4 Deadliest Diseases in the US No One Warned You About

June 18, 2018

 Advancements in medicine, technology, and improved hygiene have helped us to eradicate (or at least control) some of the most devastating infectious diseases the world has ever seen.

While infectious diseases may no longer be the killers they once were, they are still with us, as proven by the Ebola outbreak of 2014. In this article, we’ll look at the effects of the deadliest contagious diseases lurking in the US today.

Infectious vs. Contagious Diseases

These two words are often used interchangeably, but there is a major difference. Basically, infectious diseases are caused by infectious agents (such as a virus or bacteria) while “contagious” refers to the type of infections that can be passed from person to person.

Contagious infections are spread either by touching or kissing the infected person, coming into contact with bodily fluids, or even touching an object they have touched. Other contagious illnesses may be airborne and are spread by infectious microbes released through talking, coughing, or sneezing.

Infectious diseases are the second leading cause of death worldwide and third in the United States. What are the deadliest diseases still wreaking havoc on the US?

1. Dengue Virus

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 According to 2014 Tropical Medicine Reports, the Dengue virus (DENV) is one of the most common viral diseases of the past 30 years, with approximately 390 million people infected globally each year. It is a viral infection with flu-like symptoms usually appearing 4-6 days after the initial infection.

DENV Symptoms Include:

  • High fever
  • Nausea and vomiting
  • A rash appearing 2-5 days after the fever
  • Severe headaches
  • Pain behind the eyes
  • Joint and muscle pain
  • Bleeding, from the nose, gums, and easy bruising

How Does Dengue Spread?

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DENV is not a contagious illness and can’t spread directly from person to person. According to information from the World Health Organization, people contract dengue fever if they are bitten by an infected female Aedes mosquito. A healthy mosquito can also be infected by biting a person with the virus in their blood. The mosquito then transmits the disease to the next person it feeds on.

Recent Outbreaks of Dengue in America

DENV has a long history in America. First noted as far back as 1780, epidemics were mostly prevalent in warmer, southern states.

While the latest DENV cases have been travel-related, the Texas-Mexico border has the most patients admitted to hospitals. There has been an increase in southern states, however. In 2009, there was an outbreak of dengue fever in Key West, Florida, the first (not along the Texas-Mexico border) in 60 years.

In 2017, there were 80 reported cases of Dengue fever in the U.S. 43 of those were travel-related, and the 37 ‘local’ contractions were in the US territories of American Samoa, Puerto Rico, and the Virgin Islands.

How Dangerous is Dengue Fever?

If detected early, the fatality rate falls below 1%. The major problem is that symptoms can resemble the flu or other viruses. Out of the approximate 500,000 people admitted to hospital with severe dengue, 2.5% die.

There are four strains of the dengue virus, and once infected and recovered from one, the patient will have lifelong immunity for that particular strain. However, later infections by one of the others can increase the risk of severe dengue.

2. Influenza A

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 The flu may not sound like one of the deadliest diseases in the US, but this infectious disease is highly contagious, with hundreds of strains that mutate frequently. As if that isn’t troubling enough, it’s also incurable.

Strains are classified into three main categories: A, B, and C. A and B are behind the winter flu season, with A being the most severe. C strains also cause illnesses, but the symptoms are much less severe. Influenza A viruses are further broken down into H and N subtypes (eg. H1N1, also known as Swine Flu).


Flu symptoms can last anywhere from two to seven days, but four to five days is the usual time frame. Symptoms can include a combination of the following:

  • Cough
  • Runny or stuffy nose
  • Itchy/watery eyes
  • Sore throat
  • Fever
  • Body aches
  • Extreme fatigue
  • Headache

How Does The Flu Spread?

The flu is spread from person to person by droplets in the air, caused when infected people cough, sneeze, or talk. These infected droplets land in the mouths or noses of nearby people.

The flu can also be transmitted when a person touches an object infected with the influenza virus and then touches their mouth or nose. This is less common, however.

The flu is one of the most easily transmitted diseases with 5-20% of the US population contracting it each year. Better health education about self-care and flu vaccinations can not only reduce the spread of the flu but also save billions of dollars a year.

Recent Occurrences of the Influenza Virus

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 The flu in the US hits every year, most commonly from November to March. There is no way to predict how widespread it will be, nor how severe the symptoms will be.

The death toll of the 2017/18 flu season bypassed the 2009 swine flu epidemic, which infected 60.8 million Americans, hospitalized 274,304, and killed more than 12,000.

According to the CDC, hospitalizations for the 2017/18 flu season exceeded the 710,000 of the 2014/15 season, which had the highest rates of hospitalizations for people aged 65 and older.

How Deadly is The Influenza A Virus?

Influenza is extremely complex and difficult to predict, which is why it remains one of the greatest challenges to international public health.

While most people recover from the flu with no lasting effects, many have a higher risk of developing additional complications such as pneumonia, either due to a weakened immune system or underlying conditions.

Young children under 5, adults over 65, pregnant women, and those with chronic health conditions (such as asthma or heart disease) are at higher risk for serious flu complications.

The flu vaccine is advised for those in these higher risk groups. However, due to the constant mutation of the flu virus, the vaccines aren’t always effective.


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 Methicillin-Resistant Staphylococcus Aureus (MRSA), is known as the ‘superbug’ as well as ‘flesh-eating disease’. Caused by a particular type of Staphylococcus (staph) bacteria, MRSA is resistant to many commonly-used antibiotics.

MRSA can start as a simple skin infection, but if the infection is left untreated (or forms deeper into the body) it can cause severe pain, infections in the organs, and even death.

What Are the Symptoms of MRSA?

At first, MRSA appears like any other skin infection, with small red bumps, pimples, or boils that may be swollen, tender, or warm to the touch. As the infection progresses, these can turn into painful, pus-filled abscesses. The skin infection may also be accompanied by fever.

If the infection enters the body through broken skin or a cut, more serious conditions may develop such as:

  • Urinary tract infection (bladder infection)
  • Osteomyelitis (bone infection)
  • Endocarditis (heart valve infection)
  • Septicemia (blood poisoning)
  • Pneumonia (lung infection)
  • Septic bursitis (small fluid-filled sacs under the skin)

How is MRSA Spread?

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MRSA is a highly-contagious bacteria spread by either touching a person who has it on their skin, or by touching objects that have the bacteria on them. MRSA not only spreads from person to person, but the bacteria can live up to 6 months on some surfaces.

Although the bacteria can be found anywhere, it is most commonly found in hospitals and healthcare facilities. As these locations are naturally full of people with lowered immune function, there are more ‘entry points’ for MRSA to invade the body and cause serious damage.   

Approximately one in three (33%) people carry the staph bacteria usually without any major infection. Only 2% of the population carry the MRSA version of staph bacteria. However, even with the ‘safe’ staph, the bacteria multiplies at an alarming rate, and it takes only one mutated cell to allow the infection the ability to withstand antibiotics.

Recent Outbreaks of MRSA

MRSA is a recognized urgent and serious threat by the CDC, yet at the same time only 35 states are required to report cases of MRSA contracted by patients while in a healthcare facility. This makes knowing the full extent of the issue almost impossible.

How MRSA is reported and tracked has come under fire from the media in recent years. In 2016, a Reuters Investigation highlighted a number of deaths resulting from MRSA infections which were contracted while the patient was in hospital care, but medical records and cause of death showed no mention of the infection.

The investigation showed thousands of unreported cases of MRSA throughout the period of 2003-14.

The fact that MRSA can breed in a supposedly sterile environment makes one wonder what other mistakes are being made in the US healthcare system?

How Deadly is MRSA?

The CDC estimates that in the US there are at least two million illnesses and 23,000 deaths caused by antibiotic-resistant bacteria each year. Their study examined 699 patients with MRSA. Out of the 699, 31.5% died, with the elderly most at-risk.

Like influenza A, MRSA is constantly evolving and becoming resistant to more antibiotics.

4. Marburg Virus Disease

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Marburg Virus Disease (MVD) is closely related to the Ebola virus and is a serious – and often fatal – illness. Formerly known as the Marburg Haemorrhagic Fever, MVD is transmitted from infected animals to humans, then continuing to spread between humans.

The virus is named after the German city, Marburg, where it was first discovered in 1967. 31 laboratory staff contracted the disease from infected Ugandan monkeys.

What Are the Symptoms?

Marburg virus disease hits in stages, with symptoms usually appearing after an incubation period of about five to ten days. The first symptoms include:

  • Fever
  • Chills
  • Headaches
  • Muscle aches

Around five days after the onset of symptoms, others start to appear:

  • Rash on the chest, back, and stomach
  • Nausea and vomiting
  • Chest and abdominal pain
  • Sore throat
  • Diarrhea in some cases

Symptoms can worsen to cause further complications such as jaundice, pancreatic inflammation, severe weight loss, delirium, liver failure, and hemorrhaging with organ damage.

How Does MVD Spread Today?

MVD is transmitted through contact with blood, bodily fluids, or tissue of those infected. Medical staff, healthcare workers, and laboratory technicians are at a higher risk, as are those who work with wild animals such as monkeys and fruit bats.

Recent Outbreaks of MVD

MVD outbreaks in Uganda happen relatively regularly, the most recent being in 2017, killing one person. In 2008, however, an American woman contracted MVD in Uganda while visiting a bat cave. She returned to the United States with the disease and was later hospitalized. Luckily the disease didn't spread and the woman made a full recovery.

How Deadly is Marburg Virus Disease?

While Marburg is relatively rare, outbreaks can be dramatic and fatality rates are high. The first laboratory outbreak in Marburg had a 25% fatality rate. When the virus hit the Democratic Republic of Congo the virus had an 80% death rate.

However, the worst scenario was in Angola, where Marburg had a 90% fatality rate, killing 227 people out of 252 infected.  

There is no specific antiviral treatment or vaccine is available, making this all the more deadly.

The Healthcare Heroes Fighting the Good Fight

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Some of these infections can be rather stomach-churning to deal with, so spare a thought for the medical staff and healthcare workers who come into contact with them on a regular basis.

Dealing with dangerous diseases is somewhat expected in the medical field, but healthcare workers’ bravery doesn’t stop there.

Check out the 3 Unexpected Risks Healthcare Workers Face Every Day for more information.