Review of Peste des Petits Ruminants Occurrence and Spread in Tanzania.

Peste des petits ruminants (PPR) is an important transboundary animal disease of domestic small ruminants, camels, and wild artiodactyls. The disease has significant socio-economic impact on communities that depend on livestock for their livelihood and is a threat to endangered susceptible wild species. The aim of this review was to describe the introduction of PPR to Tanzania and its subsequent spread to different parts of the country. On-line databases were searched for peer-reviewed and grey literature, formal and informal reports were obtained from Tanzanian Zonal Veterinary Investigation Centres and Laboratories, and Veterinary Officers involved with PPR surveillance were contacted. PPR virus (PPRV) was confirmed in northern Tanzania in 2008, although serological data from samples collected in the region in 1998 and 2004, and evidence that the virus was already circulating in Uganda in 2003, suggests that PPRV might have been present earlier than this. It is likely that the virus which became established in Tanzania was introduced from Kenya between 2006-7 through the cross-border movement of small ruminants for trade or grazing resources, and then spread to eastern, central, and southern Tanzania from 2008 to 2010 through movement of small ruminants by pastoralists and traders. There was no evidence of PPRV sero-conversion in wildlife based on sera collected up to 2012, suggesting that they did not play a vectoring or bridging role in the establishment of PPRV in Tanzania. PPRV lineages II, III and IV have been detected, indicating that there have been several virus introductions. PPRV is now considered to be endemic in sheep and goats in Tanzania, but there has been no evidence of PPR clinical disease in wildlife species in Tanzania, although serum samples collected in 2014 from several wild ruminant species were PPRV sero-positive. Similarly, no PPR disease has been observed in cattle and camels. In these atypical hosts, serological evidence indicates exposure to PPRV infection, most likely through spillover from infected sheep and goats. Some of the challenges for PPRV eradication in Tanzania include movements of small ruminants, including transboundary movements, and the capacity of veterinary services for disease surveillance and vaccination. Using wildlife and atypical domestic hosts for PPR surveillance is a useful indicator of endemism and the ongoing circulation of PPRV in livestock, especially during the implementation of vaccination to control or eliminate the disease in sheep and goats. PPR disease has a major socio-economic impact in Tanzania, which justifies the investment in a comprehensive PPRV eradication programme.

Characterisation of Peste Des Petits Ruminants Disease in Pastoralist Flocks in Ngorongoro District of Northern Tanzania and Bluetongue Virus Co-Infection.

Peste des petits ruminants (PPR) disease was first confirmed in Tanzania in 2008 in sheep and goats in Ngorongoro District, northern Tanzania, and is now endemic in this area. This study aimed to characterise PPR disease in pastoralist small ruminant flocks in Ngorongoro District. During June 2015, 33 PPR-like disease reports were investigated in different parts of the district, using semi-structured interviews, clinical examinations, PPR virus rapid detection test (PPRV-RDT), and laboratory analysis. Ten flocks were confirmed as PPRV infected by PPRV-RDT and/or real-time reverse transcription-polymerase chain reaction (RT-qPCR), and two flocks were co-infected with bluetongue virus (BTV), confirmed by RT-qPCR. Phylogenetic analysis of six partial N gene sequences showed that the PPR viruses clustered with recent lineage III Tanzanian viruses, and grouped with Ugandan, Kenyan and Democratic Republic of Congo isolates. No PPR-like disease was reported in wildlife. There was considerable variation in clinical syndromes between flocks: some showed a full range of PPR signs, while others were predominantly respiratory, diarrhoea, or oro-nasal syndromes, which were associated with different local disease names (olodua-a term for rinderpest, olkipiei-lung disease, oloirobi-fever, enkorotik-diarrhoea). BTV co-infection was associated with severe oro-nasal lesions. This clinical variability makes the field diagnosis of PPR challenging, highlighting the importance of access to pen-side antigen tests and multiplex assays to support improved surveillance and targeting of control activities for PPR eradication.

Pastoralist knowledge of sheep and goat disease and implications for peste des petits ruminants virus control in the Afar Region of Ethiopia.

Pastoralist areas of Ethiopia are vulnerable to drought, causing livelihood loss and famine. One approach to increasing pastoralist resilience is the control of livestock disease, but there is limited information from pastoralist areas to inform control strategies. This study aimed to explore pastoralist concepts of small ruminant disease and implications for infectious disease surveillance and control in the pastoralist Afar Region. During 2013-14, qualitative and quantitative methods were applied in two villages of one district in the mid-west of the region. Semi-structured group interviews, incorporating participatory tools, explored pastoralist knowledge of small ruminant diseases and their impact. These were followed by multiple visits in different seasons to 70 households for semi-structured and informal interviews, observation of management practices, clinical examinations, and weekly questionnaires of mortality and morbidity. Thematic analysis was applied to interview transcripts and field notes, and descriptive statistical analysis to quantitative data. Afar concepts of disease causation, terminology and treatment were predominantly naturalistic, related to observable signs and physical causes, rather than personalistic factors (misfortune due to magical or spiritual agents). Disease occurrence was associated with malnutrition and adverse weather, and disease spread with contact between animals during grazing, watering and migration. Disease occurrence varied by season with most syndromes increasing in frequency during the dry season. Names for disease syndromes were related to the main clinical sign or body part affected; 70 terms were recorded for respiratory syndromes, diarrhoea, sheep and goat pox, lameness, skin diseases, ectoparasites, urinary and neurological syndromes and abortion. Some syndromes with pathognomonic signs could be linked to biomedical diagnoses but most were non-specific with several possible diagnoses. The syndromes causing greatest impact were diarrhoea and respiratory disease, due to mortality, reduced milk production, weight loss, abortion, weak offspring and reduced market value. Afar applied a range of traditional methods and modern medicines to prevent or treat disease, based on livestock keeper knowledge, advice of local specialists and occasionally advice from district veterinarians or animal health workers. In relation to surveillance for peste des petits ruminants (PPR), several terms were used for PPR-like syndromes, depending on the predominance of respiratory or diarrhoea signs. Therefore, whenever these terms are encountered during surveillance, the associated disease events should be fully investigated and samples collected for laboratory confirmation. The Afar naturalistic concepts of disease parallel biomedical concepts and provide a good foundation for communication between veterinarians and pastoralists in relation to PPR surveillance and control measures.

The risk of rinderpest re-introduction in post-eradication era.

In 2011, ten years after the last reported outbreak, the eradication of rinderpest was declared. However, as rinderpest virus stocks still exist, there remains a risk of rinderpest re-introduction. A semi-quantitative risk assessment was conducted to assess this risk, which was defined as the probability of at least one host becoming infected and infectious outside a laboratory anywhere in the world within a one-year period. Pathways leading to rinderpest re-introduction were: deliberate or accidental use of virus in laboratories, deliberate or accidental use of vaccines, host exposure to an environmental source of virus, and use of virus for anti-animal biological warfare. The probability of each pathway step occurring was estimated through expert opinion elicitation. The risk estimate was associated with a high degree of uncertainty. It was estimated to range from negligible to high, with the median being very low. The accidental use of laboratory virus stocks was the highest risk pathway. Reducing the number of virus stocks and restricting their use, as well as upgrading the laboratories to a higher biosafety level, would effectively decrease the maximum and median risks. Likewise, ensuring that remaining vaccine stocks are not used and are instead destroyed or relocated to a limited number of regional repositories would also have a major effect on these estimates. However, these measures are unlikely to eliminate the risk of rinderpest re-introduction so that maintaining response preparedness is essential.

The economic value of One Health in relation to the mitigation of zoonotic disease risks.

The essence of One Health is an interdisciplinary approach combined with some degree of intersectoral integration that is aimed at mitigation of human and animal health risks, taking account of environmental, ecological, social and economic factors. While a large number of international stakeholders now consider the One Health approach necessary for more effective protection of the global community against health threats, there is still no systematic allocation of resources to integrated national or multinational programmes, partly due to the inertia of existing sectoral systems and the lack of convincing economic arguments in support of the approach. We propose different degrees of sectoral integration depending on system types and associated economic efficiency gains to be expected from a One Health approach. International and regional organisations have an important role in facilitating the adoption of the approach, since the costs and the benefits are often of a regional or even a global nature, such as in the case of avian influenza.

Introduction of African swine fever into the European Union through illegal importation of pork and pork products.

Transboundary animal diseases can have very severe socio-economic impacts when introduced into new regions. The history of disease incursions into the European Union suggests that initial outbreaks were often initiated by illegal importation of meat and derived products. The European Union would benefit from decision-support tools to evaluate the risk of disease introduction caused by illegal imports in order to inform its surveillance strategy. However, due to the difficulty in quantifying illegal movements of animal products, very few studies of this type have been conducted. Using African swine fever as an example, this work presents a novel risk assessment framework for disease introduction into the European Union through illegal importation of meat and products. It uses a semi-quantitative approach based on factors that likely influence the likelihood of release of contaminated smuggled meat and products, and subsequent exposure of the susceptible population. The results suggest that the European Union is at non-negligible risk of African swine fever introduction through illegal importation of pork and products. On a relative risk scale with six categories from negligible to very high, five European Union countries were estimated at high (France, Germany, Italy and United Kingdom) or moderate (Spain) risk of African swine fever release, five countries were at high risk of exposure if African swine fever were released (France, Italy, Poland, Romania and Spain) and ten countries had a moderate exposure risk (Austria, Bulgaria, Germany, Greece, Hungary, Latvia, Lithuania, Portugal, Sweden and United Kingdom). The approach presented here and results obtained for African swine fever provide a basis for the enhancement of risk-based surveillance systems and disease prevention programmes in the European Union.