Middle East respiratory syndrome
Last May, the first Middle Easy respiratory syndrome coronavirus (MERS-CoV) patient was confirmed in Korea. And within a month, there were more than hundreds of patients in South Korea suffering from such virus. In fact, the number of patients in South Korea quickly outnumbered the number of patients in Saudi Arabia, where the virus was first found and studied in 2012. How did this happen in such a short time?
The first patient in South Korea is known to be a 68-year-old business man who had been travelling to Bahrain and Qatar. As he innately has a weak respiratory system, after the travel, he started to show a minor respiratory illness and was tested for MERS-CoV. And as soon as he was confirmed to be infected with such virus, he was segregated but it was too late when the hospital and Ministry of Health and Welfare took action. As a business man, he had made hundreds of contacts with other people, and numerous nurses and doctors also came in physical contact with him. By the time he was separated from other people, other patients who had an “edge” with him were affected. Despite the strength of ties, the existence of edges quickly spread the disease to various nodes—it went to different regions within Korea, even went international and influenced Thailand, Hong Kong and China.
It seemed impossible to stop the spread of disease as everyone is somehow connected to each other through other people, and making physical contacts not happen is simply implausible. The spread of MERS stopped only when all of the patients were segregated and the edges were cut off. The cutting of the edge through the removal of the patient–the node–resulted in the successful separation of the graph into two: a graph of patients and the non-patients.
From this incident, I realized how global the friendship graph is—most likely there is only one as mentioned in the lecture and this is probably why MERS spread so quickly to many different regions—and how serious contagious diseases could as everyone is connected through pathway of edges.
http://www.who.int/csr/don/07-july-2015-mers-korea/en/
http://www.cidrap.umn.edu/news-perspective/2015/05/south-korea-has-its-first-mers-case-uae-finds-2
http://www.cidrap.umn.edu/news-perspective/2015/06/thailand-reports-first-mers-case-south-korea-adds-3