| Country | Major infectious diseases |
| Greece | void |
| Greenland | void |
| Grenada | void |
| Guam | void |
| Guatemala | degree of risk: high food or waterborne diseases: bacterial diarrhea, hepatitis A, and typhoid fever vectorborne disease: dengue fever and malaria water contact disease: leptospirosis (2009) |
| 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 animal contact disease: rabies aerosolized dust or soil contact disease: Lassa fever (2009) |
| 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 animal contact disease: rabies (2009) |
| 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 (2009) |
| 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 (2009) |
| 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 (2009) |
| Hong Kong | void |
| Hungary | degree of risk: intermediate food or waterborne diseases: bacterial diarrhea and hepatitis A vectorborne diseases: tickborne encephalitis (2009) |
| Iceland | void |