At our meeting on Thursday, 17th February our own member Trevor Blease presented his very detailed and informative talk “Pandemics Past and Present”. Trevor began by saying he was curious how SARS – Covid infections compared with other pandemics.
Bubonic Plague or Black death, a bacterial originated disease, has killed 200 million people. It is spread by rats carrying infected fleas and is still prevalent in Congo and Madagascar.
SARS – Covid virus exists in nature and provides a reservoir of virus.
Small Pox has no natural reservoir and through vaccination programmes has now been eliminated.
Spanish Flu which killed many people in 1918 is now known to have been H1N1 Avian Flu virus.
HIV which leads to AIDS was via infection from Primates to Humans in West Central Africa. Up to 25 million people died from AIDS complications like pneumonia and cancers.
Polio virus exists in nature and is spread by faecal to oral transmission. It affects mainly children up to 5 years and peaked in developing countries during 1940 -50s.
SARS- Covid virus has a natural reservoir in bats and therefore, unlike Small Pox, it will not be possible to eliminate. The virus was identified in 2003. Associated virus disease MERS affected older adults. Covid infection is spread by respiratory droplets containing the virus. A person infected with Alpha or Delta variants have virus in the upper and lower respiratory tract. The Omicron variant is mainly in the upper tract leading to higher transmission rates.
Research has identified that Covid virus levels peak before a person has any symptoms. This is described as Asymptotic Transmission. This explains why Covid can spread rapidly through a localised group of people.