A member of the medical staff comforts a patient infected by the novel coronavirus at the Covid-19 division at the ASST Papa Giovanni XXIII hospital in Bergamo, Italy on April 3, 2020. Picture: Piero CRUCIATTI / AFP
Covid-19 is not the first virus to have created a feeling of fear and unease among the world’s people and, while not all viruses have led to pandemics, most have led to endemic spreads that have led to many fatalities, reports Bedfordview and Edenvale News.
Scientists have found treatments, cures and ways of preventing some of these viruses from spreading throughout the world through vaccines and anti-viral drugs which have helped the infected people to recover or which have even eradicated the disease.
New viruses, however, rear their heads occasionally, claiming many lives when triggered.
A number of these viruses are zoonotic (spreading from animals to people) and all pose a threat to public health.
Scientists take months to find a suitable treatment plan to combat or eradicate these diseases.
LiveScience has listed the top 12 viruses to kill vast numbers of people.
The Marburg virus was identified in 1967 when German laboratory workers were exposed to infected monkeys from Uganda. It causes haemorrhagic fever (high fevers and bleeding throughout the body leading to shock, organ failure and possibly death) in humans and non-human primates.
The World Health Organisation (WHO) said the mortality rate in the first outbreak was 25%, but it was more than 80% in the 1998-2000 outbreak in the Democratic Republic of Congo and in the 2005 outbreak in Angola.
Ebola struck in Sudan and the Democratic Republic of Congo simultaneously in 1976. It is spread through contact with blood or other bodily fluids, or tissue from infected people or animals. There are various strains of Ebola that have different viral strengths. Ebola Reston has no symptoms while Ebola Bundibugyo has a fatality rate of 50%, and the Sudan strain has a 71% fatality rate, according to the WHO. The present outbreak in West Africa began in early 2014, and is the largest and most complex outbreak of the disease to date, according to the WHO.
Rabies destroys the brain and will lead to death if not treated. One gets it if bitten by a rabid animal. Scientists developed a vaccine for domesticated animals a century ago. This has helped make the disease really rare in the developed world. This condition remains a serious problem in India and parts of Africa, however. People who are bitten by infected animals can be cured if they are treated. If not, they will die.
HIV is considered to be the deadliest virus and biggest modern world killer. The virus was recognised in the early 1980s and has claimed the lives of around 32 million people. Powerful antiviral drugs have been able to suppress the disease so that lifespans have increased for those afflicted. Even so the disease still runs rife in many low and middle-income countries where 95% of new infections occur. Nearly one in every 25 adults within the WHO African region is HIV-positive.
The world was declared to be smallpox free in 1980 after humans had battled the virus for, literally, thousands of years. The disease killed about one in three of those infected. Survivors were left with deep scarring (pox) and often went blind. European explorers spread the virus across the world wiping out an estimated 90% of the Native American population. Worldwide, around 300 million people have died of smallpox.
Hantavirus pulmonary syndrome (HPS) came to light in the USA in 1993. A healthy, young Navajo man and his fiancée living in the Four Corners area of the USA died within days of developing shortness of breath. More than 600 people in the USA have contracted HPS to date, and 36% have died from the disease, according to the Centers for Disease Control and Prevention. People contract the disease from exposure to the droppings of infected deer mice.
In 2009, this virus (known as swine flu) caused a pandemic, killing around 500,000 people worldwide during a typical flu season, according to WHO. The mortality rate can increase when a new flu strain emerges. The Spanish flu, began in 1918, affected 40% of the world’s population and killed around 50 million people and close on 130,000 South Africans.
Dengue virus, caused by the bite of a mosquito first, appeared in the 1950s in the Philippines and Thailand and has spread throughout the tropical and subtropical regions of the globe affecting around 40% of the world’s population. Global warming will likely lead to the spread of this virus. Between 50 and 100 million people a year are affected, according to WHO.
Although the mortality rate is 2.5%, it can lead to dengue haemorrhagic fever with a mortality rate of 20% if left untreated. A vaccine has been developed for those between nine and 45 years old who have contracted the disease before. Those who have not caught the virus before could be put at risk of developing severe dengue if given the vaccine. Dengue is caused by a virus while malaria is caused by a parasite.
Worldwide, 453,000 children younger than age five died from rotavirus infection in 2008, according to the WHO. The virus spreads rapidly through the faecal-oral route and causes severe diarrhoea. It is a problem and claims fatalities where the young victims cannot be rehydrated adequately. A vaccine that was developed has led to a sharp decline in fatalities.
The severe acute respiratory syndrome, or SARS virus, first appeared in 2002 in the Guangdong province of southern China, according to the WHO. The virus likely spread from bats to civets and then to humans. SARS spread to 26 countries around the world, infecting more than 8,000 people and killing more than 770 over the course of two years. The symptoms are fever, chills and body aches, often leading to pneumonia. SARS has an estimated mortality rate of 9.6%, and as of yet, has no approved treatment or vaccine. No new cases of SARS have been reported since the early 2000s.
Known as Covid-19, the SARS-CoV-2 virus was first identified in December 2019 in the Chinese city of Wuhan. The virus likely passed through an animal before infecting people. It has reached pandemic status across the world. It has an estimated mortality rate of about 2.3%. People who are older people and those with underlying health conditions seem to be most at risk. Symptoms include fever, dry cough and shortness of breath which, in severe cases, can progress to pneumonia.
The virus that causes Middle East respiratory syndrome, or MERS, caused an outbreak in Saudi Arabia in 2012 and another in South Korea in 2015. This virus belongs to the SARS-CoV and SARS-CoV-2 virus family. The disease infected camels before passing into triggering fever, coughing and shortness of breath and progressing to severe pneumonia. The mortality rate is between 30% and 40%.
Reference: LiveScience: The 12 Deadliest viruses on earth
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