People struggled with the virus since ancient times. For some viral diseases, vaccines and antiviral drugs has helped to prevent widespread infection and helped heal the sick. Only one disease — smallpox — we’ve been able to eradicate, rid the world of new cases. This writes Live Science.
But humanity is far from winning the fight against viruses. In recent decades, several viruses have passed from animals to humans and caused significant outbreaks, which claimed thousands of lives. The viral strain that caused the Ebola outbreak in West Africa in the years 2014-2016, kills up to 90% of the people it infects, making it the most lethal member of the Ebola family.
But there are other viruses that are equally deadly, and some are even deadlier. Some viruses, including the new coronavirus, which is currently the cause of outbreaks worldwide, have lower mortality rates, but still represent a serious threat to public health because we have no tools to deal with them.
The Marburg Virus
Scientists have found the Marburg virus in 1967, when there was a small outbreak among laboratory workers in Germany exposed to infected monkeys imported from Uganda. The Marburg virus is similar to Ebola in that both can cause hemorrhagic fever, meaning that infected people develop high fever and bleeding throughout the body that can lead to shock, multiple organ failure and death.
According to the world health organization (who), the mortality rate during the first outbreak of the disease was 25%, but at the outbreak of 1998-2000 in the Democratic Republic of Congo, as well as during the outbreak in Angola in 2005, it exceeded 80%.
The Ebola Virus
The first known Ebola outbreak among humans occurred simultaneously in the Republic of the Sudan and the Democratic Republic of Congo in 1976. Ebola is spread by contact with blood or other body fluids or tissues of infected people or animals. Known strains differ from each other in their deadliness, said Elke Muhlberger, an expert on Ebola and associate Professor of Microbiology at Boston University.
From one strain, Ebola Reston, people do not even feel the symptoms of the disease. According to the who, for a strain between Bundibugyo mortality rate is up to 50%, and for the Sudanese strain to 71%.
According to who, the outbreak in West Africa began in early 2014 and is the largest and most complex outbreak to date.
Although rabies vaccines for Pets, which were introduced in 1920-ies, helped to make the disease exceedingly rare in developed countries, this disease remains a serious problem in India and some parts of Africa.
“It destroys the brain, it is very, very bad disease, said Muhlberger. — We have vaccine against rabies, and we have antibodies, so if someone is bitten by a rabid animal, we can cure this man.”
However, she said, “if you do not receive treatment from beshentseva almost 100% probability that you will die.”
In the modern world most deadly virus can be HIV.
“It is still the leading cause of death,” said Dr. Amesh Adalja, infectious disease physician and a representative of the American society of infectious diseases.
An estimated 32 million people have died from HIV since the disease was first discovered in the early 1980-ies.
“Infectious disease that currently causes the greatest damage to humanity — is HIV,” said Adela.
Powerful antiviral drugs allow people to live with HIV. But the disease continues to devastate many low and middle income, where 95% of new HIV cases. Almost one out of every 25 adults in the who African region is infected with HIV, representing more than two thirds of people living with HIV worldwide.
In 1980 the world health Assembly declared the world free from smallpox. But before that, people were fighting with smallpox for thousands of years, and as a result of this disease killed about one-third of infected. Wymysla also got deep scars and very often, blindness.
The mortality rate was much higher among the population outside of Europe, where people almost had no contact with the virus before visitors brought it back. For example, according to historians, 90% of native Americans died from smallpox introduced by European explorers. Only in the 20th century, smallpox killed 300 million people.
“It was something that brought enormous consequences on a planetary scale, not only death, but also blindness. This is what stimulated to start a campaign to eradicate the disease,” — said Adela.
Hantavirus pulmonary syndrome (HPS) first attracted widespread attention in the United States in 1993, when a healthy young man of Navajo and his bride died within a few days from the development of shortness of breath. A few months later, health authorities withdrew the Hantavirus from the mouse living in the house of one of the infected people. According to the Centers for control and prevention of diseases, in the United States more than 600 people got sick HPS, and 36% died from the disease.
The virus is not transmitted from one person to another, people get infected from contact with infected rodents.
Earlier, a different Hantavirus caused the outbreak in the early 1950s, during the Korean war, according to a 2010 article in the journal Clinical Microbiology Reviews. More than 3,000 troops were infected, and about 12% of them died.
While the virus was new to Western medicine when he was discovered in the US, later researchers realized that the medical traditions of the Navajo describe a similar disease and associate the disease with mice.
According to who, in the course of a typical flu season in the world, the disease kills up to 500,000 people. But sometimes, when there is a new strain of influenza, the pandemic leads to a more rapid spread of the disease, and often higher mortality.
The most deadly flu pandemic, sometimes called the Spanish flu, began in 1918 and led to the disease up to 40% of the world’s population, killing about 50 million people.
“I think it’s possible that something like the flu outbreak of 1918 could occur again, said Muhlberger. — If a new strain of flu got into the human population and could easily be transmitted between people and cause severe disease, we would have a big problem.”
The Dengue virus first appeared in the 1950-ies in the Philippines and Thailand and has since spread throughout tropical and subtropical regions of the globe. Currently up to 40% of the world population lives in areas where Dengue is endemic, and the disease — with the mosquitoes that carry it, probably will be propagated, when the temperature of the planet will rise.
According to who, Dengue sick from 50 to 100 million people a year. Although the mortality rate from it is lower than some other viruses, at 2.5%, the virus can cause abrapalabra disease called hemorrhagic Dengue, and the disease has a mortality rate of 20%.
“We really need to think more about the Dengue virus, because it is a real threat for us,” said Muhlberger.
A vaccine against Dengue has been approved in the 2019 Control on control of products and medicines USA for use in children 9-16 years of age living in areas where there is Dengue with a proven history of infection. In some countries, the approved vaccine is available to all aged 9-45 years, but, again, the recipients should be subject to contamination in the past.Those who have not been infected in the past may be at risk of developing severe Dengue in the vaccine.
Currently two vaccines available to protect children from rotavirus, which is the main cause of severe diarrhoeal disease among infants and young children. The virus can spread rapidly through what researchers call the fecal-oral route.
Although children in developed countries rarely die from rotavirus infection, this disease is a killer in the developing world, where rehydration treatment is available.
Who estimates that globally 453 000 children under 5 years died from rotavirus infection in 2008. But countries that introduced the vaccine, reported a sharp decline in the number of hospitalizations and deaths from rotavirus.
According to who, the virus that causes severe acute respiratory syndrome, first appeared in 2002 in Guangdong province in southern China. Probably the first virus came from bats and then infecting nocturnal mammals called civetone, before finally infecting people. After the start of the outbreak in China, SARS spread to 26 countries, infecting more than 8,000 people and killing more than 770 people within two years.
The disease causes fever, chills and pain in the body and often progresses to pneumonia, a severe condition in which the lungs become inflamed and filled with pus. According to estimates, the death rate from SARS is 9.6%, and at the moment there is no approved treatment or vaccine. However, according to the CDC, since the beginning of 2000-ies has not been registered cases of SARS.
SARS-CoV-2 belongs to the same large family of viruses that SARS-CoV is known as a coronavirus and was first detected in December 2019 in the Chinese city of Wuhan. Possibly, the virus originated in bats, as SARS-CoV, and to the infection of people passed through an intermediate animal.
Since its introduction the virus had infected tens of thousands of people in China and a few million other people around the world. Ongoing outbreak has caused extensive quarantine around the world.
The disease caused by SARS-CoV-2, also called COVID-19, has estimated the mortality rate is about 2.3%. The elderly and those who have chronic diseases are most at risk of serious disease or complications. Common symptoms include fever, dry cough and shortness of breath, and in severe cases, the disease can develop into pneumonia.
The virus that causes respiratory syndrome middle East, or MERS, has caused the outbreak in Saudi Arabia in 2012 and another in South Korea in 2015. The MERS virus belongs to the same family of viruses that SARS-CoV and SARS-CoV-2, and probably originated from bats. The disease infects camels before you go to the people and causes fever, cough and shortness of breath in infected individuals.
MERS often progresses to severe pneumonia, and has estimated mortality rate from 30% to 40%, making it the most deadly of known coronaviruses, which are passed from animals to humans. As in the case of SARS-CoV and SARS-CoV-2, MERS has no approved treatments or vaccines.