Experimental quantification of the transmission of Sarcoptes scabiei var. suis among finishing pigs.
In this study, the rate of S. scabiei var. suis transmission among finishing pigs was quantified in a contact transmission experiment. Forty piglets originating from a mange free farrow-to-finish herd were randomly allocated to three groups and one S. scabiei var. suis infested finishing pig was subsequently added to each of these groups. After 35 days, the three seeder pigs were removed from the groups and the remaining 40 pigs were re-allocated to five pens. Ear scrapings, to be examined for mites, were collected from each pig on days 1, 14, 28, 42, 56, and 84 of the experiment. Blood samples, to be tested for antibodies against S. scabiei, were collected from each pig on days 0, 14, 28, 42, 56, 70, 84 and 112 after the introduction of the seeder pigs. From the results of the ear scrapings and the blood samples the number of susceptible (not infested) and infested pigs was derived at the time of each sample collection and the number of new infestations in the intervals between the sample collections. From these data the infestation rate parameter beta (average number of new infestations per infested pig per day) was estimated by use of a Generalised Linear Model (GLM) and accordingly, beta was estimated at 0.056 (95% CI: 0.037-0.085) infestations per infested pig per day.Next, by use of beta, the transmission of S. scabiei was simulated in a population of 100 finishing pigs for 100 days after the introduction of a single infested pig. For this purpose, 500 simulations were done. The 90% confidence interval of the number of infested pigs at day 100 ranged from 12 to 88 (median: 63). It was concluded that transmission of S. scabiei among finishing pigs is slow. Due to the presumed lower contact rate between sows as compared to finishing pigs, it is anticipated that transmission of S. scabiei among sows will even be slower than among finishers These findings are of particular interest for the development of surveillance programmes for S. scabiei free herds.
Stegeman
J A
JA
Institute for Animal Science and Health, Department of Immunology, Pathobiology and Epidemiology, P.O. Box 65, 8200 AB, Lelystad, The Netherlands. j.a.stegeman@vet.uu.nl
Rambags
P G
PG
van der Heijden
H M
HM
Elbers
A R
AR
Hunneman
W A
WA
D000818:Animals; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D008954:Models, Biological; D012520:Sarcoptes scabiei; D012532:Scabies / Q000635:transmission / Q000662:veterinary*; D013552:Swine; D013553:Swine Diseases / Q000635:transmission*