A plague that’s been making the rounds through seal populations may be attributed to melting ice in the Arctic

For the last three decades, the Phocine distemper virus, otherwise known as PDV, has been sweeping through the seal, otter, and sea lion populations, causing mass mortality among the sea animals. The plague has caused tens of thousands of deaths since scientists first discovered it.

The problem was that it was spreading throughout other regions of the world, so scientists began to wonder where it was coming from and why it was spreading so rapidly.

Phocine distemper virus affects the nervous system

PDV starts by attaching itself to the host’s respiratory epithelial cells, and once it gets into the mammal, it spreads rapidly and without mercy. The virus spreads through bodily fluids among seals and other sea creatures, and once the mammal is infected, the likelihood of them dying from the disease is high.

When the seals become infected, they start experiencing horrible symptoms such as seizures, inability to swim for food, conjunctivitis (also known as pink eye), mucosal cyanosis (discoloration of the skin and mucous membranes), and emphysema. If a pregnant female catches the virus, it can lead to spontaneous abortion of her young.

Steve Halama / Unsplash 

The proof is in the details

Over the course of 15 years, data was collected and documented to see if the hypothesis that the rising PDV rates were directly correlated to the ice melting rang true. They monitored the ice melt in areas all over the world and put it up against the documented cases of PDV in sea mammals.

They also tested the blood and nasal samples of over 150 dead sea mammals for the infection during that time. In one specific year, the ice melting appeared to have a direct consequence, resulting in over 30 percent of the population of seals being infected with the virus.

The release of old disease isn’t the only culprit

It’s not just the uptick in diseases across the globe that has caused the spread of the deadly plague. It also has to do with how, when seals lose their habitat, they are forced to move, and thus come into contact with species they may not have otherwise had to.

As animals move and come in contact with other species, they carry opportunities to introduce and transmit new infectious disease, with potentially devastating impacts.

This commingling of species can cause the transmission of certain viruses across the animal groups that otherwise wouldn’t take place if the ice had not melted at all, and the seals weren’t forced to uproot themselves to find a more habitable home.

A warming globe is a virus’ playground

When sea ice begins to melt, all viruses or bacteria that were once trapped and lying dormant, are released into the environment. Scientists who studied the spread of PDV found that during years with record-high ice melt, the overall rate of the infected population rose, too.

Climate change is on the rise, and the planet has reached a tipping point when it comes to reversing the damage that’s been caused, but so far, this reversal hasn’t begun. The human activities that have led to climate change have caused ice to melt rapidly in the Arctic, and other ice-covered areas.

It’s not the only disease making a comeback

When the ice melts it can set new bacteria free and it’s been shown around the world that the melting ice is causing different kinds of diseases in animals. When old carcasses that were infected with the virus thaw out, they give these diseases a new life.

In 2016, the anthrax virus took out over 2000 deer in Siberia and it was shown that it came from a thawed out deer carcass and in 2015, researchers discovered that a “giant virus” was still viable even after being frozen in permafrost for 30,000 years.

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