Understanding Pandemics and Epidemics


One of the more dangerous disasters that can strike us is an epidemic or pandemic. Throughout world history, there have been a number of major epidemics which have struck. In each of these cases, the difficulty in treating the disease made for high death tolls, sometimes in the millions. What added to that was the lack of understanding about how disease spreads.

Today we have a much better understanding of disease and the disease mechanism. The “germ theory of disease” which was developed in the 1870s, helps us in that we know that disease is caused by bacteria, viruses and protozoa entering the body and infecting it.

When a few people are infected by a particular pathogen, giving them a disease, it is referred to as an “outbreak” of that disease. In the case of diseases which are pretty much always with us, a sudden rise in the incidents of that disease would qualify as an outbreak. When that disease spreads to the point where it is infecting a region or nation it is referred to as an epidemic. If it gets to the point where it is affecting the whole world, it is referred to as a pandemic. Most pandemics are caused by “novel” (new) viruses.

Spreading of Disease

This information isn’t prefect though. While we may understand the various mechanisms of disease spread, we don’t know every possible disease-creating organism in the world. So even with all the medical knowledge we do have, when a new or “novel” disease shows up, our scientific community has to study it before they can figure out how to treat it.

There are a few common ways in which disease spreads:

  • Through the fecal-bocal route – This is a contamination of the water supply, caused by human or animal feces, which are bacteria-laden. Modern water treatment and disposal largely eliminate this in developed countries, although it is still common in underdeveloped countries.
  • Through contaminated food – E-coli, the bacteria most often associated with food poisoning comes from improperly or under-cooked foods.
  • Through bodily fluids – One of the more common ways of disease spread, blood, spittle and other bodily fluids can carry bacteria and viruses. Those who are nursing sick family members can catch disease by contact with these fluids. This means of transmittal also accounts for disease that is sexually transmitted.
  • Through physical contact – Physical contact with a sick person or with items that a sick person has used, coughed or sneezed on can cause a healthy person to pick up disease pathogens on their hands. Then when they touch their faces (something we all do, all day long) those germs can enter the body through the mouth, nose or eye sockets.
  • Through aerosol – Often mistakenly referred to as “airborne,” respiratory diseases especially can travel through tiny drops of spittle that leave the mouth when one coughs or sneezes. It can even happen when talking or singing. These droplets can travel as far as 12 feet under favorable conditions, or even farther if they have a tail-wind.

One of the problems we face is that in most cases, people infected with a disease are contagious before they are symptomatic. With the flu, they are typically contagious for two days before symptoms occur. With COVID-19, it is possible for someone to be contagious, even though they never become symptomatic.

Once inside the body of a healthy person, these bacteria, viruses and protozoa begin to eat and multiply, infecting the person. The body’s autoimmune system rallies to fight back, but that takes time. It becomes a race to see which is faster, the ability of the pathogen to multiply or the ability of the body to produce antigens. In the beginning, the pathogens have the advantage, bringing about disease. The question then is whether the body can produce enough antigens to kill off the pathogen.

Medicine and the Treatment of Disease

In our modern world, this is where medical science steps in. In the case of bacteria-caused diseases, antibiotics are administered, augmenting the body’s antigens and helping to kill off the disease pathogens. For protozoa-caused diseases (which are much rarer), antimicrobials are needed.

The real problem is with viral diseases. There are few antiviral medications in existence and unlike antibiotics, they are virus specific. For example, an antiviral that works against one version of influenza probably won’t work against any other. In addition to this, viruses mutate easily, making it so antiviral medications that do exist, don’t work against them.

This is why the common way of dealing with viral disease is through vaccination. Vaccines are developed which will trigger the body’s immune system to produce the right antigens for the virus, when administered. That “teaches” the immune system how to defend against the disease, so that if the virus makes it into the body, it is more readily defeated.

However, vaccines are difficult to develop and don’t always work. It’s rare for medical science to find a vaccine that is 100% effective the first time around. It’s not uncommon for scientists to have to develop a number of different vaccines for a disease, in order to find one that is sufficiently effective to make it worth manufacturing and distributing.

There has only been one disease that has been defeated worldwide by vaccination; smallpox. An intensive worldwide effort at vaccination led to the demise of this virus, allowing the World Health Organization (WHO) to declare it eradicated in 1980.

Treating an “Incurable” Disease

With the difficulty in developing antivirals and vaccines, most viral diseases can seem to be incurable. In these cases, it is up to the body’s autoimmune system to defeat the disease on its own. All that our doctors, nurses and hospitals can do is provide what is known as “supportive care,” keeping the patient alive and treating symptoms, while the body’s immune system fights the disease. There are exceptions, but if they can keep the patient alive, the body will usually succeed in its battle.

This is what we do with influenza. Doctors don’t have a cure for the flu, but rather will treat the symptoms, knowing that in most cases, the body will defeat the disease in a few days. Even COVID-19 is treated in this way, whether it is through the administration of hydroxychloronquine (even though the use of this medicine has been controversial) or the use of ventilators.