Anna Posyniak‑Dutka Three Riders of the Apocalypse

The difference between an epidemicepidemicepidemic and pandemicpandemicpandemic is a matter of scale. While the first one affects a community or population residing in a given region, the latter has a much more global reach. A pandemic spreads over many countries or continents. Scientists also use the term outbreakoutbreaks [outbreak]outbreak to refer to the situations of a more significant than usual increase in the number of cases of a given disease. These are usually controlled quickly, as otherwise they may easily become epidemics or even pandemics.

COVID‑19

The first cases of the novel human coronavirus disease were reported in December 2019 in Wuhan, China. It was a new addition to the family of coronaviruses quite well known to scientists. SARS and MERS belong to the same category of viruses and we experienced the epidemics of those viruses in Asia in 2002 and 2012 respectively. In March 2020 the WHO officially declared COVID‑19 a pandemic. What’s interesting is that the first human trialshuman trials [human trial]human trials of an mRNA vaccine started at the same time. The virus caused global chaos. Many countries decided to introduce strict lockdownsintroduce strict lockdowns [introduce a strict lockdown]introduce strict lockdowns which affected supply chainssupply chains [supply chain]supply chains and wreaked havocwreaked havoc [wreak havoc]wreaked havoc across many branches of the economy. Some countries, such as Sweden, applied a different strategy and tried to achieve herd immunityachieve herd immunityachieve herd immunity by allowing people to take their own decisions about social distancingsocial‑distancingsocial distancing and prevention measuresprevention measures [prevention measure]prevention measures. One of the challenges of this disease was the fact that many carrierscarriers [carrier]carriers were asymptomaticasymptomaticasymptomatic and did not even know that they were transmitting the virus to other members of the community. Thanks to the combined effort of pharmaceutical companiespharmaceutical companies [pharmaceutical company]pharmaceutical companies from a few countries, vaccinationsvaccinations [vaccination]vaccinations were developed, tested, and ready to use in under 9 months. They started to be distributed in December 2020. Until April 2022, COVID‑19 killed 6.22 million people worldwide from over 508 million infected.

HIVHIV [human immunodeficiency virus]HIV/AIDSAIDS [Acquired Immune Deficiency Syndrome]AIDS

By the time HIV, which is an acronym for human immunodeficiency virusHIV [human immunodeficiency virus]human immunodeficiency virus, was named by epidemiologists in the early 1980s, it had been spreading for at least 50 years. It is believed that it comes from West Africa where it transferred from chimpanzees to humans through the contact with monkeys’ infected blood during hunting. When doctors started reporting more and more cases of unusual cases of pneumoniapneumoniapneumonia, cancer, and some other diseases, scientists looked into those situations more closely and identified a new virus, which caused AIDS, Acquired Immune Deficiency Syndrome. In the following years scientists discovered that the virus can be transmitted through sexual contacts, contact with infected blood, and from mother to child from breastfeedingbreastfeedingbreastfeeding. The WHO recognised the seriousness of the problem by declaring AIDS to be a pandemic. In 1999 it was the 4th biggest cause of death worldwide. Scientists have been working hard on treatments and vaccinations for AIDS. It is estimated that there are a little under 38 million people living with HIV all over the world nowadays. 75% of them use ART, which is the antiretroviral therapyantiretroviral therapyantiretroviral therapy, which allows one to have a relatively normal life.

Bubonic plague

Bubonic plaguebubonic plagueBubonic plague, also referred to as the Black Death, was a pandemic which is believed to have arrived in Europe in the mid‑1300s and over the 5 years which followed, it wiped outwiped out [wipe out]wiped out 20 million people, which at the time was one‑third of the continent’s population. We know that before it appeared in Europe, it was present in China, India, and Egypt. The plague is a contagious bacterial diseasecontagious bacterial diseasecontagious bacterial disease. It has a 7‑day incubation periodincubation periodincubation period after which an infected person’s lymph nodeslymph nodes [lymph node]lymph nodes swell and subsequently start to bleed and seep puspuspus. A patient suffers aches, fever, vomiting, and shortly after that dies. 14th century Europe was hardly ready to handle such an outbreak. They knew next to nothing about the mechanisms of infection. Now we know that it is transmitted by infected fleasfleas [flea]fleas and rats as well as from person to person through the air. People tried to isolate themselves from the infected ones by escaping cities and moving to the countryside. That, unfortunately, did not help much, as the disease also affected cattle and poultry. Many believed that it was God's punishment. Because the disease was mostly spread from city to city by ships carrying sailors, they were not allowed to leave their ships for forty days until it was clear that they were healthy and could enter the city, which is the origin of the word quarantinequarantinequarantine.

As one can notice, pandemics have always been a part of human history. While deadly and terrifying, often leading to economic breakdowns and falls of political regimes, they also led to many scientific discoveries. It's thanks to them humans have learned how to stop new pandemics from occurring and keep the emerging ones under control.

1 Źródło: Anna Posyniak‑Dutka, licencja: CC BY-SA 3.0.