Using serological monitoring, internet-based feedback and on-farm auditing to improve Toxoplasma gondii control at Dutch pig farms

Toxoplasma gondii is a relevant foodborne pathogen due to its human disease burden. In the Netherlands, pork is estimated to contribute to 11% of the meatborne T. gondii infections. The European Food Safety Authority advised to perform serological testing of pigs and on farm audits on risk factors for T. gondii infection

Genetic diversity of Streptococcus suis isolates as determined by comparative genome hybridization

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus suis </it>is a zoonotic pathogen that causes infections in young piglets. <it>S. suis </it>is a heterogeneous species. Thirty-three different capsular serotypes have been described, that differ in virulence between as well as within serotypes.</p> <p>Results</p> <p>In this study, the correlation between gene content, serotype, phenotype and virulence among 55 <it>S. suis </it>strains was studied using Comparative Genome Hybridization (CGH). Clustering of CGH data divided <it>S. suis </it>isolates into two clusters, A and B. Cluster A isolates could be discriminated from cluster B isolates based on the protein expression of extracellular factor (EF). Cluster A contained serotype 1 and 2 isolates that were correlated with virulence. Cluster B mainly contained serotype 7 and 9 isolates. Genetic similarity was observed between serotype 7 and serotype 2 isolates that do not express muramidase released protein (MRP) and EF (MRP^-EF^-), suggesting these isolates originated from a common founder. Profiles of 25 putative virulence-associated genes of <it>S. suis </it>were determined among the 55 isolates. Presence of all 25 genes was shown for cluster A isolates, whereas cluster B isolates lacked one or more putative virulence genes. Divergence of <it>S. suis </it>isolates was further studied based on the presence of 39 regions of difference. Conservation of genes was evaluated by the definition of a core genome that contained 78% of all ORFs in P1/7.</p> <p>Conclusions</p> <p>In conclusion, we show that CGH is a valuable method to study distribution of genes or gene clusters among isolates in detail, yielding information on genetic similarity, and virulence traits of <it>S. suis </it>isolates.</p

Mycoplasma bovis in Nordic European Countries: Emergence and Dominance of a New Clone

Mycoplasma (M.) bovis is an important pathogen of cattle implicated in a broad range of clinical manifestations that adversely impacts livestock production worldwide. In the absence of a safe, effective, commercial vaccine in Europe, reduced susceptibility to reported antimicrobials for this organism has contributed to difficulties in controlling infection. Despite global presence, some countries have only recently experienced outbreaks of this pathogen. In the present study, M. bovis isolates collected in Denmark between 1981 and 2016 were characterized to determine (i) genetic diversity and phylogenetic relationships using whole genome sequencing and various sequence-based typing methods and (ii) patterns of antimicrobial resistance compared to other European isolates. The M. bovis population in Denmark was found to be highly homogeneous genomically and with respect to the antimicrobial resistance profile. Previously dominated by an old genotype shared by many other countries (ST17 in the PubMLST legacy scheme), a new predominant type represented by ST94-adh1 has emerged. The same clone is also found in Sweden and Finland, where M. bovis introduction is more recent. Although retrieved from the Netherlands, it appears absent from France, two countries with a long history of M. bovis infection where the M. bovis population is more diverse

Methods to assess the effect of meat processing on viability of Toxoplasma gondii: towards replacement of mouse bioassay by in vitro testing

Consumption of meat containing viable tissue cysts is considered one of the main sources of human infection with Toxoplasma gondii. In contrast to fresh meat, raw meat products usually undergo processing, including salting and mixing with other additives such as sodium acetate and sodium lactate, which affects the viability of T. gondii. However, the experiments described in the literature are not always performed in line with the current processing methods applied in industry. It was our goal to study the effect of salting and additives according to the recipes used by industrial producers. Mouse or cat bioassay is the ‘gold standard’ to demonstrate the presence of viable T. gondii. However, it is costly, time consuming and for ethical reasons not preferred for large-scale studies. Therefore, we first aimed to develop an alternative for mouse bioassay that can be used to determine the effect of processing on the viability of T. gondii tissue cysts. The assays studied were (i) a cell culture method to determine the parasite’s ability to multiply, and (ii) a propidium monoazide (PMA) dye-based assay to selectively detect DNA from intact parasites. Processing experiments were performed with minced meat incubated for 20 h with low concentrations of NaCl, sodium lactate and sodium acetate. NaCl appeared to be the most effective ingredient with only one or two out of eight mice infected after inoculation with pepsin-digest of portions processed with 1.0, 1.2 and 1.6% NaCl. Results of preliminary experiments with the PMA-based method were inconsistent and did not sufficiently discriminate between live and dead parasites. In contrast, the cell culture method showed promising results, but further optimization is needed before it can replace or reduce the number of mouse bioassays needed. In future, standardised in vitro methods are necessary to allow more extensive testing of product-specific processing methods, thereby providing a better indication of the risk of T. gondii infection for consumers

Separated by a Common Language: Awareness of Term Usage Differences Between Languages and Disciplines in Biopreparedness

Preparedness for bioterrorism is based on communication between people in organizations who are educated and trained in several disciplines, including law enforcement, health, and science. Various backgrounds, cultures, and vocabularies generate difficulties in understanding and interpretating terms and concepts, which may impair communication. This is especially true in emergency situations, in which the need for clarity and consistency is vital. The EU project AniBio- Threat initiated methods and made a rough estimate of the terms and concepts that are crucial for an incident, and a pilot database with key terms and definitions has been constructed. Analysis of collected terms and sources has shown that many of the participating organizations use various international standards in their area of expertise. The same term often represents different concepts in the standards from different sectors, or, alternatively, different terms were used to represent the same or similar concepts. The use of conflicting terminology can be problematic for decision makers and communicators in planning and prevention or when handling an incident. Since the CBRN area has roots in multiple disciplines, each with its own evolving terminology, it may not be realistic to achieve unequivocal communication through a standardized vocabulary and joint definitions for words from common language. We suggest that a communication strategy should include awareness of alternative definitions and ontologies and the ability to talk and write without relying on the implicit knowledge underlying specialized jargon. Consequently, cross-disciplinary communication skills should be part of training of personnel in the CBRN field. In addition, a searchable repository of terms and definitions from relevant organizations and authorities would be a valuable addition to existing glossaries for improving awareness concerning bioterrorism prevention planning

Multiplex PCR Assays for Simultaneous Detection of Six Major Serotypes and Two Virulence-Associated Phenotypes of Streptococcus suis in Tonsillar Specimens from Pigs

Multiplex PCR assays for the detection and identification of various Streptococcus suis strains in tonsillar specimens from pigs were developed and evaluated. In two separate reactions, five distinct DNA targets were amplified. Three targets, based on the S. suis capsular polysaccharide (cps) genes specific for serotypes 1 (and 14), 7, and 9, were amplified in multiplex PCR I. Two other targets, based on the serotype 2- (and 1/2-) specific cps gene and the epf gene, encoding the EF proteins of virulent serotype 2 and highly virulent serotype 1 strains, were amplified in multiplex PCR II. To identify false-negative results, firefly luciferase (luc) DNA and primers based on the luc gene were included in the assay. The multiplex PCR assays were evaluated with tonsillar specimens from pigs infected with S. suis strains. The results obtained with the PCR assays were compared with the results obtained with a bacteriological examination. Most (94%) of the results obtained with multiplex PCR assays were confirmed by the bacteriological examination. The PCR method seems to be more sensitive compared to the bacteriological method, since the remaining 6% of the samples were positive by PCR and negative by bacteriological examination. These results indicate that the PCR method is highly specific for the detection of S. suis strains most frequently involved in clinical disease in infected pig herds. The serotypes found by PCR in tonsillar specimens from diseased pigs were compared with the serotypes of the strains isolated from the affected tissues of the same pigs. The results showed that there is significant association between carriership and clinical illness for S. suis serotype 9 and EF-positive serotype 2 strains and not for serotype 7 and EF-negative serotype 2 (or 1/2) strains

Behavioural factors of Dutch pig producers related to control of <i>Toxoplasma gondii </i>infections in pigs

Toxoplasma gondii (T. gondii) is a food safety hazard which causes a substantial human disease burden. Infected pig meat is a common risk source of toxoplasmosis. Therefore, it is important to control T. gondii infections in pigs. Improving farm management to control the introduction risk likely contributes to that aim. A pig producer only implements control measures when he or she is aware of the underlying problem, wants to solve it, and is able to solve it. If a pig producer is not implementing appropriate control measures, behavioural change interventions can be introduced to overcome constraining behavioural factors. To aid in designing behaviour change interventions, this study analysed behavioural factors of Dutch pig producers in terms of capability, opportunity and motivation to control T. gondii infections in pigs. Key risk sources analysed focused on the life cycle of T. gondii, with cats as primary host, rodents as intermediate host, and uncovered feed as an important risk source. A survey was conducted among Dutch pig producers. Responses were analysed using descriptive and cluster analysis. Results showed that around 80% of the 67 responding pig producers was aware of key risk sources of T. gondii infections in pigs. Respondents also rated risk sources that are not known to increase the risk of T. gondii infections in pigs as somewhat important. Many respondents did not know about potential consequences of a T. gondii infection in pigs on human health. Two third expected some impact on pig performance, which is incorrect because T. gondii generally does not make pigs ill. Most respondents indicated to have the motivation and opportunity to control the risk sources cats, rodents and uncovered feed. Three pig producer clusters were identified: one with higher capability to control rodents, one with lower motivation to control rodents and cats and to cover feed storages, and one with lower scores on the importance of rodent control for pigs, human health and farm profit. We conclude that, although many pig producers have knowledge about risk sources for and consequences of T. gondii infections in pigs, the public health impact and risks of T. gondii infections in pigs are not yet common knowledge among all Dutch pig producers. Furthermore, Dutch pig producers differ in opportunity and motivation to control T. gondii infections. Targeted interventions to address these specific constraining behavioural factors can help to improve the control of T. gondii infections in pigs