Babi Dairou lost a third of his goat herd in 2019, when a viral disease attacking small ruminants, such as sheep and goats, swept through northern Cameroon. And he was among the better off, Dairou said, as many of his neighbours lost all their animals to the devastating disease, known by its scientific name of peste de petits ruminants (PPR). But now, the goats of this factory worker and part time farmer as well as those of others in his village are safe from the disease, thanks to a mass vaccination campaign under the PPR Global Eradication Programme, 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 domesticated herds across borders – and despite earlier 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 borders with Chad to the east and Nigeria to the west are never very far away, so transboundary animal diseases can invade fast. This part of the country, known as the north and the far north, is home to 80 per cent of Cameroon’s livestock, said Gabriel Toumba, Regional Coordinator of the Livestock Development Project, a World Bank supported programme that coordinated the vaccination campaign on the ground. An average 88 per cent of small ruminants were vaccinated in each of the three years of the campaign, using vaccines produced by the National Veterinary Laboratory (LANAVET), located just 15 kilometers south of Garoua.
LANAVET produces 25 million doses of vaccines each year to fight various veterinary diseases infecting cattle, small ruminants and poultry. It performs the diagnosis and quality controls through the application of nuclear and related technologies (see The role of nuclear and related techniques in diagnosing PPR). Indeed, as a walk across its 1200 square meter plant reveals, around half its equipment has been donated by the IAEA through its technical cooperation programme and the VETLAB Network, a global network of national veterinary diagnostic laboratories promoting research and the transfer of technologies and information coordinated by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture based in Vienna, Austria.
The longstanding support by the IAEA, in partnership with FAO, has included much more: the organizations have provided training and expert advice, as well as reagents and consumables to LANAVET to carry outs its research and quality control work, said Simon Dickmu Jumbo, Director of the national laboratory’s Animal Diagnosis Department. This skills development, complemented by regular advice from the IAEA has led to the successful accreditation of the lab as ISO 17025-compliant, the only such veterinary laboratory in Central Africa. It’s been able to increase its capacity as a result, and now supports several countries in the region by exporting seven different veterinary vaccines. Farmers in Benin, Burkina Faso, Chad, Cote d’Ivoire, Gabon, Ghana and Nigeria all benefit from support by LANAVET, including regional trainings and fellowship it now offers – via the IAEA – to veterinary researchers from these countries. Besides diagnosing diseases and producing vaccines, LANAVET also performs quality control tests on veterinary drugs imported by Cameroon. This, too, uses nuclear and related technologies.
An outbreak that spread quickly
It was the diagnosis by LANAVET experts back in 2019 that confirmed the epidemic: 44 per cent of animals surveyed were found to be infected.
After the campaign that led to the vaccination of around 5 million small ruminants nationwide, less than 5 per cent in the surveyed sample fell sick, and the ratio keeps falling, Jumbo said.
“This is the proof that LANAVET met the main objective of the project with the IAEA: to help alleviate poverty among small-scale farmers through the control of PPR by supporting the national vaccination programme and informing the country’s vaccination strategy,” Jumbo said.
While the campaign will come to an end by January 2023, vigilance will be required, said Toumba of the Livestock Development Project. The migration of wild ruminants and the mingling of herds driven across large sways of land by pastoralist farmers could ignite another outbreak at any time. To mitigate this risk, the government will remain on the alert and use its vaccination and control strategy in order to quickly stop the thread of any new outbreak, he added.
Vigilance by farmers like Dairou will probably be required until 2030 – the target year for worldwide eradication of the disease set by the FAO, which supports countries across Africa in the fight against PPR. “Only then will we be able to be sure that PPR does not come back from our neighbours,” Dairou said.
The role of nuclear and related techniques in diagnosing PPR
Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are two nuclear-derived techniques 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 onto a precoated microtiter plate and, if the sample contains antibodies for the suspected disease, it causes a change in the enzymatic reaction which changes the liquid’s colours, confirming the presence of the disease. ELISA is often used for initial tests and for screening large populations, but it cannot be used to precisely identify virus strains.
PCR is a nuclear-derived method for detecting the presence of specific genetic material of any pathogen, including a virus in the samples. Originally, the method used radioactive isotope markers to visualize the targeted genetic materials, but subsequent refining has led to the replacement of isotopic labelling with specific markers, most frequently fluorescent dyes.