Prevention and Control of African Swine Fever in the Smallholder Pig Value Chain in Northern Uganda: Thematic Analysis of Stakeholders' Perceptions

African swine fever (ASF) is endemic in Uganda and considered a major constraint to pig production. In the absence of a vaccine, biosecurity is key for ASF prevention and control. To improve prevention and control on farm and community level there is need for more knowledge on current application of biosecurity practises, and better understanding of how pig value chain actors perceive prevention and control. To achieve this, a qualitative interview study involving focus group discussions (FGD) was conducted with actors from the smallholder pig value chain in northern Uganda. Six villages were purposively selected based on previous outbreaks of ASF, preliminary perceived willingness to control ASF, and the representation of several different value chain actors in the village. Results indicated that biosecurity practises such as basic hygiene routines including safe carcass handling, minimising direct and indirect contacts between pigs or between pigs and people, trade restrictions and sharing of disease information were implemented in some of the villages. Thematic analysis based on grounded theory revealed six categories of data relating to ASF prevention and control. Together these categories form a logical framework including both enablers and hindrances for ASF prevention and control. In summary participants mostly had positive perceptions of ASF biosecurity, describing measures as effective. Participants further possessed knowledge of ASF and its transmission, some of which was in line with known scientific knowledge and some not. Nevertheless, participants were hindered from preventing and controlling ASF due to biosecurity costs and a need to prioritise family livelihood over disease transmission risks, incompatibility of current biosecurity practises with local culture, traditions and social contexts and finally lack of access to veterinarians or, occasionally, low-quality veterinary services. The constraints could be addressed by applying participatory processes in designing biosecurity measures to ensure better adaptation to local cultural and social contexts.

Risk factors for African swine fever incursion in Romanian domestic farms during 2019

African swine fever (ASF) entered Georgia in 2007 and the EU in 2014. In the EU, the virus primarily spread in wild boar (Sus scrofa) in the period from 2014-2018. However, from the summer 2018, numerous domestic pig farms in Romania were affected by ASF. In contrast to the existing knowledge on ASF transmission routes, the understanding of risk factors and the importance of different transmission routes is still limited. In the period from May to September 2019, 655 Romanian pig farms were included in a matched case-control study investigating possible risk factors for ASF incursion in commercial and backyard pig farms. The results showed that close proximity to outbreaks in domestic farms was a risk factor in commercial as well as backyard farms. Furthermore, in backyard farms, herd size, wild boar abundance around the farm, number of domestic outbreaks within 2 km around farms, short distance to wild boar cases and visits of professionals working on farms were statistically significant risk factors. Additionally, growing crops around the farm, which could potentially attract wild boar, and feeding forage from ASF affected areas to the pigs were risk factors for ASF incursion in backyard farms.

Biosecurity aspects of cattle production in Western Uganda, and associations with seroprevalence of brucellosis, salmonellosis and bovine viral diarrhoea

BACKGROUND

Many low-income countries have a human population with a high number of cattle owners depending on their livestock for food and income. Infectious diseases threaten the health and production of cattle, affecting both the farmers and their families as well as other actors in often informal value chains. Many infectious diseases can be prevented by good biosecurity. The objectives of this study were to describe herd management and biosecurity routines with potential impact on the prevalence of infectious diseases, and to estimate the burden of infectious diseases in Ugandan cattle herds, using the seroprevalence of three model infections.

RESULTS

Farmer interviews (n = 144) showed that biosecurity measures are rarely practised. Visitors' hand-wash was used by 14%, cleaning of boots or feet by 4 and 79% put new cattle directly into the herd. During the 12 months preceding the interviews, 51% of farmers had cattle that died and 31% had noticed abortions among their cows. Interestingly, 72% were satisfied with the health status of their cattle during the same time period. The prevalence (95% CI) of farms with at least one seropositive animal was 16.7% (11.0;23.8), 23.6% (16.9;31.4), and 53.4% (45.0;61.8) for brucella, salmonella and BVD, respectively. A poisson regression model suggested that having employees looking after the cattle, sharing pasture with other herds, and a higher number of dead cattle were associated with a herd being positive to an increasing number of the diseases. An additive bayesian network model with biosecurity variables and a variable for the number of diseases the herd was positive to resulted in three separate directed acyclic graphs which illustrate how herd characteristics can be grouped together. This model associated the smallest herd size with herds positive to a decreasing number of diseases and having fewer employees.

CONCLUSION

There is potential for improvement of biosecurity practices in Ugandan cattle production. Salmonella, brucella and BVD were prevalent in cattle herds in the study area and these infections are, to some extent, associated with farm management practices.

Pre-Clinical Evaluation of a Real-Time PCR Assay on a Portable Instrument as a Possible Field Diagnostic Tool: Experiences from the Testing of Clinical Samples for African and Classical Swine Fever Viruses

African swine fever (ASF) and classical swine fever (CSF) are two highly infectious transboundary animal diseases (TADs) that are serious threats to the pig industry worldwide, including in China, the world's largest pork producer. In this study, a duplex real-time PCR assay was developed for the rapid detection and differentiation of African swine fever virus (ASFV) and classical swine fever virus (CSFV). The assay was performed on a portable, battery-powered PCR thermocycler with a low sample throughput (termed as 'T-COR4 assay'). The feasibility and reliability of the T-COR4 assay as a possible field method was investigated by testing clinical samples collected in China. When evaluated with reference materials or samples from experimental infections, the assay performed in a reliable manner, producing results comparable to those obtained from stationary PCR platforms. Of 59 clinical samples, 41 had results identical to a two-step CSFV real-time PCR assay. No ASFV was detected in these samples. The T-COR4 assay was technically easy to perform and produced results within 3 h, including sample preparation. In combination with a simple sample preparation method, the T-COR4 assay provides a new tool for the field diagnosis and differentiation of ASF and CSF, which could be of particular value in remote areas.

Knowledge, Attitudes and Practices Related to African Swine Fever Within Smallholder Pig Production in Northern Uganda

Uganda is a low-income country with the largest pig population in East Africa. Pig keeping has a large potential, commercially and as a tool for poverty reduction, but African swine fever (ASF) is a major hurdle for development of the sector. The objective of this study was to evaluate knowledge, attitudes and practices related to ASF in the smallholder pig production value chain in northern Uganda. The study included three separate series of participatory rural appraisals (PRA), comprising purposively selected farmers and other actors in the pig production value chain. In the PRAs, various participatory epidemiology tools were used. A total of 49 PRAs and 574 participants, representing 64 different villages, were included. The results indicate that participants were well aware of the clinical signs of ASF, routes for disease spread and measures for disease control. However, awareness of the control measures did not guarantee their implementation. A majority of middlemen and butchers acknowledged having sold live pigs, carcasses or pork they believed infected with ASF. Outbreaks of ASF had a strong negative impact on participants' socio-economic status with loss of revenue and reversal into more severe poverty. In conclusion, lack of knowledge is not what is driving the continuous circulation of ASF virus in this setting. To control ASF and reduce its impact, initiatives that stimulate changes in management are needed. Because the behaviour of all actors in the value chain is largely influenced by the deep rural poverty in the region, this needs to be combined with efforts to reduce rural poverty.

Schmallenberg Virus beyond Latitude 65°N

Extensive and rapid spread of Schmallenberg virus (SBV) in Sweden was detected by consecutive serological bulk milk surveys conducted before and after the vector season of 2012. Whereas <0.2% of cattle herds tested positive in a first survey in spring 2012, SBV-specific antibodies were detected in almost 75% of 723 bulk milk samples randomly collected all over the country 6 months later, beyond the 65th northern latitude, and with an observed spatial distribution suggesting multiple introductions of the virus. Circulation of virus was later confirmed by the detection of SBV in malformed lambs and calves starting from November 2012 and January 2013, respectively. These observations suggest SBV circulation starting from July 2012, with a peak in transmission between August and October. A local heterogeneity of within-herd seroprevalence was found, indicating that SBV-naïve animals remain also in highly infected areas enabling the re-emergence of the infection in the coming vector season.

Development of a suspension microarray for the genotyping of African swine fever virus targeting the SNPs in the C-terminal end of the p72 gene region of the genome

African swine fever virus (ASFV) causes one of the most dreaded transboundary animal diseases (TADs) in Suidae. African swine fever (ASF) often causes high rates of morbidity and mortality, which can reach 100% in domestic swine. To date, serological diagnosis has the drawback of not being able to differentiate variants of this virus. Previous studies have identified the 22 genotypes based on sequence variation in the C-terminal region of the p72 gene, which has become the standard for categorizing ASFVs. This article describes a genotyping assay developed using a segment of PCR-amplified genomic DNA of approximately 450 bp, which encompasses the C-terminal end of the p72 gene. Complementary paired DNA probes of 15 or 17 bp in length, which are identical except for a single nucleotide polymorphism (SNP) in the central position, were designed to either individually or in combination differentiate between the 22 genotypes. The assay was developed using xMAP technology; probes were covalently linked to microspheres, hybridized to PCR product, labelled with a reporter and read in the Luminex 200 analyzer. Characterization of the sample was performed by comparing fluorescence of the paired SNP probes, that is, the probe with higher fluorescence in a complementary pair identified the SNP that a particular sample possessed. In the final assay, a total of 52 probes were employed, 24 SNP pairs and 4 for general detection. One or more samples from each of the 22 genotypes were tested. The assay was able to detect and distinguish all 22 genotypes. This novel assay provides a powerful novel tool for the simultaneous rapid diagnosis and genotypic differentiation of ASF.

Self-clearance from BVDV infections--a frequent finding in dairy herds in an endemically infected region in Peru

In this cross-sectional study, a stratified two-stage random sampling procedure was employed to select 221 dairy herds for bulk tank milk (BTM) sampling, and a subset of 55 dairy herds for individual blood sampling of a number of young animals (spot test), to predict presence or absence of current BVDV infection, and for data collection. The prediction was based on the high probability of seropositivity in groups of animals where PI animals are present because of the efficient spread of virus from PI animals to the surrounding group. BTM samples were collected in August 2003 (n=192) and February 2004 (n=195), and the 55 herds selected for spot testing and data collection were visited in December 2003. All samples were tested for presence of BVDV specific antibodies using a commercial indirect ELISA (SVANOVA Biotech AB, Uppsala, Sweden). The results demonstrated a very high level of exposure to BVDV in the region, and the proportion of herds with high antibody levels in the BTM was above 95% on both occasions. Despite this, almost two thirds of the herds had spot test results indicating absence of current infection, suggesting a high probability of self-clearance. A logistic regression model with the results from the spot tests as dependent variable was used to investigate possible herd and management factors associated with self-clearance, and suggested that this may occur regardless of herd size. Even though it is well established that the process of identification and elimination of PI animals is required within a systematic BVDV eradication programme, the present study strongly suggests that many herds may be cleared without intervention even in regions with high cattle density and high BVDV prevalence. Consequently, in any BVDV infected population (regardless of the herd-level BVDV seroprevalence), and at any given point of time, a large proportion of the herds will be free from infection due to self-clearance. Self-clearance is therefore a process that works in favour of any effort to control BVDV, which should be taken into account when planning and assessing the cost-effectiveness of a systematic control programme.

A prospective study of the effect of Neospora caninum and BVDV infections on bovine abortions in a dairy herd in Arequipa, Peru

We used a prospective seroepidemiological approach to investigate endemic abortion in a dairy herd in Arequipa, Peru, and its association with Neospora caninum and bovine viral-diarrhoea virus (BVDV) infections. Between January 2002 and March 2004, 1094 pregnancies were confirmed in 538 cows. Of these, 137 pregnancies (13%) in 121 cows ended in abortion. The serological status to N. caninum was assessed using a single serological screening, whereas BVDV status was assessed at the herd level through consecutive samplings of young stock. Cox proportional-hazards models were used to estimate the effect of N. caninum and BVDV on the hazard of early (between day 42 and day 100 in gestation), and late (after day 100) abortions, respectively. Serological status to N. caninum was included as a dichotomous variable, and the effect of BVDV estimated at the herd level, as a time-dependent seasonal effect. Because data from repeated pregnancies were included, we considered possible lack of independence between observations and included frailty effects into the models. Our models also considered the possible confounding by parity and animal origin. Only multiparity was associated with the hazard of early abortion (HR=2.8 compared to nulliparous heifers). N. caninum seropositivity significantly affected the hazard of late abortion, but interacted with parity. The HRs for Neospora-positive animals were 6.4, 3.7 and 1.9, respectively, for nulliparous heifers, first-lactation cows and multiparous cows. Evidence of BVDV circulating (or not) among the young stock was not associated with abortions, but few cows in this herd were susceptible to incident infection.

BVDV and BHV-1 infections in dairy herds in northern and northeastern Thailand

Bulk milk samples from 220 dairy herds were collected at 9 public milk collection centres in the northeastern and northern Thailand, and a subset of 11 herds was selected for individual testing. The samples were tested for presence of antibodies to BVDV and BHV-1 using an indirect ELISA. The results from the bulk milk testing demonstrated a moderate level of exposure to BVDV and BHV-1 (73% and 67%, respectively). However, the low proportion of herds with high BVDV antibody-levels (13%) and the low within-herd seroprevalence of BVDV and BHV-1 in the 11 herds (24% and 5%, respectively), particularly among the young stock (15% and 0%, respectively), demonstrated a low prevalence of active BVDV infection and a low rate of reactivation of latent BHV-1. The presence of a self-clearance process was also indicated by the results from the individual testing. Moreover, a surprisingly low prevalence of BVDV and BHV-1 antibody-positive herds at one of the milk centres was found. This centre was established 5–10 years before the others. Our impression is that this reflects the self-clearance process, where consecutive replacement of imported infected animals without further spread has resulted in a nearly total elimination of the infections.

Based on our experiences and on these results we are convinced that this process can continue if there is awareness of herd biosecurity. This is especially important in the context of a future intensification of the dairy production.

Bulk milk testing for antibody seroprevalences to BVDV and BHV-1 in a rural region of Peru

Bulk milk from 60 herds of dairy cattle in a rural region in the central highlands of Peru was tested for antibodies to bovine viral-diarrhoea virus (BVDV) and bovine herpesvirus type 1 (BHV-1). None of the herds had been vaccinated against BVDV or BHV-1. Commercially available indirect ELISA-kits were used for antibody detection. True prevalences of BVDV and BHV-1 antibody-positive herds were 96 and 51%, respectively. A relatively low proportion of strongly positive herds suggests, however, a low prevalence of active BVDV infection. BVDV optical densities (ODs) in bulk milk increased with herd size--indicating a higher within-herd prevalence in the larger herds (probably, in part a consequence of a higher rate of animal movement into these herds). For BHV-1, this pattern was not found; a relatively high proportion of the herds was free from BHV-1 infection in each size category. This could indicate a low rate of reactivation of latent BHV-1 infection.

The crystallography beamline I711 at MAX II

A new X-ray crystallographic beamline is operational at the MAX II synchrotron in Lund. The beamline has been in regular use since August 1998 and is used both for macro- and small molecule diffraction as well as powder diffraction experiments. The radiation source is a 1.8 T multipole wiggler. The beam is focused vertically by a bendable mirror and horizontally by an asymmetrically cut Si(111) monochromator. The wavelength range is 0.8-1.55 A with a measured flux at 1 A of more than 10(11) photons s(-1) in 0.3 mm x 0.3 mm at the sample position. The station is currently equipped with a Mar345 imaging plate, a Bruker Smart 1000 area CCD detector and a Huber imaging-plate Guinier camera. An ADSC 210 area CCD detector is planned to be installed during 2000.

Rutile Superstructure of Sb0.9V1.1O4

The structure of Sb0.9V1.1O4, antimony vanadium oxide, has been studied by powder X-ray diffraction, electron diffraction and high-resolution electron microscopy (HREM). The X-ray powder diffraction pattern showed only basic rutile reflections [a r = 4.6085 (1), c r = 3.0867 (1) Å] and the basic rutile structure was refined using the Rietveld method. A rutile superstructure was revealed when the sample was studied by electron diffraction. The electron diffraction patterns were indexed on the unit cell a = 21/2 a r , b = 21/2 b r , c = 2c r . Its space group, I41 md, was determined by means of convergent-beam electron diffraction (CBED). A structural model based on alternating cation ordering along c in the chains of edge-sharing octahedra is proposed and its electron diffraction patterns and HREM image are calculated and matched with the experimental ones.

Postanesthesia monitoring revisited: frequency of true and false alarms from different monitoring devices

STUDY OBJECTIVES

To determine the frequency of true and false alarms and to determine the frequency of alarm failures for various parameters when using a postanesthesia monitoring system.

DESIGN

Open prospective study.

SETTING

Postanesthesia care unit at a university hospital.

PATIENTS

123 ASA physical status I-IV patients who underwent general or spinal-epidural anesthesia for general, urologic, orthopedic, ophthalmologic, otolaryngologic, or plastic surgery.

MEASUREMENTS AND MAIN RESULTS

Monitoring included ECG, oxygen saturation, and respiratory rate (RR) by either transthoracic impedance or nasal-oral air-flow detection. We undertook careful, continuous observation of patients and monitors, recording of true and false alarms; the latter were defined as those coinciding with a clearly observed, unrelated cause. During a mean observation period of 101 minutes per patient, the average frequency of pulse oximetry alarms was once every 8 minutes, with 77% of the alarms being false, caused by sensor displacement, motion artifacts, poor perfusion, or a combination of these factors. Apnea alarms occurred on average once every 37 minutes, with the "false" fraction being 28% and 27% for impedance and flow detection, respectively. The impedance sensor failed to detect apnea on at least 6 occasions; the flow sensor failed on 1 occasion. The coincidence of pulse oximetry and apnea alarms was small, and ECG exhibited a low alarm rate but a high fraction of false alarms. Patients receiving opioids and neuromuscular relaxants had a higher frequency of "true" apneas than patients not receiving these drugs. No clear correlation was found in regard to age distribution, type of surgery, duration of anesthesia, oxygen administration, or ASA physical status between the patient groups that exhibited many apneas or many pulse oximeter alarms and the whole study population.

CONCLUSIONS

The high frequency of apnea strongly motivates the use of continuous RR monitoring, preferably by flow-sensing techniques, since both central and obstructive apneas are then detected. Further study and development is necessary before pulse oximetry can be unconditionally recommended for postanesthesia monitoring.

Using CPS120 (curved position-sensitive detector covering 120°) powder diffraction data in Rietveld analysis. The dehydration process in the zeolite thomsonite

A powder diffractometer (CPS120 by INEL) equipped with a position-sensitive detector covering 120° in 2θ has been tested and the data have been successfully used with the Rietveld method. The detector was found to have a characteristic variation in linearity of ±1.5%. A calibration compound with well known 2θ values was used to determine a cubic spline calibration function to describe the 2θ versus channel-number function, which was then incorporated in the Rietveld analysis program. A procedure is also described to correct for air and capillary scattering, taking sample absorption into account. The methods have been applied to a structure refinement of quartz and to a study of the dehydration process of the zeolite thomsonite. Quartz: Rp = 11.0%, Rw = 14.0% and RB = 7.9%, based on 10 < 2θ < 116.3° in 3470 steps, λ = 1.540598 Å. Space group P312, Z = 3, a = 4.91201 (7), c = 5.40301 (5) Å, x(Si) = 0.4702 (3), B ave(Si) = 0.77 (6) Å2, x(O) = 0.4112 (6), y(O) = 0.2712 (5), z(O) = −0.2811 (4) and B ave(O) = 1.0 (1) Å2. Thomsonite: Rp = 8.18%, Rw = 11.04% and RB = 3.33%, based on 10 < 2θ < 110° in 3270 steps. Space group Pncn, Z = 4, a = 13.0778 (3), b = 13.0398 (3) and c = 13.1970 (3) Å. The unit cell changes continuously with increasing dehydration temperatures up to 523 K, at which a = 12.9725 (3), b = 12.9537 (3) and c = 13.2288 (3) Å. In this first dehydration step, the W3 and W4 molecules coordinated to the Ca/Na site are lost and the Ca/Na and W1 sites are shifted approximately 0.3 Å from their original positions towards the framework O atoms. After dehydration at 573 K, the mode of unit-cell variations is changed: a = 12.908 (3), b = 13.039 (3) and c = 13.034 (3) Å. In this dehydration step, W1 is lost. The W2 site appears unaffected by the dehydration below 573 K. On dehydration above 573 K, the diffraction intensities decrease as the compound becomes amorphous.

Effect of 5-chloro-7-iodo-8-hydroxy-quinoline (clioquinol) on the uptake and distribution of nickel, zinc and mercury in mice

5-Chloro-7-iodo-8-hydroxy-quinoline (clioquinol) was found to induce a very marked increase in the concentration of 63Ni2+ in various tissues of mice when given orally together with the metal, compared with oral administrations of 63Ni2+ only. Markedly increased tissue concentrations, although less expressed than for the 63Ni2+, were also observed for 65Zn2+. Clioquinol increased the tissue levels of 203Hg2+ to a lesser extent. When clioquinol was given intraperitoneally and 63Ni2+ was given intravenously there were also very markedly increased tissue levels of the metal, compared with intravenous injections of 63Ni2+ only. It was also shown that the urinary excretion of 63Ni2+ was greatly increased in mice given the metal orally together with clioquinol, compared with mice given the 63Ni2+ only. Clioquinol and other 8-hydroxy-quinolines form lipophilic chelates with metallic cations and the observed effects on the tissue-disposition of the metals are probably due to a facilitated penetration through the cellular membranes. Determinations of the chloroform:water partition coefficients showed the highest lipophilicity for the nickel-clioquinol-complex followed in decreasing order by the complexes with zinc and mercury. These data suggest that the ability of the clioquinol to affect the uptake of the metals in the cells may be related to the relative lipophilicity of the metal-clioquinol-complexes. Clioquinol and other halogenated 8-hydroxy-quinolines are linked with the SMON-syndrom, which has been observed preferentially in Japan. It is suggested that the pathogenesis of SMON may involve an accumulation of toxic concentrations of metals in the tissues due to facilitated uptake by complex-formation with halogenated 8-hydroxy-quinolines.(ABSTRACT TRUNCATED AT 250 WORDS)