Global trends in infectious diseases of swine.

Pork accounts for more than one-third of meat produced worldwide and is an important component of global food security, agricultural economies, and trade. Infectious diseases are among the primary constraints to swine production, and the globalization of the swine industry has contributed to the emergence and spread of pathogens. Despite the importance of infectious diseases to animal health and the stability and productivity of the global swine industry, pathogens of swine have never been reviewed at a global scale. Here, we build a holistic global picture of research on swine pathogens to enhance preparedness and understand patterns of emergence and spread. By conducting a scoping review of more than 57,000 publications across 50 years, we identify priority pathogens globally and regionally, and characterize geographic and temporal trends in research priorities. Of the 40 identified pathogens, publication rates for eight pathogens increased faster than overall trends, suggesting that these pathogens may be emerging or constitute an increasing threat. We also compared regional patterns of pathogen prioritization in the context of policy differences, history of outbreaks, and differing swine health challenges faced in regions where swine production has become more industrialized. We documented a general increasing trend in importance of zoonotic pathogens and show that structural changes in the industry related to intensive swine production shift pathogen prioritization. Multinational collaboration networks were strongly shaped by region, colonial ties, and pig trade networks. This review represents the most comprehensive overview of research on swine infectious diseases to date.

One Health: Lessons Learned from East Africa.

Africa is faced with many of the most daunting challenges of our time. It comprises roughly 15% of the world's human population, and most of its countries are perpetually ranked "Low" on the United Nations' Human Development Index. On the other hand, Africa has arguably the largest proportion of intact natural ecosystems, biodiversity, and sociocultural capital and the lowest impact on global warming of any continent. Thus, African leaders are faced with competing demands and values among a multitude of complex issues, such as high human population growth, extreme poverty, food insecurity, land use policy, climate change, and biodiversity conservation. In this context, building sustainable national systems for human and/or animal health is one of the grand challenges of this generation. Today's complex global health and development challenges require long-term commitment and a range of approaches that are too broad for any one discipline, institution, or country to implement on its own. The One Health concept recognizes the interconnectedness of global health issues and, as such, promotes the importance of and need for international, interdisciplinary, and cross-sectoral communication and collaboration at local, national, and international levels. By taking advantage of natural cultural tendencies for shared leadership, resource allocation, and community values, African leaders are currently proactively demonstrating the principles of One Health, and thus becoming a model for this global vision. And by focusing on partnerships rather than donor-recipient relationships, they are fostering the development of shared priorities and are increasingly driving their own health agenda to fulfill their own needs.

Longitudinal assessment of two Mycoplasma hyopneumoniae enzyme-linked immunosorbent assays in challenged and contact-exposed pigs.

The objective of the current study was to compare the sensitivity of 2 Mycoplasma hyopneumoniae enzyme-linked immunosorbent assays (ELISAs) in experimentally challenged and contact-exposed pigs in a long-term longitudinal assessment. On day 0 of the assessment, twelve 2-month-old M. hyopneumoniae-negative pigs were inoculated with M. hyopneumoniae strain 232 (group A). Twelve negative pigs were placed alongside the inoculated pigs, allowing direct contact exposure (group B). A third group of 12 pigs was allocated into 2 independent pens; no direct contact was allowed (group C). A longitudinal serologic profile was performed; samples were collected on days 0, 28, 35, 42, 49, 63, 91, 119, 154, and 170 of the study. Serum samples were tested using a blocking ELISA and an indirect ELISA. Results of the study demonstrated higher sensitivity of the blocking ELISA during early infection (clinical signs). Both ELISAs were 100% sensitive in challenged and naturally infected groups at several testing points during late infection (63, 91, 119, 154, and 170 days of the study) and showed a long antibody detection period. Both tests worked equally well during the chronic phase of infection but the blocking ELISA was more sensitive during acute stages of infection.

Further assessment of houseflies (Musca domestica) as vectors for the mechanical transport and transmission of porcine reproductive and respiratory syndrome virus under field conditions.

The purpose of this study was to evaluate the potential for houseflies (Musca domestica) to mechanically transport and transmit porcine reproductive and respiratory syndrome virus (PRRSV) between pig populations under controlled field conditions. The study employed swine housed in commercial livestock facilities and a release-recapture protocol involving marked (ochre-eyed) houseflies. To assess whether transport of PRRSV by insects occurred, ochre-eyed houseflies were released and collected from a facility housing an experimentally PRRSV-inoculated population of pigs (facility A) and collected from a neighboring facility located 120 m to the northwest that housed a naïve pig population (facility B). All samples were tested for PRRSV RNA by polymerase chain reaction (PCR). To assess transmission between the 2 populations, blood samples were collected from naïve pigs in facility B at designated intervals and tested by PCR. A total of 7 replicates were conducted. During 2 of 7 replicates (1 and 5), PCR-positive ochre-eyed houseflies were recovered in facility B and pigs in this facility became infected with PRRSV. Chi-squared analysis indicated that the presence of PRRSV in an insect sample was significantly (P = 0.0004) associated with infection of facility B pigs. Porcine reproductive and respiratory syndrome virus was not recovered from other reported routes of transmission during the study period, including air, fomites, and personnel. In conclusion, while an insufficient number of replicates were conducted to predict the frequency of the event, houseflies may pose some level of risk for the transport and transmission of PRRSV between pig populations under field conditions.

In vitro assessment of the effectiveness of powder disinfectant (Stalosan F) against Lawsonia intracellularis using two different assays.

The objective of this study was to determine the in vitro efficacy of Stalosan F, a mixed chemical and heavy metal disinfectant, against two strains of Lawsonia intracellularis using both a modified tissue culture and a direct count method. For testing as a powder, 1g, 0.5g, or 0.25g of Stalosan F was applied to bacterial solutions spread into sterile dishes. For use as an aqueous suspension, Stalosan F was prepared to final concentrations of 1%, 4%, 8%, 16%, and 32%. In both applications, L. intracellularis was exposed to Stalosan F for 0.5h, 1h, 2h, and 4h. The results showed that both strains were similar in their susceptibilities to Stalosan F. The modified tissue culture assay showed no detectable L. intracellularis in cell culture after exposure to all levels of Stalosan F powder for 0.5h. Furthermore, the number of viable bacteria was markedly reduced in the aqueous concentration of 4% and no L. intracellularis was detected at concentrations of > or =8% for 0.5h. Using the direct count method, detection of live bacteria was less than 1% after exposure to the powder for 0.5h. After exposure to the aqueous form, the number of viable bacteria killed was over 99% in concentrations of > or =16% compared to controls. Our results indicate that Stalosan F in both powder and suspension forms is able to inactivate over 99% of L. intracellularis after 30min of exposure. Furthermore, both laboratory methods can be used to determine the effect of disinfectants on L. intracellularis viability.

Further assessment of fomites and personnel as vehicles for the mechanical transport and transmission of porcine reproductive and respiratory syndrome virus.

This study re-evaluated the role of fomites and personnel in the mechanical transport and transmission of porcine reproductive and respiratory syndrome virus (PRRSV) between pig populations. Swabs were collected from hands, boots, coveralls, and other fomites following contact with infected pigs and compared with identical samples collected in the absence of PRRSV exposure. Naïve pigs were provided contact with contaminated fomites/personnel and blood tested periodically post-exposure [positive exposure population (PEP)] and compared with populations that did not gain exposure via these routes [negative exposure population (NEP)]. The majority of swab samples from hands, coveralls, and boots from personnel and fomite samples (cable snare and bleeding equipment) following contact with the PRRSV-infected Source Population. Transmission of PRRSV to the PEP was observed (7/7) cases but not in the NEP. In conclusion, under the proper conditions, transport and transmission of PRRSV by fomites and personnel may occur between swine populations in the absence of intervention.

Evaluation of systems for reducing the transmission of porcine reproductive and respiratory syndrome virus by aerosol.

The purpose of this study was to compare 3 methods for the reduction of aerosol transmission of Porcine reproductive and respiratory syndrome virus (PRRSV): high-efficiency particulate air (HEPA) filtration, low-cost filtration, and ultraviolet light (UV) irradiation. The HEPA-filtration system involved a pre-filter screen, a bag filter (EU8 rating), and a HEPA filter (EU13 rating). The low-cost-filtration system contained mosquito netting (pre-filter), a fiberglass furnace filter, and an electrostatic furnace filter. For UV irradiation, a lamp emitted UVC radiation at 253.7 nm. No form of intervention was used in the control group. The experimental facilities consisted of 2 chambers connected by a 1.3-m-long duct. Recipient pigs, housed in chamber 2, were exposed to artificial aerosols created by a mechanically operated mister containing modified live PRRSV vaccine located in chamber 1. Aerosol transmission of PRRSV occurred in 9 of the 10 control replicates, 8 of the 10 UVC-irradiation replicates, 4 of the 10 low-cost-filtration replicates, and 0 of the 10 HEPA-filtration replicates. When compared with no intervention, HEPA filtration and low-cost filtration significantly reduced PRRSV transmission (P < 0.0005 and = 0.0286, respectively), whereas UV irradiation had no effect (P = 0.5). However, low-cost filtration and UV irradiation were significantly less effective (P = 0.043 and P < 0.0005, respectively) than HEPA filtration. In conclusion, under the conditions of this study, HEPA filtration was significantly more effective at reducing aerosol transmission of PRRSV than the other methods evaluated.

Pain detection and amelioration in animals on the farm: issues and options.

Pain in nonhuman animals is a difficult concept to identify and measure. This article briefly describes the consequences of pain in animals on the farm and explains the reasons for the minimal use of analgesics in farmed animals. Pain can have implications for both animal welfare and economics. The reasons for a low use of analgesics in farmed animals include the lack of recognition of animal pain owing to the apparent lack of anthropomorphically identifiable behavioral changes, concern over human food safety, and lack of research efforts to develop safe analgesics for farm use. Treatment cost relative to the benefits expected is another hindering factor. Interventions to minimize pain must begin with developing objective and practical measures for pain identification and measurement at the farm level. A suggested use of a combination of different behavioral and physiological indicators would help to identify pain in animals. To facilitate continued usage of the methodologies on the farm it also is necessary to evaluate the economic implication of the pain alleviation intervention.

An assessment of sanitation protocols for commercial transport vehicles contaminated with porcine reproductive and respiratory syndrome virus.

The objective of this study was to develop and test a rapid (< 2 h) sanitation protocol designed for porcine reproductive and respiratory syndrome virus (PRRSV) positive commercial transport vehicles involving cold water washing and disinfection via fumigation using scale models of weaned pig trailers. The study consisted of 2 phases. Following experimental contamination of model trailers with PRRSV MN 30-100 (5 x 10(5)TCID50), phase 1 evaluated the presence or absence of PRRSV RNA by polymerase chain reaction (PCR) on swabs collected from the trailer interiors 0, 60, and 90 min after treatment. Phase 2 consisted of evaluating the infectivity of trailers 90 min posttreatment by monitoring changes in the PRRSV-status of naive sentinel pigs housed for 2 h. Treatments included washing only (treatment 1), washing plus formaldehyde fumigation (treatment 2), washing plus fumigation with glutaraldehyde-quaternary ammonium chloride (treatment 3), and washing plus overnight drying (treatment 4). Porcine reproductive and respiratory syndrome virus RNA was detected in all trailers (20 out of 20 replicates) at 60 and 90 min following the application of treatments 1 and 2. These trailers also contained infectious PRRSV, as determined by the infection of naive pigs housed in treated trailers and the testing of organic debris collected from the interior of trailers by swine bioassay. At 90 min posttreatment, all trailers treated with glutaraldehyde-quaternary ammonium chloride were PCR-negative, non-infectious to sentinel pigs, and swine bioassay negative. Similar results were observed in trailers allowed to dry for 8 h. Under the conditions of this study, it appears certain disinfectants may possess different levels of efficacy against PRRSV and PRRSV-positive models may be effectively sanitized in the absence of overnight drying.