Mink enteritis parvovirus - Stability of virus kept under outdoor conditions

Feces from mink with acute mink enteritis were pooled and then allowed to d ry out in open tubes kept under a roof in an open shed for one year startin g in January. Samples of feces were harvested approximately once a month. T hese were reconstituted to their original volume and tested for antigen con tent and infectivity both in in vitro cell cultures and - on selected sampl es - in vivo. During the first 8 months, the antigen level in the feces sam ples decreased slowly. At this time point, a plateau was reached at 30-40% of the original viral antigen contents. The infectivity in vitro was unchan ged for the first 5 months, but after mid-summer it decreased abruptly to b elow the detection level. Based on the in vitro infectivity, 10 samples wer e selected for inoculation into mink to measure the in vivo infectivity. Th e transmission of the infection to the experimental animals was successful for all samples showing infective virus by cultivation. In addition, it was possible to infect mink using material harvested one month after the cell culture test had turned negative. One mink inoculated with material collect ed in October excreted virus. We conclude that parvovirus can survive for a t least 5-10 months (or during the winter period) under natural conditions, but complete drying out seems to lead to its inactivation. Mechanical clea ning of the premises is thus as critical as disinfection since virus can on ly survive the dry summer period if protected by protein or buried in moist soil on the premises.