| Country | Major infectious diseases |
| Bangladesh | degree of risk: high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A and E, and typhoid fever vectorborne diseases: dengue fever and malaria are high risks in some locations water contact disease: leptospirosis animal contact disease: rabies note: highly pathogenic H5N1 avian influenza has been identified in this country; it poses a negligible risk with extremely rare cases possible among US citizens who have close contact with birds (2009) |
| Barbados | void |
| Belarus | void |
| Belgium | void |
| Belize | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever vectorborne diseases: dengue fever and malaria water contact disease: leptospirosis (2009) |
| Benin | degree of risk: very high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne diseases: malaria and yellow fever respiratory disease: meningococcal meningitis animal contact disease: rabies (2009) |
| Bermuda | void |
| Bhutan | degree of risk: intermediate food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne diseases: dengue fever and malaria water contact disease: leptospirosis (2009) |
| Bolivia | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever vectorborne diseases: dengue fever, malaria, and yellow fever water contact disease: leptospirosis (2009) |
| Bosnia and Herzegovina | void |
| Botswana | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever vectorborne disease: malaria (2009) |
| Bouvet Island | void |
| Brazil | void |
| British Indian Ocean Territory | void |
| British Virgin Islands | void |
| Brunei | void |
| Bulgaria | void |