Disease Transmission From Humans, Animals, and Insects

Some bacteria, viruses, and other biological agents can be spread from person to person or from animals or insects to people. The ease of international travel has made many of these health threats more difficult to contain. Recent health threats such as SARS (severe acute respiratory syndrome), the West Nile virus, and monkeypox have made people more aware of how easily disease can spread not only within a community but from one community to the next.

With some exceptions such as smallpox and pneumonic plague, which are contagious diseases, most biological agents that could be used as bioterror weapons are not spread from person to person.

The U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have current, reliable information on communicable diseases and health concerns throughout the world. For updates on specific health emergencies, visit their websites:

• www.cdc.gov
• www.who.int/en
• www.pandemicflu.gov

What you can do

To reduce your chances of being infected with or spreading a contagious disease:

• Wash your hands with soap and water frequently, especially if you live with or come into contact with someone who is sick.
• Do not share bedding, towels, utensils, or other items with someone who is sick or, if you are sick, with anyone else.
• Avoid exposure to disease-carrying animals and insects if you are in an area where these are a problem.
• Follow the advice of local health authorities if there has been a disease outbreak in your community or in an area where you are traveling. It is especially important to follow health experts' instructions if you live or work with someone who becomes sick. For instance, you may be advised to wear a properly fitted surgical mask if you are in close contact with someone who has a serious contagious illness, such as SARS.
• If there is an outbreak of a contagious disease in your area, do not leave the area unless authorities tell you to. If you have already been infected, you may spread the disease. Leaving the area may also cause a delay in your diagnosis or treatment.

Also see the Bioterrorism and Vaccinations section of this topic. A vaccine for smallpox is available for certain high-risk groups but is not recommended for the general public at this time.