These Are the Most Terrifying Contagious Diseases on the Planet

Not all types of infection spread easily from person to person. Those that do put many lives at risk, especially if they aren’t easy to treat. Some of the most contagious diseases on the planet are also the most deadly. Read on to see how much you really know about these dangerous illnesses.


syringe with vial

Being diagnosed with meningitis is not good news for your brain. |

According to Mayo Clinic, meningitis involves inflammation of the membranes surrounding your spinal cord and brain. Some cases go away on their own within weeks; others are life-threatening. It can cause hearing loss, seizures, brain damage, and death.

It’s spread from person to person as it travels through the air while coughing or sneezing. College students living in dorms are at high risk because they live in close proximity to one another.


Sick man with thermometer in mouth

Be on the look out for a fever and a skin rash. |

The National Institute of Allergy and Infectious Diseases says smallpox killed 3 of every 10 of its victims before its eradication in 1980. The virus that causes the infection still exists — though it’s quarantined in only two locations in the world.

The infection causes fevers and a disfiguring skin rash that could spread the virus from person to person. Researchers continue to study how to combat it, in case it’s ever used as a form of bioterrorism.

Middle East respiratory syndrome (MERS)

Sick woman blowing her nose

Scientists aren’t even sure how this infection spreads. | Sam Edwards/OJO Images/Getty Images

This viral infection wasn’t discovered until late 2012, so there’s a lot we still don’t know about it. The CDC reports that 1 in 4 people with MERS die from it. It can cause severe respiratory distress, including coughing and shortness of breath.

Experts aren’t exactly sure how the virus spreads. People who come into close contact with MERS patients are at risk of catching it, since it might enter the air when someone coughs.


Blood collection tube with HIV test label

There are multiple ways you can contract HIV. |

The human immunodeficiency virus (HIV) destroys a person’s white blood cells, compromising their immune system. AIDS is the final developmental stage of HIV, though not everyone with HIV develops AIDS. Unprotected sex is the most common form of transmission, but it isn’t the only way the infection spreads.

According to MedlinePlus, the virus is often also spread through the reuse of needles used by persons already infected with HIV.

The plague

Middle-aged businessman suffering chest pains

Living in an overcrowded area can help spread the plague. |

According to Healthline, the plague — sometimes called black death — gets transmitted from infected fleas to humans. It can cause weakness, muscle pain, seizures, chest pain, and excessive bleeding. You’re at higher risk of contracting the disease if you live in an overcrowded area with poor sanitation.

Once you’re infected with the bacteria associated with the plague, the resulting infection progresses rapidly if you don’t get treatment immediately.


Ill man coughing

TB is commonly spread through the air. |

The Centers for Disease Control and Prevention says people with TB transmit it through the air when they cough, sneeze, or speak. It’s only non-infectious when bacteria has traveled from the lungs to other parts of the body, such as the kidneys.

TB causes fever and chills, fatigue and weight loss, and loss of appetite. Some of its most well-known symptoms include a bad cough, chest pain, and coughing up blood.

Marburg virus disease

Man sneezing into tissue

Marburg virus is in the same family as Ebola. |

According to the World Health Organization, Marburg kills up to 88 percent of its victims. In the same family of diseases as Ebola, it’s spread between humans through contact with the bodily fluids of those infected. Hemorrhaging is a common side effect, usually the ultimate cause of death due to shock and excessive blood loss.

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