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Peste des petits ruminants (PPR) is an emerging, economically important viral disease of goats and sheep in the Indian subcontinent. In the present investigation, 15 hill goats were experimentally infected with 2 ml of 10% splenic suspension of a virulent isolate of PPR virus (PPR/Izatnagar/94) that had caused heavy mortality (>75%) in goats during 1994 outbreaks in northern India. More than 86% (13 of 15) animals died between 9 and 13 days post inoculation at the height of temperature or when temperatures were declining. Necropsy findings included congestion of gastrointestinal tract (GIT), nasal sinuses, consolidation of antero-ventral lobes of lungs, engorged spleen, and occasionally oedematous lymph nodes. Histopathological examination of major organs of GIT revealed degeneration and necrosis of labial mucosa, severe mucosal and submucosal congestion, degeneration and necrosis of intestinal epithelium and lymphoid cell depletion from Peyer's patches along with presence of syncytia at times. Lungs showed broncho-interstitial changes and presence of intracytoplasmic and intranuclear eosinophilic inclusions in alveolar macrophages and syncytial cells. These changes in lungs were frequently complicated with serofibrinous pneumonia (57%, eight of 14). Lymphocytolysis and occasional syncytia formation were evident in the lymphoid tissues. Immunohistochemical (IHC) findings included presence of PPR virus antigen in the labial, intestinal, and bronchiolar epithelial cells, pneumocytes, macrophages and syncytial cells in lungs, and lymphoid (intact and necrotic) and reticular cells in lymphoid organs. The findings of the study indicated the highly virulent nature of the PPR virus isolate (PPR/Izatnagar/94), causing 100% mortality and characteristic pathological changes in the target organs such as lungs, intestines and lymphoid tissues. The results of the IHC study suggested that indirect immunoperoxidase could be an alternative method in the absence of more sophisticated methods of laboratory diagnosis of PPR virus infection in goats.

Rinderpest was such a devastating disease throughout Africa, Asia and Europe, capable of shaping the destinies of governments as well as the livelihoods of producers and consumers alike, that all sectors of society demanded that scientists should strive to develop a means of protecting cattle against the constant risk. The history of vaccination as a tool for the control of rinderpest is a long one but finally spawned a vaccine which certainly ranks highly among the safest and most efficacious of vaccines. Having this Tissue Culture Rinderpest Vaccine (TCRV) available generated aspirations of global rinderpest control and even eradication, which could now be considered feasible.

This paper describes an objective system of monitoring the performance of disease surveillance. The system was developed through dialogue with a number of countries in Africa and adopted as part of the Global Rinderpest Eradication Programme of the Food and Agriculture Organization of the United Nations. The performance monitoring system uses a clinical stomatitis-enteritis case definition, an outbreak investigation classification scheme, and a series of eight performance indicators to measure the sensitivity, specificity and timeliness of the surveillance system. Field-testing indicates that the approach is successful when good record-keeping is practiced and highlights the importance of dialogue in helping to ensure that the system is simple and acceptable. The system provides a quantitative measure of the efficacy of national disease surveillance programmes and of the quality of data derived from such programmes for use in international disease control, animal health information exchange and trade risk analysis.

In 1994, rinderpest virus of African lineage 2 was detected in East Africa after an apparent absence of more than 30 years. In 1996, a disease search, based on participatory epidemiological techniques supplemented by serological and virological analyses, was undertaken in southern Somalia and north-eastern Kenya to collate past and current epidemiological information about rinderpest-compatible disease events, and to test the hypothesis that African lineage 2 rinderpest virus persists in populations of transhumant cattle in the Somali ethnic areas. The findings in Afmadu in Lower Juba led the search for rinderpest to the communities in the Bardera area and then on to the Kenya/Somalia border areas between Mandera and El Wak. The herders had a specific knowledge of the clinical signs of rinderpest and provided detailed and accurate descriptions of cases. They differentiated between classical acute rinderpest and a milder syndrome characterised by an ocular discharge and diarrhoea, few oral lesions, corneal opacity and occasional mortality. The studies provided evidence for the endemic occurrence of rinderpest back to at least 1981, with a periodicity of five years in the incidence of the disease. After a period of high mortality in 1992 to 1993, around Afmadu, herders reported a mild disease, with occasional increases in mortality, from other areas of Lower Juba and the Gedo Region. Reports by herders of a rinderpest-compatible disease in the El Wak area were pursued until active cases were located and rinderpest was confirmed.

Based on passive and active data, we report on an epidemiological assessment of surveillance and control of rinderpest (RP) in Uganda between 1990 and 1998. Active data were collected by administration of questionnaires to animal health personnel and their auxiliaries and to stockowners in six selected districts of eastern and northeastern Uganda. Passive data were extracted from vaccination and seromonitoring reports, and from field and laboratory reports. RP events were classified as "confirmed outbreaks", "suspected outbreaks" and "rumours". The classification of 56% of the RP events as "suspected outbreaks" indicates the difficulty in investigating disease outbreaks in Uganda. Although vaccination coverage and seroprevalence were <85% (the recommended target), they nevertheless corresponded well-reflecting effective vaccination. However, because of the low seroprevalence, a sizable population of cattle in Uganda remained at risk of RP. The agreement between the local and national disease reporting systems was low-to-moderate (kappa=0.39); this indicates inefficiency in disease reporting. Risk factors for RP outbreaks were cattle raids and communal grazing. Based on overlaid thematic maps of seroprevalence, vaccination coverage and RP events, close spatial and temporal associations were observed between cattle raids, transhumance and outbreaks and rumours. The high-risk areas were in the eastern and northeastern parts of the country. The results of this study support a phase approach of following the OIE pathway.

Rinderpest is an acute and highly contagious viral disease of ruminants, often resulting in greater than 90% mortality. We previously reported the development of first- and second-generation recombinant vaccinia virus vaccines which provide complete protection against rinderpest virus (RPV) and peste-des-petits ruminants virus (PPRV). These vaccines are safe even for immunodeficient mice and macaques with acquired immunodeficiency syndrome. We developed a third-generation recombinant vaccinia virus vaccine (v2RVFH) that expresses the fusion and haemagglutinin genes of RPV under strong synthetic vaccinia virus promoters. Cattle vaccinated intramuscularly with as little as 10(3) plaque-forming units (PFU) of v2RVFH were completely protected from rinderpest. Vaccinated animals did not develop pock lesions or transmit v2RVFH to contact animals. Cattle vaccinated with a standard dose of 10(8) PFU of v2RVFH developed long-term, sterilizing immunity against rinderpest. Thus, v2RVFH is safe, efficacious, heat stable, inexpensive, easily administered, and allows serological differentiation between vaccinated and infected animals. To aid in diagnosis and differentiation of vaccinated from infected animals, we developed indirect ELISAs (iELISAs) that use baculovirus-expressed RPV or PPRV nucleoprotein as coating antigens. A single larva contains enough viral antigen to test more than 10,000 serum samples, in duplicate. African scientists trained at the ILMB successfully transferred the iELISA kit technology to more than 30 countries in Africa, providing a model for technology transfer among developing countries. Vaccination with v2RVFH, in conjunction with the iELISA kits, greatly enhances the prospects for global eradication of rinderpest, as developing nations achieve independence in control efforts.

Rinderpest, also known as cattle plague, was for centuries the most dreaded bovine plague known and one that changed the course of history and still seriously compromises trade. It can lay waste not only to farming communities but the wildlife heritage of countries also is threatened because its broad host spectrum extends across cattle, Asian buffaloes, yaks, and many other artiodactyls, both domesticated and wild, including swine. This article provides a brief history of rinderpest before describing its clinical, pathologic, epidemiologic, and diagnostic features. In dealing with control, the prospects for total eradication are described in the context of the Global Rinderpest Eradication Programme, which is on target to achieve that goal by 2010--the first time that an animal disease will have been eradicated.

In January 1997, Tanzania requested international assistance against rinderpest on the grounds that the virus had probably entered the country from southern Kenya. Over the next few months, a variety of attempts were made to determine the extent of the incursion by searching for serological and clinical evidence of the whereabouts of the virus. At the clinical level, these attempts were hampered by the low virulence of the strain, and at the serological level by the lack of a baseline against which contemporary interpretations could be made. Once it became apparent that neither surveillance tool was likely to produce a rapid result, an infected area was declared on common-sense grounds and emergency vaccination was initiated. The vaccination programme had two objectives, firstly to prevent any further entry across the international border, and secondly to contain and if possible eliminate rinderpest from those districts into which it had already entered. On the few occasions that clinical rinderpest was subsequently found, it was always within this provisional infected area. Emergency vaccination campaigns within the infected area ran from January to the end of March 1997 but were halted by the onset of the long rains. At this time, seromonitoring in two districts showed that viral persistence was still theoretically possible and therefore a second round of emergency vaccination was immediately organized. Further seromonitoring then indicated a large number of villages with population antibody prevalences of over 85%. These populations were considered to have been 'immunosterilized'. Although no clinical disease had been observed in them, it was decided to undertake additional vaccination in a group of districts to the south of the infected area. Serosurveillance indicated that rinderpest could have been present in a number of these districts prior to vaccination. Serosurveillance in 1998 suggested that numerous vaccinated animals had probably moved into districts outside the infected and additional vaccination areas, but did not rule out the continued presence of field infection.

Forging a scientific career in 19th-century Britain was difficult for most middle-class scientists. Despite his discovery of thallium in 1861 and later distinction as an experimental physicist that led him to the Presidency of the Royal Society (1913-1915), William Crookes (1832-1919) never obtained one of the limited number of academic or official positions. Scientific journalism and commercial activities were eventually to bring him financial security, but before that he was an opportunist willing to try his hand at anything that would win him national publicity. This is illustrated by his intervention in the great cattle plague epidemic that swept the UK between 1865 and 1866.

Wildlife mortality involving bongos, Tragelaphus eurycerus, and other ungulates was investigated in the north of the Congo Republic in 1997. Four bongos, one forest buffalo, Syncerus caffer nanus, and one domestic sheep were examined and sampled. Although an outbreak of rinderpest had been suspected, it was found that the animals, which had been weakened by an Elaeophora sagitta infection and possibly also by adverse climatic conditions, had been exsanguinated and driven to exhaustion by an unusual plague of Stomoxys omega.

Rinderpest had been reported in most parts of Ethiopia when the Pan African Rinderpest Campaign (PARC) was launched. As a result of intensive disease investigation and strategic vaccination, most parts of the country are now considered provisionally free, and widespread vaccination has been replaced by clinical and serological surveillance. Details of any episodes of disease are recorded and followed up after laboratory confirmation of suspected cass using antigen-capture ELISA. This paper is based on observations on the performance of the antigen detection ELISA compared to the agar gel immunodiffusion (AGID) test, which also differentiates rinderpest from peste des petits ruminants (PPR). The stability of the specific viral antigen was monitored for 4 days, and rinderpest and PPR antigens were still detected, depending on the type of specimen. Antigen capture ELISA is more rapid, sensitive and virus specific than the AGID. Even if the cold chain of the specimen is compromised for a day or two during sample collection and submission, the specimen may still be suitable for testing by ELISA.

A competitive enzyme-linked immunosorbent assay has been standardised for the detection of antibodies to rinderpest virus in sera from cattle, sheep and goats. The test uses a neutralising monoclonal antibody (MAb) directed against the haemagglutinin protein of rinderpest virus. The test is specific for rinderpest, as it failed to detect antibodies to peste des petits ruminants virus in convalescent goat sera. A 45% inhibition of the binding of the MAb to the antigen was used as the cut-off point for deciding the rinderpest status of the test samples. The specificity and sensitivity of the test and the stability of the test reagents were determined and compared to the results obtained using a commercial kit with approximately 1,200 serum samples from cattle, sheep and goats in India. The current test compared very well with the commercial kit. The test is expected to be extremely useful for sero-monitoring and sero-surveillance of rinderpest in countries which are actively pursuing a rinderpest eradication programme.

Epizootiological aspects of peste des petits ruminants (PPR) and rinderpest in sheep and goats in Saudi Arabia are examined. The presence of PPR has been suspected on occasions, but virus isolation has been successful only once. Information regarding PPR and rinderpest in sheep and goats in Saudi Arabia is scarce. The only survey conducted indicated that neither disease is endemic in the country.

A simple chromatographic strip-test based on Clearview technology, is under development as a pen-side test for the detection of rinderpest antigen in eye swabs taken from cattle in the field. An outbreak of rinderpest occurred in the northern zone of Tanzania from late February to June 1997. The affected cattle exhibited very mild clinical signs, which made clinical diagnosis difficult. One hundred and seven eye swabs were collected from cattle suspected of infection with rinderpest. These were tested in the field using a prototype of the pen-side test and 13 (12.15%) of the samples were found to be positive for the presence of rinderpest antigen. These were confirmed by ICE. The positive cases were predominantly found in the Ngorongoro district. This demonstrates the usefulness of such a simple, rapid pen-side diagnostic assay, particularly when clinically 'mild' strains of rinderpest are present.

The World Reference Laboratories for Foot-and-Mouth Disease and for Rinderpest provide a worldwide diagnostic and surveillance service for these disease for FAO and OIE. Both laboratories are housed within the high security facility of the Institute for Animal Health, Pirbright, UK. Foot-and-mouth disease (FMD) and rinderpest (RP) are OIE List A diseases and historically have caused huge losses to agricultural economies around the world, prompting the establishment of veterinary colleges in Europe and environmentally controversial control programs in Africa. FMD and RP have now been geographically restricted, but the large legal and illegal world trade in live animals and animal products constantly threatens to allow them to spread back into disease-free areas. The Reference Laboratories provide a center of excellence for the development of improved diagnostic techniques and a repository of isolates collected over many years. These libraries provide material for investigations of the molecular epidemiology and evolution of the viruses and a data base against which new isolates can be compared. Thus it is possible to individually characterize new outbreak strains, identify their likely origin and provide the most up-to-date support for their control.

Cattle plague (rinderpest) caused serious loss of cattle in Europe up to the beginning of the 20th century. Effective control measures were developed in the 18th century by Lancisi in Italy and Vicq d'Azyr in France long before the viral nature of the disease was understood. Similar measures are used to control BSE, which unlike rinderpest, also infects man. Much can be learned from earlier work on such problems as failure to notify outbreaks, inadequate application or deliberate evasion of control measures, and the value of compensation. Still renowned as a comparative anatomist, Vicq d'Azyr not only practised comparative medicine but as permanent secretary of the Societé Royale de Médecine in Paris (1776-1793) developed a national scheme for collecting public health data. His views on how doctors face an unknown disease and on the problems of administration could have been written today.

A severe epidemic of rinderpest, affecting mainly wild ruminants, occurred between 1993 and 1997 in East Africa. Buffalo (Syncerus caffer), eland (Taurotragus oryx) and lesser kudu (Tragelaphus imberbis) were highly susceptible. The histopathological changes, notably individual epithelial cell necrosis with syncytia formation, were consistent with an infection with an epitheliotrophic virus. Serology, the polymerase chain reaction, and virus isolation confirmed the diagnosis and provided epidemiological information. The virus was related to a strain which was prevalent in Kenya in the 1960s, of a second lineage (II), and distinct from isolations of rinderpest virus in the region since 1986. The source of the virus was presumed to be infected cattle from the Eastern region of Kenya and Somalia. The pathogenicity of the virus varied during the epidemic. The mortality in buffalo populations was estimated to be up to 80 per cent, and population data suggested that the virus had an adverse effect on a wide range of species. The virus caused only a mild disease in cattle, with minimal mortality. The results confirmed the importance of wildlife as sentinels of the disease, but although wildlife were important in the spread of the virus, they did not appear to act as reservoirs of infection.

The authors assess the economic impact of the Pan-African Rinderpest Campaign (PARC). The PARC programme commenced in 1986 with the objective to control and ultimately eradicate rinderpest from Africa. From among the thirty-five countries that participated in PARC, ten countries were selected for the analysis, based on data availability. The three following key socio-economic issues were addressed: cost-effectiveness, returns to investment and the welfare gains of the intervention. The standard cost-benefit approach based on a computer spreadsheet model was used to assess the economic impact of rinderpest control. Benefits of the intervention consisted of increased revenue due to avoided production losses. Estimates of the value of production losses were obtained under both 'with PARC' and 'without PARC' scenarios and the incremental benefits were derived as the difference between the two scenarios. In addition, an economic surplus model was used to assess the distribution of welfare effects generated by the intervention. Analysis of funding for the national campaigns showed roughly equal commitment to the programme by national governments and the principal donor, the European Union. Examination of the implementation costs in the ten countries indicated that with the exception of one country, PARC was implemented in a cost-effective manner with average costs appearing within a relatively narrow range. The figures obtained in ECU (European currency units) were between ECU0.27 and ECU0.60 per head of cattle vaccinated. The estimated average return from the ten countries (ECU1.8 for each ECU invested in the campaign) demonstrates that based on the sample of countries, rinderpest control in Africa has been economically profitable. In each of the ten countries, estimated benefits at least covered the value of the investment in PARC. The programme has provided a total net present value of ECU29 million for the ten countries, suggesting that the implementation of PARC has been a wise public investment decision. Analysis of the distribution of the welfare gains from PARC revealed that producers derived the greater share of the ECU58 million in net value of production losses avoided due to rinderpest control in the ten countries. Consumer gains accounted for approximately one-fifth of the total, due to lower prices from increased supplies.

Emergency preparedness planning for animal diseases is a relatively new concept that is only now being applied in Africa. Information can be drawn from numerous recent disease epidemics involving rinderpest, contagious bovine pleuropneumonia (CBPP) and Rift Valley fever. These examples clearly demonstrate the shortcomings and value of effective early warning with ensured early reaction in the control of transboundary animal disease events. In concert, the Food and Agriculture Organization (FAO), through the Emergency Prevention-System for Transboundary Animal and Plant Pests and Diseases (EMPRES), and Organisation of African Unity/Inter-African Bureau for Animal Resources (OAU/IBAR), through the European Commission-funded Pan-African Rinderpest Campaign (PARC), have been actively promoting the concepts and application of emergency preparedness planning and should continue to do so under the proposed successor of PARC, namely: the Pan-African Programme for the Control of Epizootics (PACE). The potential partnership between the normative function of the FAO in developing and promoting emergency preparedness and the implementation of improved national and regional disease surveillance by PACE and other partners could witness the commencement of more progressive control of epidemic diseases in Africa and greater self-reliance by African countries in coping with transboundary animal disease emergencies.

In 1994, the Food and Agriculture Organization undertook to revitalise its activities in the control of transboundary animal disease by establishing a new special programme known as the Emergency Prevention System (EMPRES) against transboundary animal and plant pests and diseases. The emphasis of the EMPRES livestock component is placed on pre-empting outbreaks and losses experienced by agriculture through the enhancement of local capacity to detect and react rapidly to plague events. EMPRES concentrates on the co-ordination of the Global Rinderpest Eradication Programme--a time-bound eradication programme--whilst addressing the progressive control of the most serious epidemic diseases within a broad framework of emergency preparedness. Programme activities are discussed in relation to early warning, early reaction, facilitating research and co-ordination. In addition to rinderpest, particular attention has been paid to contagious bovine pleuropneumonia, a re-emerging disease in Africa targeted for strategic attention, and foot and mouth disease, for which co-ordinated regional control in Latin America and South-East Asia has been initiated. Tactical responses to other disease emergencies such as African swine fever, classical swine fever (hog cholera), Rift Valley fever, peste des petits ruminants and lumpy skin disease are described.

The history of rinderpest and control of the disease in Africa and Asia is reviewed briefly. The present distribution of rinderpest virus in relation to its phylogenetic lineages is presented. Rinderpest-free countries bordering rinderpest-infected countries are considered to be under permanent threat of a transboundary rinderpest incursion and therefore face continuous and serious emergency situations. The nature of these emergencies in relation to the remaining foci of the three lineages is described. It is argued that the Global Rinderpest Eradication Programme (GREP) eradication strategies now need to focus on the use of epidemiological studies to define foci of infection and guide targeted, pulsed vaccination campaigns rather than broad, routine vaccination. The emergency posed by the re-emergence of African lineage 2 virus in East Africa and the challenge of mild rinderpest is explored in some detail as a phenomenon which may be more widespread than has been assumed. Points at which the future of GREP is threatened are illustrated and means of removing some of the dangers are suggested. The lessons which need to be learnt from the experience of the Indian National Project on Rinderpest Eradication and the Pan-African Rinderpest Campaign are discussed, including the value of strengthening surveillance systems in accordance with the Office International des Epizooties Pathway and how to cope with the problem associated with cryptic foci of rinderpest persistence--perhaps the greatest challenge facing GREP. The value of vaccine buffer zones is considered in detail and the authors conclude that unless those zones are of considerable depth and are well maintained, they are unlikely to prevent dissemination of the virus. The role of emergency preparedness planning in preventing the spread of rinderpest is discussed, with the understanding that effective surveillance, as a component of emergency preparedness planning, is safer than vaccination as a means of ensuring that the disease does not re-enter or penetrate a population. The swift initiation of a programme for the eradication of rinderpest from Pakistan is seen as the key issue in dealing with the Asian lineage rinderpest emergency. Development and implementation of strategies with the benefit of experience gained in Africa and India could provide a rapid resolution of the emergency.

In January 1997, serum samples from 1346 adult sheep and goats were tested by a competitive ELISA to determine the prevalence of rinderpest in the northern zone of Tanzania. Seroconversion rates of 20%, 13%, 9%, 7% and 3% in sheep and goats were recorded in Ngorongoro, Monduli, Hai, Arumeru and Simanjiro districts, respectively. The low profile and insidious nature of the rinderpest virus involved caused very mild disease in cattle in some of these area. The mild signs associated with this outbreak of rinderpest resulted in difficulty in its diagnosis. In these circumstances, the presence of rinderpest antibody in sheep and goats served as a valuable and effective indicator of the rinderpest outbreak in cattle.

Rinderpest is an ancient plague of cattle and other large ruminants, with descriptions of its effects dating back to Roman times. It is caused by a morbillivirus closely related to human measles virus. Although a very effective vaccine is available, it is heat labile, and logistical and financial problems hamper its delivery to the remote areas of Africa and Asia where enzootic foci remain. Periodic epizootics emerge from these foci and spread into neighboring areas, mainly as a result of uncontrolled livestock movement and trading. This is particularly true during wars or civil disturbances when normal veterinary controls do not operate. The disease continues to cause devastating economic losses in domestic livestock in areas of the world where it remains endemic.

Approximately 0.2% (n = 4397) of the bovids (cattle and buffalo) in Sri Lanka were sampled, from June 1992 using a multi-stage sampling procedure. Serum antibodies for the rinderpest virus were detected using the competitive enzyme-linked immunosorbent assay. The age, the agroclimatic zone, the management system practiced in the farms, and the vaccination history of the sampled bovids were studied as potential risk factors for being seropositive. The prevalence of rinderpest antibodies in non-vaccinated bovids was 3.5% (n = 4101). The prevalence was higher in the dry zone (9%; where the outbreak emerged in 1987), compared to bovids in the other zones (1%). Seropositive bovids over three years of age were approximately at fourfold higher chances of being seropositive compared to those that were < or = 3 years old. The higher prevalence in older animals is probably due to exposure to the virus during the 1987 epidemic. Bovids from the dry zone (annual rainfall 20 to 35 inches) were at higher odds of being seropositive even after controlling for the possible effects of age, agroclimatic zone, management system and vaccination. The fact that 62% of bovids from the dry zone in this study were reared under extensive management system (free grazing) which allow unrestricted contact between animals, may be the reason for the above finding. A relatively poor response to vaccination observed in vaccinated bovids (seroprevalence = 12%; n = 296) could be attributed to difficulties in maintaining the vaccine at recommended temperatures in the field. This is the first island-wide study on seroprevalence of rinderpest in Sri Lanka.

A process involving time-bound steps used to verify the transition from the status of freedom from rinderpest to that of freedom from infection with the rinderpest virus is described. The procedure, informally but widely known as the 'OIE Pathway' (OIE: Office International des Epizooties), originated with the report of the 1989 Expert Consultation on Rinderpest Surveillance Systems. The OIE Foot and Mouth Disease and Other Epizootics Commission, with the assistance of experts on the disease, proposed a revision of the recommended standards in the reference document presented at the 66th General Session of the OIE (66 SG/12/CS3 B, Appendix III). During that General Session, the standards were amended and adopted by the OIE International Committee (Resolution No. IX dated 28 May 1998).

The practical implementation of epidemiological surveillance programmes for rinderpest prescribed by the standards of the Office International des Epizooties (OIE) is described. The rationale of surveillance is discussed in relation to the stages of disease control, discontinuation of vaccination, clinical surveillance and serological surveillance. These stages lead to provisional and confirmed declarations of freedom from disease, and the confirmed declaration of freedom from infection. Practical methods of stratification of livestock populations, and selection of samples of herds and animals within selected herds are explained. The actions to follow any discovery of disease, or any clinical or serological signs of disease, are discussed. In the serological surveillance stage, balancing the number of herds and the number of animals within selected herds tested can result in considerable reduction in the overall number of serum samples to be tested. The methods used in rinderpest surveillance can readily be adapted to surveillance programmes for other diseases.

Historical population collapses caused by rinderpest epidemics are hypothesized to have resulted in notable genetic losses in populations of the African buffalo. Polymorphism in the major histocompatibity complex (MHC) DRB3 gene was probed by means of restriction analysis of the sequence encoding the peptide-binding region. Nucleotide substitution patterns agreed with a positive selection acting on this fitness-relevant locus. Buffalo populations from four National Parks, situated in eastern and southern Africa, each revealed a surprisingly high allelic diversity. Current high levels of heterozygosity may be reconciled with historical bottlenecks by assuming that local extinctions were followed by fast recolonization, in accordance with the high dispersive capabilities of buffalo. The specific amplification of DRB3 alleles also enabled the assignment of individual genotypes. For each population sample a deficiency in the expected number of heterozygous animals was found. As overdominant selection on the MHC is predicted to yield an excess of heterozygous individuals, this may not be a locus-specific effect. Several other explanations are discussed, of which increased homozygosity caused by nonrandom mating of buffalo in populations seems the most probable.

Between April 1994 and November 1995 the most severe epidemic of rinderpest reported in the world for over a decade affected domestic livestock in the Northern Areas of Pakistan. As many as 40,000 cattle and yaks died, more by some estimates, and mortality rates may have exceeded 80 per cent in these species in several villages. This report describes some of the clinicopathological and epidemiological features peculiar to the outbreak, including laboratory-confirmed rinderpest in a goat, and the difficulties encountered before the disease was eradicated. It also describes the human costs and emphasises the need to accelerate the global eradication of this most eradicable disease.

The Karimojong CAHW program, in which members of the pastoral Karimojong community were trained as basic veterinary care providers, was evaluated using ethnoveterinary techniques. A serological study of rinderpest antibody titers was also completed to compare serological results with ethnoveterinary results in the case of one disease, rinderpest. An outbreak of rinderpest-like disease that occurred during the field phase of the study was also investigated. The results show that rinderpest does exist in Karamoja in an apparently endemic form. Given the significant value placed by Karimojong herders on vaccinated animals, it can be concluded that they would adequately vaccinate their herds if they could trust the vaccine and the vaccinator. Discrepancies between ethnoveterinary and serological results show that ethnoveterinary techniques do not provide numerically accurate data concerning protection from disease, but that they can, nonetheless, provide basic, cost effective indications of disease patterns.

Using the competitive enzyme-linked immunosorbent assay for the seromonitoring of rinderpest in Saudi Arabia, antibodies were detected in 30% of the sera of 1,018 cattle slaughtered at Riyadh abattoir during June and July 1995. The correlation between the detection of antibodies and the origins of the slaughtered animals was analysed. All the culled dairy cows had detectable antibodies. The proportions of bulls giving serologically positive results were as follows: 57% for animals imported from rinderpest-free countries and vaccinated upon arrival in Saudi quarantine, 20% for native breeding animals and 17% for five- to ten-month-old bull calves born on commercial dairy farms and then raised on separate feedlot farms. In addition, of 105 native cattle sacrificed during the Hajj season in May 1994, 77% had antibodies against rinderpest virus. On the other hand, testing of 17 groups of dairy heifers (from 1 week to 24 months of age), born to immune dams and vaccinated against rinderpest at the ages of six and ten months, revealed the absence of detectable antibodies in the sera of some animals which were between two and ten months of age. Results are interpreted in relation to evaluation of the continuing vaccination programmes and their efficacy as an element of the national programme for the control of rinderpest.

To commemorate the centenary of the outbreak of rinderpest in South Africa, the historical events leading up to and following this major epidemic are recounted. Its impact on livestock and human populations, as well as initial and eventual successful attempts to control it are discussed.

This paper reports on livestock mortality in Afghanistan where a war has been going on for more than a decade, with complete disruption of the veterinary field services. The study attempted to measure the impact of a veterinary field programme carried out mainly by paravets. The study also provides valuable data on the impact of diseases in the absence of any veterinary intervention. The veterinary programme, implemented by a Dutch non-governmental organisation (NGO) for approximately 3 years, consisted essentially of vaccination against major infectious diseases and administration of anthelmintic drugs for nematodes and liver flukes. Veterinary personnel were also involved in curative treatments. Livestock mortality figures were collected by questionnaire over a period of 2 years from more than 700 farmers in randomly selected villages in 4 covered districts with a veterinary programme and 4 control districts without a veterinary programme. The average annual mortality rates for calves, lambs and kids respectively were 16.2%, 17.3% and 19.1% in the covered areas, against 21.5%, 25.2% and 24.6% in the control areas. Adult mortality figures were 3.8%, 7.4% and 5.4% in the covered areas, against 5.3%, 13.6% and 15.6% in the control areas for cattle, sheep and goats respectively. The survey indicated significant differences (P < 0.01 in cattle, P < 0.001 in small ruminants) in livestock mortality between the control and covered areas and it is concluded that these differences were attributable to the presence or absence of the animal health programme.

Within the epidemiological surveillance of rinderpest in Mali a serological survey has been carried out on 58 herds of small ruminants. Out of 567 tested sera for the detection of antibodies against rinderpest 2 were positive. These sera were collected from two animals over 6 years old, probably infected during the last outbreak of rinderpest in Mali in 1986. Therefore, it can be assumed that the rinderpest virus has not circulated in Mali since that year. However, the infection rate among goats and sheep due to the PPR virus seemed to be high: 74% of herds had already been infected. The prevalence of individual infection is 32%. A similar serological survey was conducted on 450 cattleheads, without antibodies against the rinderpest virus and showed that 1.78% of these animals had been in contact with the PPR virus. With such a low infection rate in cattle, the PPR virus probably has no incidence in the epidemiology of rinderpest in Mali.

Rinderpest (RP), a lethal disease of cattle, was almost eradicated from the African continent under Joint Project 15 (JP15), using an excellent modified live virus vaccine. Due to marked instability of the vaccine, a cold chain was required to ensure that the vaccine was potent at the time of application. Rinderpest re-emerged in the early 1980s. The Pan African Rinderpest Campaign (PARC) was developed to combat the new epidemic. For PARC to be efficacious and affordable, there was a clear need to have a vaccine that was thermostable. The need for a stable vaccine was underscored in politically unstable areas such as the Sudan, where the veterinary infrastructure has diminished and vaccination has been left in the hands of personnel who must act expeditiously. This paper reviews studies on various stabilizers and a modified lyophilization cycle that resulted in a highly thermostable RP vaccine. The useful shelf life of the vaccine, under African field conditions, was increased from less than one week to at least 100 days. For practical reasons, PARC recommends that the vaccine be used within 30 days of leaving refrigeration (the cold chain).

Between 1870 and 1929, nine separate outbreaks of foot and mouth disease (FMD) occurred in the United States of America (USA); additional outbreaks in North America include one in Mexico (1947) and two in Canada (1870 and 1952). In 1930, the United States Congress enacted a law prohibiting importation of live ruminants or swine or fresh meat from these species into the USA from countries affected with FMD or rinderpest. Although the effect of this prohibition may be debated, the USA has remained free of FMD since its enactment. A hidden benefit of this prohibition was probably the limitation on importing other disease agents from countries of the world where FMD was present. As many regions of the world make progress towards the control and eradication of FMD, North America must take greater cognizance of other disease agents with which it has not been concerned to date, as these existed only in regions of the world affected with FMD and/or rinderpest. One of the methods of dealing with these other diseases is by using risk assessment and risk management methodologies. For risk assessment to work, however, the available management technologies must be examined, and levels of risk assigned to match the available technology. The authors explore risk analysis options for the importation of animals and animal products in a manner which will continue to protect the livestock industry in the USA. They also examine the role of veterinary biologicals as a management tool to mitigate the attendant risks.

Isolates of rinderpest virus (RPV) recovered from outbreaks of the disease in Kenya and Southern Sudan between 1986 and 1993 were compared to each other and to earlier isolates from East and West Africa. The recent isolates were mildly pathogenic for susceptible cattle and thus resembled other mild strains of RPV recovered from cattle and wildlife in East Africa more than 30 years ago. Monoclonal antibody analysis using a panel of 12 anti-RPV haemagglutinin protein-specific antibodies (mAbs) revealed that individual isolates were distinguishable. However, the panel of mAbs could not be used to relate the isolates on the basis of their pathogenicity or geographic origin. Immunoprecipitation of the virus-induced proteins from infected Vero cells, followed by SDS-polyacrylamide gel electrophoresis, showed that the recent mild RPV isolates from eastern Africa were closely related to each other and to their contemporary isolates from Nigeria and Egypt, but they were distinct from another mild isolate recovered from the region three decades ago. Two distinct lineages of African RPV isolates were identified by sequencing a region of the genome around the proteolytic enzyme cleavage site of the fusion protein from the old and new isolates. One lineage, which included virus isolates recovered from East and West Africa during the 1960s, showed a closer phylogenetic relationship to Asian and Middle Eastern RPV isolates. The other lineage consisted mainly of isolates recovered from East, West and North Africa between 1983 and 1993. The results showed that there was co-circulation of two different lineages of RPV in Nigeria during the epizootics of the 1980s.

The three members of the morbillivirus genus that infect wildlife in ecosystems where domestic animals occur are rinderpest, peste des petits ruminants (PPR) and canine distemper. Data on the relative susceptibility of species of the Order Artiodactyla for rinderpest have been obtained from historical records of outbreaks. Rinderpest in wildlife has only occurred in equatorial and eastern Africa since the great pandemic of 1889-1897. The distributions, densities and population dynamics of susceptible species in this region are described. There has only been one recorded outbreak of PPR in wildlife but the possibility of its occurrence in the future now that it is present in many parts of west and eastern Africa is discussed. Wild carnivora are not likely to be important maintenance hosts for canine distemper but the disease is of significance in free-ranging carnivores and particularly in small populations of endangered susceptible wildlife species. It is also of great significance in zoo populations.

The author presents detailed information on traditional methods, the majority of which remain in use, for the recognition, prevention and treatment of the principal infectious diseases prevalent on the African continent. The information provided relates to the observations and practices of peoples in three main regions, namely West, East and Southern Africa. Data are presented for ten diseases of major importance, with the widest range of practices being recorded for the control of foot and mouth disease, rinderpest and anthrax.

Monoclonal antibody-based competitive ELISA (C-ELISA) have been used for the specific measurement of antibodies to both rinderpest and peste des petits ruminants (PPR) viruses in cattle, sheep and goats. Examination of serum samples from sheep and goats in Gambia, before and after vaccination with rinderpest vaccine, suggested that antibodies to PPR virus could prevent an immune response to the rinderpest vaccine. Cattle sera from Nigeria and Ghana showed a high prevalence of antibody against PPR virus which may explain the difficulty experienced in some countries in achieving high post-vaccination immunity levels against rinderpest. Because antibodies against PPR virus are both cross-neutralizing and cross-protective against rinderpest virus further vaccination in the presence of antibodies against PPR virus may be a waste of national resources. This paper presents serological evidence for the transmission of PPR virus from sheep and goats to cattle and highlights the need to include PPR serology in the sero-monitoring programme to give a better indication of national herd immunity.

Sequence analysis of part of the fusion protein gene from recent isolates of rinderpest virus revealed that distinct lineages of the virus exist which reflect the geographical location of their isolation in Africa and Asia. Current strains circulating in Kenya and Sudan were most similar, both in terms of nucleotide sequence and pathogenic nature, to viruses isolated in Egypt and in Nigeria in 1983/1984 and they were quite distinct from an East African isolate (RBT-1) from the 1960s. Two older isolates of the virus, the Japanese avianized/lapinized vaccine strain dating from the 1930s and the Old Kabete strain dating from 1911, each differed considerably from the other viruses. The sequence data were derived from the region where the precursor protein is cleaved to yield the biologically active F1/F2 heterodimer; all strains analysed had a highly basic connecting peptide which is required for efficient cleavage by endogenous host cell proteases. No correlation was found between amino acid changes at this site and the rinderpest virus pathogenicity unlike the association reported for Newcastle disease virus.

The author demonstrates that rinderpest prevailed among the cattle population in the Al-Ain region of the United Arab Emirates from 1987 to 1989. A total of twenty-four outbreaks of rinderpest were recorded during the study period. Similarly, evidence of the peste des petits ruminants (PPR) or a PPR-like disease was regularly encountered in small ruminants in a total of forty-one outbreaks.

The levels of antibodies against rinderpest measured by the haemagglutination inhibition (HI) test were titrated in 640 randomly collected sera. Out of 640 samples, 586 (91%) exhibited high titres of > 4 while 54 (9%) had low titres of < or = 4. Of the 400 samples collected in Zaria, 354 (88.5%) had high titres while 46 (11.5%) had low titres. In Funtua, 140 samples were collected with 132 (94.3%) recording high titres while 8 (5.7%) had low titres. All samples (100) collected from Shika had high titres (100%). Statistical evaluation with analysis of variance and Tukey's HSD tests showed no significant difference at the alpha = 0.05 level of significance between mean antibody titres in the areas under investigation; this showed the vaccines used during the anti-rinderpest campaign to be of good immunogenic quality.