A quantitative risk assessment model to evaluate effective border control measures for rabies prevention.

Border control is the primary method to prevent rabies emergence. This study developed a quantitative risk model incorporating stochastic processes to evaluate whether border control measures could efficiently prevent rabies introduction through importation of cats and dogs using Taiwan as an example. Both legal importation and illegal smuggling were investigated. The impacts of reduced quarantine and/or waiting period on the risk of rabies introduction were also evaluated. The results showed that Taiwan's current animal importation policy could effectively prevent rabies introduction through legal importation of cats and dogs. The median risk of a rabid animal to penetrate current border control measures and enter Taiwan was 5.33 x 10(-8) (95th percentile: 3.20 x 10(-7)). However, illegal smuggling may pose Taiwan to the great risk of rabies emergence. Reduction of quarantine and/or waiting period would affect the risk differently, depending on the applied assumptions, such as increased vaccination coverage, enforced custom checking, and/or change in number of legal importations. Although the changes in the estimated risk under the assumed alternatives were not substantial except for completely abolishing quarantine, the consequences of rabies introduction may yet be considered to be significant in a rabies-free area. Therefore, a comprehensive benefit-cost analysis needs to be conducted before recommending these alternative measures.

Electrophysiological mapping and histological examinations of the swine atrium with sustained (> or =24 h) atrial fibrillation: a suitable animal model for studying human atrial fibrillation.

OBJECTIVES: Interventional elimination of chronic persistent atrial fibrillation (AFib) remains difficult. An animal model mimicking the clinical situation is important. METHODS AND RESULTS: Twenty-five adult pigs were implanted with a high-speed atrial pacemaker. After continuous pacing at 600 bpm for 6 weeks, 20 (91%) of the 22 survivals developed sustained AFib lasting for at least 24 h. Epicardial dense mapping revealed multiple coexisting reentrant wavelets in the left and the right atrium (LA and RA, respectively; 10.6 +/- 2.9 vs. 7.6 +/- 2.4 wavelets/cm(2)/s; p < 0.002). The mean local A-A intervals were 87.2 +/- 14.6 ms in the LA and 103.3 +/- 19.0 ms in the RA (p < 0.0002). Acute termination of sustained AFib was successful in 3 of the 5 pigs by propafenone, but in none of the 6 by dl-sotalol. Epicardial cryothermal ablation failed to terminate any AFib by compartmentalization of the RA free wall alone (4 pigs) or together with the LA appendage (4 pigs). Electron microscopic examination demonstrated diffuse perinuclear myolysis, myofibrillar fragmentation and mitochondrial crystal disruption in the atrium. CONCLUSIONS: Pacing-induced sustained AFib (> or =24 h) in adult pigs is a feasible and efficient animal model with electrophysiological and histological characteristics closely similar to those seen in humans.

Effective synthetic peptide vaccine for foot-and-mouth disease in swine.

We have designed a peptide-based vaccine for foot-and-mouth disease (FMD) effective in swine. The peptide immunogen has a G-H loop domain from the VP1 capsid protein of foot-and-mouth disease virus (FMDV) and a novel promiscuous T helper (Th) site for broad immunogenicity in multiple species. The G-H loop VP1 site was optimised for cross-reactivity to FMDV by the inclusion into the peptide of cyclic constraint and adjoining sequences. The incorporation of consensus residues into the hypervariable positions of the VP1 site provided for broad immunogenicity. The vaccine protected 20 out of 21 immunised pigs from infectious challenge by FMDV O1 Taiwan using peptide doses as low as 12.5 microg, and a mild adjuvant that caused no lesions. A safe chemically-defined product would have considerable advantages for vaccination against FMD.

Influence of Age on the Electrocardiographic Waves in Taiwanese Lan-Yu Miniature Pigs.

The purpose of the study reported here was to determine baseline information of the electrocardiogram (ECG) and the influence of age on cardiac function in Taiwanese Lan-Yu (TLY) miniature pigs. Non-anesthetized TLY minipigs (from birth to 6 months of age) were placed on a webbed stanchion, simulating a standing position, for acquisition of an ECG, using six limb leads (I, II, III, aVR, aVL, and aVF), with each as a single-channel ECG recorder. The P and T waves obtained from leads I, III, and aVL were useful in determining the subtle cardiac changes during maturation of TLY minipigs. Interestingly, changes in the QT interval analyzed from all 6 leads were almost indistinguishable. Shortening of the QT interval was induced (p < 0.05) between days 1 and 7 of postnatal life. The QT interval lengthened to a steady state at day 60, and paralleled pigs' physical maturation. The longer QT interval was conversely correlated to heart rate as pigs matured. In the QRS complex interval, only lead aVR was significantly decreased at day 7 (p < 0.05). Further changes in the QRS interval from day 21 were not observed in any lead. Because the duration of the ventricular complex represents the period required for the excitation front to reach the terminals of the Purkinje fibers in the ventricular myocardium, the increase in QRS interval observed within 21 days of birth could be attributed to an increase in the thickness of ventricular myocardium. The data suggest that cardiac maturation was achieved at 60 days of age, although the body weight of minipigs continued to increase beyond 60 days of age. Because the body weight of these newly developed TLY minipigs can be maintained within 25 to 30 kg at one year of age and their major ECG findings did not significantly differ from those of domestic pigs and humans, they may be useful as a model for cardiovascular and pharmacologic research. The similarity of ECG profiles between pigs and humans also was evaluated.