Human diseases are often caused by bacteria, viruses and other microbes. Identifying the causative agent of a disease is a common exam question in general science.
Bacterial Diseases
- Tuberculosis (TB): caused by Mycobacterium tuberculosis; affects the lungs.
- Cholera: caused by Vibrio cholerae; affects the intestine.
- Typhoid: caused by Salmonella typhi.
- Tetanus, Plague and Leprosy are also bacterial.
Viral Diseases
- Polio, Measles, Mumps and Chickenpox.
- Dengue and Chikungunya: spread by mosquitoes.
- Influenza, Hepatitis and AIDS.
- AIDS is caused by the HIV virus.
Diseases Caused by Protozoa
Malaria is caused by the protozoan Plasmodium and spread by the female Anopheles mosquito. Amoebic dysentery is caused by Entamoeba.
Advertisement
Mode of Spread
- Air: TB, influenza, measles.
- Water and food: cholera, typhoid.
- Insects (vectors): malaria, dengue.
- Contact: AIDS, hepatitis B.
Important Facts
Antibiotics work against bacteria but not viruses. Vaccines build immunity against diseases. The female Anopheles mosquito spreads malaria, while the Aedes mosquito spreads dengue.
Quick Revision Points
- Malaria is caused by Plasmodium (Anopheles mosquito).
- Dengue is spread by the Aedes mosquito.
- TB is a bacterial disease of the lungs.
- AIDS is caused by the HIV virus.
- Antibiotics act on bacteria, not viruses.
- Cholera and typhoid spread through water.
- Polio and measles are viral diseases.