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Hunting for Viruses in Sierra Leone with the Help of Nuclear Technology


Veterinary scientists catching a bat in the jungles of Sierra Leone. Disease surveillance is ever more relevant as the Democratic Republic of the Congo, or DRC, faces a new Ebola crisis. (Photo: L. Gil/IAEA)

Njala, Sierra Leone — It sleeps upside down, comes to life at night and can carry Ebola. What is it? A bat. After suffering from a devastating Ebola outbreak in 2014, veterinary scientists in Sierra Leone are training their peers from around Africa to catch, sample and diagnose — using nuclear-derived techniques — potentially virus-transmitting bats.

“We’ve gone through the epidemic, unfortunately,” said Dickson Kargbo, a local veterinary scientist, shoving branches aside as he walked into the depths of the jungle at dusk, net in hand, head lamp shining, blue scrubs on and a queue of vets behind him. “But on the bright side, we now have the technology, the experience and much to share.”

Veterinary scientists and wildlife specialists participating in the training came from seven African countries: Burkina Faso, Burundi, Cameroon, the Central African Republic, Ghana, Liberia, Nigeria and Togo. Their objective? Disease surveillance. With the support of the IAEA and the Food and Agriculture Organization of the United Nations (FAO), they learned to understand bats’ behaviour to trap and sample them following the right biosafety measures.

“The idea is for them to get hands-on experience and the right scientific knowledge to be able to capture free-roaming bats and probe them without killing them, so they can return to the wild,” said Hermann Unger, technical officer at the Joint FAO/IAEA Division of Nuclear Applications in Food and Agriculture. “Throughout the process, you have to protect both yourself and the animal.”

During the two-week training course, vets, forest rangers and wildlife specialists trapped more than 30 bats for laboratory analysis in the jungles of Njala, central Sierra Leone.

Back in the lab, the animals were identified, measured and probed for blood, faecal and oral samples for analysis of any of the hundreds of viruses they can transmit to animals and humans, Ebola included. To do this, they use nuclear-derived techniques and equipment donated by the IAEA technical cooperation programme. So far, they have not found any viruses.

“In Togo, we didn't even dare to touch bats for sampling because we didn't have the skills. But now we do, and we ought to. We cannot let our guard down,” said Komlan Adjabli, an animal scientist from the Livestock Directorate of Togo, who attended the course.

This is the second in a series of training courses intended for African veterinary and wildlife scientists to join forces and, through active disease surveillance, anticipate or even prevent outbreaks in the region. Surveillance is ever more relevant as the Democratic Republic of the Congo, or DRC, faces a new Ebola crisis and a risk of further spread.

In the jungle

To achieve a high level of surveillance, scientists study the species in their natural, wild habitat. This entails getting their hands dirty, figuratively and literally.

“It's not easy. To diagnose and identify a virus, you need a high-quality sample, taken properly and shipped the right way,”  Unger said. To capture a bat, a team of at least six people must enter the jungle during daylight, set up poles and nets to make traps, and wait until dark for the first bats to appear, he added.

Scientists are learning to study the species from their wild, natural habitat all the way to the lab, where they use nuclear-derived techniques to diagnose any potential virus. (Photo: L. Gil/IAEA)

The idea is to cause as little disruption as possible to the ecosystem. As bats are nocturnal mammals, the virus hunters work at night, respecting the animals’ rhythm. Once captured, the bats are introduced carefully into a special bag, transported back to the lab for sampling and analysis. To learn more about the entire bat-capturing process, check out this photo essay.

“Bats come out at night, so that’s when we can get them. We catch them and return them to the wild,” said Temidayo Adeyanju, wildlife researcher from Nigeria and one of the course lecturers. Scientists and researchers learned about different bat-capturing methods according to habitat types and bat species.

Despite the stigma surrounding bats, Adeyanju said, they are key to the ecosystem. “They’re strange creatures. They come out at night, they eat insects or fruits, and people are scared of them. But if you take out the bats, you affect all the other species. They are a keystone.”

While bats play a vital part in ecosystems, they also continue to carry threats to people; every year, around ten new viruses are discovered in bats. Among these are viruses like Ebola, which can be transmitted through close contact with infected bats’ blood, secretions, organs or other fluids.

“People are scared of Ebola,” added Hawa Walker, conservation specialist from Liberia, the country neighbouring Sierra Leone that also suffered from the epidemic in 2014. “They are obsessed with washing their hands, washing their houses. But in many households, bats are still food. They’re a source of life for those who have no other choice.”

Every year, around ten new viruses are discovered in bats, including Ebola. (Photo: L. Gil/IAEA)

When Walker goes back to Liberia, she will hold a consultation meeting with representatives from the relevant ministries to raise awareness about the importance of surveying for viruses in bats.

In parallel, local scientists are also conducting research on a newly discovered strain of Ebolavirus, the Bombali strain. First reported in July this year in Sierra Leone, little is known about its pathogenic nature, other than that it has the capacity to infect human cells.

“We need a holistic approach to health,” said Michel Warnau, an IAEA project manager who oversees these courses. “One of the issues during the 2014 to 2015 Ebola outbreak in West Africa was the lack of preparedness. Through these courses, we want to build capacities to study and diagnose zoonotic diseases in livestock and wildlife before an outbreak in order to better anticipate risks to human populations.”


Nuclear-derived techniques for detecting animal diseases

The enzyme-linked immunosorbent assay (ELISA) and the polymerase chain reaction (PCR) are two nuclear-derived techniques commonly used for disease diagnosis.

ELISA is easy to set up and use, which makes it suitable for any veterinary laboratory. Scientists place a diluted serum sample from an animal on a prepared dish. If the sample contains the suspected disease, an enzyme in the fluid changes the liquid’s colours, confirming the presence of the disease. ELISA is often used for initial tests, but it has a limited sensitivity and specificity and cannot be used to identify virus strains.

PCR is a technique that involves more sophisticated equipment and procedures than ELISA, and is highly sensitive and accurate, making it well-suited for identifying virus strains and bacteria. It uses an enzyme to replicate, or amplify, a specific genetic region of a pathogen’s DNA one-billion-fold in just half an hour. Scientists then detect and monitor this DNA amplification through either radioisotopes or by counting fluorescent molecules attached specifically to the created gene sequences.

Both methods originally worked with radioisotopes and now apply enzymes instead, which has helped the IAEA and its partners refine and streamline the testing process.

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