| Country | Major infectious diseases |
| Grenada | void |
| Guam | void |
| Guatemala | degree of risk: intermediate food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever vectorborne disease: dengue fever and malaria (2008) |
| Guernsey | void |
| Guinea | degree of risk: very high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne diseases: malaria and yellow fever water contact disease: schistosomiasis respiratory disease: meningococcal meningitis aerosolized dust or soil contact disease: Lassa fever (2008) |
| Guinea-Bissau | degree of risk: very high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne diseases: malaria and yellow fever water contact disease: schistosomiasis respiratory disease: meningococcal meningitis (2008) |
| Guyana | degree of risk: high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne diseases: dengue fever and malaria water contact disease: leptospirosis (2008) |
| Haiti | 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 water contact disease: leptospirosis (2008) |
| Heard Island and McDonald Islands | void |
| Holy See (Vatican City) | void |
| Honduras | 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 (2008) |
| Hong Kong | void |
| Hungary | degree of risk: intermediate food or waterborne diseases: bacterial diarrhea and hepatitis A vectorborne diseases: tickborne encephalitis (2008) |
| Iceland | void |
| India | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A and E, and typhoid fever vectorborne diseases: chikungunya, dengue fever, Japanese encephalitis, and malaria 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 (2008) |
| Indian Ocean | void |
| Indonesia | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A and E, and typhoid fever vectorborne diseases: chikungunya, dengue fever, and malaria 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 (2008) |
| Iran | degree of risk: intermediate food or waterborne diseases: bacterial diarrhea and hepatitis A vectorborne diseases: Crimean Congo hemorrhagic fever and malaria 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 (2008) |
| Iraq | degree of risk: intermediate food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever 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 (2008) |
| Ireland | void |
| Isle of Man | void |
| Israel | void |
| Italy | void |
| Jamaica | void |
| Jan Mayen | void |
| Japan | void |
| Jersey | void |
| Jordan | void |
| Kazakhstan | void |
| Kenya | degree of risk: high food or waterborne diseases: bacterial and protozoal diarrhea, hepatitis A, and typhoid fever vectorborne disease: malaria water contact disease: schistosomiasis (2008) |
| Kiribati | void |
| Korea, North | void |
| Korea, South | void |