Persistence of Trichinella spiralisin Rat Carcasses Experimentally Mixed in Different Feed

Abstract

-Trichinella spiralis infected rat carcasses were incubated for 6 weeks in several animal feeds to assess how long Trichinella can present a risk for an outbreak in contaminated feeds. In groups of 6, 24 infected target rats were placed in silage, grained barley, propionic acid-preserved feed, and also into simulated pasture conditions. Test environments were sampled after one-, 2-, 4-, and 6-week-incubations. Trichinella larvae were recovered by digestion, and their infectivity was evaluated in rats. A two-week incubation reduced the number of recovered larvae, but still after 6 weeks low numbers were isolated from all feeds except from the experimental group simulating pasture conditions. After 2 weeks storage, the larvae were infective in all storage environments. However, up to 4 weeks, they survived only in the propionic acid-fermented feed and there in small numbers with reduced reproductive capability. This indicates the possibility of farm animals to get infection from rats or other infected material being hazardously mixed with hay or other feed. If silage is stored for at least one month before use, however, the risk from this forage appears to be minimized.

Smart carnivores think twice: Red fox delays scavenging on conspecific carcasses to reduce parasite risk

“…and other meat-borne parasites is known to be highly related to environmental conditions and the changes that occur during carrion decay ( Bengis, 1997 , Pozio, 2000 ). For instance, high humidity and low temperature favours the survival and transmission of Trichinella larvae ( Fariña et al, 2017 , Oivanen et al, 2002b , Pozio, 2016 , Riva et al, 2012 , Rossi et al, 2019 ). In cold environments, at constant low temperatures such as those reached beneath the snow, the infective capacity of T. britovi larvae in red fox carcasses does not show important reductions during the first four months.…”

“…However, above the snow, with more oscillating temperatures, the parasite’s reproductive capacity sharply decreases after two months, and almost no viable larvae are present after three months ( Rossi et al, 2019 ). At higher temperatures (average: 23ºC), the number of infective T. spiralis larvae in rat carcasses decreases severely after the first week ( Oivanen et al, 2002b ). In the case of decaying fox meat, the number of infective larvae of several Trichinella genotypes has been found to decrease rapidly during the first two weeks at 22-27°C and 100% relative humidity ( Von Köller et al, 2001 ).…”

Influence of different processing procedures on the reproductive capacity of Trichinella spiralis in pork meat

“…A reliable procedure to determine viability of T. spiralis is the calculation of the reproductive capacity (Oivanen et al 2002;de-la-Rosa et al 2007;Hill et al 2007). In this study, the reproductive capacity of Trichinella spiralis ML was used for the determination of the effect of several meat-processing procedures on the infectivity of Trichinella: freezing, drying, cold storage and seasoning with "adobo" or "wet-curing".…”

Validation Parameters of the Magnetic Stirrer Method for Pooled Sample Digestion for Trichinella spp. in Horse Meat Based on Proficiency Tests Results

“…transmission to horses. It may occur incidentally by grazing in pastures contaminated with infected small animals and rodent carcasses, or on hay containing pieces of rodents, or even through being fed with animal products [ 21 , 22 ]. However, it was empirically proved that moist feces of rats fed with Trichinella spp.…”