That was how John Anderson, the head of the United Nations Food and Agriculture Organisation, described yesterday’s announcement by the Global Rinderpest Eradication Programme (GREP) that the dreaded cattle disease Rinderpest has been eradicated. For over a millennium Rinderpest has stalked cattle herds around the world, often leaving famine in its wake, and in the past century it has had a particularly devastating effect on both domestic cattle and wild animals in Africa.
Rinderpest, which once devestated cattle herds around the world, has become the second deadly virus to be eliminated.
Eradicating Rinderpest was a huge undertaking, requiring the co-operation of international bodies, national governments, and non-governmental organizations, and on the ground thousands of scientists, veterinarians, and farmers made sure that outbreaks were detected, contained and eradicated. A key part of both the GREP campaign that finally eliminated Rinderpest, and of the national and regional programs that preceded it, is vaccination.
The first attempts to develop a vaccine for Rinderpest took place at the end of the 19th century, including a vaccine derived from the bile of an infected ox by the famous Robert Koch. A more effective vaccine developed by Arnold Theiler and Herbert Watkins-Pitchford which involved simultaneously injecting the animal with blood from an infected animal that contains the virus (at that time not yet identified) and antiserum from an infected animal that protects the animal for long enough to allow the animals own immune system to respond to the virus. While these methods were effective they were also risky, a small minority of cattle would often succumb to the disease following vaccination, so these vaccines were usually only used during Rinderpest outbreaks. They did however allow outbreaks to be controlled in a number of countries including India, Egypt and Russia during the first three decades of the 20th century.
An important breakthrough was in the 1920’s when J. T. Edwards of the Imperial Bacteriological Laboratory at Izatnagar (now the Indian Veterinary Research Institute) modified Rinderpest by growing it serially in goats, and after 600 serial passages, and many tests of the virus in cattle along the way, the virus was sufficiently attenuated so that it did not cause the disease but rather conferred lifelong immunity to rinderpest. This live–attenuated vaccine could be freeze-dried for storage and was easier to, but the vaccine still had the drawback that it could cause disease in cattle with a weakened immune system.
The next great advance was in 1962 when Walter Plowright and R.D. Ferris applied the methods used by Albert Sabin to develop the oral Polio vaccine to produce tissue culture rinderpest vaccine (TCRV), a live-attenuated vaccine grown in vitro in calf kidney cells. To produce the TCRV required many passages of the virus in cell culture, accompanied by frequent and thorough assessment of the virus in cattle. A virus produced by the 90th passage was found to confer immunity while being stable, not spreading between animals, and not causing disease even in cattle with weakened immune systems. Due to its safety the vaccine developed by Plowright could be used to immunize cattle even when there was no immediate threat from Rinderpest, and it vaccines developed from Plowright’s vaccine were key to the final push to eliminate Rinderpest. Walter Plowright did not confine his work to the laboratory, he also worked to improve production of the vaccine and its use in the field, including a program to immunize wildebeest (an important wild reservoir for the virus); small wonder that he was awarded the World Food Prize in 1999.
Walter Plowright, who developed the tissue culture rinderpest vaccine. Image courtesy of the World Veterinary Association.
The eradication of Rinderpest is a timely reminder that while we may often focus on the contribution animal research makes to human medicine, we should also remember that it is also key to many advances in veterinary medicine.
Addendum: Veterinary blogger The Dog Zombie notes that the eradication of Rinderpest, which involved decades of interplay between human medical research and veterinary research, is a good illustration of One Health in action.
Reference: ”Rinderpest and Peste des Petits Ruminants: Virus Plagues of Large and Small Ruminants” Edited by: Thomas Barrett, Paul-Pierre Pastoret and William P. Taylor, Academic Press Inc. (2005) ISBN: 978-0-12-088385-1