And you thought there was only one to worry about...
With news that the Zika virus outbreak in Latin America has been declared a global public health emergency, panic is growing in the West. The virus, which is has been blamed for the thousands of babies recently born with microcephaly, was relatively unknown at the start of the New Year, but it has since flooded the media bringing the mosquito-borne illness to the center of attention. The first case of Zika virus has already been detected in the United States, and there are currently no treatments or vaccines available.
Not to alarm anyone further, but Zika isn’t the only virus to be concerned about. In a recent news release, a professor at the University of Melbourne’s Institute for Infection and Immunity, Cameron Simmons, and his associate professor Jason Mackenzie point out what they consider to be today’s most worrying viruses.
Nipah virus, named after a village in Malaysia, was first discovered in 1998 and causes flu-like symptoms. The virus is carried by tropical fruit bats and is usually transmitted to humans who have been in contact with pigs that were infected by the bats.
To date, there have been roughly 477 recorded infections in humans, with a high mortality rate of over 50 percent. Another concerning fact is that human-to-human transmission has drastically increased since 2001.
In a statement, Mackenzie explained, “Bats harbour hundreds of viruses, many of which can affect humans, but we don’t understand a lot about how the transmission occurs, Nipah is a very serious issue.”
There is currently no vaccine for Nipah.
Roosting Grey-headed flying-foxes. Image credit: Justin Welbergen (CC BY 3.0)
MERS (Middle East Respiratory Syndrome Coronavirus)
The Middle East Respiratory Syndrome Coronavirus, also known as camel flu, is a very serious viral respiratory infection that manifests itself in camels. It was first discovered in Saudi Arabia in 2012, with a lot of similarities to SARS (Severe Acute Respiratory Syndrome) that broke out in China in 2002. Unlike SARS, which can be easily transmitted between humans, MERS has difficulties infecting humans and spreading from person to person, at least for the moment.
Camels are hosts for the MERS virus.
In the release, Simmons says, “What worries us is that the virus will mutate and evolve an ability to transmit easily between people. So far it has required very close contact with someone severely sick with this virus to have a chance of getting infected.”
So far, there have been 1626 laboratory-confirmed cases, of which 586 (36 percent) died. All cases had links to the Middle East where the population of camels is much higher than anywhere else on the planet, with 80 percent linked to Saudi Arabia specifically.
AVIAN INFLUENZA (H7N9)
Another major candidate for a potential viral outbreak of a new respiratory disease that is caused by the avian influenza virus, also known as H7N9.
The virus was first reported in China in 2013, and thus far there have been 667 cases of infection, of which 229 resulted in death. The infections have been mostly linked to China and have predominantly affected elderly men with direct contact and exposure to live birds and poultry
Poultry and birds tend to spread the Avian Influenza virus.
“This is another one on the radar that makes us nervous, particularly about it evolving into a virus that jumps easily from human to human,” said Professor Simmons. “So far there is no really good evidence that that this virus is fit for that.”
NOROVIRUS (Gastric flu)
The norovirus can literally take a person down in a few days, causing severe diarrhoea, vomiting, and stomach pain.
The virus spreads through contaminated food and infects roughly 10 percent of the world’s population every year. For the elderly and children, this virus could be fatal, causing up to 200,000 deaths each year, of which 70,000 are children from developing nations. The virus is more commonly linked to environments around industrial cruise shipping, and nursing homes where the virus can rapidly spread.
X-ray crystallographic structure of the Noro virus capsid.
In the paper, Mackenzie says, “Vaccine development and anti-viral therapy for Norovirus is almost non-existent. It changes rapidly and every three-to-five years there is a strain that will spread across the planet causing pandemic infections.”
Thus far, it has been tremendously difficult for scientists to create a vaccine or a drug treatment for the virus because it continues to adapt.
THE AEDES ALBOPICTUS MOSQUITO
The Aedes albopictus is not actually a virus but a mosquito that is able to bring a virus to place near you. So far, the geographical spread of the Zika Virus has been limited by the fact that the virus is carried by the Aedes aegypti mosquito, which is restricted and can only survive in the warmer climates of the world. However, the cousin of Aedes aegypti, Aedes albopictus, can survive in much colder climates like Europe or Canada and the US. The spread of Aedes albopictus is a major problem because it can also transmit Dengue and Zika viruses to humans.
“Wherever Aedes albopictus is are the same locations where Dengue, or Chikungunya or Zika could be transmitted,” says Professor Simmons.
This is an Aedes albopictus female mosquito. Image under public domain
“Mosquito-borne viruses like Zika, West Nile, Dengue and Chikungunya have emerging potential because if you change the distribution of the vector a greater amount of the population can now be exposed to that virus and many of them are highly pathogenic. So there are a lot of people who are concerned about how the climate is affecting vector distribution and exposing humanity to these new viruses. That is a big concern at the moment,” says Mackenzie.
Although this might sound worrying, we can be comforted by the improved scientific detection and surveillance we have in place, the fact that we already know about these viruses, and that we can prepare for an outbreak. The unsettling thing now is what remains unknown in the realm of viruses.
“We now spend our time worrying about a whole lot more things than 20 years ago, but you’d rather know than not know,” says Professor Simmons.