Potential for epidemic take-off from the primary outbreak farm via livestock movements

Background

We consider the potential for infection to spread in a farm population from the primary outbreak farm via livestock movements prior to disease detection. We analyse how this depends on the time of the year infection occurs, the species transmitting, the length of infectious period on the primary outbreak farm, location of the primary outbreak, and whether a livestock market becomes involved. We consider short infectious periods of 1 week, 2 weeks and 4 weeks, characteristic of acute contagious livestock diseases. The analysis is based on farms in Scotland from 1 January 2003 to 31 July 2007.

Results

The proportion of primary outbreaks from which an acute contagious disease would spread via movement of livestock is generally low, but exhibits distinct annual cyclicity with peaks in May and August. The distance that livestock are moved varies similarly: at the time of the year when the potential for spread via movements is highest, the geographical spread via movements is largest. The seasonal patterns for cattle differ from those for sheep whilst there is no obvious seasonality for pigs. When spread via movements does occur, there is a high risk of infection reaching a livestock market; infection of markets can amplify disease spread. The proportion of primary outbreaks that would spread infection via livestock movements varies significantly between geographical regions.

Conclusions

In this paper we introduce a set-up for analysis of movement data that allows for a generalized assessment of the risk associated with infection spreading from a primary outbreak farm via livestock movements, applying this to Scotland, we assess how this risk depends upon the time of the year, species transmitting, location of the farm and other factors.     

Unexpected photobleaching of Alexa 488 in a fixed bacterial sample during 2-photon excitation

A sample of fixed bacterial cells was examined by immunofluorescence microscopy using an Alexa 488 conjugated secondary antibody for visualization. Excitation using visible light confirmed the expected photostability of this fluorophore; however, when using 2-photon excitation, Alexa 488 was rapidly and substantially photobleached. The unexpected instability of Alexa 488 under certain conditions may have deleterious consequences if not anticipated and accommodated in experimental protocols.     

The canine isolate Lactobacillus acidophilus LAB20 adheres to intestinal epithelium and attenuates LPS-induced IL-8 secretion of enterocytes in vitro

Background

For a good probiotic candidate, the abilities to adhere to intestinal epithelium and to fortify barrier function are considered to be crucial for colonization and functionality of the strain. The strain Lactobacillus acidophilus LAB20 was isolated from the jejunum of a healthy dog, where it was found to be the most pre-dominant lactobacilli. In this study, the adhesion ability of LAB20 to intestinal epithelial cell (IECs) lines, IECs isolated from canine intestinal biopsies, and to canine, porcine and human intestinal mucus was investigated. Further, we studied the ability of LAB20 to fortify the epithelial cell monolayer and to reduce LPS-induced interleukin (IL-8) release from enterocytes.

Results

We found that LAB20 presented higher adhesion to canine colonic mucus as compared to mucus isolated from porcine colon. LAB20 showed adhesion to HT-29 and Caco-2 cell lines, and importantly also to canine IECs isolated from canine intestinal biopsies. In addition, LAB20 increased the transepithelial electrical resistance (TER) of enterocyte monolayers and thus strengthened the intestinal barrier function. The strain showed also anti-inflammatory capacity in being able to attenuate the LPS-induced IL-8 production of HT-29 cells.

Conclusion

In conclusion, canine indigenous strain LAB20 is a potential probiotic candidate for dogs adhering to the host epithelium and showing intestinal barrier fortifying and anti-inflammatory effects.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-014-0337-9) contains supplementary material, which is available to authorized users.     

Molecular evidence places the swallow bug genus Oeciacus Stål within the bat and bed bug genus Cimex Linnaeus (Heteroptera: Cimicidae)

The genera Cimex Linnaeus and Oeciacus Stål (Heteroptera: Cimicidae) are common haematophagous ectoparasites of bats or birds in the Holarctic region. Both their phylogenetic relationship and the systematics of the entire family previously were based on data from morphology and host relationships. Relationships among nine species of the genus Cimex and three species of the genus Oeciacus were analysed here using two mitochondrial and three nuclear genes. Cimex was shown to be paraphyletic with respect to Oeciacus. Oeciacus is thus proposed as a synonym of Cimex. The characteristic phenotype of Oeciacus results from the specific host association with different species of swallows (Hirundinidae). The morphological characters that have been used as diagnostic for the genera were shown to be valid and can be further used for determination at species level. The present analyses recovered the four traditional morphologically defined species groups of the genus Cimex. However, their relationships were poorly resolved – only the C. hemipterus group showed a well‐supported relationship to the C. pipistrelli group. The molecular differentiation within the Palaearctic C. pipistrelli and the Nearctic C. pilosellus species groups correlates with their karyotype differentiation. Furthermore, the analyses suggest poly‐ or paraphyly of the former genus Oeciacus. Either way this indicates there is a large amount of host‐associated phenotypic convergence in either bat‐ or bird‐associated groups of species. The probability of host choice and subsequent switch in Cimicidae are discussed and possible scenarios of the evolution of host association in species of Cimex are suggested.