Deadliest infectious diseases in the world, ranked

COVID-19 has spread to nearly every corner of the Earth, save Antarctica, forcing border closures and stay-at-home orders and triggering a global economic downturn. 

The latest U.S. government estimate is that between 100,000 and 240,000 Americans could die from the dangerous respiratory infection before the pandemic is brought under control.

It is still too early to know the mortality rate for this coronavirus. Around the world, testing supplies remain inadequate. And the U.S. Centers for Disease Control and Prevention says about 25% of people infected with the virus may exhibit no symptoms at all.

But for other major outbreaks, the global medical community —including the CDC, the World Health Organization, and the National Institutes of Health — tracks mortality rates.

Understandably, the death rate for any disease varies depending on access to vaccines and medical care. The data in this gallery represents the high end of those ranges.

Some of these illnesses — like the novel coronavirus — spread from person to person. Others come from infected substances, animals or microscopic organisms.

But before we get to the ranking...

Coronavirus: New cases every day

The White House has advised Americans to practice social distancing — that means avoiding non-essential travel, telecommuting, home-schooling and staying at least 6 feet away from other people outside of the home — at least through April 30.

This recommendation came after President Trump floated the idea of reopening businesses, schools and public spaces by Easter, but then shifted gears in the face of grim projections about the death toll.

Coronavirus outbreak in New York

New York is of the hardest hit places in the United States. Deaths in the state topped 2,000 on April, 1, 2020. 

One estimate, provided by a group founded by the Gates Foundation, projected there may be 16,000 deaths in New York alone.

50. Measles

Mortality rate: 1.46%

In 2019, there were 1,282 cases of measles in 31 states, mostly among unvaccinated people. That was the largest number of cases in the U.S. in more than a quarter-century.

Measles (continued): Immunity amnesia

Recent studies have shown that measles can do more harm beyond the symptoms of the acute illness.

Scientists believe that the measles virus can actually cause a person's immune system to "forget" previously built-up resistances to other, unrelated infections.

49. Lassa fever

Mortality rate: 1.67%

This viral hemorrhagic fever spreads through contact with mouse excrement or from one infected person to another. It is treated with the antiviral drug Ribavirin.

Lassa Fever (continued): Outbreak in Nigeria

According to the Nigeria Centre for Disease Control, there is currently an outbreak centered in southwest Nigeria.

As of mid February 2020, more than 100 people had died from this outbreak.

48. Rabbit fever

Mortality rate: 2%

Rabbit fever, also known as tularemia, is primarily spread by tick and fly bites. Symptoms include fever, skin ulcers and enlarged lymph nodes.

Left untreated, this disease kills 15% of infected individuals.

47. HIV/AIDS

Mortality rate: 2.03%

HIV is most often spread through sexual activity or sharing drug needles. Antiviral medications can help keep it in check and reduce the risk of transmission.

Here, members of a fraternity at the University of the Philippines in Manila participate in a nude run to promote sex education in the country.

46. Larval tapeworm infection

Mortality rate: 2.2%

Cysticercosis is a parasitic tissue infection caused by tapeworm larvae. The disease is spread through contact with waste from an infected person.  

45. Rotavirus

Mortality rate: 2.4%

Rotavirus is the most common cause of severe diarrhea in infants and young children. There is a vaccine available worldwide.

44. H. Influenzae

Mortality rate: 2.45%

This bacteria can cause many kinds of illnesses, from ear infections to blood infections, but it does not cause the flu, despite the name.

42 (TIE). Cholera

Mortality rate: 4%

Cholera, an infection that causes severe diarrhea and dehydration, is very rare in the developed world. It is almost always fatal if left untreated. There was an outbreak of cholera in Democratic Republic of Congo in January 2020. 

42 (TIE). Typhoid

Mortality rate: 4%

This bacterial infection is often spread through contaminated food and drinking water. In refugee camps like this one in Syria, rain can flood waste pits and contaminate the drinking water supply. 

Without treatment, 30% of those infected will die.

40 (TIE). Shiga toxin-producing E. coli

Mortality rate: 5%

This dangerous form of E. coli is most often spread by contaminated food products. 

40 (TIE). Louse-borne relapsing fever

Mortality rate: 5%

This disease, most commonly seen in northeast Africa, is spread by lice and results in high fever, chills and joint pain, among other symptoms. Between 10% and 40% of infected people die in the absence of treatment.

39. Weil's disease

Mortality rate: 5.72%

Though extremely rare in the developed world, approximately 1 million people contract this blood infection annually. Also known as leptospirosis, it's spread through contact with animal urine — often in water or soil.

Severe cases of Weil's disease can lead to bleeding in the lungs or kidney failure.

38. Yellow fever

Mortality rate: 6%

This mosquito-borne illness got its name from the jaundiced skin, hair and nails of infected people suffering from liver failure. Without medical treatment, 50% of infected people die.

In 2018, there was an epidemic of yellow fever in Sao Paulo, Brazil. Parks like this one were closed to prevent further infection.

37. Rocky Mountain spotted fever

Mortality rate: 7%

This tick-borne bacterial disease is not limited to the Rocky Mountains; it occurs in many states and most commonly reported in North Carolina, Tennessee, Missouri, Arkansas and Oklahoma. Symptoms include fever, body aches and a spotted rash.

36. Zika

Mortality rate: 8.3%

Adults rarely die from this mosquito-transmitted disease. More than 8% of babies born from infected mothers die from complications of microcephaly, or abnormally small head circumference.

Zika: Mosquitoes in the U.S.

There have been no reported mosquito-born cases of Zika in the United States since 2017. That year, seven people were infected by mosquitoes in the U.S. — five in Texas and two in Florida.

Most Zika patients in the United States got the disease while traveling abroad.

35. Plague

Mortality rate: 9%

In the 14th and 15th centuries, around half of Europe's population was wiped out by this contagious bacterial infection. While modern medicine has driven the plague's mortality rate down significantly, outbreaks of plague still happen. In 2017, the World Health Organization warned of an outbreak in Madagascar.

Plague (continued): What didn't work

In the 14th century, doctors sometimes wore long trench coats and beak masks filled with aromatic substances like herbs, spices or onions. This costume was thought to protect the doctors from infection. 

Treatments for the plague in the Middle Ages included everything from drinking urine to eating the heart of a stag.

Today, plague is treated with antibiotics.

31 (TIE). Diphtheria

Mortality rate: 10%

Diphtheria is a contagious respiratory infection spread by bacteria in a cough or a sneeze. It is particularly dangerous to children. In Indonesia, where outbreaks are common, these students waited nervously before receiving diphtheria vaccinations in October 2019.

31 (TIE). Botulism

Mortality rate: 10%

Botulism infections are rare, but potentially fatal. Bacteria enter the body through improperly processed foods or through an open wound and produce a dangerous neurotoxin.

Symptoms of botulism include weakness, blurred vision and muscle paralysis.

31 (TIE). Legionnaires disease

Mortality rate: 10%

Legionnaires disease is an atypical pneumonia spread by inhaling mist from bacteria-ridden water.

This photo shows a culture of the bacteria in a petri dish.

Legionnaires disease (continued): Outbreak in Flint, Michigan

An outbreak killed at least 12 people in Flint in 2014 and 2015. Scientists allege that low chlorine levels in the city's municipal water supply were to blame.

31 (TIE). Anthrax

Mortality rate: 10%

This illness became a household name in 2001 when letters containing anthrax spores were mailed to news media and to two U.S. senators. Five people died.

The most common way anthrax is spread, however, is through contact with infected animals or animal products. In 2019, at least ten buffalo died from an outbreak in Kenya.

29 (TIE). SARS

Mortality rate: 11%

Severe Acute Respiratory Syndrome, or SARS, is a strain of coronavirus that reached epidemic levels in 2003, infecting more than 8,000 people in 29 countries and killing 774.

Here, Secretary for Education and Manpower Arthur Li Kwok-cheung visited a primary school in Hong Kong on the first day of classes after the SARS outbreak had subsided.

29 (TIE). Monkeypox

Mortality rate: 11%

The monkeypox virus is most often spread through contact with the bodily fluids of an infected animal, though human-to-human transmission is possible. It occurs most often in rainforests of Central and West Africa.

People suffering from the virus will experience fever and swollen lymph nodes followed by a rash that concentrates on the face and extremities.

28. Toxic shock syndrome

Mortality rate: 12%

Toxic shock is a dangerous bacterial infection most commonly associated with the use of tampons, but it also occurs in other settings such as post-surgical infections, burns and catheters.

Rapid diagnosis and antibiotic treatment is key to reducing mortality.

27. Guillain-Barré syndrome

Mortality rate: 13%

The exact cause of Guillain-Barré syndrome is unknown. The disorder causes the immune system to attack the nervous system. Scientists have linked cases to the presence of other pathogens like the Zika virus and influenza. 

This church in Caracas, Venezuela was fumigated for mosquitoes after three people died from what doctors believe to be Zika-related Guillain-Barré syndrome.

26. Tetanus

Mortality rate: 13.2%

Fun fact: That old story that tetanus is caused by stepping on rusty nails is not altogether accurate. Rust does not cause tetanus. 

Rusty objects are often found outdoors where bacteria live. And while the rough, porous rust does provide a convenient habitat for dangerous bacteria, you can also contract tetanus from a nail with no rust at all — or from an animal bite. It's the low-oxygen environment under the skin that provides the perfect breeding ground for dangerous toxins.

Tetanus vaccines are widely available.

24 (TIE). Meningococcal meningitis

Mortality rate: 15%

This is a severe bacterial infection of the thin layer of tissue that surrounds the brain. Untreated, 50% of infected people die.

Tony Nassif shows a photo of his daughter, Jenah, who died of the disease after she was misdiagnosed.

24 (TIE). Tuberculosis

Mortality rate: 15%

Tuberculosis causes respiratory symptoms like a severe cough with occasional blood. It is curable, but it remains one of the top 10 causes of death, globally.

23. Reye syndrome

Mortality rate: 20%

The exact cause of this severe brain disease is not known, but it often occurs in children recovering from a virus — like chickenpox  — especially if aspirin was administered.

This correlation led to warnings against aspirin use in children in the 1970s and '80s. When children's aspirin use declined, so did instances of Reye sydnrome.

18 (TIE). Smallpox

Mortality rate: 30%

Smallpox causes severe flu-like symptoms in addition to a rash and large lesions on mucous membranes. The disease was declared globally eradicated in 1979 and administration of the vaccine was halted.

These women in Kolkata, India perform a ritual for the goddess Shitala, the folk deity believed to cure smallpox and similar diseases.

18 (TIE). Staphylococcus aureus

Mortality rate: 30%

Staph infections are notoriously difficult to treat, especially the antibiotic-resistant strain known as MRSA.

18 (TIE). Invasive Listeria

Mortality rate: 30%

Listeriosis, the illness caused by the listeria bacteria, is primarily transmitted through contaminated foods. Listeria is particularly dangerous for pregnant women and the elderly.

In 2011, 33 people died from eating Listeria-contaminated cantaloupe.

18 (TIE). Eastern equine encephalitis

Mortality rate: 30%

This rare brain infection is spread by mosquitoes and affects both humans and animals. Survivors often suffer from ongoing neurological problems.

18 (TIE). Crimean-Congo hemorrhagic fever

Mortality rate: 30%

This virus is spread several ways: tick bites, contact with animal blood, and close contact with an infected person. 

Flu-like symptoms and irritability progress to liver failure, kidney deterioration and pulmonary failure.

In this photo, a worker in India sprays livestock for ticks.

17. Invasive Aspergillosis

Mortality rate: 30.22%

This X-ray shows lungs infected with a dangerous fungus called Aspergillus. This infection, which primarily affects people with poor immune systems, is 100% fatal if left untreated.

16. Vibrio illness

Mortality rate: 34.16%

Vibrio illness is related to cholera. It is usually contracted from eating contaminated seafood. The bacteria can cause sepsis and wound infections that require amputation.

15. MERS

Mortality rate: 34.4%

Middle East Respiratory Syndrome, or MERS, is a coronavirus that originated in Saudi Arabia in 2012. Since then, intermittent outbreaks have been reported across 27 countries, including a 2015 outbreak in Thailand.

14. Hantavirus pulmonary syndrome

Mortality rate: 36%

This rare but dangerous cardiopulmonary disease is spread by deer mice. In 2012, 10 campers staying in Yosemite's Camp Curry contracted Hantavirus; three of them died.

The camp was later demolished.

13. Raccoon roundworm

Mortality rate: 38.46%

Baylisascariasis is a parasitic brain tissue infection caused by raccoon roundworm larvae. It most often affects young children who encounter raccoon excrement while playing outdoors.

12. Glanders

Mortality rate: 40%

Glanders is an extremely rare but deadly bacterial disease transmitted through infected animals and people. With Glanders, flu-like symptoms quickly progress to pneumonia, pulmonary abscess and fatal blood infection.

Only one case of Glanders has been confirmed in the United States since 1945, when a lab worker was accidentally exposed during research. The disease is endemic in animals in Africa, Asia and the Middle East.

11. Monkey B virus

Mortality rate: 42%

B virus, spread by macaque monkeys, is quite rare but can cause severe brain damage if not treated quickly. 

Since B virus was discovered in 1932, 50 people have contracted the disease; 21 of them died.

10. African sleeping sickness

Mortality rate: 42.5%

African trypanosomiasis is a parasitic infection transmitted by the tsetse fly. It is characterized by fever and headache followed by sleep disturbances.

Untreated, the disease will always lead to coma and death. 

A technician screened villagers in Ivory Coast for the disease in October 2019. These blood tests help doctors identify people in the early stages of the disease and provide earlier, more effective treatment.

African sleeping sickness (continued): Eliminating the crisis

In 2018, the World Health Organization stated a goal of ending the disease as a public health crisis by 2020.

Community health workers like this man are instrumental in lowering the fatality rates.

8 (TIE). Ebola virus

Mortality rate: 50%

Fruit bats and other African wildlife are the natural hosts of Ebola. Once passed to a human population, the virus is contagious through direct contact with another person.

There are no proven treatments or vaccines for the virus at this time.

As of late January 2020, there was an ongoing outbreak of the disease in Democratic Republic of Congo.

Ebola (continued): Fighting brain cancer

Researchers at Yale University are studying how Ebola genes might be harnessed to treat certain brain tumors.

The same characteristics that make the virus difficult for the immune system to fight make it a compelling candidate for cancer treatment.

8 (TIE). Marburg virus

Mortality rate: 50%

Marburg virus is clinically similar to Ebola. It is initially transmitted to humans through contact with Rousettus bats. Once the virus enters a human population, it is contagious via human bodily fluids.

In fatal cases, death from severe blood loss usually occurs 8 or 9 days after the onset of symptoms.

7. Hendra virus

Mortality rate: 57%

This virus, also spread by fruit bats, infects humans and horses. It was discovered in Australia in 1994. Cases are rare; between 1994 and 2013, 7 people were diagnosed and 4 of them died.

Symptoms include flu-like respiratory issues, followed, in severe cases, by encephalitis. 

This photo shows a Queensland man mowing his lawn while a colony of fruit bats fly around nearby mango trees.

6. Bird flu

Mortality rate: 60%

Severe avian flu is spread from close contact with infected birds. According to the World Health Organization, human-to-human transmission does not appear to happen often.

An outbreak of the deadly H5N1 strain among poultry was reported in China on February 1, 2020.

5. Nipah virus

Mortality rate: 75%

This bat-borne virus is related to Hendra virus. It also presents with acute respiratory illness and fatal encephalitis.

Nipah virus is more common than Hendra virus, resulting in near annual outbreaks in Bangladesh since 2001.

4. Brain-eating amoeba

Mortality rate: 95%

Naegleria fowleri — also known as the brain-eating amoeba — is commonly found in warm, fresh water, and enters the human body through the nose.

The disease is causes is difficult to diagnose and almost always fatal. Early symptoms of neck stiffness and headache quickly progress to confusion, seizures and, frequently, death.

It is also rare. Between zero and 8 cases are reported annually in the United States.

3. Balamuthia encephalitis

Mortality rate: 98%

These dangerous amoebas can infect many different parts of the body including the skin, sinuses, and brain. The amoebas live in soil and can enter the body through open wounds or be breathed in.

This disease is very rare, with only 200 reported cases since it was discovered in 1986.

1 (TIE). Rabies

Mortality rate: 100%

There have been only a handful of cases in human history of unvaccinated people surviving the rabies virus.

Ninety-nine percent of cases are spread by dog bites. This child in Bali holds his dog's rabies vaccine certificate after a visit to the vet. In 2010, Indonesian authorities launched a campaign to vaccinate 400,000 dogs after an outbreak left more than 130 people dead.

1 (TIE). Mad cow disease

Mortality rate: 100%

When humans contract mad cow disease, doctors call it Creutzfeldt-Jakob disease. It is considered rare: An average of 350 cases are reported in the United States each year.

It is not clear what causes most cases of the deadly neurologic disorder. Symptoms include personality changes, insomnia, loss of muscle control and hallucinations.