Serosurvey of peste des petits ruminants virus in small ruminants from different agro-ecological zones of Nigeria

Can pigs add another "P" to the PPR? Serological evidence of frequent Peste des petits ruminants infections in pigs in Nigeria

To achieve the global eradication of Peste des petits ruminants (PPR), the epidemiological role of atypical hosts must be fully understood. Among domestic animals, pigs are, until now, the only species that has proven to fulfil criteria relevant for hosts to act as disease reservoir. This entails the susceptibility to infection via contact with infected animals as well as the shedding of infectious virus, resulting in new infections. However, these features have been observed only in infection experiments, lacking information from the field. In this study, for the first time, we provide evidence for frequent PPR virus exposure in pigs, detected in Nigeria. The prevailing husbandry systems targeted for sampling entailed predominantly free roaming pigs and small ruminants. The sampling area was selected on the basis of the occurrence of endemic PPR in small ruminants in recent years. Sera from 183 small ruminants and 495 pigs were analysed. The 25.68% apparent seroprevalence (95% CI 19.5-32.7 at the population level) observed in small ruminants matched values detected in Nigeria. The apparent seroprevalence in pigs of 4.24% (95% CI 2.6-6.5 at the population level) distributed across Nigeria provides evidence that PPR infections in pigs are not rare events. The ability of swine populations to propagate and maintain autonomous PPR infections over time remains to be clarified at this stage. Countries engaged in PPR eradication with substantial pig populations under extensive husbandry practices, including contact with small ruminants, should, however, consider surveillance strategies that address this possibly problematic interspecies interaction.

Seroprevalence and associated risk factors of Peste des petits ruminants in selected districts of Awi zone, Northwest Ethiopia

A cross-sectional study to estimate the antibody seroprevalence of the PPR virus and determine the associated risk factors was conducted from February 2021 to May 2022 in the Guangua and Jawi districts of the Awi zone. Of the total 380 sera samples tested using cELISA, 231 (60.8 %) were found positive for the PPRV antibody. A significantly higher prevalence of 76.2 % (OR = 4.5, P = 0.000) was observed in the Jawi district than in the Guangua district (45.5 %). Seroprevalence of 61.9 % (109/176) in sheep and 59.8 % (122/204) in goats was also detected in the present study (P > 0.05). Significantly higher prevalence was revealed in old (69.7 %, OR = 3.4) and adult (65.7 %, OR = 2.3) age groups compared to young (48.9 %) age groups. A prevalence of 63.4 % and 55.6 % were reported in female and male animals respectively (P > 0.05, χ2 = 1.85). As evidenced by the serological test result, PPR is highly circulated in the Guangua and Jawi districts of the Awi zone. The higher circulation of the PPR virus, the uncontrolled movement of animals, and the regular practice of communal grazing systems in the area indicate the chance of continued dissemination within and to other places. Hence, proper implementation of prevention and control measures and further study on sequencing and characterization of the circulating virus are advised.

Seroepidemiology of peste des petits ruminants virus in small ruminants in selected districts in Northwest Ethiopia

BACKGROUND

Peste des petits ruminants (PPR) is one of the most severe diseases of small ruminants, causing the loss of millions of dollars annually. A cross-sectional study was conducted to determine the seroepidemiology of peste des petits ruminants virus (PPRV) in unvaccinated sheep and goats in selected districts in Northwest Ethiopia.

OBJECTIVES

The study was designed to investigate the epidemiology of PPRV in unvaccinated sheep and goats and risk factors in the study areas.

METHODS

A multi-stage sampling was used to select study districts, villages and households with a random sampling approach. Study animals (403 sheep and goats) older than 5 months were selected with a systematic random sampling approach. From the animals, blood samples were aseptically collected and PPRV antibodies from the serum were analysed with enzyme-linked immunosorbent assay (ELISA).

RESULTS

The overall seroprevalence of antibodies to PPRV was 32.5% in both species. It was higher in goats with a prevalence of 34.7% than in sheep (28.3%). District, herd size, sex, animal origin and grazing management were significantly associated with seropositivity of animals to PPRV antibodies. If an animal was from the Dangur district, it had 2.6 times higher chance of being positive than in the Dibati district (OR = 2.6, p = 0.01 and 95% CI = 1.2- 5.6). Herd size was also significantly correlated with the seropositivity with (OR = 4, p = 0.001, and 95% CI = 1.8-9). Also, male animals had 1.7 times higher chance of being positive than females. Further, if an animal comes from the market, it has 2.7 times higher chance of being positive compared to animals born and raised on the farm.

CONCLUSIONS

The seropositivity indicates that the disease is circulating in the study areas. Hence, preventive approaches, like vaccination campaigns and strict biosecurity measures, are highly advised to avoid the catastrophic impact of the diseases if an outbreak occurs.

Epidemiology of Peste des Petits Ruminants in Nigeria: A Review

Peste des petits ruminants (PPR) is a major constraint to the productivity of small ruminants in Nigeria. Understanding of the current epidemiological status of PPR is crucial to its effective control. A review of the epidemiology of PPR in Nigeria was performed and research gaps were identified. Thirty-seven eligible articles were reviewed: these presented information from 30 of the 36 states of Nigeria. Most studies focused on goats and/or sheep (n = 33) but camels (n = 4), cattle (n = 1) and wild ruminants (n = 2) were also considered. Fourteen (37.8%) of the articles reported seroprevalence in small ruminants, which varied from 0.0% to 77.5% where more than 10 animals were sampled. Molecular characterization and phylogenetic analysis were performed in 6 studies, with lineages II and IV, detected in sheep and goats. In one study in small ruminants, sequences clustering into lineage I showed a similarity to the vaccine strain, Nigeria 75/1, based on phylogenetic analysis of F gene sequences. However, if the preferred method of sequencing the N gene had been performed, this isolate would have been grouped into lineage II. According to N gene phylogenetic analysis in the other studies, sequences were identified that clustered with clade II-NigA, II-NigB (closely related to the Nigeria 75/1 vaccine strain), and others which were well separated, suggesting a high diversity of PPRV in Nigeria. Five articles reported the detection of lineage IV in 22/36 states, with IV-NigA and IV-NigB detected, highlighting its widespread distribution in Nigeria. Risk factors for PPRV seropositivity were reported in 10/37 (27.0%) articles, with a higher seroprevalence observed in female animals, although differing results were observed when considering species and age separately. There were inconsistencies in study design and data reporting between studies which precluded conduct of a meta-analysis. Nevertheless, several research gaps were identified including the need to investigate the low uptake of PPRV vaccine, and the economic benefits of PPR control measures to small ruminant farmers. Such data will inform PPR control strategies in Nigeria and subsequently contribute to the global 2030 PPR eradication strategy.

Retrospective Characterization of Initial Peste des petits ruminants Outbreaks (2008-2012) in the Democratic Republic of the Congo

Peste des petits ruminants (PPR) is an acute, contagious viral disease of small ruminants, goats and sheep. The Democratic Republic of the Congo (DRC) was a PPR-free country until 2007, although in 2006, scare alerts were received from the east and the southwest of the country, reporting repeated mortalities, specifically in goats. In 2008, PPR outbreaks were seen in several villages in the west, leading to structured veterinary field operations. Blood, swabs and pathological specimens consisting of tissues from lungs, spleens, lymph nodes, kidneys, livers and hearts were ethically collected from clinically infected and/or dead animals, as appropriate, in 35 districts. Epidemiological information relating to major risk factors and socio-economic impact was progressively collected, revealing the deaths of 744,527 goats, which converted to a trade value of USD 35,674,600. Samples from infected and dead animals were routinely analyzed by the Central Veterinary Laboratory at Kinshasa for diagnosis, and after official declaration of PPR outbreaks by the FAO in July 2012, selected tissue samples were sent to The Pirbright Institute, United Kingdom, for genotyping. As a result of surveys undertaken between 2008 and 2012, PPR virus (PPRV)-specific antibodies were detected in 25 locations out of 33 tested (75.7%); PPRV nucleic acid was detected in 25 locations out of 35 (71.4%); and a typical clinical picture of PPR was observed in 23 locations out of 35 (65.7%). Analysis of the partial and full genome sequences of PPR viruses (PPRVs) obtained from lymphoid tissues of dead goats collected in Tshela in the DRC in 2012 confirmed the circulation of lineage IV PPRV, showing the highest homology (99.6-100%) with the viruses circulating in the neighboring countries of Gabon, in the Aboumi outbreak in 2011, and Nigeria (99.3% homology) in 2013, although recent outbreaks in 2016 and 2018 in the western part of the DRC that borders with East Africa demonstrated circulation of lineage II and lineage III PPRV.

The influence of intranasal peste des petits ruminants (PPR) vaccine administration alone or with phytogenic mucoadhesive delivery system on PPR outbreak outcomes in goats

This study reports the influence of peste des petits ruminants (PPR) vaccination on the clinico-pathological outcomes of PPR in the face of an outbreak. Twenty-two West African dwarf goats procured for a different study started showing early signs of PPR during acclimatization. In response, PPR vaccine was administered either intranasally with phytogenic mucoadhesive gum (Group A; n = 6) or without gum (Group B; n = 6); subcutaneously (Group C; n = 6) or not vaccinated (Group D; n = 4) and studied for 21 days. The clinical scores, hematology, serology and pathology scores were evaluated. Clinical signs of PPR were present in all groups, presenting a percentage mortality of 33%; 33%; 64% and 100% for Groups A, B, C, and D, respectively. Polycythemia and mild leukopenia were observed in all groups, and all animals were seropositive by day 7 post-vaccination. The lung consolidation scores were low in Groups A and B, compared to Group C. Histopathological lesions consistent with PPR was observed in the lymphoid organs, gastrointestinal tract, and lungs with the presence of PPR antigen as detected by immunohistochemistry. The findings suggest that intranasal vaccination with or without mucoadhesive gum may influence the outcome of PPR infection more than the subcutaneous route in the face of an outbreak.

Field survey of major infectious and reproductive diseases responsible for mortality and productivity losses of ruminants amongst Nigerian Fulani pastoralists

Background: Animal disease constitutes a major hurdle to improved livelihoods in rural Nigeria through the challenges of loss of productivity, livestock morbidity and mortality including reproductive losses. In order to design and implement impactful interventions, baseline data on the causes of such losses are needed. Therefore, the objective of the present study was to carry out targeted field surveys, including interviews with ruminant farmers, veterinary professionals and other stakeholders in livestock farming to establish the main causes of disease and mortality including abortions in cattle and small ruminants (SR). Methods: Northern Nigeria was selected because the majority of the nation's ruminants belong to pastoralists who are primarily resident in this region. Seven states; Bauchi, Kaduna, Kano, Nasarawa, Niger, Sokoto and Zamfara states were surveyed. The responses were collated and a comprehensive descriptive analysis was carried out. Results: Average cattle herd sizes ranged from 28 in Zamfara to 103 in Nasarawa; and from 27 in Kano to 128 in Sokoto for SR. In cattle, Trypanosomosis (with 4.27% mortality rate), foot and mouth disease (3.81%), nutritional insufficiency (1.93%) and contagious bovine pleuropneumonia (CBPP; 1.44%) were the top four diseases/health problems that resulted in the highest mortality due to diseases within each state surveyed. For SR, trypanosomosis (with 6.85% mortality rate), Peste des Petits Ruminants (4.99%), orf (3.06%), foot rot (2.97%) and foot and mouth disease (2.94%) were the most important diseases responsible for the highest number of mortalities and culling for disease. Conclusions: The study revealed that there are significant losses via mortalities due to the occurrence of disease amongst the ruminant populations countrywide, as evidenced by the high overall mortality rates of both cattle (15.3%) and small ruminants (30.9%) from various diseases. Also, reproductive losses of 8.7% and 16.6% in cattle and SR, respectively, were recorded amongst the farmers involved.

Update on Peste des petits ruminants status in South East Nigeria: serological and farmers' awareness investigation, and potential risk factors

Peste des petits ruminants (PPR) is a highly contagious, trans-boundary viral disease of sheep and goats that have hindered successful small ruminant farming. Its current status in South East Nigeria with respect to its prevalence and farmers' awareness was studied. Three states, Anambra, Ebonyi, and Enugu, were randomly selected for the study. Sera samples from 113 goats and 172 sheep (collected from December 2017 to June 2018) were randomly collected and analysed for the presence of PPRV antibodies, while structured interview schedules were conducted to elicit information on farmers' awareness of the disease and PPR vaccination and use of veterinary services. An overall seroprevalence of 42.5% (121/285) was recorded. The seroprevalence in decreasing order was 62.2% (Enugu), 34.8% (Anambra) and 20.3% (Ebonyi). There was a significant association (X² = 36.08, df = 2, p = 0.0001) between seroprevalence and the state sampled. Lack of awareness of PPR vaccination among small ruminant farmers, their limited use of veterinary services (38% consult veterinarians) and non-availability of the vaccine at veterinary establishments in the sampled states are potential risk factors of PPR prevalence in South East Nigeria. Consequently, an effective control measure like mass vaccination is recommended for the study area. Also, there is a need for an extension program for stakeholders and farmers in the study area and country on the grave importance and economic benefits of PPR vaccination and the use of veterinary services.

Peste des Petits Ruminants (PPR) virus serological surveillance in goats in Lao PDR: Issues for disease eradication in a low-resource disease-free setting

Peste des Petits ruminants (PPR) is an economically important transboundary viral disease of goats. This study aimed to determine a baseline of serological evidence for Peste des petits ruminants virus (PPRV) in Lao goats. A total of 1,072 serum samples were collected by convenience sampling across five provinces in Laos and tested for antibody response to PPRV using a commercially available competitive ELISA. Positive antibody responses were found in 2.2% (95% CI 1.4, 3.2) of the samples. True prevalence calculations indicated a total overall sample prevalence of 1.7% (95% CI 0.9, 2.8). The highest provincial seroprevalences were Xiangkhouang (3.5%, 95% CI 1.6, 6.9) and Xayaboury (2.9% (95% CI 1.3, 5.7). There was no association between antibody response and each of the following factors: location, breed, gender or age. Considering the apparent absence of disease manifestation of PPR in Laos, likely explanations for the antibody positivity could include cross reaction to other Morbilliviruses such as Measles or Canine Distemper, importation of pre-vaccinated goats, need for test cut-off re-evaluation to be region specific, or a subclinical and a less virulent circulating virus. This study highlights that the sampled Lao goat population is highly likely to be naïve to PPRV and therefore at risk of an outbreak, possibly by transboundary incursion of livestock from PPR endemic China. Further work is required in the testing of small ruminants in Laos that may eventually provide evidence for a status of freedom from disease, particularly in support of programs aimed at global PPR eradication.

Advances in peste des petits ruminants vaccines

Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants that leads to high morbidity and mortality thereby results in devastating economic consequences to the livestock industry. PPR is currently endemic across most parts of Asia and Africa, the two regions with the highest concentration of poor people in the world. Sheep and goats in particularly contribute significantly towards the upliftment of livelihood of the poor and marginal farmers in these regions. In this context, PPR directly affecting the viability of sheep and goat husbandry has emerged as a major hurdle in the development of these regions. The control of PPR in these regions could significantly contribute to poverty alleviation, therefore, the Office International des Epizooties (OIE) and Food and Agricultural Organization (FAO) have targeted the control and eradication of PPR by 2030 a priority. In order to achieve this goal, a potent, safe and efficacious live-attenuated PPR vaccine with long-lasting immunity is available for immunoprophylaxis. However, the live-attenuated PPR vaccine is thermolabile and needs maintenance of an effective cold chain to deliver into the field. In addition, the infected animals cannot be differentiated from vaccinated animals. To overcome these limitations, some recombinant vaccines have been developed. This review comprehensively describes about the latest developments in PPR vaccines.