Detection of porcine circovirus type 2 (PCV2) in the Philippines and the complexity of PCV2-associated disease diagnosis.

Porcine circovirus type 2 (PCV2), an important pig viral pathogen, can cause porcine circovirus-associated disease (PCVAD), resulting in economic losses associated with decreased growth and mortalities. The diagnosis of PCVAD is complex requiring clinical, pathological and virological approaches. This study assessed PCV2 infection using histopathology and immunohistochemistry (IHC) on tissue samples and quantitative polymerase chain reaction (qPCR) on serum samples from 47 grower-finisher pigs allocated in three clinical groups in the Philippines. Typical PCV2 histopathological lesions were observed in mediastinal lymph nodes (MLN) of eight of 47 pigs. Lymphoid depletion was seen in all eight pigs and granulomatous inflammation in one of these pigs. Four of these eight pigs were PCV2 positive by both IHC and qPCR. IHC revealed PCV2 antigen in 8 pigs in at least one of the following tissues: MLN (5/8), spleen (3/8), tonsils (4/8) and lungs (5/8). PCV2 antigen was observed in 3/8 MLN with lymphoid depletion and in one MLN with depletion and granulomatous inflammation. The qPCR test showed that 33 sera had a non-detectable level, twelve had < 106 and two had > 106 PCV2 DNA copies/ml serum. One pig with lymphoid depletion had > 106 PCV2 DNA copies/ml serum, and another pig without MLN lesions also had > 106 PCV2 DNA copies/ml serum. These findings suggest that PCVAD is present in the Philippines and confirm the challenges of PCVAD diagnosis as different patterns of results were obtained from the different tests.

Development of a Luminex microbead-based serotyping assay for Glaesserella parasuis.

Glaesserella parasuis consists of 15 serovars with some of them highly virulent and some of them avirulent. As killed vaccines do not provide crossprotection across serovars, serotyping is of importance. Serotyping, previously done by gel diffusion, is now done by multiplex PCR followed by electrophoresis. Accurately differentiating 15 serovars by electrophoresis is problematic. To overcome this problem, a Luminex microbead-based multiplex assay was used to differentiate the serovars. The assay consisted of a multiplex PCR assay followed by hybridisation to microbeads which were then analysed on a Luminex machine. The newly developed assay was compared to the multiplex serotyping PCR and the gel diffusion/indirect haemagglutination assay (GD/IHA). The microbead-based assay worked very well for the 15 reference strains but when used on the 74 Australian field strains displayed some problems. The main problems were with the eight out of nine serovar 4 field isolates and the five serovar 7 and three serovar 14 field isolates. While the microbead-based assay could differentiate between the serovar 5 and 12 reference strains, which the serovar multiplex PCR could not, all four field isolates identified by GD/IHA as serovar 12 were identified as serovar 5 by the microbead-based assay. Serovar 4 has been noted to have a high diversity especially among strains from different countries. Our work clearly shows that the diversity of strains at both the national and the international level has to be taken into account when developing diagnostic assays.

Latent class analysis identifies multimorbidity patterns in pigs with respiratory disease.

Respiratory disease is one of the major causes of losses to the pig industry worldwide. The pig subsector is the largest component of the livestock sector in the Philippines. Using lung scoring, this study aimed to estimate the prevalence of thoracic lesions in slaughter-age pigs in two provinces in the Philippines (Batangas and Albay) and define classes for respiratory health of pigs characterised by different patterns of thoracic lesions. A total of 260 pigs from Batangas and 300 pigs from Albay from either commercial or backyard farm types were included in this cross-sectional study. Lungs were scored for cranio-ventral pneumonia (0-55) and pleurisy (0-3). Presence or absence of pericarditis as well as focal dorso-caudal pneumonia were recorded. Latent class analyses considering four indicator variables, and province and farm type as covariates were used to explore different patterns of thoracic lesions across the study populations. Using a threshold of ≥7, the prevalence of a high lung score was 51.9% (95% confidence interval [CI]: 42.3-61.4%) and 13.7% (95% CI: 8.1-22.2%) in Batangas and Albay, respectively. Similarly, the prevalence of a pleurisy score of ≥1 was 56.9% (95% CI: 37.5-74.4%) and 5.0% (95% CI: 2.9-8.4%), pericarditis 24.6% (95%CI: 10.1-48.6%) and 1.7% (95%CI: 0.3-6.7%) and focal dorso-caudal pneumonia lesions 7.7% (95% CI: 3.7-15.5%) and 0% (97.5% one-sided CI: 0-1.2%), respectively. Latent class analyses identified four classes based on lung score, pleurisy score and the presence/absence of pericarditis: "healthy", "mild respiratory disease", "moderate pneumonia", and "multi-lesion". The relative frequency of these classes differed with province and farm type. Most pigs from Albay were "healthy", whereas in Batangas most pigs from commercial farms were "multi-lesion" and those from backyard farms were in the "mild respiratory disease" class. This study has provided baseline data on thoracic lesions in slaughter-age pigs for the provinces of Batangas and Albay in the Philippines. Targeting farms and areas where "multi-lesion pigs" are most common and further research to identify risk factors for particular classes should maximize impact of future control measures. The latent class analysis approach used could be applied more widely and could add value to analysis of multi-morbidity data collected routinely as part of ongoing monitoring schemes.

First steps in managing the challenge of African Swine Fever in Timor-Leste.

Since September 2019, African Swine Fever has caused extensive mortalities to the pig population of Timor-Leste, where pigs are important for traditional ceremonies and for monetary income. At the time of the outbreak we were developing a sustainable model for smallholder pig raising in Timor-Leste. We added basic biosecurity measures at our nine trial sites and conducted public awareness meetings in trial sukus (villages). This approach was largely successful as, despite extensive pig mortalities in the areas, few pigs died at trial sites once measures had been adopted and trial pig mortalities appeared to be linked to social issues that could be reduced through improved public awareness. We believe this approach can cost-effectively reduce the risk of mortalities due to African Swine Fever in settings where smallholder pig raising is very basic and resources limited, but pigs are of great socio-economic importance.

Combining conventional and participatory approaches to identify and prioritise management and health-related constraints to smallholder pig production in San Simon, Pampanga, Philippines.

Pork is the main meat produced and consumed in the Philippines. The majority of pigs are raised by smallholders who experience a range of constraints to their pig production. This study presents the findings of the first part of an overarching project that used an Ecohealth approach and aimed to improve the production and competitiveness of the smallholder pig system in an area of the Philippines. A participatory approach was embraced, combining conventional and participatory epidemiology methods followed by a stakeholder discussion. The first aim was to identify management and health-related constraints to pig production among smallholder famers in San Simon, Pampanga, Philippines. The second aim was for the project team and stakeholders to jointly prioritise activities for the immediate future to address these constraints. Key management and health-related constraints identified included inadequate water supply to pigs, particularly lactating and gestating sows, and a range of feeding-related issues. Diarrhoea was recognised as the disease syndrome of highest priority and limited record keeping meant that farmers were unable to assess the productivity and profitability of their pig farming enterprises. Actions jointly prioritised by stakeholders and the project team were: the appointment of a project coordinator within each barangay; conduct two sets of seminars, the first covering water and nutrition and the second piglet management and diarrhoea, to be delivered by technical experts but with farmer "trusted sources" also sharing their experiences; development of easily understandable leaflets and posters covering key technical information; promotion of nipple drinkers attached to five-gallon water containers and creep boxes for piglets, and conduct of a record keeping workshop with a small group of innovative farmers to develop a useful and usable tool for record keeping. The use of multiple approaches to data-gathering enabled triangulation of study findings. Without any one of these components the understanding of the pig production system would have been less complete and it is possible that the proposed actions would not have been as well-tailored to the needs of the farmers. The participatory approach, in particular the stakeholder discussion, provided the opportunity to embrace the "deciding together" and "acting together" stances of participation rather than the lower "information giving" stance, thereby giving stakeholders greater ownership of the future activities of the overarching project and beyond.

Prevalence and Risk Factors Associated with Gross Pulmonary Lesions in Slaughtered Pigs in Smallholder and Commercial Farms in Two Provinces in the Philippines.

A cross-sectional study of lungs from 1,887 randomly selected pigs from 471 farms from two provinces in the Philippines was carried out to estimate the prevalence of gross pathological lesions, identify potential risk factors and spatial clustering associated with high lung or pleurisy score farms. Lungs from pigs were scored at slaughter. Interviews with the farm managers were conducted to collect information about farm management and biosecurity practices. Of lungs examined, 48% had a lung score above 6 (maximum was 55) and 22% showed pleurisy. When data were aggregated at the farm level, commercial farms were at higher risk of being high lung score farms and high pleurisy farms compared to smallholder farms (P < 0.01). Variables that were associated with an increased risk of a farm being a high lung score farm included the presence of a market pen on the farm, not vaccinating against hog cholera and the presence of another piggery within 500 m. Practicing "feedback" (feeding pig manure, viscera or aborted material to pigs), presence of another piggery within 500 m, and allowing commercial livestock vehicles on farm were all associated with an increased risk of being a high pleurisy farm. Spatial analyses revealed a primary 9.6 km-radius cluster of 39 farms with high lung and pleurisy scores in the southeast of Bulacan province. High lung and pleurisy score farms could be targeted to improve on-farm disease control programs to reduce the risk of respiratory diseases. Clusters of high scoring farms could be prioritized for further investigations or for coordinating intervention efforts.