Disease Facts - Rinderpest

Once known as cattle plague, due to its devastating effect, rinderpest has not been seen in Europe since the early 1900s. It remained a serious problem in sub-Saharan Africa and southern Asia until the late 1990s. However, due to a well co-ordinate international vaccination campaign, known as the Global Rinderpest eradication programme (GREP). the disease has now been eliminated from most of the world. There remains only one possible endemic focus of the disease in eastern Africa, in an area bordering Somalia and Kenya (The Somali Ecosystem - SES).

The disease

World authorities have set a target date of 2010 for the declaration of the eradication of rinderpest from the world. This target is achievable if the situation in the SES can be clarified in the near future. If successful, it will be the first veterinary viral disease to have been eradicated globally and only the second after smallpox which was eradicated in the late 1970s.

Rinderpest is caused by a morbillivirus which is a subgroup of the family Paramyxoviridae. The virus is related to those that cause measles in people, distemper in dogs, and peste des petits ruminants in sheep and goats. Cloven hoofed animals are susceptible to the virus, but not all show clinical signs. There is evidence that Bos taurus cattle (humpless) is more susceptible to the virus than Bos indicus cattle (Indian, humped). The incubation period is usually 3 to 5 days, but with particularly mild strains it can extend to 14 days .

Treatment

There is no treatment for infected animals. It is a highly contagious disease and mortality is high. However a combination of quarantine, bans on the movement of susceptible animals, and good hygiene will normally limit the extent of the outbreak. The virus is particularly fragile and is quickly inactivated by heat, desiccation and sunlight. Prevention relies on the above together with vaccination. The current vaccine, whilst highly effective, suffers from being heat sensitive. Nevertheless there are good prospects for the elimination of the disease over the next few years.

The main players in the fight against rinderpest are two international agencies - the Office International des Epizooties (OIE) and the Food and Agriculture Organisation (FAO) of the United Nations; the International Atomic Energy Agency; Regional Co-ordinating Units such as the Pan-African Rinderpest Campaign and the South East Asian Rinderpest Eradication Campaign; affected countries and their neighbours; and the Institute for Animal Health.

Diagnosing suspected outbreaks

The Institute for Animal Health houses the World Reference Laboratory for Rinderpest (WRLR) on behalf of the FAO. The WRLR provides a diagnostic service and also acts as an interface between all parties involved. The WRLR is currently developing a disease information and communication network which will allow 'real time' access to the WRLR database to give information on current sample status.

Quick and accurate diagnosis, followed by the swift introduction of suitable control measures, are key to managing any outbreak of an infectious disease, especially rinderpest. Staff in the field must be trained in clinical diagnosis and also in the collection of suitable clinical specimens.

Whilst samples may be sent for initial diagnosis to the nearest Regional Laboratory, it is particularly important that the WRLR also receives duplicate samples so that it can trace the origin of the outbreak using the genetic fingerprint of the virus. This information is invaluable in deciding how the outbreak will be controlled.

It is essential that test results are always reliable. This requires some form of external quality control system for all the laboratories involved in the campaign. The WRLR contributes to the development of this system by providing suitable panels of sera for external quality control. In time this activity will lead to the accreditation of laboratories.

As the eradication campaign moves forward, emphasis will shift from simple diagnosis of rinderpest towards differential diagnosis, that is, being able to tell the difference between animals that are infected from those that are vaccinated. A simple diagnostic test will not distinguish between virus that causes an infection from a harmless virus from a vaccine.

A pen side test which is specific for rinderpest can give a result in 5 minutes

What more can we do?

Until eradication is complete, there are opportunities for further improvements to diagnostic assays and vaccines. Scientists at IAH are currently developing a pen-side diagnostic test that is rinderpest-specific. The test uses eye-swab material and gives an result within 5 minutes. Trials are in progress in Africa and India.

Other research is centred on the development of vaccines that are less affected by the high temperatures that are found in Africa. The Regional Laboratory in Kenya have been invaluable in running field trials of the capripox recombinant vaccine developed by the Institute.

IAH-Pirbright is an active training centre and also runs training courses overseas so that everyone involved in the programme can be trained to a suitable standard and have access to 'international standard' information. At the same time we have helped to develop a number of CD-ROMs designed to facilitate distance learning on rinderpest.