When we talk about pandemic, endemic, epidemic, syndemicamong others, these are epidemiological terms regulated or unified internationally from the World Health Organization (WHO), these correspond to different stages of the presentation of diseases at the population level, but today thanks to the coronavirus called SARS-CoV-2 and the pandemic Covid-19 that has been generated, these terms have become popular in the population without being clearly identified.
For the above, in The Economist We talked with Dr. Igor Martín Ramos Herrera, head of the Public Health Department of the University Center for Health Sciences of the University of Guadalajara, who explains in detail the terminology and its scope in order to understand the current moment.
When there are several cases in a given place and time, -where a disease is not expected to occur, had not been, or had passed a long time since the last time it occurred-, it is called an epidemic outbreak.
A next level occurs when the number of cases in people delimited in a geographical area (town, city, region, country…) begins to reproduce very actively and cannot be contained in a specific physical space. This is an epidemic.
Subsequently, the who has divided the planet into six regions, we belong to the region of the Americas, which covers the entire American continent. To consider a pandemic, the criterion is that there are cases in at least one country in each region. Another criterion is that the cases that occur there are not imported, but that there is already community transmission in the region itself, that is, contagion.
All this is located in a certain time, “today it can be said that Mexico is experiencing a moment and condition of epidemic by Covid-19” and it has not yet been identified how much longer it will last, but if that process were to be cut at some point , that is to say that there are no longer cases, it could be said that the epidemic ended in the country. But another scenario is that if the cases go down but continue to occur permanently after a certain time, statistical projections are made and it is given endemic category.
Mexico in the endemic phase?
Today the discussion is open to see if the pandemic or epidemic of Covid-19, which has generated a health emergency, is beginning to generate a endemic, but that is not yet defined worldwide, it has not been declared anywhere as such.
According to Dr. Ramos Herrera, all these epidemiological decisions, including the one to go to the term endemic, are made through the Ministry of Health and the corresponding undersecretary, in this case the Health Promotion, who together with the analysts epidemiologists make the statistical and projection calculation based on historical data and with certain characteristics established by the WHO.
Currently we have endemic diseases in the country, such as: Influenza, dengue, malaria. The specialist assures that it is important “not to see it as an alarm term. This implies that the population has sufficient defenses so that only a certain number of people get sick. This in turn generates an endemic channel, that is, locating at what times of the year there is an expected number of cases.
for a moment of endemic there must also be a population adaptation, that is, a group or herd immunity, as it is known. A first form of adaptation is when 70% or more of the population is vaccinated or has already generated defenses due to exposure, and the rest of the population is protected because the disease is no longer transmitted.
Finally, a term that has also been present is that of syndemic, which refers to the confluence of two diseases simultaneously. For example, dengue and influenza, Covid and influenzawhich has already occurred in the Mexican population.
Ramos Herrera concludes that we will probably soon be seeing asynchronous movements in the world, that is, areas or countries still with an epidemic, others with endemicothers with outbreaks and others without, but so far we are not clear about the behavior of the disease and we are still in a pandemic.