'Is there a pathogen, and can it pass to another person?' If yes to both, it is infectious.
Cancer is non-infectious. It is caused by uncontrolled division of the body's own cells (due to carcinogens, oncogenes, radiation, etc.), not by a germ passing from another person. You cannot 'catch' cancer from a patient. NCERT uses cancer as the classic example of a non-infectious disease, so this is a common NEET point.
No. Only infectious diseases are caused by pathogens (bacteria, viruses, fungi, protozoa, helminths). Many diseases have no pathogen at all: cancer, diabetes, and genetic disorders. So 'disease' is a wide word, and 'pathogen' explains only one group of them.
Communicable means the disease can be passed (communicated) from person to person. For NEET, infectious and communicable are treated as the same thing. Non-infectious diseases are also called non-communicable, meaning they do not pass between people.
Because prevention depends on it. Infectious diseases are controlled by hygiene, vaccination, and vector control (breaking the spread). Non-infectious diseases cannot be stopped by these methods, since nothing is spreading. NEET often frames prevention questions around this logic.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Typhoid, pneumonia, common cold, malaria, amoebiasis, ascariasis, elephantiasis (filariasis), and ringworm are all infectious. Each is caused by a specific pathogen and can spread through water, food, air, or a vector like a mosquito.
Cancer is the main NCERT example. Others include diabetes, high blood pressure, and inherited genetic disorders. These are not caused by pathogens and do not spread between people.
No. The classification depends on the cause. If there is no pathogen and no way to spread it, the disease stays non-infectious. The cause does not change into a germ.
Bacteria, viruses, fungi, protozoans, and helminths (worms). NCERT lists these as the disease-causing organisms (pathogens). Learning which pathogen causes which disease is a high-yield NEET skill.
