Veterinary authorities in Cameroon are fighting ruminant diseases using nuclear methods

Babi Dairou lost a third of his goat herd in 2019 when a viral disease affecting small ruminants such as sheep and goats swept through northern Cameroon. And he was among the better off, Dairou said, as many of his neighbors lost all their animals to a devastating disease known scientifically as Plague of Small Ruminants (PPR). But this factory worker and part-time farmer’s goats, along with those of other villagers in his village, are now immune to the disease thanks to a mass vaccination campaign under the Global Program to Eliminate PPR, supported by the IAEA, the Food and Agriculture Organization of the United Nations (FAO ) and the World Organization for Animal Health.

PPR is endemic in the region – its spread is facilitated by the movement of wild animals as well as domestic herds across borders – and despite previous control campaigns, it has returned to Cameroon. In the north, where a narrow strip of Cameroonian territory cuts into the southern edge of the Sahel, the border with Chad to the east and Nigeria to the west is never very far, so transboundary animal diseases can quickly invade. This part of the country, known as the North and Far North, is home to 80 percent of Cameroon’s livestock, said Gabriel Tumba, regional coordinator of the Livestock Development Project, a World Bank-backed program that coordinated the field vaccination campaign. . On average, 88 percent of small ruminants were vaccinated in each of the three years of the campaign with vaccines produced by the National Veterinary Laboratory (LANAVET), located just 15 kilometers south of Garois.

Every year LANAVET produces 25 million doses of vaccines to combat various veterinary diseases of cattle, small ruminants and poultry. It performs diagnostics and quality control using nuclear and related technologies (see Role of nuclear and related techniques in PPR diagnosis). Indeed, as a tour of the 1,200-square-meter plant shows, about half of the equipment has been donated to the IAEA through the Technical Cooperation Program and the VETLAB Network, a global network of national veterinary diagnostic laboratories that promote research and the transfer of technology and information. coordinated by the Joint FAO/IAEA Center for Nuclear Methods in Food and Agriculture, located in Vienna, Austria.

The IAEA’s multi-year support in partnership with FAO includes much more: the organizations provide training and expert advice, as well as LANAVET reagents and consumables for research and quality control, said Simon Dikmu Jamba, director of the National Laboratory’s Animal Diagnostics Division. This skill development, supplemented by regular advice from the IAEA, led to the laboratory’s successful accreditation as the only such veterinary laboratory in Central Africa to comply with the ISO 17025 standard. As a result, it was able to increase its capacity and now supports several countries in the region, exporting seven different veterinary vaccines . Farmers in Benin, Burkina Faso, Chad, Côte d’Ivoire, Gabon, Ghana and Nigeria benefit from LANAVET’s support, including the regional training and fellowships it now offers through the IAEA for veterinary researchers from these countries. In addition to disease diagnosis and vaccine production, LANAVET also performs quality control tests on veterinary drugs imported by Cameroon. Nuclear and related technologies are also used here.

An outbreak that quickly spread

It was the diagnosis made by LANAVET specialists back in 2019 that confirmed the epidemic: 44 percent of the examined animals were found to be infected.

After a campaign that resulted in the vaccination of about 5 million small ruminants nationwide, less than 5 percent of the sample surveyed became ill, and that rate continues to fall, Jamba said.

“This is proof that LANAVET has achieved the main objective of the project with the IAEA: to help reduce poverty among smallholder farmers through PPR control, supporting the national vaccination program and informing the country’s vaccination strategy,” Jamba said.

Although the campaign will come to an end by January 2023, vigilance is needed, said Tumba of the Livestock Development Project. The migration of wild ruminants and the mixing of herds, which are driven by livestock farmers over large areas of land, can at any moment cause a new outbreak. To reduce this risk, the government will remain alert and use its vaccination and control strategy to quickly stem the tide of any new outbreak, he added.

The vigilance of farmers like Dairu is likely to be needed by 2030, the target year for global disease eradication set by the FAO, which is supporting countries across Africa to fight PPR. “Only then can we be sure that PPR will not come back from our neighbors,” Dairu said.

SCIENCE

The role of nuclear and related methods in the diagnosis of PPR

Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are two methods of nuclear origin used to diagnose the disease.

The ELISA is easy to set up and use, making it suitable for any veterinary laboratory. Scientists place a diluted sample of an animal’s serum on a pre-coated microtitre plate and, if the sample contains antibodies to the suspected disease, this causes an enzymatic reaction that changes the color of the liquid, confirming the presence of the disease. ELISA is often used for initial tests and for screening large populations, but it cannot be used to accurately identify virus strains.

PCR is a nuclear method for detecting the presence of specific genetic material of any pathogen, including a virus, in samples. Initially, the method used radioactive isotope markers to visualize the target genetic materials, but subsequent refinements have led to the replacement of isotope labeling with specific markers, most commonly fluorescent dyes.

Distributed by APO Group on behalf of the International Atomic Energy Agency (IAEA).