Ebola is a devastating virus that causes both internal and external bleeding. The number of human cases has dropped dramatically since the 2014 outbreak, but what about our primate cousins?

G1photo taken by Burrard-Lucus (Burrard-Lucas.com)

By Hayley Fryer

Everyone remembers the devastating Ebola pandemic that swept across Western Africa in 2014. With no cure being imminently found, people panicked an Ebola plague could spread worldwide and wipe out mankind, in a Survivoresque fashion.

Thankfully, an effective cure was finally developed, but not before a shocking 11,325 people lost their lives.

Although this issue has been addressed in humans, it is still a rampant and devastating disease for our primate cousins, accounting for 1/3 of gorilla deaths worldwide.

Why hasn’t anything been done before?

Vaccinating primates can prove difficult as they live in hard-to-reach tropical forests and fear humans. Thankfully, Peter Walsh and his team have come up with a novel way of fighting this virus.

What is Ebola?

A viral haemorrhagic fever in humans and primates that causes flu like symptoms followed by internal and external bleeding

g2Photo taken from Getty Images

The Ebola virus is not spread like a common cold. You can only catch it through skin-to-skin contact or the intake of an infected animal’s bodily fluids. Many species can carry the virus including chimps, gorillas, fruit bats, and humans. It was believed that the first human cases arose from the consumption of infected bush meat, and then rapidly spread through human interaction.

The early symptoms of Ebola mimic those of the common flu. High fever, headaches, muscle pain, and loss of appetite are often reported within the first 2 to 21 days after infection. Therefore, many people probably passed on the virus before they even realised they were infected. However, once the initial period is over, things become much worse. Bleeding internally and from the eyes, ears, and nose are common place before the patient passes away.

The risk of Ebola, combined with other threats such as poaching and habitat loss, means that there is a very real risk that species such as gorillas and chimps could be lost forever.

The research

The research team found that vaccinations increased Ebola antibodies and did not have adverse side effects

g3photo taken by Matthias Schnell

The aim of this study was to determine if oral administration of a vaccine proves as effective as injection into the muscle.

As wild apes live in small populations in dense tropical forests, and fear humans, trying to inject vaccines directly into their muscle proves challenging. Walsh therefore hoped that orally giving the vaccines to the chimps would solve this issue and provide protection against Ebola.

Walsh and his team used 10 captive chimpanzees to test out their new vaccine against the Ebola virus. They used the filorab1 vaccine, an inactivated rabies virus used as a vector to treat the Ebola. For 4 of the chimps, the vaccine was injected into the muscle, and the remaining 6 were given it orally.

They tested the blood of the chimps up to 28 days after vaccination. They found that Ebola specific antibodies, a component of the blood that fights infection, increased exponentially as the trial progressed.

“We found the vaccine gave a very robust immune response and didn’t cause any health complications,” said Dr Walsh to the BBC, suggesting oral administration of the filorab1 vaccine could prove to be an effective tool in treating Ebola in primates.

The Future

“oral vaccination holds great promise as a tool for the conservation of apes and other endangered tropical wildlife”

Although this experiment shows promising results, it’s important to note that the vaccines were given to captive chimps. In the wild, it’s possible that non-target species could eat the vaccines, meaning few chimpanzees receive treatment.

Currently, there are ongoing tests on oral bait prototypes on wild apes and methods for controlling the rate of uptake by non-target species are being explored. If these studies prove successful, it’s probable that oral vaccination of chimps could be implemented worldwide, and hopefully stop the spread of Ebola.

Unfortunately, the trial size is very small, with only 10 chimps being tested, but this is because a new ban on chimp research was enforced in the US mid-trial. This also meant that the trial had to stop after only 28 days. Consequently, it cannot be known if there are any long-term adverse effects that were not apparent after the first month.

Although there are some issues associated with this trial, Walsh and his team have given an exciting look into what the future of wildlife vaccination may hold for chimps, and other species.

The paper: http://www.nature.com/articles/srep43339