Transmission of encephalomyocarditis virus (EMCV) among pigs experimentally quantified

Maurice, H P M; Nielen, M.; Stegeman, J.A.; Vanderhallen, H.; Koenen, F.

doi:10.1016/s0378-1135(02)00127-x

Cited by 18 publications

(35 citation statements)

References 22 publications

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“…The final size was assessed from serology at the second sampling. The probability distribution of the final size per pen can be described in terms of the transmission parameter R 0 (reproduction ratio) [4,15,17,27], where the likelihood l(R|x) gives the probability of final size x if the reproduction ratio is equal to R. This probability can be calculated by the algorithm described by De Jong and Kimman [4]. In the same way, a combined likelihood can be obtained using the final sizes from independent groups (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Exact final sizes in terms of serology were known for the six fully sampled pens. For those six pens the individual probabilities for the observed final sizes at the pen level were aggregated into a combined likelihood l(R|x 1 ,.., x 6 ), which at its maximum value represents the maximum likelihood estimate (MLE) for R 0 [15,17,27] (see Tab. I for estimated R 0 in case of 15 animals/pen).…”

Section: Discussionmentioning

confidence: 99%

“…In Britain a seroprevalence of 28% was found [21], in Italy 69% [8], in the USA 8.5% [29] and in Japan 25.8% [23]. Neutralising antibodies can be detected as early as 5 days postinoculation in experimentally infected pigs [1], whereas the virus can be isolated from blood and excreta already one day after inoculation [3,7,17]. EMCV-transmission has been described from rodents to a wide variety of other species, including humans [1,16,22], while a recent study indicated that rats easily spread the virus among each other [24].…”

Section: Introductionmentioning

confidence: 99%

“…EMCV-transmission has been described from rodents to a wide variety of other species, including humans [1,16,22], while a recent study indicated that rats easily spread the virus among each other [24]. Although EMCV-transmission from rodents to pigs is considered important, also the impact of horizontal and vertical pig-to-pig transmission needs to be known/quantified to understand their contribution to the spread of the disease on a pig farm [7,17]. This could be of great significance for control programmes, since it could indicate whether control should be focussed on rodent-to-pig transmission or, depending on its magnitude, also on pigto-pig transmission.…”

Section: Introductionmentioning

confidence: 99%

“…This could be of great significance for control programmes, since it could indicate whether control should be focussed on rodent-to-pig transmission or, depending on its magnitude, also on pigto-pig transmission. Transmission between pigs has been quantified under experimental conditions [17], but so far never in the field. A commonly used parameter to quantify virus transmission is the basic reproduction ratio (R 0 ), which is defined as "the mean number of secondary cases produced by a typical infectious individual during its entire infectious period in a completely susceptible population" [6].…”

Section: Introductionmentioning

confidence: 99%

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Transmission of encephalomyocarditis virus in pigs estimated from field data in Belgium by means of R₀

Kluivers

Maurice

Vyt³

et al. 2006

Vet. Res.

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-Transmission of encephalomyocarditis-virus (EMCV) has been estimated in experiments, but never using field data. In this field study, a farm in Belgium was selected where the presence of EMCV was confirmed by necropsy and virus isolation. Serology was used to estimate the transmission parameter R 0 . In one compartment with 630 pigs, 6 pens were fully sampled, in the remaining 38 pens, 2 randomly selected pigs were bled. The 151 pigs were bled twice and their serum was tested in a virus neutralisation test. Seroprevalence at the first and second sampling was 41 and 43% respectively, with a cut off value of 1:40. R 0 was estimated for 2 scenarios, in-and excluding mortality based on the final sizes from the serological results of the second sampling. The R 0 for the fully sampled pens was estimated between 0.6 and 1.7, the combined estimated R 0 of these 6 pens was 1.36 (95%-CI 0.93-2.23). The median of the estimated R 0 of the partially sampled pens was 1.3 and 1.4. Sampling two pigs per pen provided insight into the spread of the virus in the compartment, while the fully sampled pens provided an accurate estimation of R 0 . The low R 0 strongly suggests that EMCV is not very effectively transmitted between pigs. The number of seropositive pigs in a pen and the spread in the compartment suggests that other routes of infection are more important, in this case most likely rodents. Preventing viral spread should therefore be focussed on rodent control instead of reduction of contact between pigs. encephalomyocarditis virus / pigs / transmission / R 0 / field data

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