TOP 10 Scariest Viruses in the 21st Century

Pacing into the 21st century, as the technology becomes more and more modern, viruses also become stronger and stronger to spread worldwide. Until today, there are still some scary viruses that we, as humans, fail to find treatment to cure the illnesses. Here, it is worth mentioning that the world is still in lockdown condition due to the widespread cases of the COVID-19.

So, today, let’s go through the list of the top ten scariest viruses in the 21st century which are evaluated based on the infected cases, transmission methods and death rates.

10. Hantavirus

What is hantavirus? Hantavirus is part of the family viruses which is seen to be spread by rodents. The most serious outbreak of the hantavirus traced back in 1993. It was widespread in the four corners in the United States, including Arizona, Colorado, New Mexico and Utah. In the 21st century, it is seen to be infected in Korea, infecting 17 people in 2017 and 10 cases in 2012.

The transmission method of this disease occurs when humans are in close contact with infected urine. This happens when the virus enters the body through broken skin or membranes of the mouth, nose and eyes. Therefore, the infectious case happens when people are bitten by the rodents.

The symptoms of the virus may take about 8 weeks to develop and appear. It includes headache, body pain, nausea, fever and chills. It may also cause blurred vision in some cases.

9. H5N1

H5N1 is one kind of influenza which is caused by avian, especially chicken. It is known to be highly infectious, and it results in severe respiratory problems. It is also known as the bird flu worldwide. However, it is almost impossible to transmit from human to human.

Despite this low transmission chance, if a person gets infected by this disease, the chance of survival is only 40%. The first case of H5N1 disease was found in Hong Kong in 1997. However, the outbreak began in 2003.

The symptoms of this disease include fever, cough, malaise, sore throat and body pain, especially in muscles. After that, it may appear in diarrhea and chest pain in the chest. It is considered as a global pandemic since the mortality rate is as high as 10%. Until today, there are still confirmed cases of H5N1 in the world.

8. Lassa Fever

Lassa Fever is an endemic occurring in the Western part of Africa. The disease was discovered long ago since 1969; however, it still causes deaths about 5000 annually. Each year, there are approximately between 100,000 and 300,000 Africans getting infected by the Lassa Fever.

The symptoms of Lassa Fever do not show up until 3 weeks after the contact. However, most infected cases result in mild conditions. The mild symptoms include malaise, headache, fever and other weaknesses. In the serious case, on the other hand, patients may feel the hemorrhaging in many body parts, such as eyes and nose.

The most common type of complication of this disease is deafness. It accounts for about 30% of all the infected cases. Moreover, about 15% of the infected patients die from the disease.

7. Malaria

Malaria is an infectious disease caused by the Plasmodium virus. It is seen to be spread especially by mosquitoes which carry plasmodium in their body. Therefore, it is transmitted to humans whenever they are bitten by mosquitoes, especially female mosquitoes.

However, the disease can now be prevented and cured. Still, there are over 200 million reported cases worldwide each year. In 2018, it is estimated to have a death number of 405,000 caused by Malaria.

The most vulnerable affected group of this disease is children. They are accountable for about 67% of the total infected and death cases worldwide. Most countries that get infected by Malaria centered in Africa, where there are not enough advanced facilities and treatment.

6. Dengue

Dengue is widely known as Dengue Fever, which is spread by the dengue virus carried by mosquitoes. Dengue disease happens every year with a total case of approximately 50 – 100 million cases each year, scattering in more than 100 countries in the world.

Once a mosquito carrying the disease bites a person, that person will show the symptom of fever within 2 – 7 days. In the case of severe, the mortality rate of the dengue is about 2% to 5%, whereas in normal cases, only 1% of the infected cases died from the disease. However, without treatment, the death rate could go up to 20%.

In order to prevent yourself from Dengue, it is recommended to protect yourself from getting bitten by a mosquito which is the cycle of the Dengue disease.


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Back in 2003, there was an animal virus outbreak from Guangdong, China, which is known as SARS, or Severe Acute Respiratory Syndrome. Back then, 29 countries were infected with the disease, increasing the infected case to 8,098 cases. The global death rate was 774 people, or equivalent to 15% of mortality rate.

The first case was found in November, 2002. The symptoms of this disease include fever, cough, malaise and respiratory symptoms. The disease was transmitted through any respiratory droplets as well as contaminate surfaces.

Luckily, the outbreak ended by the summer, which was in July, 2003. The vaccine was found after the outbreak ended.

4. Ebola

Ebola was reported to be a serious outbreak due to the high death rates, and it is caused by the Ebola virus. It was found in Guinea in December of 2013, and the outbreak started in March 2014. There were 10 countries getting infected in total, and most of them were centered in Africa.

Among all the 10 countries, the reported case number was 28,652 cases, yet about 11,300 died from the disease, which means about 50% of the infected population died from the disease. The virus was transmitted through bodily fluids, such as sweat, blood as well as feces.

The symptoms of the disease include pains and aches in the body, fever, vomits and diarrhea. Until today, there is no treatment to the disease yet, and it is treated by IV fluids with oral rehydration.

3. H1N1

H1N1 is also one of the most serious pandemics in the 21st century, which is caused by a novel influenza A virus. The number of infected patients is considerably large since it was estimated to be about 24% of the world population. In the United States alone, there are 60.8 million infected cases.

The first case was reported in Mexico back in January, 2009. Despite the large number of global cases, the death rate is only about 0.02%. The total death in the US is about 284,000.

The main target of this virus is children and old people. Among all the infected populations, 47% were the children and teenagers with the age between 5 and 19 years old, whereas another 11% is old people at the age of 65 or more. It is transmitted through droplets and contaminated surfaces. The symptoms include chills, body aches, fever and cough. Luckily, it ended in August of 2010.

2. HIV

Although HIV is a relatively old disease, it is still one of the deadliest diseases in the century. HIV stands for Human Immunodeficiency Virus. Until today, there is still no treatment to fully stop the disease, yet treatment can only extend the lifetime of the patients.

The main target of the virus is the human’s immune system, especially the T cells, or immune cells. There are a variety of transmission methods, including blood, anal fluids, vaginal secretions, semen and breast milk. The symptoms of HIV vary on the time of the infection. The early symptoms include fever, joint pain, chills, body pain, sweats at night, sore throat and tiredness.

The death rate from HIV is still relatively high. In 2018, 1.7 million populations were infected with HIV, and there are 770,000 deaths from any diseases caused by HIV in 2018. However, in the world today, there are still about 40 million people living with HIV.

1. COVID-19

Last but not least, Coronavirus disease 2019, or widely known as COVID-19. According to Worldometer, there are 210 countries and territories infected by the disease, and it also includes 2 additional international conveyances as well. This is known as the most serious outbreak in the world since the Spanish Flu.

The first case of COVID-19 was found in Wuhan, China back in December, 2019. However, within 5 months, the disease spreads quickly to the world, increasing the global case to almost 2 million cases. Among the active cases, about 96% are found in mild condition, whereas the other 4% results in serious or critical. Only about 23% of the total infected cases are fully recovered from the disease.

This pandemic results in the lockdown of many countries. Interestingly, it is spread so quickly through droplets and other contaminated surfaces. The symptoms only appear after 14 days, which include cough, fever and respiratory symptoms.


So, above are the top ten scariest viruses in the 21st century. It is important to take good care for yourself and prevent infection.


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