Infectious

Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They're normally harmless or even helpful. But under certain conditions, some organisms may cause disease.

Causes

Infectious diseases can be caused by:

• Bacteria. These one-cell organisms are responsible for illnesses such as streptococcus, staphylococcus, and pneumonia.
• Viruses. Even smaller than bacteria, viruses cause a multitude of diseases — ranging from the common cold to AIDS.
• Fungi. Many skin diseases, such as ringworm and athlete's foot, are caused by fungi. Other types of fungi can infect your lungs or nervous system.
• Parasites. Malaria is caused by a parasite that is transmitted by a mosquito bite. Other parasites may be transmitted to humans from animal feces or from the bite of an insect.

Symptoms

Symptoms of an infectious disease vary but often include fever and fatigue. Mild infections may respond to rest and home remedies, while some life-threatening infections may require hospitalization.

Treatment

Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines. Frequent and thorough hand-washing also helps protect against most infectious diseases.

See also

• Epidemiology
• Infection
• Pathogen
• Vaccine

References

Infectious Resources
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