Different areas of the world have different diseases and different prevalence rates of disease. Factors that contribute to these differences include climate (tropical, subtropical, temperate, arid, and so forth), native insects, parasites and animals, and population density.

Travelers to foreign countries (any country not of the traveler's origin) may encounter diseases to which they have no natural immunity, to which they are not exposed in their own country, and which are likely to have a significant impact on their health.

Below is a listing of countries and some of the diseases you may encounter there. The risk of infectious diseases varies in different countries, and depends on local conditions, including local outbreaks of particular diseases. The Centers for Diseases Control and Prevention (CDC) routinely updates information on the risk of particular diseases for travelers planning to visit different countries. This up-to-date information (called the "CDC Yellow Book") can be obtained by calling the CDC at 1-800-311-3435. In addition, the Yellow Book and additional information for travelers is found on the CDC website (www.cdc.gov/travel). This information is updated frequently. Prior to traveling, you may want to read about the individual diseases that are common in the areas you are planning to visit.

Northern Africa (Algeria, Egypt, Libyan Arab Jamahiriya, Morocco, Tunisia)

• Insect-borne diseases (uncommon here, but may be encountered): leishmaniasis, malaria, relapsing fever, Rift Valley fever, typhus, sandfly fever, West Nile fever
• Water and food-borne diseases: dysentery (caused by many different organisms), cholera, Hepatitis A, typhoid fever, giardiasis, brucellosis, echinococcosis, intestinal worms (helminthic infections), poliomyelitis (polio)
• Rabies

Nile delta

• Filariasis, schistosomiasis

Libyan Arab Jamahiriya

• Plague

Sub-Saharan Africa

• Insect-borne diseases (very common here): malaria, filariasis, onchocerciasis (river blindness), cutaneous and visceral leishmaniasis, sleeping sickness (trypanosomiasis), relapsing fever, typhus, plague, yellow fever, hemorrhagic fevers (such as Dengue hemorrhagic fever, etc.)
• Water- and food-borne diseases: intestinal worms (helminthic infection), dysentery, giardiasis, typhoid fever, Hepatitis A, Hepatitis E, cholera, dracunculiasis, echinococcosis, poliomyelitis
• Other: Hepatitis B, trachoma, Lassa fever, Ebola fever, Margburg fever, meningococcal meningitis

Southern Africa

• Insect-borne diseases: malaria, plague, relapsing fever, Rift Valley fever, tick-bite fever, typhus
• Water- and food-borne diseases: amebiasis, typhoid fever
• Other: Hepatitis B, rabies

Botswana, Namibia

• Sleeping sickness (trypanosomiasis), schistosomiasis

South Africa, Swaziland

• Schistosomiasis

North America

• Insect-borne: Lyme disease, and rare cases of Rocky Mountain spotted fever and tularemia
• Water- and food-borne diseases: rare outbreaks of cryptosporidium, rare giardiasis
• Other: extremely rare case of rabies

Central America (general area)

• Insect-borne diseases: malaria, cutaneous and mucocutaneous leishmaniasis, American trypanosomiasis (Chagas disease), dengue fever, Venezuelan equine encephalitis
• Water- and food-borne diseases: amoebic dysentery, dysentery, typhoid fever, cholera, Hepatitis A, intestinal worms (helminthic infection)
• Other: rabies

El Salvador, Guatemala, Honduras, Mexico

• Visceral leishmaniasis

Mexico, Guatemala

• Onchocerciasis

Costa Rica

• Filariasis

Caribbean Islands

• Insect-borne diseases: see below
• Water- and food-borne diseases: Hepatitis A, dysentery, amebic dysentery 
• Other: see below

Costa Rica, Honduras, Panama

• Oriental lung fluke (paragonimiasis)

Dominican Republic

• Malaria, schistosomiasis

Cuba

• Liver fluke (Fasciola hepatica)

Haiti

• Malaria, tularemia

Guadeloupe, Martinique, Saint Lucia

• Schistosomiasis

Tropical South America

• Insect-borne diseases: malaria, American trypanosomiasis (Chagas disease), cutaneous and mucocutaneous leishmaniasis, yellow fever, viral encephalitis, Dengue fever
• Water- and food-borne diseases: amebiasis, dysentery, intestinal worms, helminthic infections, Hepatitis A

Brazil, Colombia, Venezuela

• Visceral leishmaniasis

Brazil, Guyana, Suriname

• Filariasis

Bolivia, Brazil, Ecuador, Peru

• Plague

Colombia, Peru

• Typhus

Temperate South America

• Insect-borne diseases: American trypanosomiasis (Chagas disease)
• Water- and food-borne diseases: salmonellosis, tapeworm (taeniasis), typhoid fever, echinococcosis, Hepatitis A
• Anthrax

Argentina

• Malaria, cutaneous leishmaniasis, cholera, Hepatitis A, rabies

Chile

• Cholera

East Asia (general area)

• Insect-borne diseases: see below
• Water- and food-borne diseases: Hepatitis A, diarrheal diseases, oriental liver fluke (clonorchiasis), oriental lung fluke (paragonimiasis)
• Other: Hepatitis B
• Rabies

China

• malaria, visceral leishmaniasis, plague, typhus, trachoma, leptospirosis

Mongolia

• Korean hemorrhagic fever, Japanese encephalitis, Dengue fever

Japan, Republic of Korea

• Scrub typhus

Southeast Asia

• Insect-borne diseases: malaria, filariasis, plague, Japanese encephalitis, Dengue fever, Dengue hemorrhagic fever, typhus
• Water- and food-borne diseases: cholera, dysentery, amebic dysentery, typhoid fever, Hepatitis A, Hepatitis E, giant intestinal fluke (fasciolopsiasis), paragonimiasis, melioidosis
• Other: Hepatitis B, schistosomiasis
• Rabies

Vietnam

• Plague, trachoma

Indochina, Myanmar, Thailand

• Trachoma

Indian subcontinent

• Insect-borne diseases: malaria, filariasis, sandfly fever, visceral leishmaniasis, cutaneous leishmaniasis, relapsing fever, typhus, dengue fever, hemorrhagic fevers
• Water- and food-borne diseases: cholera, typhoid fever, Hepatitis A, Hepatitis E, intestinal worms (helminthic infections), brucellosis, echinococcosis
• Other: Hepatitis B, poliomyelitis, trachoma,
• Rabies

Islamic Republic of Iran

• Giardiasis

India, Nepal

• Meningococcal meningitis

The Middle East

• Insect-borne diseases: cutaneous leishmaniasis, typhus, relapsing fever
• Water- and food-borne diseases: typhoid fever, hepatitis A, tapeworm (taeniasis), brucellosis, echinococcosis
• Other: hepatitis B, schistosomiasis

Northern Europe (general area)

• Insect-borne diseases: rare occurrences of tick-borne encephalitis, Lyme disease, Crimean-Congo hemorrhagic fever
• Water- and food-borne diseases: tapeworm, trichinellosis, fish tapeworm (diphyllobothriasis), liver fluke (Fasciola hepatica), Hepatitis A
• Other: rabies

Siberia

• Typhus

Russian Federation, Ukraine

• diphtheria

Southern Europe (general area)

• Insect-borne diseases: murine and tick-borne typhus, West Nile fever, tick-borne encephalitis, Lyme disease
• Water- and food-borne diseases: dysentery, typhoid fever, brucellosis, echinococcosis, Hepatitis A
• Other: Hepatitis B, rabies

Australia, New Zealand, Antarctic

• Insect-borne diseases: mosquito-borne polyarthritis, viral encephalitis
• Water- and food-borne diseases: amebic meningoencephalitis

Melanesia, Micronesia-Polynesia

• Insect-borne diseases: malaria, filariasis, typus, Dengue fever
• Water- and food-borne diseases: dysentery, typhoid fever, intestinal worms (helminthic infections), Hepatitis A
• Other: Hepatitis B, trachoma

MALARIA

Malaria is one of the most important infectious diseases in the world, affecting millions of people every year. Malaria is not a problem in cold climates, and is a lesser problem in temperate climates, but it is a threat to those living or traveling in subtropical and tropical climates.

Resistance of the malaria organism changes rapidly, and frequent updating on resistant strains, especially the falciparum, is necessary for safe travel. Travelers should visit the CDC Web site for complete, up-to-date information: www.cdc.gov/travel. Prophylaxis -- medicine to prevent malaria -- is recommended for travelers to endemic regions. Malaria prophylaxis usually involves taking a medication prior to travel, during travel, and for a short period after returning.

YELLOW FEVER

There is an effective vaccination for yellow fever -- a mosquito-borne, frequently fatal viral infection that causes fever, jaundice, and bleeding. Travelers to areas where yellow fever is present should be vaccinated a minimum of 10 days prior to entering a yellow fever zone. Certificates of immunization may be required for entrance into some countries if the travel has just been in an endemic zone.

• SOUTH AMERICA: Bolivia, Brazil, Columbia, Ecuador, French Guyana, Guyana, Panama, Peru, Surinam, Venezuela
• AFRICA: Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Congo, Cote d'Ivoire, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Mali, Niger, Nigeria, Rwanda, Sao Tome and Principe, Senegal, Sierra Leone, Somalia, Sudan, Togo, Uganda, United Republic of Tanzania, Zaire, Zambia