Project to wipe out East Coast fever ongoing

Scientists have launched a multi-million dollar battle against East Coast fever, a disease that kills a cow every 30 seconds in Africa.

Cattle herders and smallholder farmers are looking forward to a breakthrough in the development of a new drug against the disease, which is a threat to about 28 million livestock in East, Central and Southern Africa.

In Kenya, out of an estimated 17.5 million cows, three quarters are at risk of the disease that typically kills cattle within three to four weeks of infection.

International Livestock Research Institute (ILRI) says the new East Coast fever vaccine project is supported by a $11 million (about Sh880 million) grant from the Bill and Melinda Gates Foundation, with additional funding from consortium partners.

The partners include the Centre for Ticks and Tick-Borne Diseases (Malawi); GALVmed, a livestock-oriented non-profit product development partnership (UK); the Institute for Genome Sciences (University of Maryland, US); the Institute of Tropical Medicine Antwerp (Belgium).

Others are the Roslin Institute (University of Edinburgh, UK); The Royal Veterinary College (UK); the United States Department of Agriculture-Agriculture Research Service (USDA-ARS); and Washington State University.

The new approach the researchers will use to develop a new vaccine against East Coast fever could also help advance efforts to come up with malaria vaccines and inform efforts to adopt new ways to treat cancer.

East Coast fever and malaria are both caused by single-cell parasites, which have proven extremely challenging to control.

Just like the researchers working on East Coast fever, malaria vaccine scientists are interested in developing formulations that deliver a similar one-two punch to the malaria parasite by simultaneously prompting the production of antibodies and killer T-cells.

Dr Vish Nene, who leads ILRI’s vaccine biosciences programme said informal talks are already underway among malaria vaccine experts. The researchers, he said, are eager to see their livestock-oriented colleagues test these novel vaccine approaches in the fight against a similar protozoan disease.

East Coast fever resembles cancer; having invaded the cow’s white blood cells, the disease parasite causes them to proliferate rapidly, a phenomena closely resembling the mechanisms of blood cancer, lymphoma.

Dr Nene said understanding how cells infected with the East Coast fever parasites increases in number in cattle could provide a model for work on possible interventions in human cancers, because the process is reversible.

“It’s exciting to work on a project that offers enormous benefits for poor livestock keepers while also providing insights for burdensome human diseases,” said ILRI director-general Jimmy Smith.

“It’s a sort of back to the future benefit. This is because it’s only been in the last century that human and veterinary medicine have diverged, when in fact they have a lot to offer one another.”

Although there is a drug to treat East Coast fever and a vaccine to prevent it, the medicine is out of reach for many poor African livestock keepers.

The vaccine currently in use was developed by the Kenya Agricultural Research Institute (KARI) with several decades of support from ILRI and many other partners. It is basically made by grinding up ticks infected with the parasite that causes East Coast fever.

This ‘first-generation’ vaccine is credited with saving at least 620,000 heads of cattle in East, Central and Southern Africa. Produced in 2008, the one million doses have almost been depleted, indicating the high demand for fresh supplies by livestock keepers.

However, like the drug, the vaccine’s cost — $8 (about Sh640) to $12 (about Sh960) per animal — is high for many poor pastoralists and smallholder farmers in the endemic regions such as Narok, Trans Mara and Kajiado as well as Central Rift Valley and Central Kenya.

The drug’s strict refrigeration requirements and production difficulties also slows its wide adoption. It takes 18 months to make a single batch of the vaccine. In addition, the vaccination must be carried out by a trained personnel.

“Working with this first-generation vaccine has taught us a lot about how animals develop immunity to East Coast fever and we hope to translate this knowledge into a more practical and affordable drug capable of protecting cattle and preventing them from spreading the parasite,” said Ivan Morrison, an expert in cattle immunology at the Roslin Institute (UK).

To develop a new vaccine, the researchers will focus on recent breakthroughs that have isolated proteins — antigens — in the parasite, that are likely to be crucial in protecting cattle from East Coast fever attack.

Some of the antigens appear capable of stimulating production of protective antibodies. Other parasite antigens could help endow the vaccine with the capacity to stimulate the cow to produce a type of lymphocyte known as cytotoxic or ‘killer’ T-cells that target and destroy the animal’s white blood cells infected with the parasite.

Meanwhile, the East Coast fever research team will devote part of its work to improving the existing vaccine so that it can serve as a more effective interim solution while the new drug is being developed. Coming up with the fresh vaccine could take 10 years or more.

ILRI has become a hub for research of livestock vaccines in the developing world. The study centre and its partners are also leading efforts to come up with better drugs for African swine fever, peste des petits ruminants (goat plague), contagious bovine pleuropneumonia (lung plague) as well as Rift Valley fever.