Читать книгу Viruses: More Friends Than Foes (Revised Edition) - Karin Moelling - Страница 11

A comparison is also possible with the first SARS-corona outbreak in 2003 or the MERS epidemic in 2009. Both of these were of short duration and left a shock. SARS 2003 started in South China. The animal source was a bat population that passed the virus on to a civet cat, as intermediate host, on a food market. From there it was passed on to humans, and was transmitted from person to person. It spread into 29 countries around the world in only six months.

A skyscraper in Hongkong became known as a “spreader” because of dissemination of the disease through aerosols and contacts in the building. These first cases allowed a follow-up to Singapore and to Vancouver in Canada. Worldwide, the number of patients was 8,098 and the death toll was 774, i.e., the death rate was about 10%. Even today it is not quite clear where and how the virus disappeared; as far as we know it has not returned. Did it lose a gene fragment? — as has been described, although the disappearance of the virus could not be attributed to it. Nobody can tell. This virus also left a shock, and some people may have remembered it when recently SARS-CoV-2 showed up. Could it disappear also?

MERS is also a “species-hopper” (in technical language: a zoonosis). It too started in bats and was then transmitted to dromedaries as an intermediate host. From there the virus infected and killed a sheikh and his son. The virus made it as far as Korea, and one may wonder whether the reason why Korea was so successful in fighting the COVID-19 outbreak was perhaps because people there had experienced an epidemic twice in the recent past. In 2009, 2,465 people fell ill with MERS and 850 died. This virus did not disappear: there are still local foci where it shows up, and the death rate remains very high, some 36%. Where does MERS hide? It has some similarity to a coronavirus in bats, which has not yet caused a severe disease but which shows up in the seasonal winter flus. Do we have to be on the alert?

Another epidemic, analyzed for comparison, is HIV/AIDS, of which 30 million people have died since the early 1980s. However, this is a sexually transmitted disease and can also be transmitted through blood and blood products. Therefore, this disease is spread by different mechanisms. Ebola viruses may also be worth mentioning: these have some of the highest death rates among present-day viruses, reaching to about 90%. However, most of the outbreaks are local, and they remain confined because infected people are too ill to travel. This virus also originates from bats and is transmitted through blood, feces, urine and saliva; funeral rituals also strongly promoted transmission of the virus. Ebola was one of the examples where antibodies were recovered from the serum of survivors of the disease and could be used to immunize and save deadly-sick people.