Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the
learning and teaching of Biology at a variety of levels.
|
Site author Richard Steane
|
The BioTopics website gives access to interactive resource material, developed to support the
learning and teaching of Biology at a variety of levels.
|
|
| Disease -
Caused by |
(Signs) and Symptoms | Control/ prevention | Spread by | Background |
| SARS
(severe acute respiratory syndrome) SARS CoV 
Image courtesy CDC
(2003) |
Influenza-like illness that occasionally leads to progressively severe respiratory insufficiency.
Symptoms: a high temperature (fever), extreme tiredness (fatigue), headache, dry cough, chills, diarrhoea, breathlessness, muscle pain (aches) This may develop into Pneumonia, a severe lung infection, and can lead to organ failure (lungs, heart, or liver) |
Isolation of infected persons and screening of air passengers from areas of infection
Said to be 'self-limiting' No vaccine at present |
Person to person transmission by close personal contact, by respiratory droplets produced when an infected person coughs or sneezes.
Also from contaminated surfaces 
Original source is presumed to be civet 'cats', which had been infected through contact with a bat before they were sold in a live meat market. The virus is thought to have mutated, becoming able to infect humans. In fact the masked palm civet is a relative of the mongoose.
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First detected in the Guangdong province of China in November 2003 and subsequently spread to more than 30 countries.
Over 8000 cases were reported worldwide, with 774 deaths (about a 10% case fatality rate). More than half of the deaths were in people over 65 years in age, and unsurprisingly people living with or caring for them were at risk of also catching it. In 2004 there was secondary and lesser outbreak of SARS, linked to medical laboratory incidents in China - not caused by animal-to-human or human-to-human transmission. No new cases since 2004 |
| MERS
Middle East Respiratory Syndrome MERS coronavirus (MERS-CoV) 
Image courtesy BBC |
Fever, cough, shortness of breath
Infection may lead to further (pre-existing?) complications such as gastrointestinal conditions (eg, diarrhoea, vomiting, abdominal pain) Some infected people have had mild symptoms (cold-like symptoms) or no symptoms at all. |
CDC routinely advises that people help protect themselves from respiratory illnesses by taking everyday preventive actions like washing their hands often, avoiding touching their face with unwashed hands, avoiding close contact with people who appear sick, and cleaning frequently touched surfaces.
In November 2019 a MERS vaccine entered clinical trials in Saudi Arabia. |
Most cases have been spread by human-to-human contact, but it was thought to be initiated by contact with (young) dromedary camels, and bats have been found to carry a similar virus. A vaccine for camels was tested in 2015.
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First detected in Saudi Arabia in 2012. It has spread to 26 other countries e.g just two cases (healthcare workers) in the US in May 2014 and in 2015 186 people in hospital in South Korea, resulting in 36 fatalities. All cases have had links to individuals recently returning from the Arabian Peninsula.
Up to Nov 2019, WHO has confirmed 2,499 MERS cases and 861 deaths (34% fatality). CDC tests specimens by RT-PCR and by serology testing. |
| Disease -
Caused by |
(Signs) and Symptoms | Control/ prevention | Spread by | Background |
|
Coronavirus disease 2019
(abbreviated to COVID-19) SARS-CoV-2 
Image courtesy CDC |
Fever, dry cough, difficulty breathing, pain in the muscles, tiredness.
Loss of sense of smell and taste have also been recorded as symptoms. Older people and those with certain underlying health conditions like heart disease, lung disease and diabetes, seem to be at greater risk of serious illness. A proportion of people surviving an attack have gone on to develop a condition known as 'Long Covid' |
Thorough hand washing with soap, or alcohol-based hand sanitisation gels.
Personal hygiene should include not touching face and eyes.
Face masks have been widely adopted, but their effectiveness is uncertain. They might catch droplets from coughing, but they are unlikely to filter out viruses which are sneezed out, or breathed in. These have been seen as a requirement in enclosed spaces such as public transport, and doctors' surgeries. More effective personal protective equipment (PPE) has been necessary for hospital and carehome workers. Social distancing has been seen as a key control measure. Keeping at least 2m distance away from other members of the public was initially recommended. This was followed by total lockdown (staying at home) and widespread switching to working from home. International travel was affected in the early stages. Body temperature screening has been widely used to check travellers. And different periods of quarantine have been imposed for newcomers to some countries. Vaccines were quickly developed as a result of publication of the RNA sequence of the virus in China. This avoided the use of active viruses , or inactivation procedures which slowed down the development of vaccines for other conditions. Two main approaches emerged:
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Person to person transmission by close personal contact, by respiratory droplets produced when an infected person coughs or sneezes. Also by contact with contaminated surfaces.
Contact tracing to identify people possibly infected by confirmed cases has not been entirely successful, leading to conclusion that this can quickly become a community-based condition . It was declared a global pandemic by the WHO on 11 March 2020. Original source uncertain. Bats seem likely to have been involved, but other species such as pangolins or possibly snakes have been suggested, and also rejected. 
Circumstantial evidence related to environmental samples taken some time ago in the Huanan Seafood Wholesale market suggests that Covid 19 moved from bats to raccoon dogs which were on sale (for food) and from here the infection spread to humans, around the world.
And of course there are colonies of different types of bats in caves across China, and there is a Wuhan Institute of Virology which had been involved in research about the role of horseshoe bats in SARS. They found the newly discovered coronavirus virus had 96% genetic similarity to a virus its researchers had discovered in horseshoe bats in Yunnan Province, southwest China, about a thousand miles from Wuhan. |
First detected in Wuhan, China and reported in December 2019.
Diagnosis: Reverse transcriptase-polymerase chain reaction (RT-PCR) testing of upper and lower respiratory secretions is a laboratory-based technique. Simpler and more immediate lateral flow tests have been developed to detect viral antigens - nucleocapsid proteins - in swabs of the nasal passages. These have been very useful on following the spread of outbreaks. It is thought that healthy people under 70 are at much less risk of infection, and some may have been exposed and recovered without being included into statistics accounting for the seriousness of infections. The infection cycle appears to last about 14 days, with symptoms and infectivity appearing from about day 7. However some infections do not display symptoms, but virus particles are still released so disease outbreaks can spread dramatically. Shocking statisticsAs of mid-March 2023 (i.e. about 3 years after it was declared a pandemic), the WHO Coronavirus (COVID-19) Dashboard states that globally there have been 760,360,956 confirmed cases of COVID-19, including 6,873,477 deaths.And a total of 13,232,780,775 vaccine doses have been administered. In USA there have been 102,417,985 confirmed cases of COVID-19 with 1,113,229 deaths, This compares with 220,437 deaths in the UK. |
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