Simply the thought of disease is frightening. For those with a deep imagination, a whole assortment of ugly pictures will appear before the mind’s eye. What makes one illness more frightening than another? The number of people it affects? The way it is transmitted? Or the effects it has on a person’s body? All must be paid their due, though this list pays particular attention to the number of fatalities, relatively healthy people affected, and, in some cases, the possibility of the illness growing into a pandemic.

1. The Flu

Old-fashioned flu, what’s scary about that?  Basically everything. A new strain of flu may appear at any time, and the path it cuts as it circles the globe may be deadly. When considering numbers of people and easy transmission, experts believe, according to an article in The New York Times, the next global pandemic is likely to be caused by a virus that can mutate especially quickly or one that can recombine elements of its genetic material while replicating. In other words, it will be a highly adaptable, easily evolving organism, one able to thrive under unfamiliar conditions in which it resides, including the human body, its host. Although various diseases may meet this criteria, seasonal flu should be considered first.

Influenza is a contagious respiratory illness that can be mild or severe though at times may lead to death. It is caused by viruses that infect the nose, throat, and lungs. Viruses — the word comes from the Latin word for "toxin" — are parasitic in that they are only able to replicate inside the living cells of another organism; having infected a healthy cell, the virus takes over its function and reproduces more of itself within the host body. As a viral infection, the flu can either be prevented by a vaccination or be treated with an antiviral drug. Flu is said to become pandemic when it is spread across a large geographical area, often worldwide. Compared to an epidemic, which is specific to a region or even a city, a pandemic infects many more people.

The 1918 Flu pandemic, commonly referred to as the Spanish Flu, infected 500 million people worldwide and killed, by some accounts, five percent of the world’s total population. There is real reason to fear a new and as-yet-unknown strain of pandemic flu.

2. Antibiotic-Resistant Superbugs

Among the newest kids on the block are antibiotic-resistant bacteria, commonly referred to as "superbugs." The infections caused by such bacteria turn frightening when they do not respond as expected to a commonly prescribed medication. An infectious disease caused by a superbug, then, means a doctor has no weapons to fight it and the body is left to fight for itself. Strains doctors frequently cite include CRE (carbapenem-resistant enterobacteriaceae), MRSA (Methicillin-resistant Staphylococcus aureus), and C. diff (Clostridium dificile). Infections from resistant bacteria are becoming increasingly common, with some bacteria already having developed resistance to multiple classes of antibiotics. Each year, in fact, roughly two million people acquire serious infections with resistant bacteria, while nearly 23,000 people die. “A post-antibiotic era means, in effect, an end to modern medicine as we know it,” warned Dr. Margaret Chan, the director-general of the World Health Organization. “Things as common as strep throat or a child’s scratched knee could once again kill.”

3. Chagas Disease

Named after the Brazilian physician Carlos Chagas, Chagas is caused by the parasite Trypanosoma cruzi, which is transmitted to animals and people by insects and is found only in the Americas. For this reason, Chagas disease is also referred to as American trypanosomiasis. It is most common in rural areas of Latin America where poverty is widespread. What is frightening about Chagas disease is that it begins with an acute phase, with symptoms that include fever and malaise. There may also be a swollen red area at the site of an insect bite. After this phase passes, though, the disease goes into remission and no symptoms may appear for many years. When Chagas "returns," and this may take 20 years, it afflicts the heart and digestive organs and symptoms include: constipation, digestive problems, heart failure, pain in the abdomen, and swallowing difficulties. At this point, a person may die suddenly and in an instant. Chagas may be the literal drop dead disease. By some estimates, there are already about 300,000 cases in the U.S., by other estimates up to one million. Experts believe this disease could become a pandemic.

...and the West Nile Virus (an example of what could happen)

The virus makes the list simply to prove that what was once, as its name suggests, a "remote illness" has now become relatively common in the U.S. Globalism, for all its wonders, also means a previously unheard of disease may easily come our way.

Typically transmitted by mosquitoes, this virus first appeared in the U.S. in 1999 and since then — a mere 15 years — it can be found in the 48 contiguous states. Most infections with West Nile virus cause no illness at all, yet about one out of every five infected people suffer flu-like symptoms including:

  • fever
  • nausea
  • vomiting
  • headache
  • fatigue

Here’s where it gets scary, though: Nearly one in 150 infected people develop neurologic symptoms, including encephalitis (inflammation of the brain), meningitis (inflammation of the membrane that covers the brain and spinal cord), and poliomyelitis (paralysis combined with fever and meningitis).