This year, there are some particularly pertinent holidays to observe. Please consider Teacher Day on the 5th and Nurse’s Day on the 6th (Tourism Day on the 7th will have to wait for next year). We should also acknowledge Receptionists on the 13th, the Armed Forces on May 16 and Waitstaff on the 21st. If you are still confined to your house, you could participate in Clean Your Room Day (May 10) or No Dirty Dishes Day (the 18th). However, Eat What You Want Day (the 11th), Scavenger Hunt Day on the 24th and Paper Airplane Day (May 26) sound like more fun.
By now, you may be longing to reenter society, even (or especially) if the only person you currently encounter is your number one fan. To help you prepare for this transition, I have prepared some semi-random musings on the subject of Public Health.
According to Britannica.com, Public Health is “the art and science of preventing disease, prolonging life, and promoting physical and mental health, sanitation, personal hygiene, control of infectious diseases, and organization of health services”. It is focused on the entire community, whether the community involved is a neighborhood or the whole world. This is a little different from the front-line health care workers who concentrate on treating individual patients.
Public Health is a requisite part of every veterinarian’s training. We strive to prevent the spread of disease within the animal population as well between animals and humans. When you take your dog or cat to the vet, the primary focus is on your pet. When the vet goes on a farm call, their concern extends from the individual to the entire herd or flock (or caravan of camels or crash of rhinos or prickle of porcupines). In addition to these not insignificant tasks, farm and USDA vets are also tasked with the safety of the food supply.
Although all aspects of Public Health are vital, and often interrelated, this BLOG blog shall focus primarily on the timely topic of the control of disease in humans.
Outbreaks of contagious diseases are by no means a new phenomenon. Smallpox, Yellow Fever, various incarnations of Influenza and the infamous
Bubonic Plague have all, at various times throughout recorded history, run amok and caused widespread death and destruction. Other epidemics of (dis)honorable mention include Ebola, HIV and Polio. There is much to be learned from previous episodes of pestilence, and I shall attempt to offer a brief overview. But first, please enjoy this miniature medical terminology lesson!
In the public health sense, Morbidity refers to being sick, not just having a fascination with the macabre. Mortality refers not to the inability to live forever, but rather the portion of the population succumbing to a particular condition.
Although they are used interchangeably in the common vernacular, there is technically a difference between Infectious and Contagious diseases. Infectious diseases are all of those caused by microorganisms. Contagious (aka communicable) diseases are only those that are spread within (or between) species by direct, indirect or droplet contact. So, all contagious diseases are infectious, but those that are infectious are not necessarily contagious.
Another important category of diseases is zoonotic infections. These normally exist in animals, but can spread to humans. There are even a few zooanthroponoses (aka reverse zoonoses) that are transmitted from people to animals. These can indeed be troublesome, but the spread within a species is usually more rapid and widespread than the interspecies sort.
Epidemiology is “a branch of medical science that deals with the incidence, distribution and control of disease in a population” (merriam-webster.com). In short, it is the study of epidemics. What constitutes an epidemic? According to the CDC, endemic refers to the amount of a particular disease that is usually present in a particular area. If there is a sudden increase above this baseline level, it is considered an epidemic. If the epidemic spreads to other countries and other continents, it becomes a pandemic. Pandemonium is the chaos (and shortages of personal paper products) that may ensue in response to a pandemic.
Herd Immunity is a state that occurs when enough people are immune to the particular disease (through vaccination or natural immunity) that it can’t spread. (Herd impunity would be a bunch of holy cows wreaking havoc in India.) How many immune people do you need? It depends on the pathogen’s ability to spread. This is known as the basic reproductive rate, which is expressed as a number known as its R0 (Arrrr-knot for pirates and Ah-naught for New Englanders). This number indicates how many others to whom, on average, an infected person will pass the disease. This means that the higher the number, the more contagious the disease and the more people who have to be immune to prevent spread. For example, measles is extremely contagious (R0 ranging from 12-18, depending on population density), and will spread unless >90% of the population is immune. Influenza is less contagious, with an R0 that ranges from 0.9 -2.1, so herd immunity would be expected to take effect when around 50% of the population is immune. Also note that herd immunity relies on a random distribution of the susceptible population. If there is a cluster of potential hosts, the pathogen will have no problem spreading amongst them, regardless of the status of the general population.
To minimize the impact of an outbreak of contagious disease, it is necessary to control its spread. This relies on the tried-and-true methods of isolation and quarantine to protect the larger community. Isolation is used for someone who is known to be infected; quarantine is applied when someone is suspected of having or carrying or has been exposed to disease. Both rely on physical separation of the (potentially) infected from the general population. Forms of these protective measures have been practiced for thousands of years. One early recorded use of isolation is the Old Testament’s instructions for the treatment of people afflicted with leprosy. Much has been learned about the condition since then, from the causative agent (Mycobacteria leprae) to the fact that armadillos are a natural host for it. The disease is also not as contagious as once thought, and a cure has been available since the 1940s. Nevertheless, some leper colonies remain.
The word “Quarantine” has its roots in Venice during the 14th century, according to bbc.com/travel. Ships arriving from plague-infested ports were ‘required’ to sit at anchor for 40 days (quarantino in Italian) before landing. However, the standards were not applied universally and wealthy people were able to bypass the procedure.
The standards are different (and more precise) in a medical setting. To prevent the health care provider from contracting disease, physical precautions are taken to avoid exposure to infectious materials. There is specially designed garb, including gloves, gowns and goggles, which is known collectively as Personal Protective Equipment. It is often abbreviated PPE (even though that sounds more like a potential potty emergency). Modern masks are also more effective than the beaked versions worn by the doctors of the 1600s (not during the Black Death, but during a later outbreak of bubonic plague). In a health care setting, the level of precautions necessary depends on the method by which a disease is spread. If the mode of transmission is contact, gown and gloves are required. If the pathogen is spread by droplet, face protection is needed in addition to the gown and gloves. The patient should also wear a mask, if possible. People with airborne infections require isolation rooms equipped with a special ventilation system. Personnel entering the room also need special masks (N95 respirators) that are fit tested to ensure a good seal. Please note that PPE is used in addition to, not instead of, hand washing, respiratory hygiene/cough etiquette and proper cleaning/disinfection.
Some people are more susceptible to pathogens than others. Groups commonly considered at risk are those who are very young, elderly, immunocompromised by a medical condition or treatment thereof and those living in crowded and/or unsanitary conditions. It is imperative that preventative measures be used to protect vulnerable populations.
For an idea of what happens when a communicable disease makes its debut, let’s review the history of Canine Parvovirus (aka Parvo). In the late 1970s a new virus appeared in the canine population. It was very similar structurally to the Feline Panleukopenia virus, and is presumed to be a strain that mutated and then jumped hosts. It erupted dramatically in 1978 and rapidly spread around the world, leaving myocarditis, diarrhea and many, many deaths in its wake. There was (and still is) no specific treatment; supportive care is provided until the dog fights off the virus or succumbs to it. Thankfully, vaccines became available within a couple of years of the major outbreak. Over time, new strains of the virus have appeared, and the vaccines have had to be reformulated to protect against the new incarnations. Puppies are at the highest risk of contracting it. They (usually) get some immunity from their mother, but it (usually) wears off when they are between 8 and 16 weeks of age. It is important to protect pups with a series of vaccinations, prevent contact with unvaccinated dogs and avoid areas of high canine concentration, like dog parks. The virus is still present in the environment, and we see it all too often.
A composition about public health would not be complete without a nod to a few of the great innovators in the field. First up is Dr. Ignaz Semmelweis. Although not sufficiently appreciated during his lifetime, this Hungarian physician was an early (and sometimes vocal) advocate of hand washing. His findings encountered such significant backlash that it has since been named for him. According to sciencedirect.com, the Semmelweis reflex (aka Semmelweis effect)
is “a human behavioral tendency to stick to preexisting beliefs and to reject new ideas that contradict them (despite adequate evidence)”.
Next, we must pay homage to the father of antiseptic surgery, British surgeon Dr. Joseph Lister. His work inspired, but he himself did not create, the mouthwash that bears his name.
Although I did expound extensively on his virtues in an earlier BLOG blog (March 2019), I am compelled to briefly mention the remarkable accomplishments of Louis Pasteur. His impressive resume includes contributions to food safety, the development of several vaccinations and evidence that germs, not spontaneous generation, cause disease.
I must also mention Dr. Edward Jenner, who used material from cowpox lesions to protect people from the speckled monster known as smallpox. He may not have invented it, but he popularized the notion of vaccination. He also deserves at least some credit for the name – vacca is a Latin word for cow.
These pioneers (and many others) have led the way in disease management by demonstrating that germs cause disease, the spread of germs between people can be minimized with proper hygiene and one’s immune system can be prepared in advance to fight off diseases. These basic tenets still hold true. It is up to us to use this knowledge for the greater good.
So how does this relate to the average person (and the most excellent people who read the BLOG blog)?
On a grand scale, public health effects everyone. When a disease outbreak threatens a community, information, communication and cooperation are vital. Well documented, science–based data is crucial. It needs to be dispersed clearly and efficiently to the those directly involved and to the masses. People need to have the best possible information provided by a reliable source. Public health organizations need to work quickly and coordinate efforts to contain outbreaks. People, even those who are not currently ill, will need to follow prescribed measures to support containment, even if that means dressing like a bandit every time you go out in public.
On a personal level, the existence and importance of contagious diseases needs to be appreciated. That means that people get sick due to microorganisms, not personal weakness. When you are ill, you are (probably) not doing your best work. You are also exposing others to pathogens. Therefore, people should stay home when they are sick. Going to work sick is not really doing anyone any favors. Yes, your coworkers will have to do some of your work and things will not run as smoothly. However, infecting them (and perhaps your customers) is unpleasant and counterproductive. Your absence will also make them appreciate how much you do contribute when you are there. In America, unfortunately, tending to one’s personal health needs is complicated by the fact that entirely too many people cannot afford to take the day off when they are sick. The threat of lost wages or even a lost job is commonplace. The situation is further complicated by the pervasiveness of the health-insurance-via-employer model and prohibitively expensive health care. This is a recipe for disaster during a pandemic. (Note – thereactually is an emergency preparedness cookbook called “Recipes for Disaster” that was published by the American Public Health Association.)
Hopefully the human race can learn from the current pandemic and take appropriate steps to prepare for the next one. There will be a next one. And it may be a whole lot worse. We have been warned.
There are many potential benefits we could reap from this pandemic. I would now like to offer a few possible improvements that could be instituted to help control future public health emergencies. Yes, they will require time, effort and a reallocation of resources, but the future of humanity may be at stake.
Cooperation and communication between public health agencies around the world is imperative. Early intervention can mean the difference between an epidemic and a pandemic. There should also be a thorough investigation into the COVID-19 countermeasures taken by various locales, and a comparison of the results. Knowing the most effective protocols would be good to know beforeProject Blue escapes from the lab.
Hygiene is a necessity, not a luxury. Clean, running water is essential to the health of all humans, including those in abject poverty. Water sources also need to be protected from pollution. The lives of humans (and the prevention of three-eyed fish) depend on it.
There also needs to be a higher regard for the truly vital workers in our society- and respect for their humanity. It’s not just the jobs that are “essential”. These people provide invaluable services and need to be protected as much as possible and properly compensated for their sacrifice. After all, cashiers did not sign up to work on crab boats.
It is now time for me to climb down from my soapbox (that looks suspiciously like a gigantic pyramid of toilet paper) and draw this particular composition to a close. In case I have instilled in you a tremendous longing for more epidemiology, I offer some suggestions to help you get your fix. There are multiple free online courses (via Coursera). You can watch movies like Outbreak and Pandemic on Netflix. The “Infographics Show” on YouTube also has a variety of interesting videos about the Black Death and other epidemics. There are even computer games like Vax (vax.herokuapp.com) that are oddly addictive. Of course, now that you have the time, you can also read the unabridged edition of The Stand.
Until next time, Bored Surfer, keep calm, wash your hands and observe appropriate distancing standards (6 feet from other people, 39 and 1⁄2 feet from Grinches). May your May be healthy and happy.
Dr. Debbie Appleby