VEGA News Item

Rinderpest Cattle Plague Has Been Eliminated - 10/01/2011

Doctors Won the Battle Over Small Pox - Vets Get The Victory Over Rinderpest

1.  Rinderpest is a disease of cloven-hooved animals, characterized by fever, necrotic stomatitis, gastroenteritis, lymphoid necrosis and high mortality.  Commitments to eradicate rinderpest globally through mass medication, cooperative efforts of national, regional and internal organizations in Africa and Asia in eradication campaigns have succeeded in obliterating this scourge, the cause of which has been a morbillivirus closely related to the viruses of peste des petits ruminants, canine distemper and measles.

2.  In its epidemic form rinderpest has been the most lethal plague known in cattle.  Susceptibility varies among species.  It is high in African buffalo, giraffes, wild swine, antelopes and breeds of cattle such as Ankole, Channel Islands and Japanese Black; moderate in wildebeest and East African zebus; mild in gazelles and small domestic ruminants.

3.  Rinderpest in hippopotamus and European pigs takes a subclinical form.  It is endemic in India and Africa; lack of control in bordering countries has recently led to epidemics in west, east and north Africa, the Near East and parts of Asia.  In endemic areas the virus infects most susceptible animals and tends to limit itself unless the population is large enough to support endemicity.  In endemic areas, morbidity is low and clinical signs are often mild; in epidemics, morbidity is often 100% and mortality up to 90%.

4.  The transmission and pathogenis is of rinderpest have for long attracted concerns over the farmed and wild livestock in areas such as Africa and the herding of ruminants and herbivores, in terms of evolution and climatic changes as demands for food as sustenance and signs of affluence permeate cultures with low intakes of animal-derived protein; persistence of lactose-intolerance indicates at least one sign of risks in ignoring such factors and the need to broaden dietary choices with plant-derived (directly) sources of protein, to give effect to demands for sustenance and uncompromised security.  These considerations are increasingly relevant with big movements of animals, humans included, enjoying the freedom to travel in pursuit of pleasure (such as tourism) or pilgrimage (such as the hajj and crowds demonstrating similar fervour for sports events).  Therefore environmentalists have much to think over in, say, the run-up to the Olympics in the UK in 2012 and well-founded evidence of global warming or other climatic changes.  However, the confinement of the rinderpest virus in a secure fridge in a lab removes a big threat to the world, especially in zoonotic examples, of which several more remain to tax the vigilance of life scientist and the need to ensure that academic resources are adequately and collaboratively assured; and that zoos, travelling circuses and other collections of animals (which would include the breeding and keeping of livestock as pets or for the purposes of “sports,” e.g. racing and other forms of competition, as in hunting and exhibition) are supervised likewise.

5.  We must face the challenges to wellbeing in all animals in the affected areas.  The virus is present in small amounts in nasal secretions and excretions during the first week 1 to 2 days before fever and are high during the first week of clinical disease; they decrease rapidly as animals develop antibody and begin to recover.  Transmission requires direct or close contact; infection is via the nasopharynx.  There is no carrier state: the virus maintains itself by continuous transmission among susceptible animals.  After primary growth in lymph nodes associated with the nasopharynx, the virus proliferates throughout the lymphoid tissue and spreads via the blood to the mucosae of the gastrointestinal tract (GI) and upper respiratory tracts, where damage to tissue ensues.  Viral antigens induce a potent immune response that controls the infection and allows recovery if damage to the tissues is not too severe.  Despite its extreme lethality, the virus is particularly fragile and is quickly inactivated by heat, desiccation, and sunlight.  However, it remains viable for long periods in chilled or frozen tissues.

6.  Typical clinical findings of rinderpest, in advice to vets, describe an incubation period of 3 to 15 days, followed by fever, anorexia and depression.  Occulonasal discharge develops 1 to 2 days later.  Within 2 to 3 days pinpoint necrotic lesions, which rapidly enlarge to form cheesy plaques, appear on the gums and tongue and elsewhere in the mouth.  The discharge become mucopurulent and the muzzle becomes dry and cracked.  Diarrhoea, the final clinical sign, may be watery and contain blood, mucus and mucousmembrane.  Animals show severe signs of distress: abdominal pain, thirst, dyspea (laboured or difficult breathing) and they may die from dehydration.  Convalescence is prolonged and may be complicated by concurrent infections due to immunosuppression.  Rinderpest is a cruel affliction in many ways.

7.  Guidance for vets in areas where rinderpest was uncommon or absent required diagnosis made to exclude these possibilities; infectious bovine diarrhoea (BVD) in particular, as well as East Coast fever, foot and mouth disease, infectious bovine rhinotracheitis and malignant catarrhal fever.  These and similar diseases persist and illustrate the challenges in cattle farming the world over.  BVD virus (BVDV) is common in the UK sporadically.  It occurs in young animals.  Congenital defects occur in the offspring of females infected during pregnancy but not themselves showing clinical signs.  Bovine malignant catarrh involves at least 2 viruses.  A wildebeest associated form of the disease is caused by bovine herpes virus 3 (also called Alcephaline herpes virus) and a sheep-associated disease caused by an unidentified virus, presumably a herpes virus, transmitted to cattle from lambing ewes showing no clinical signs.

8.  An incident during a Royal Smithfield Show about 15 years ago, when the threat of BSE was beginning to emerge and confuse vets trying to reach firm diagnoses.  The situation was tense because a vegetarian demonstration was going on at the time an ailing animal was delivered, being intended for the judging in the following day or two.  Presentation in the ring was out of the question but what was the diagnosis on the fallen animal and its fate?  Urgent veterinary opinions were sought, after which the new disease (BSE) was eliminated but a firm opinion was arrived at that this was a case of malignant catarrhal fever, attributed to the stress of transport that the animal, who died a day or two later, had been subjected to.  Signs of bad handling and husbandry were obvious – especially when the animal was valuable and should have been given the treatment due to a potential ‘prize winner.’ 

9.  These are incidents and observations that increased demand all over the world and in different systems represent feckless farming policies, which VEGA is insistent in opposing and in seeking less questionable methods of food production.  Fortunately these viral diseases remain without zoonotic effect on humans; but BSE demonstrates such risks and still requires inspections and warnings. If the demand for animal protein is so clamant in countries with special deficiency diseases (e.g. vitamins D and F, and B12) poultry kept in low input systems and adequately immunized (e.g. against salmonella enteridites and S. typhimurium) would seem the best option at low cost and short intervals between “crops” on continuity of supply.  However, such offensive husbandry should be avoided by resort to alternative means of sustainability and survival.  Likewise with fishing.  All such livestock denied their usual choices of escape from predators need appropriately managed forms of protection.

10.  Simple, rapid tests for antigen detection (immundiffusion, counterimmunelectrophoresis, and competitive ELISA) are now valuable in the field. Dr Walter Plowright, a British veterinary scientist, was awarded the World Food Prize in 1999 of the RBOK strain of the rinderpest virus; also in 1999 the FAO predicted that with vaccination, the cattle plague would be eradicated by 2010.  The final vaccines were administered in 2006 and the last surveillance operations took place in 2009.  They failed to find any evidence of the disease.  The Food and Agriculture Organization (FAO), which had been coordinating the global eradication program for the disease, announced in November 2009 that it expected the disease to be eradicated within 18 months.  In October 2010 the FAO pronounced its confidence that the disease had been eradicated.  If confirmed, the virus would become only second recognized in history known to have been eradicated by humans, after smallpox.  According to the UN a formal announcement concerning eradication of the disease would be held in mid-2011, after a final review of reports concerning the disease had taken place. Stocks of the rinderpest virus are still being maintained by highly specialized labs.

11.  In the closing stages of the eradication program pockets of the virus remained in war-torn areas of southern Sudan and Somalia.  Dr Mike Baron  of the Institute for Animal Health (IAH) at Pirbright (UK) said that it had been too dangerous for outsiders to enter those areas.  He said that locals described as “barefoot vets” had been trained to recognize the disease and administer vaccines.  They could work with nomadic tribesmen in the regions and vaccinate herds “on the move.”

12.  Eradication of the virus has been described as the biggest achievement in veterinary history and one that will save the lives and livelihoods of millions of the poorest people in the world. Conversationists are unlikely to rue this eradication of a species.  However, as we ponder the enormous significance of Britain’s farming 70 years ago we might remember that rinderpest was one of more than a dozen agents that the USA appraised as potential biological weapons, before it suspended its specific program in 2002.  The last major outbreak of the disease in the whole of Britain occurred in 1865 to 1866.  Records of the contemporaneous weather would be interesting.



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