What is the most dangerous disease in the world, which diseases are the most deadly, and what to against it if you go abroad or travel?

What is the most dangerous disease in the world if you go abroad or travel?

• The most dangerous disease is malaria. In addition to the 600,000 people who die from malaria every year, it is often an intense travel experience for those who survive.
• While effective vaccines exist for many life-threatening diseases, you must try to prevent malaria yourself during your trip by getting bitten as little as possible.
• The number of countries where this nasty disease is prevalent continues to decrease, and with timely treatment, only a few travelers die from malaria.
• More about malaria and preventing malaria

What is the most deadly disease in the world that you can contract abroad?

• The deadliest disease in the travel-related diseases category is Hepatitis B, with more than 1 million deaths worldwide every year.
• Close behind are HIV/AIDS and Tuberculosis, numbers 2 and 3.
• However, by far the majority of deaths from these diseases do not occur among travelers, but among residents of developing countries and people who, for one reason or another, have limited to no access to healthcare.

What are the 25 most dangerous viral diseases in the world if you go abroad or travel?

1. Hepatitis B: 1.2 million deaths annually
2. HIV/AIDS: nearly 1 million deaths per year
3. Hepatitis C: 1.5 million infections per year; 290,000 deaths per year
4. Norovirus: 700 million infections per year - 200,000 deaths
5. Measles: 130,000 deaths per year; 20 million sick people per year
6. Rabies: 60,000 deaths per year
7. Hepatitis E: 20 million infections per year, of which 3 million are serious, and over 40,000 deaths annually
8. Dengue fever: 390 million sick people per year; 500,000 seriously ill, 25,000 deaths per year
9. Japanese encephalitis: 70,000 infections per year; 17,000 deaths per year
10. Yellow fever: 200,000 sick people per year; approximately 15,000 annual deaths
11. Hepatitis A: 1.4 million infections per year; 11,000 deaths annually
12. Lassa fever: 500,000 infected per year; 5,000 deaths per year
13. Chikungunya: 3 million sick per year; around 3,000 annual deaths
14. West Nile virus: 70 deaths per year in Southern Europe, an unknown multiple worldwide
15. MPOX / monkeypox: outbreaks of up to 100,000 infections per year; approximately 1 to 2% fatal
16. Tick-borne encephalitis: 10,000 infections per year, fatal in approximately 100 cases per year
17. Crimea-Congo hemorrhagic fever: approximately 100 sick people per year; up to 25 deaths per year
18. Barmah Forest virus: non-fatal virus in Australia
19. Murray Valley encephalitis: non-fatal virus in Australia
20. Ross River virus: non-fatal virus in Australia; 5,000 infections per year
21. Mumps
22. Eastern equine encephalitis: usually a mild course, but can be fatal; only in North and Latin America
23. Ebola: fatal in 25-90% of cases, but outbreaks are rare and, for the time being, often limited in terms of spread
24. Hand, foot, and mouth disease: mainly children up to 10 years old, rarely fatal, in outbreak waves, mainly in Asia
25. Hantavirus (Hantaan virus, Seoul virus, Puumala virus, and Dobrava-Belgrade virus): 100,000 sick people per year; not very deadly; mainly in China

What are the other dangerous viral diseases in the world?

• Kunjin virus: non-lethal variant of the West Nile virus that can be contracted in Oceania/Australia
• Marburg virus: very rare, mainly in Africa, a few dozen cases in 10 years; very deadly, up to 100% of infections
• MERS-CoV: Rare, in isolated, sometimes severe outbreaks then very deadly (up to 50% of cases)
• Oropouche virus: outbreaks in South America during the rainy season; in principle not fatal
• Polio: Rare due to large-scale vaccination; still mainly in Afghanistan and Pakistan
• Rift Valley fever: in outbreaks in Africa usually first in animals; rarely fatal
• Measles: 20,000 cases per year
• Saint Louis encephalitis: via mosquitoes, mainly in the United States; only a few hundred per year, fatal in 3-30% of cases
• Zika virus: number of infections occurs in waves; rarely a severe course of illness

What are the 10 most dangerous bacterial infectious diseases in the world if you go abroad or travel?

1. Tuberculosis: 8 million infections per year; 1 million deaths per year
2. Shigellosis / Bacillary dysentery: 80 million infections per year; 700,000 deaths
3. Typhoid fever: 20 million infections; 161,000 fatalities per year
4. Syphilis: 6 million infections per year; 100,000 deaths per year
5. Cholera: 3 million sick people per year; 95,000 deaths per year
6. Melioidosis: 150,000 sick people per year; 89,000 deaths per year; particularly Southeast Asia
7. Tetanus: 200,000 serious infections; 60,000 deaths per year
8. Leptospirosis: 1 million seriously ill people per year; 60,000 deaths per year
9. Whooping cough: 16.3 million per year; 60,000 deaths per year
10. Meningococcal disease: 350,000 infections per year; 35,000 deaths per year

What are the other dangerous bacterial infectious diseases?

• Paratyphoid fever: 16 million infections per year - 25,000 deaths annually
• Diphtheria: around 30,000 cases per year; 3,300 deaths annually
• Gonorrhea: 88 million sick people per year; increasingly difficult to treat; usually not immediately fatal
• Chlamydia: 61 million sick people per year; approximately 200 deaths per year
• Legionella: 13,000 seriously ill people annually in the US; worldwide unclear, mostly occurs in local outbreaks
• Leprosy: 200,000 infections per year; usually not fatal
• Lyme disease: 500,000 infections per year; rarely fatal, but very nasty chronic symptoms are possible, read more under tick bites
• Botulism: has become rare; 1,000 cases per year; about 100 of them die
• Plague: 600 infections per year; 60 deaths per year
• Anthrax / splenic fever: 2,000 cases per year; with treatment rarely fatal anymore
• Malta fever / Brucellosis: rare; rarely fatal

What are the 10 most dangerous parasites if you go abroad or travel?

The most dangerous diseases spread via parasites that you may encounter as a traveler are:

1. Malaria: 250 million infections per year; 600,000 deaths per year - single-celled parasite via mosquito bite
2. Schistosomiasis / bilharzia: 230 million infections per year worldwide; 200,000 annual deaths - parasitic flatworm via water (containing freshwater snails)
3. Leishmaniasis: 1.5 million infections per year; 50,000 deaths per year - single-celled parasite via sandfly bite
4. Chagas disease / American trypanosomiasis: 170,000 new cases per year, 10,000 deaths per year - single-celled parasite via assassin bug feces
5. Sleeping sickness / African trypanosomiasis: 5,000 cases per year; particularly fatal if left untreated - single-celled parasite via tsetse fly bite
6. Echinococcosis: 1.4 million infections per year; 1,200 deaths per year - tapeworm via contaminated food
7. Lymphatic filariasis / elephantiasis: 40 million infections worldwide; limited lethality - parasitic roundworm via mosquito bite
8. River blindness: 21 million people infected, resulting in over a million blindness - parasitic roundworm via biting midge bite
9. Scabies: 300 million infections per year; not fatal, but contagious - caused by the scabies mite
10. Tungiasis: in over 80 countries; not fatal - caused by the sand flea

Other dangerous parasites when traveling abroad?

• Fox and dog tapeworm: rare; often fatal without treatment - tapeworm mainly via the feces of dogs and foxes
• Taeniasis via pig or beef tapeworm: 50 million infections per year; rarely fatal - tapeworm via raw pork or beef
• Trichinosis: 10,000 per year; rarely fatal - roundworm via eating raw or undercooked pork
• Dracunculiasis: nearly extinct species (parasitic roundworm) with only a few sightings and infections per year; in the 1980s, there were still millions of infections per year

What other causes can trigger illness when you go abroad or travel?

• The sun: sunstroke, sunburn, and dehydration are dangerous, common consequences of too much sun
• Venomous animals: think of snake bites, poisonous corals, jellyfish stings, and, for example, poison dart frogs; read more about this in the overview of the most dangerous animals abroad
• Venomous plants and mushrooms
• Alcohol and drugs: (usually) self-inflicted illness where the ingested amount exceeds the body's tolerance. For travelers, the use of local products such as home-distilled alcohol, ayahuasca, or licking a poison dart frog is particularly risky.
• Disrupted oxygen balance in your blood: altitude sickness
• Air pressure: decompression sickness, also known as diver's disease or Caisson disease
• Smog: stinging eyes, difficulty breathing, coughing. Especially on hot days in large cities.
• Movement: motion sickness, seasickness
• Mental illness: homesickness can have fatal consequences for your enjoyment of your trip

Which dangerous diseases are prevented by vaccinations when you go abroad or travel?

Depending on your year of birth, the following vaccinations are offered through the National Vaccination Program:

• Diphtheria
• Whooping cough
• Tetanus
• Polio
• Hepatitis B
• Mumps
• Measles
• Ruminococcal rubella
• Meningococcal A, C, W, Y

Travelers' vaccinations

You can get all vaccinations from National Vaccination Programs as a booster, a repeat, or as a travel vaccination. In addition, you can also get vaccinations against:

• Typococcal fever
• Cholera
• Dengue
• Yellow fever
• Hepatitis A
• Rabies
• Japanese encephalitis
• Rift Valley fever
• Tick-borne encephalitis
• Tuberculosis

When is a disease considered a travel-related illness, and what can you do to prevent or treat these diseases?

Travel-related diseases

• Many diseases occur worldwide or used to occur worldwide.
• When the risk of contracting a disease in your country of residence is low, but higher at travel destinations, you can classify the disease as a travel-related illness.
• Many deadly or life-threatening infectious diseases have been eradicated or significantly reduced in developed Western countries, causing us to view them partly as travel-related diseases.

Preventing or treating travel-related diseases

• Read more about what you can do regarding travel-related illnesses and diseases in the tropics at:
  • Staying healthy while traveling and arranging healthcare abroad
  • The links lead to the specific diseases