Rinderpest virus in livestock

The relative number of cases in each state is based on the disease progression parameters. Specifically lineage-1 is started with 6 animals in state E , 2 in state I , and 1 in state H. Lineage 2 is started with 3 animals in state E , 2 in state I and 2 in state H.

When the Pakistan parameters are used, the simulation is started with 3 animals in E , 2 in I and 1 in H. The timestep for the solution of the differential equations has to be set so that nearly identical answers are obtained if any shorter time step is used. Cumulative cases were simulated using different time steps for the lineage-1 and lineage-2 disease transmission and progression parameters in Table 5 and for two population densities.

The agreement between the hybrid simulations, which use a stochastic computation when the number of diseased animals in a grid element is small, and the wholly deterministic simulations is quite good over this large range of parameters as shown in Figure 4. For time steps of 0. Therefore, the threshold population density needed in the exposed state of 0. The deterministic results show very little change over a range of 0. Consequently, a time step of 0.

A time step of 0. Figure 4. Cumulative case counts at simulation ends vs. For the hybrid model, the mean and standard deviation of 5 simulations each averaging 30 runs of the model are shown.

A severe epidemic of rinderpest afflicted northern Pakistan in — The disease was recognized during the first 6 months of the epidemic. At least 40, animals died and possibly as many as 50,, approximately 7, of which died in the first 5 months. The first reported case was in Parri, a village south of Gilgit, in March The Pakistani government confirmed that the disease was rinderpest in August.

Vaccination also began in August, but some of the vaccine used was later found to be subpotent and many vaccinated animals were afflicted by rinderpest. By October, rinderpest was prevalent in the upper Indus watershed including the Hunza and Gilgit valleys 1 However, due to the onset of winter and poor road conditions, only limited vaccination was performed.

A final vaccination effort was started in April The outbreak ended in a village to the west, Khaplu, in November In the Pakistan outbreak, the infection moved along the roads as cattle were taken to market or to relatives. Therefore long distance movement was modeled by having the epidemic moving along the roads. The road data were taken from the OpenStreetMap project 2. The cattle trade in this region is directional, with cattle rarely traveling south from the junction of the Gilgit with the Indus river personal communication, Paul Rossiter.

Consequently, southern movement of the epidemic along roads south of this junction was forbidden in the simulation.

Subsequently, vaccination is performed at a rate of effective cattle vaccinations per day with a vaccination ring of 30 km to simulate the use of subpotent vaccine. When more effective vaccine did arrive, winter had set in and only limited vaccination was performed. Consequently, we continue at a rate of effective vaccinations per day until the simulation ends in mid-winter.

Short range, isotropic movement was modeled with an exponentially decaying function with a decay constant of 1. Movement along the roads was always in a distance range of 28—42 km.

The percentage of disease spread occurring via the road network is initially 0. However starting in September , the amount of long distance spread is reduced by a factor of 5 under the hypothesis that if people couldn't move around very well to vaccinate cattle, the virus was not spread long distances either.

Parameters are summarized in Table 2. Gridded cattle population data from the Food and Agriculture Organization of the United Nations 25 were reduced by a factor of 1. With so many cattle in the area dying it is expected that hygiene would be improved even before confirmation that the disease was rinderpest and the commencement of vaccination. However, reports from the time indicate that hygiene was generally poor The results of the simulation are consistent with known features of the epidemic.

After week 20 of the simulation, i. Furthermore, Figure 5 shows that rinderpest was prevalent in the Hunza and Gilgit valleys as reported. Therefore, geographical and temporal spread are satisfied simultaneously with reasonable parameterization. Figure 5. Results of simulating the — rinderpest outbreak in Pakistan.

The outbreak in Fremantle, Australia near Perth was controlled by culling and quarantine To roughly model this outbreak, a rinderpest epidemic starting just north of Fremantle was simulated. Mitigations began 2 days after disease detection. Culling was performed at a total rate of 1, animals per day with the culling radius set at 7 km and a 1 day delay between animals becoming infectious and when they are culled. Quarantine was modeled as a factor of 2 reduction in transmission. The parameters are in Table 3.

The starting cattle population in Figure 6 shows that the population density is low with most of the cattle in a very localized region. Culling alone was able to extinguish the epidemic as shown in Table 4. This level of transmission reduction alone does not end the epidemic. Without culling, the outbreak would continue and many more cattle would die after the 10 week simulation period.

This smaller number of culls is likely due to the lower animal population in The regions were chosen to have relatively uniform population densities and a few examples are shown in Figure 7. Figure 7. Cattle populations in two of nine regions where rinderpest introduction was simulated are shown in areas 0. For some simulations the area modeled was increased.

Rinderpest varies in virulence 20 , consequently simulations were performed with several parameter sets. Parameters of the strain in the Pakistan outbreak and lineage 1 and 2 from Mariner et al. For all simulations the characteristic distance for spreading was 1. Cumulative case counts at the end of simulations are shown as a function of population density in Figure 8.

Simulations with lineage-1 parameters were run for 5 weeks, while simulations with lineage-2 parameters were recorded for 5 and 30 weeks. Figure 8. A Cumulative case counts at the end of the simulation increase with population density. B Geographical spread of disease including both local and long distance spread for lineage-1 at 5 weeks.

Before rinderpest is detected it could spread to locations distant from the original outbreak. This type of spread occurred in the FMD outbreak Once rinderpest is detected, we assume that long distance movement of cattle will be banned and stopped.

Nonetheless, the initial spread leads to a more rapidly progressing epidemic. A final input to investigate is the characteristic distance of spread, d. Increasing d from 1. This increase is greater for areas with lower populations. This population dependence can be explained as the increased spread providing a larger susceptible population.

The variation in the general trends are due to the fact that these real world populations are not homogeneous. Figure 9. The characteristic distance of spread, d, was increased from 1. The cumulative cases at 30 weeks increased for both sets of disease parameters for uncontrolled epidemic propagation. Three mitigations are modeled: reduction in transmission, vaccination, and culling.

As discussed in the historical perspective section, transmission can be reduced by better hygiene and by movement control. These measures can slow an epidemic, but do not extinguish it. Vaccination and culling both have the potential to extinguish an epidemic, but the the details of implementation are critical to both the success of the effort and the final impact of the epidemic.

In the following we look at how the efficacy of mitigation is affected both by controllable parameters such as the number of vaccinations per day as well as by uncontrollable parameters such as population density and characteristic spread distance.

Results are presented only for lineage-1 because the results are a more stringent test of a mitigations efficacy. In the simulations, 10, doses were assumed to be available each day and the vaccination radius is set to 6 km. Vaccination started 7 days after the disease was identified which occurred after only 5 cattle showed clear signs of rinderpest.

The length of time needed to extinguish the epidemic, the cumulative cases and the number of cattle immunized are given in Table 6 for several different regions with varying average cattle population densities. Ending an epidemic solely by vaccination is more difficult in higher population density regions. For the highest population densities, these vaccination conditions were not sufficient to stop the epidemic.

If highly effective transmission reduction, begun only 1 day after disease identification, is combined with these vaccination conditions, then the epidemic can be extinguished as shown on the right of Table 6.

The effect on epidemic progression of the start time for vaccination was studied. The length of the epidemic is reduced further as the delay is decreased.

Clearly, the delay in starting vaccination is a critical parameter. Figure If the delay is long enough, the epidemic can not be extinguished. A No long distance spread and no transmission reduction. B Long distance spread is allowed to the locations shown in Figure 8B until 1 day after disease detection. Transmission is reduced by a factor of 2 also 1 day after disease detection.

All the results thus far concerning vaccination have been obtained using a characteristic spread distance of 1. While this parameter can not necessarily be controlled as part of a mitigation, it is important to know how stable our results are to the variety of geographical spread conditions which may occur in different parts of the world. With this increase in geographic spread, the epidemic can no longer be controlled by the same vaccination parameters used to obtain the results in Table 6.

Rather, both the number of available doses and the radius around active cases where vaccination is performed must be increased. Table 7. With extensive movement controls transmission of highly infectious diseases can be reduced by roughly a factor of 2 as was shown for FMD in an analysis of the outbreak The right three columns of Table 6 show that it is possible to extinguish a rinderpest epidemic with vaccination under nearly ideal circumstances; i the disease was identified when only 5 cattle had become seriously ill and before any infected animals were transported and the disease spread to distant locations, ii effective vaccination was begun 7 days after disease identification and veterinarians were able to vaccinate when and where needed, iii hygiene and movement control reduced transmission by a factor of 2 one day after disease identification.

However, if some of the circumstances are not ideal, such as the disease spreading before identification and a delay in starting vaccination then the outbreak may not be extinguished. The potential to stop the lineage-1 strain of rinderpest by culling was examined for several areas with different population densities using the parameters from Table 5. The maximum rate of killing cattle was assumed to be 10, per day and cattle were culled regardless of disease state.

The area of the geographic bins was reduced by a factor of 4 for this work, so that the radius of culls around an infectious grid element could be examined at higher resolution. In the initial examination of culling for control, the culling radius was set at 3 km, culling was started 7 days after the epidemic was detected, and the time between an animal becoming infectious and the start of culling in that grid element and the surrounding elements defined by the cull radius was set at 2 days.

The FAO and OIE launched the Sequence and Destroy project in — one of only two rinderpest research initiatives approved after a moratorium on studies was lifted in Sequence data is put into the public domain and could be used for forensic investigations into the origin of an outbreak in the case of a reintroduction. Should live virus be needed one day, researchers could also reconstruct strains from their whole genome sequences.

The Pirbright Institute became the first to destroy stocks under the initiative in June. It got rid of around 3, vials of material representing some 50 strains and kept a small amount of live virus, says Michael Baron, who works on rinderpest at the institute.

But authorities will hang on to some live rinderpest vaccines for use in an emergency. This would help with diagnostic measures needed in any rinderpest outbreak, and eliminate the need to retain stocks of live rinderpest vaccine. The virus kills millions of sheep and goats every year, the main livestock owned by some million poor rural families in developing countries.

The experience of eradicating rinderpest and managing the post-eradication era will be invaluable, says Eloit. Holzer, B. Article Google Scholar. Download references. Comment 03 JAN It has been suggested that rinderpest originated in central Asia.

Apart from an isolated outbreak in Brazil in and one in Australia in , rinderpest has not affected countries in the Americas or Australia 4. During the 20th century, control efforts became better coordinated and more effective, greatly facilitated by the availability of improved diagnostics and vaccine technologies 5. After a concerted international eradication campaign, success was finally achieved at the beginning of the 21st century; global freedom was declared in , a decade after the last reported case of rinderpest had been detected in wildlife in Kenya in 6.

After smallpox, rinderpest is the second infectious disease to have been eradicated through the efforts of mankind. Throughout the eradication campaign, in affected and nonaffected countries, rinderpest material became widely disseminated in diagnostic laboratories, vaccine production facilities, and research institutes.

While efforts were focused on eradication, less thought was probably given to what would happen to this material after eradication. In , although natural infections in animals have been eradicated, live rinderpest virus, vaccines, and genetic material remain stored in scientific institutes across the world.

Today an outbreak of rinderpest could occur only if infectious material held in these laboratories and other institutions were accidentally released into a susceptible animal population or if animals were deliberately infected. The social and economic effects of a recurrence for the international community would be substantial.

Vaccination against rinderpest has been prohibited 7. Therefore, cattle populations are fully susceptible and infection would spread rapidly if the virus were reintroduced. Recurrence of the disease would seriously damage agricultural economies, would paralyze trade in animals and animal products in affected regions, and would undermine the decades of investment and effort that went into its eradication.

Accidental inoculation of cattle with a rinderpest vaccine would also be disruptive because the detection of seropositive animals would lead to suspicion of rinderpest recurrence 7.

To ensure that rinderpest remains confined to the history books, international efforts are now focused on ensuring that all remaining stocks of infectious material are destroyed or stored safely in a minimum number of approved high-containment facilities.

Recombinant morbilliviruses segmented or nonsegmented containing unique rinderpest virus nucleic acid or amino acid sequences are considered to be rinderpest virus. Subgenomic fragments of morbillivirus nucleic acid that are not capable of being incorporated in a replicating morbillivirus or morbillivirus-like virus are not considered as rinderpest virus—containing material 8.

To safeguard remaining rinderpest material and to facilitate and monitor its destruction, knowledge of where the material is stored and close monitoring of the status of these stocks are crucial. Updated international standards on rinderpest in the OIE Terrestrial Animal Health Code make it a legal requirement for countries to report annually to the OIE on the nature, whereabouts, and quantity of rinderpest material held in each country 7.

During —, the OIE conducted the first official survey to identify the precise location of remaining stocks of rinderpest material, and during —, the second official survey was conducted. This article summarizes the results from these 2 surveys. The following countries were selected to participate in the survey: OIE Member Countries and Territories as of which includes all countries that have a large livestock population 10 , 11 , and 2 other non—OIE Member Countries that may potentially have held rinderpest material.

When the first survey was initiated in , there were OIE Member Countries; however, 2 additional countries were adopted as OIE Members in May , bringing the total to before the survey was completed. Data on the number of countries that had reported an outbreak of rinderpest and the date of the last reported infection were collected from the OIE World Animal Health Information Database 4. To maintain confidentiality and to prevent identification of individual countries, the data in this article have been anonymized.

To facilitate reporting, OIE developed a standard questionnaire and a secure electronic system for returning completed questionnaires. A username and unique secure password were issued to the OIE Delegate in each Member Country and the Delegate identified as the responsible person in the National Veterinary Service to oversee completion of the questionnaire. When 1 of the other 3 options no, unknown, or never held was selected, then no further responses were required, and the questionnaire was considered complete.

Countries that reported having rinderpest material were required to provide details about the nature and quantity of material held for the following categories:.

Responders were asked to provide information about rinderpest material currently held, material destroyed during the previous 12 months, and material that had been transferred to or from another institute. Questions also asked whether the institute had conducted any manipulation of rinderpest material in the previous 12 months and whether they intended to destroy material or transfer it to another institute for safer keeping. After responders had submitted the completed questionnaire to the OIE, they still had access to their respective completed questionnaire in a noneditable PDF format.

If institutes held a large number of different strains of virus, or types of tissue, then the country could return information in an Excel Microsoft, Redmond, WA, USA spreadsheet format. However, because countries were unable to meet this deadline, deadlines for the first 2 surveys were extended until May 26, , and June 11, , respectively. A weekly Excel report was exported from the electronic database for evaluation of information received and to enable the OIE to follow up on erroneous reports and nonresponders.

Weekly follow-up with nonresponders included telephone calls and email correspondence. When countries were unable to use the electronic reporting system, they were asked to submit a hard copy paper report to the OIE on a template provided. Countries were given 2 opportunities to validate their data: 1 Member Countries that had submitted their report to the OIE were sent a noneditable PDF version of their completed questionnaire and asked to confirm the accuracy of their data; and 2 during the May and May OIE General Sessions, all Member Countries were given the complete datasets and a final opportunity for comment.

Additionally, 2 countries that are still as of September not OIE Members reported in but they did not report again in In , of the countries that responded to the survey, 23 All countries that reported holding stocks of rinderpest material in reported still holding rinderpest material in One country that had reported not holding stocks of rinderpest material in the survey subsequently discovered that it did hold stocks and reported holding rinderpest material in For 1 country that reported in both surveys that it held rinderpest material, whether the material a subgenomic fragment of DNA constituted the intended meaning of rinderpest material was in doubt.

Of the 24 countries that reported holding rinderpest material, 1 country reported holding it in 5 institutes in ; this country subsequently destroyed all the stocks that were held in 1 institute. Although the number of viruses submitted for characterization was never large, the elucidation of viral phylogeny was very informative, demonstrating three largely geographically distinct viral clades: African lineages 1 and 2 and the Asian lineage. Viruses within clades that were indistinguishable serologically showed significant genomic differences, enabling the identification of origins of outbreaks.

The source was traced to a hitherto undisclosed reservoir of rinderpest in the Somali ecosystem. Molecular epidemiology suggested that outbreaks of rinderpest in the Middle East were derived from viruses repeatedly introduced from Asia and not from Africa as many had assumed and this was confirmed when such outbreaks ceased with the control of rinderpest in the Indian subcontinent [ 11 , 22 ].

Similarly, viruses derived from outbreaks in the vaccination buffer zone surrounding the Soviet Union and the vaccine virus used were shown to be virtually identical, indicating that reversion to virulence of the vaccine on three occasions over 20 years had been responsible for the outbreaks and not a persisting unknown reservoir figure 2. Last occurrence of wild rinderpest virus red , and outbreaks of vaccine-derived rinderpest blue.

Development of the Plowright tissue culture rinderpest vaccine TCRV in [ 23 ] was an important milestone in rinderpest control that gave impetus to the first coordinated effort to eradicate rinderpest from all of Africa.

TCRV was one of the finest vaccines ever developed in human or veterinary medicine. It protected against all clades of rinderpest virus, provided lifelong immunity to cattle, was never associated with any adverse reactions, and a single tissue culture infectious dose was immunogenic.

The vaccine benefited hundreds of millions of livestock-dependent people and, properly, Plowright received the World Food Prize in The principal limitation of the vaccine was that it required a strict cold-chain—a significant impediment to field vaccination programmes. The production process using primary bovine kidney cells was a potential source of contaminants and a constraint to large-scale manufacturing.

Production of TCRV was established in national laboratories across Africa, but the annual demand of 50 million doses was insufficient to achieve economies of scale, maintain quality of production or recapitalize their facilities.

In , rinderpest vaccines were typically of low quality in terms of both potency and purity. This led to establishment of the Pan-African Veterinary Vaccine Centre that successfully institutionalized independent quality control for rinderpest and other key livestock vaccines for the national production laboratories and assured an ample supply of safe and efficacious rinderpest vaccine for the eradication effort.

The transfer of technology to African production facilities led to the commercial availability of ThermoVax in quantities sufficient for rinderpest eradication by The Russian vaccine-associated incidents suggested that the use of attenuated vaccines posed a threat to rinderpest eradication even though TCRV had never been suspected of reversion to virulence.

As a result, timely cessation of vaccination became a key element of GREP policy. To capture the full benefit of ThermoVax vaccine, institutional change was needed that would have far-reaching effects on the relationships and roles of public, private and community animal health service actors [ 25 ].

Refrigerating a vaccine requires a network of ice-making capacity, static refrigeration and portable cold boxes that determine the reach of vaccination programmes. The cold-chain essentially requires significant organizational support, logistics and a vehicular transport network, which was one of the single largest costs in the delivery of vaccine. Rinderpest vaccination was one of the principal activities of the public veterinary services in the affected countries in Africa and Asia [ 11 ], and a large part of veterinary services budgets.

For individual veterinarians and para-professionals, income from rinderpest vaccination activities was a major component of their livelihoods, and involvement with campaigns was also a source of power and prestige. With ThermoVax, vaccine could be delivered on foot, by bicycle or using animal transport by a wide range of stakeholders, and this flexibility was perceived as a threat to the prestige and resource flows to conventional veterinary systems.

Early advocates for change recognized that community-based animal health workers CBAHWs could make a major contribution to rinderpest eradication [ 26 ]. CBAHWs are livestock owners selected by their communities to be trained and equipped for treating priority animal diseases. Incorporation of vaccination, especially vaccination for a critical disease, was a new concept.

With difficulty, permission was obtained from national authorities to conduct pilot programmes to test the reliability of CBAHWs in rinderpest vaccination. These pilots worked with communities to select trainees; they provided training on vaccination against rinderpest and treatment of key diseases, and built supply and supervision networks.

Initial programmes incorporated seromonitoring to measure the quality and impact of the vaccination activity. The results demonstrated that CBAHW vaccination programmes were achieving over 80 per cent herd immunity [ 27 ], matching or surpassing the levels achieved by national veterinary services in more accessible areas [ 28 ].

The reason for the success of community-based vaccination relates largely to incentives. The communities perceived rinderpest as a major threat and access to vaccination was sought by livestock owners. They were vaccinating the cattle of their extended families and neighbours figure 3 and had every reason to work diligently to assure the success of the vaccination.

They were able to offer vaccination in safe and easily accessible locations consistent with the movement needs of the herds. Remuneration was based on the quantity of work and, in most cases, provided by the livestock owners. By contrast, government vaccination programmes were implemented by personnel in receipt of daily field allowances; payment was not linked to the quantity or quality of work, but to the number of days spent in the field.

In our experience, the single most important factor improving the performance of vaccination programmes is to establish incentive systems that motivate the staff to reinforce the quality and quantity of their outputs. In many settings, veterinarians were possibly not the best-suited actors to deliver effective services in rural Africa and it was clear that a rethinking of veterinary service models could result in a better service to farmers.

The result was a new business model that teamed veterinary practitioners with CBAHWs in a synergistic partnership that expanded the opportunities for veterinary practice, gave livestock owners a greater role and enhanced access to services. Accreditation, overseen by the OIE Rinderpest Ad Hoc Group, required that a country operate a surveillance system that would be able to detect rinderpest, if it were present.

This enabled countries to monitor their own progress towards accredited freedom from infection and to plan their own eradication timelines. This process proved to be very useful for the duration of the global programme, only being modified to a one-step process of accreditation of freedom from infection in once it became clear that rinderpest disease had not been seen for several years.

During the early s, epidemiological studies in Ethiopia showed that rinderpest had persisted in parts of the pastoral ecosystems of eastern Africa throughout the JP15 campaign and that annual mass vaccination campaigns generally reached less than one-third of the 35 million cattle believed to be present. Official discouragement of investigation of outbreaks and insecurity in the lowland areas which were home to the nomadic pastoralists and their large herds of cattle obscured the true incidence of rinderpest [ 11 ].

From to , repeated outbreaks were studied in the highlands, in the Afar lowlands, in the Rift Valley and in the highland—lowland interface areas to understand the relationship of these outbreaks to each other and to determine the persistence of infection.

In the lowland areas, Afar livestock owners were desperate for vaccination to help them control rinderpest outbreaks in cattle less than 3 years of age. Drs W. Asfaw, G. Van't Klooster and P. Roeder conducted field investigations in focusing on interviewing government veterinary officers and livestock owners, and collecting samples from cattle for testing for rinderpest in the highland—lowland interface and along the border with Eritrea through Wollo and Tigrai provinces.

It became clear from this mission that. In the endemic pastoralist areas, vaccination could be limited to cattle between 1 and 3 years of age, because older cattle were immune from earlier contact with infection. Involvement of the community and the use of ThermoVax proved critical for the endgame success.

Based on these observations, a new rinderpest elimination strategy was developed for Ethiopia, the essence of which was to. ThermoVax was to be used in cattle between 1 and 3 years of age; and. Strategy was refined as more epidemiological information became available to clarify the situation in the Rift Valley, where rinderpest was being introduced by exchange of heifers from the Arssi highlands with Afar plough oxen. West of Lake Tana, vaccination teams were taken into the most inaccessible areas by military helicopters provided by the new government, quickly eliminating this reservoir.

The Afar region took longer with the last outbreak occurring in October , the same time as the last incursion from Sudan into western Ethiopia.

Since that time, Ethiopia has been free from rinderpest. Once there was growing confidence that rinderpest virus was no longer present, it was possible to progressively reduce the vaccinated zones eventually ceasing vaccination completely and commencing verification of freedom through clinical, participatory and serological surveillance.

However, official recognition by OIE of freedom for Ethiopia had to await determination of the freedom of neighbouring countries, which took until following a regional coordination of strategy.

The other significant event, which contributed to defining the final phase of eradication, was a severe epidemic in wildlife from to [ 29 ], apparently originating from the coastal lowlands of eastern Kenya, and affecting mainly lesser kudus T. Mortality in buffaloes of 60 per cent was estimated from aerial census and possibly reached up to 90 per cent in some kudu populations.

The outbreak showed the value of wild animals as sentinels and contributed to defining the final eradication phase, initiating an intensive, regional search for rinderpest infection in wildlife populations [ 30 , 31 ]. Given there were no known foci of rinderpest nearby, and the extent of control in Ethiopia, the outbreak came as a total surprise.

It was assumed to be due to virus spreading through livestock trade movements deep into the country from the Sudan—Ethiopia—Kenya border areas. This sparked a mass vaccination campaign in Kenya despite the apparent failure to detect the disease in cattle herds. Experimental studies showed the virus to cause mild disease in indigenous livestock, whereas it was severe in grade cattle [ 32 ]. Recorded observations of rinderpest in wild populations over a period of 30 years provided evidence of where the virus had been present across eastern, West and Central Africa.

Of profound importance to eradication was the demonstration that a rinderpest virus causing only mild disease in cattle was still persisting [ 33 , 34 ] in the Somali ecosystem, a region comprising contiguous areas of northeastern Kenya, southeastern Ethiopia and southern Somalia figure 4.

In retrospect, there were indications of persistent enzootic mild rinderpest in Somalia well before its confirmation in [ 33 , 38 ]. The apparent independent persistence of this reservoir of infection in wildlife generated pessimistic predictions about the outcome of GREP.

Evidence accrued that the wildlife reservoir was not an insurmountable obstacle to eradication [ 11 ]. In the s, seroconversion indicative of endemic rinderpest in the wildlife of the Serengeti National Park in Tanzania became undetectable soon after intensive vaccination campaigns were mounted in the dense cattle herds surrounding the park [ 39 — 41 ]. Historical accounts of rinderpest in Vietnam, Laos and Cambodia in the s, which must have been caused by the Asian lineage, bear similarities to that of rinderpest in East Africa at around the same time caused by African lineage 2.

Rinderpest in Southeast Asia affecting wild pigs and a diversity of wild ruminants [ 42 , 43 ], spread rapidly and died out spontaneously; local cattle were apparently resistant. Based on studies of rinderpest epidemics in wildlife in eastern Africa in the s and s, an upper limit of 4 years for virus circulation in wildlife was proposed [ 30 ]. As a first step in the establishment of CBAHW programmes, participatory rural appraisal PRA techniques [ 44 ] were used to understand the community perceptions regarding animal health and to prioritize disease problems.

It was evident from these activities that the communities had very detailed knowledge of the presentation, gross pathology and epidemiology of many disease problems affecting their livelihoods.

Local knowledge included terms for clinical conditions that often translated into specific diseases in modern terminology. Given the importance of rinderpest to pastoral livestock keepers, the history and behaviour of rinderpest was often an important topic in the oral traditions of communities. Elders and community animal health workers identified rinderpest outbreaks and could describe the risk factors that created the conditions for endemic persistence of the virus.

They proved to be key informants often providing more accurate disease intelligence than the formal surveillance systems [ 45 ]. For example, Tom Olaka, a CBAHW from Karamoja, Uganda, identified an outbreak of rinderpest and provided information on livestock movements that led to an effective response, enabling the completion of rinderpest eradication from Uganda [ 25 ]. A similar participatory disease-searching technique documented aforementioned mild disease in the cattle in the Somali ecosystem [ 33 ].

Participatory disease surveillance was further developed in Pakistan and was widely used as a tool to contribute to the validation of rinderpest eradication. Today, participatory epidemiology has become an accepted and valued tool for the veterinary profession [ 25 ] and is one of the legacies of rinderpest eradication [ 16 ].

Modelling allows data from diverse sources to be integrated into analytical systems that can then be used to assess the probable impact of alternative control scenarios. Combined with field intelligence, models can assist decision-makers to make informed choices and to set intervention targets. In the case of rinderpest, stochastic SEIR Susceptible, Exposed, Infectious and Recovered models of transmission were constructed using parameters estimated from the literature and livestock owner information on population contact structure and the clinical behaviour of rinderpest in their herds [ 46 ].

Estimates of R 0 ranged from 1. Values of R 0 for rinderpest transmission in African buffaloes calculated from post-outbreak seroprevalence estimates ranged from 2 to 7.