Yaounde, Cameroon and Bangui, Central African Republic � An animal as tiny as a bat can carry up to 137 different virus species. Many of these, including Ebola, can be transmitted to humans. After years of studying bats and other animals in the jungles of central Africa, scientists are joining forces under IAEA projects to prevent the spread of diseases that can be transmitted from animals to humans, known as zoonotic diseases.
Around 75% of human diseases originate from animals, which is why it is so important to stop them at the animal level, said Abel Wade, Director of the National Veterinary Laboratory in Yaounde, Cameroon. Nuclear-derived technology helps us do this.
During the Ebola epidemic of 2014, the IAEA quickly reacted to provide specialized diagnostic equipment to help Sierra Leone in its efforts to combat the virus. With the immediate crisis over, the focus now is on longer term prevention. The IAEA, in cooperation with the Food and Agriculture Organization of the United Nations (FAO) and through funding from the Peaceful Uses Initiative (PUI) and from the African Regional Cooperative Agreement for Research, Development and Training related to Nuclear Science and Technology (AFRA), is helping countries use nuclear-derived techniques to detect zoonotic diseases and respond to them.
To African countries facing the threat of new outbreaks, the IAEA’s help in equipping their laboratories and training their scientists in the use of these techniques and the corresponding biosafety measures has been critical. Polymerase chain reaction (PCR) technology, for example, allows the identification of viruses such as Ebola within a few hours and with a high degree of accuracy (see Nuclear-derived techniques for detecting animal diseases). Early diagnosis helps curtail the spread of a disease by making it possible to rapidly isolate and treat infected animals and patients earlier.
With this technology we’re better prepared to respond at the first sign of a disease, said Emmanuel Nakoune, Scientific Director at the Institut Pasteur in Bangui, Central African Republic. But if one country’s surveillance is weak, it can put the whole region in danger. That’s why we’re working together to strengthen surveillance throughout the region.
In 1999, Nakoune spent three weeks in the jungle in south-west Central African Republic living with the local pygmies until he found a potential source of the Ebola virus: rodents. Back in his lab, he used the PCR technique to discover that these were the animals that were transmitting the virus to humans in that area.
Early March he hosted Wade for a week of information exchange and joint work.
The ongoing information exchange between various disciplines and different countries is an exemplary case of knowledge transfer under the United Nations-supported One Health approach, said Michel Warnau, who is in charge of the technical cooperation project on Emerging Zoonotic Diseases at the IAEA. For example, Wade is learning how doctors in Bangui spotted Ebola in the early 2000s and a monkey pox outbreak more recently using nuclear-derived techniques. Vice versa, Wade is sharing his expertise and experience in stopping the spread of a dangerous zoonotic disease that affected Cameroon.
During his tour of central Africa, the Cameroonian veterinarian had a tale to share.
Controlling the 2016 bird flu
In mid-2016, a farm complex near Yaounde lost 15 000 chickens. Veterinary scientists from LANAVET � Cameroon’s National Veterinary Laboratory � collected samples of the dead chickens and took them to their laboratory in Yaounde, which was almost completely furnished through the IAEA’s Peaceful Uses Initiative. The vets used nuclear-derived techniques, such as PCR and ELISA (see Nuclear-derived techniques for detecting animal diseases), to discover that they were witnessing an outbreak of H5N1 avian influenza, a dangerous disease that can also be transmitted to humans.
As soon as we detected it, we informed all the relevant ministries, the army, everyone, Wade said during a presentation to researchers from the University of Bangui. After imposing all necessary sanitary measures, killing all exposed animals, disinfecting all affected farms and halting chicken trade, Cameroonians managed to stop the outbreak.
It was a success, but at a significant cost to the country, Wade said. At the peak of the outbreak, farmers in western Cameroon were losing FCFA 6 billion (EUR 9 million) every day. Animal diseases can present devastating consequences to farmers, families and communities. Once they identify the animal disease in the lab, veterinarians can provide farmers with drugs or vaccines, but in some cases � like avian influenza � killing the flock is the only way to stop the spread.
Wade’s message to researchers from the University of Bangui was clear: Nuclear-derived diagnostic techniques allow us to detect the virus early but once you’ve identified the disease, you need to act. Farmers might suffer economic losses, but saving one human life is priceless.
Guimdo Tshicitoing Guy Flaubert, owner of a chicken farm on the outskirts of Yaounde, was still losing animals seven months after the outbreak when he called the LANAVET scientists for help. After they used PCR and ELISA to discover that his chickens were not dying due to avian influenza, Guy Flaubert could sleep again. I could’ve tried everything but I would’ve never got to the real cause of the problem by myself, he said. There are things only these machines can see.
Thanks to the precision that LANAVET’s molecular diagnostics laboratory offered during the avian influenza crisis, more and more farmers are reaching out for help. In 2016 alone, 230 farmers took dead or sick animals to LANAVET in Yaounde for examination.
In Bangui, Wade learnt how PCR can be used to identify a relatively new disease spotted in the jungles of the Democratic Republic of the Congo (DRC): monkey pox, a virus of rodents and primates that also causes smallpox-like symptoms in humans. In recent years, monkey pox has re-emerged in several countries, including the Central African Republic.
At his next stop in Ndjamena, Chad, Wade learnt about his peers’ experience in using nuclear-derived techniques to identify rabies and tuberculosis and endeavoured to establish the collaboration so crucial for the surveillance and control of Ebola and other animal diseases that can be transmitted to humans.
In sub-Saharan Africa, the majority of pathogens are still unknown, Wade said, emphasizing the need to collaborate. In the world, a new disease appears or an old one re-emerges every four months. We cannot control this if we work alone. We need to share our expertise in using these powerful, life-saving techniques. Remember that a life saved in the Central African Republic means many lives saved in Africa.
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 setup and use, which makes it suitable for any veterinary laboratory. Scientists place a diluted serum sample from an animal on a prepared dish and if the sample contains the suspected disease, it causes an enzyme in the fluid to change 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 involving more sophisticated equipment and procedures than ELISA, and is highly sensitive and accurate, making it well-suited for identifying virus strains and bacteria. This technique uses an enzyme to replicate, or amplify, a specific genetic region of a pathogen’s DNA 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 to refine and streamline the testing process.
Source: International Atomic Energy Agency