Design and analysis of an Actinobacillus pleuropneumoniae transmission experiment

Velthuis, A.G.J.; Jong, M.C.M. de; Kamp, E. M.; Stockhofe, N.; Verheijden, J.H.M.

doi:10.1016/s0167-5877(03)00082-5

Cited by 83 publications

(92 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is an important contrast to efficacy studies in which it is susceptibility that is principally tested, and not the combined effect (Springer et al, 2001;Roesler et al, 2004;Tanaka et al, 2010). A similar approach has been used in previous transmission experiments with other pathogens (Laevens et al, 1998;Dewulf et al, 2001;Velthuis et al, 2003;Heres et al, 2004;Meyns et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs

Ridder

Maes

Dewulf

et al. 2013

The Veterinary Journal

View full text Add to dashboard Cite

a b s t r a c tDespite current control measures, Salmonella in pigs remains a major public health concern. In this in vivo study, the effect of three intervention strategies on Salmonella Typhimurium transmission in pigs was evaluated. The first intervention was feed supplemented with coated calcium-butyrate (group A); the second comprised oral vaccination with a double-attenuated Salmonella Typhimurium strain (group B), and the third was acidification of drinking water with a mixture of organic acids (group C). After challenge at 8 weeks of age, animals were individually sampled for 6 weeks (blood once per week; faeces twice per week) and then were euthanased at 14 weeks of age. Post-mortem ileum, caecum, ileocaecal lymph nodes, and tonsils were sampled, along with ileal, caecal and rectal contents, and tested for the presence of Salmonella spp. Transmission was quantified by calculating an 'adjusted' reproduction ratio 'R a ' and its 95% confidence interval (CI).The proportion of pigs that excreted Salmonella spp. via the faeces was significantly higher in group C (58%, P < 0.0001) and the positive control group (41%, P = 0.03), compared to group B (15%), and the proportion in group C was also significantly higher than in group A (23%, P = 0.01). Group A had the lowest proportion of positive post-mortem samples (18%), followed by group B (31%), the positive control group (41%) and group C (64%) (P < 0.03). The highest transmission was seen in the positive control group and group C (R a = +1 with 95% CI [1.88; +1]), followed by group B (R a = 2.61 [1.21; 9.45]) and A (R a = 1.76 [1.02; 9.01]). The results of this study suggest that vaccination and supplementation of the feed with coated calcium-butyrate limited Salmonella transmission in pigs and might be useful control measures.

show abstract

Section: Discussionmentioning

confidence: 99%

Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs

Ridder

Maes

Dewulf

et al. 2013

The Veterinary Journal

View full text Add to dashboard Cite

show abstract

“…This rather 'unnatural' infection process including the inoculation via both the intratracheal and the intramuscular routes was set up in order to get a homogeneous and comparable population of infectious pigs whatever the group (within-or betweenpen transmission). Secondary infected pigs used as seeders to infect susceptible ones as in a transmission experiment with Actinobacillus pleuropneumoniae [32] would have been relevant because it would have reproduced, in a more natural way, infections occurring within a farm. However, the addition of such supplementary phases would have led to a necessary limitation of the duration of the contact trial per se because the required space per pig had to be maintained.…”

Section: Discussionmentioning

confidence: 99%

Quantification of porcine circovirus type 2 (PCV-2) within- and between-pen transmission in pigs

Andraud¹,

Grasland²,

Durand³

et al. 2008

Vet. Res.

View full text Add to dashboard Cite

-PCV-2 within-and between-pen transmission was quantified by estimating the daily transmission rate and the basic reproduction ratio (R 0 ) using a stochastic SEIR (Susceptible, Exposed, Infectious, Removed) model fitted on experimental data. Within-pen transmission was quantified by using four groups of eight SPF (specific pathogen-free) pigs (four infected and four susceptible pigs having direct contact). Between-pen transmission was studied in two groups of 16 SPF pigs (eight infected and eight susceptible pigs having indirect contact (10 cm distance)). Pigs were monitored twice a week (blood samples) and were tested for PCV-2 antibodies (ELISA test) and viral genome load in sera (real-time PCR). Transmission parameters within and between were estimated using a maximum likelihood method and the duration of infectiousness, to compute R 0 , was estimated with a parametric survival model. Different assumptions were made to determine the end of infectiousness (seroconversion, seroconversion and decline in viral genome load, permanent infectiousness). R 0[within] (8.9 (5.1-15.4)) was greater when the end of infectiousness was assumed to be related to both seroconversion and a decline of PCV-2 genome load in sera (average duration of infectiousness = 32 days) compared with only seroconversion as the indicator of recovery (R 0[within] = 5.5 (3.3-9.0)). Whatever the assumption, between-pen R 0 (0.58 (0.23-1.47)) was always significantly lower than within-pen R 0 . Only within was sensitive to the assumption on end of infectiousness and decreased with increasing duration of infectiousness. These results showed that PCV-2 transmission is influenced by contact structure that appears worth being taken into account in an epidemic model. PCV-2 / pigs / transmission / modelling

show abstract

“…This will all lead to overestimation of R 0 . This can be prevented by setting up a so-called extended transmission experiment in which, as soon as the majority of the contact piglets pick up the contact infection, the inoculated piglets are replaced by new contact piglets [28]. However, differences in age between the infectious contact piglet and the new contact piglet and the resulting behavioural differences might affect the contact pattern and amount of stress.…”

Section: Discussionmentioning

confidence: 99%

Estimating transmission parameters of F4+ E. coli for F4-receptor-positive and -negative piglets: one-to-one transmission experiment

Geenen

Meulen²,

Bouma

et al. 2004

Epidemiol. Infect.

View full text Add to dashboard Cite

SUMMARY F4+Escherichia coli is an important agent of post-weaning diarrhoea in piglets. Piglets that express an adhesion site for F4+ E. coli in their small intestine (F4R+) shed higher numbers of F4+ E. coli than piglets lacking this site (F4Rx). We hypothesized that F4R+ piglets are more infectious and more susceptible for F4+ E. coli. This implies that in populations with F4R+ and F4Rx piglets, the transmission would be dependent on the frequency of both types of animals. To quantify the difference in infectiousness and susceptibility, a one-to-one transmission experiment was performed with 20 pairs consisting of one inoculated and one contact piglet. Based on the contact infections observed, transmission parameters were estimated with generalized linear models. F4R+ piglets were infectious for other piglets and the reproduction ratio (R 0 ) for homogeneous F4R+ populations, that is the average number of secondary infections that one F4R+ pig will cause during its entire infectious period in a population of susceptible F4R+ individuals only, was estimated as 7 . 1. F4R+ piglets were more susceptible than F4Rx piglets and reducing the fraction of F4R+ piglets of a population will reduce transmission. It was calculated that in order to prevent major outbreaks of F4+ E. coli (R 0 <1), the fraction of F4R+ piglets must be lower than 0 . 14.

show abstract

Design and analysis of an Actinobacillus pleuropneumoniae transmission experiment

Cited by 83 publications

References 19 publications

Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs

Evaluation of three intervention strategies to reduce the transmission of Salmonella Typhimurium in pigs

Quantification of porcine circovirus type 2 (PCV-2) within- and between-pen transmission in pigs

Estimating transmission parameters of F4+ E. coli for F4-receptor-positive and -negative piglets: one-to-one transmission experiment

Contact Info

Product

Resources

About