In the past decade, several types of viruses emerged from around the world. Some of these such as Covid-19 are already a reality that is leading to the loss of human lives and serious economic damages.
Unfortunately, this epidemic is not the first nor the last one, and therefore, a better prevention system, new viral therapies, and common international coordination in dealing with these types of epidemics are becoming a necessity.
I. Why Should We Worry About Emerging Viruses?
Although the Covid-19 epidemy is still underway, other viral infections that can cause similar harms, if not more, can also emerge, and questions surrounding our capacity to prevent or fight them require serious considerations .
II. What Are Zoonoses?
Zoonoses are diseases that are caused by pathogens that were transmitted to humans from animals.
The transmitted pathogens can be viruses, bacteria, fungi, or parasites that are found in saliva, organs, mucus, and blood. Humans are directly or indirectly infected through consumption of contaminated food, objects, or by direct contact with the host animal.
Some vectors can also be involved in the transmission from animals to humans such as mosquitoes, and ticks.
III. What Are the Emerging Viruses?
Several viruses are responsible for zoonoses that are currently emerging from wildlife   . However, it is likely that there are unknown viruses which do not known about, due to the diversity of the wildlife reservoirs and potential mutations in viruses that are found only in animals but that could become zoonoses.
1- What Is Avian Influenza?
The Avian influenza is a group of viruses known as avian influenza type I viruses that affect wild aquatic birds and poultry and causes respiratory symptoms, organ failure, and high mortality .
Avian influenza is present in the saliva, mucus, and feces of infected birds and infects humans in the virus gets in their nose, eyes, or mouth.
2- What Is Ebola Virus Disease (EVD)?
Ebola is a group of deadly viruses that affect humans, and non-human primates such as chimpanzees, gorillas, and monkeys. However, it can also affect other animals such as bats and pigs .
This group of viruses is mostly found in sub-Saharan regions of Africa. It is transmitted through blood and body fluids such as sweat, urine, feces, breast milk, vomit, and amniotic fluid.
The disease manifests with fever, fatigue, pain, aches, diarrhea, vomiting, and unexplained hemorrhagia
3- What Is Marburg Virus Disease (MVD)?
Marburg Virus Disease belongs to the same family as Ebola viruses known as filoviruses. This virus is found in fruit bats that transmit it to humans through feces and aerosols .
The transmission from between humans is similar to that of Ebola virus disease which involves blood and body fluids such as sweat, urine, feces, breast milk, vomit, and amniotic fluid.
The symptoms include skin rash, sore throat, chest, and abdominal pain, nausea, vomiting, diarrhea, jaundice, inflammation of the pancreas, delirium, liver failure, hemorrhagia, and defects in multiple organs.
4- What Is Hendra Virus (HeV)
Hendra Virus (HeV) is found in a bat known as flying fox and transmitted to horses through the urine of the bat. It is transmitted to humans through exposure to bodily fluids and tissues of infected horses.
The virus mostly affects the respiratory system and the brain. Individuals infected by Hendra virus may have severe flu-like symptoms and encephalitis (inflammation of the brain) .
5- What Is Nipah Virus (NiV)?
The reservoir of Nipah virus is also the flying fox found in India and Bangladesh. It affects both humans and pigs.
The transmission to humans is associated with the consumption of food and beverages (e.g., water) that are contaminated by blood, saliva or urine from infected flying fox bats and pigs.
This virus causes an inflammation of the brain (encephalitis) that can lead to death .
6- What Is Lassa virus (LASV)?
Rodents are the reservoir for Lassa virus (LASV) which is found in countries including Sierra Leone, Mali, Nigeria, Guinea, Ghana, and other west African countries.
It is transmitted to humans through food infected by urine or feces of rodents.
Although 80% of the infected individuals with Lassa virus have no symptoms, those who with symptoms have an acute hemorrhagic illness .
7- What Is Severe Acute Respiratory Syndrome (SARS)?
SARS is a coronavirus that was first identified in China in 2002 and that spread to the rest of the world before it was contained .
It is thought that specific strains of the virus mutated in small mammals, such as Asian palm civets and horseshoe bats that facilitated their infection of humans.
The virus targets the respiratory system and manifests with flu-like symptoms leading to shortness of breath and pneumonia.
8- What Is Middle East Respiratory Syndrome Coronavirus (MERS-CoV)?
MERS-CoV is also a coronavirus that was first identified in Saudi Arabia in 2012 and that spread to the United Arab Emirates and the Republic of Korea.
It is thought that MERS-Cov is originated from bats and transmitted to camels which then infect humans.
The virus also targets the respiratory system and manifests with flu-like symptoms leading to shortness of breath and pneumonia .
9- What Is Rift Valley Fever Virus (RVFV)?
This virus was first identified in the Reef Valley in Kenya in 1931 and several outbreaks were reported in Eastern Africa, Egypt, and more recently in Saudi Arabia and Yemen (2000).
It is thought that two species of bats are reservoirs for the virus, the Peter’s Epauleted Fruit bat and the Aba Round Leaf bat. The transmission to humans is through the blood and organs of infected animals but also through mosquitoes.
Symptoms associated with the Rift Valley Fever Virus (RVFV) infection include flu-like fever, muscle pains, brain infection resulting in a loss of memory, confusion, vertigo, hallucinations, convulsions, disorientation, lethargy, and coma. Other symptoms are also observed including liver problems, and hemorrhagic fever .
10- What Is Crimean–Congo Hemorrhagic Fever (CCHF)?
Crimean–Congo Hemorrhagic Fever (CCHF) is a tick-borne virus that was first identified in 1944 in Crimea and that spread in the former Soviet Union countries, Africa, the middle east, China, central Asia, southern Europe, and the Indian subcontinent .
The reservoir of this virus is a tick known as Ixodid tick that transmits it to sheep, cattle, goats, and hares. Humans are infected through the blood or body fluids of infected animals or ticks.
The symptoms associated with an infection by the Crimean–Congo Hemorrhagic Fever (CCHF) include high fever, headache, back, joint and stomach pain, vomiting, red eyes, a red throat, jaundice, and in severe cases, changes in sensory perception and mood, are observed.
Although prevention and epidemic monitoring by different international agencies are in place, therapies, such as vaccine candidates for emerging viral infections have failed to make it into clinical development.
Hopefully, this unfortunate outbreak of Covid-19 will lead to a renewed interest from multiple international agencies to develop human vaccines for certain emerging pathogens as the consequences can lead to further disasters for human health and the world economy in the future.