Outbreaks refer to a rapid increase of patients with a
(usually) new disease or disease variant at a particular place. The number
affected may vary from just a few to many thousands.
If a disease is commonly seen in a region at various times of the year, it is called “endemic”. Malaria is an example of an endemic infectious disease in tropical countries. Once an outbreak of a new disease becomes community-wide, it is often called an “epidemic”.
An endemic disease is cause for an active policy to prevent as many cases as possible, such as applying mosquito repellent when you’re in the tropics. An epidemic disease’s appearance raises an alarm and increases the actions taken by authorities to stop contagion, as is currently the case in Wuhan.
Most have heard of the word “pandemic”. When the word “pandemic” is used, it has connotations of panic and worldwide societal disintegration. This is not necessarily the case. The Spanish Flu epidemic killed 50-100 million people (at a time when only about 2 billion were on the planet). Despite this, society survived.
When does a disease reach pandemic level? How is it
different from an epidemic? I think it’s important to know where we stand with
the current coronavirus outbreak and how world health officials view a novel
Phases of a Pandemic
The World Health Organization classifies infectious diseases though a series of phases. This system is used to help determine the resources needed to prevent a worsening situation. Simplified, they are:
Phase 1: The virus is prevalent within animals only. No human infection has yet resulted from the animal virus. (We’ll take two viruses as examples: Ebola in 2014 and the latest coronavirus (known as 2019-NCoV). Both of these are thought to originate in animals like fruit bats (Ebola) and bats or snakes (2019-nCoV). These are now found in humans, so we have passed this phase).
Phase 2: An animal virus has caused an infection in a human being. At this point, there is a basic level of pandemic threat because the virus strain has mutated to make that transfer to a human. (Both Ebola and the new coronavirus has exceeded this criterion.)
Phase 3: Small clusters of human beings have contracted the virus in one community. There is potential for the spread of the virus if others outside that community come into contact with those humans who are infected. At this point, the illness may be epidemic in that community, but it is not pandemic. (both 2014 Ebola and 2019-nCoV meet and exceed this criterion.)
Phase 4: Human-to-human and animal-to-human virus transmission are causing outbreaks in many communities and more people are getting sick in those communities. More communities report outbreaks and a pandemic-in-the-making is possible. (Ebola met and exceeded this criterion. 2019-nCoV cases outside the Wuhan area have been traced to travelers from the area, so it depends on your definition of “community”. There are, likely, different communities in the Wuhan area that are experiencing outbreaks but no community-wide outbreaks exist in, say, Chicago or Paris.)
Phase 5: Human-to-human transmission is taking place in at least two countries in one WHO region. At phase 5, most countries are not affected but a pandemic is considered likely. This phase is the alarm that national health systems must prepare for large numbers of cases in the affected countries. (Ebola met this criteria for at least three adjacent countries in West Africa. 2019-nCoV does not, at present.)
Phase 6: A global pandemic exists. Illness is widespread in at least two countries in different regions of the world. At this point, health officials are actively working to curtail the spread of the disease using preventive and stop-gap measures. (Neither Ebola in 2014 nor the new coronavirus meet these criteria, but the Spanish Flu of 100 years ago did.)
As far as I know, the time period for progression from phase
1 to phase 6 may be just a month or two. It may also take years.
I place the coronavirus outbreak, at the time of this writing, as early phase 4.
Once the number of cases begin to level off and decrease, there is a post-pandemic phase that may consist of multiple waves of outbreaks. High alert is still required for an extended period of time.
When it comes to infectious diseases, rapid action is needed to send medical resources where they are most needed. The WHO outbreak levels provide a framework, but the organization sometimes is slow to declare emergencies. Hopefully, coronavirus won’t become the next pandemic, but it’s wise for every citizen to keep watch and have medical supplies to meet the possible need.
Joe Alton MD
Medical supplies are a must in disaster, epidemics, and other scenarios where help is not on the way. Be sure to check out Nurse Amy’s pandemic kits, bleeding kits, individual items and more in her entire line at store.doomandbloom.net. You’ll be glad you did.