Viability and infectivity of Trichinella spiralis muscle larvae in frozen horse tissue.
Abstract: Many aspects of the biology and epidemiology of Trichinella infection in the horse are poorly understood, including survival of Trichinella spp in horse muscle. In this study, we have assessed the freeze tolerance of T. spiralis in horse meat stored at 5, -5, and -18 degrees C for 1 day to 24 weeks. Results demonstrate a steady reduction in the number of live ML recovered from the cold stored meat samples. On Day 1, recovery of live larvae had been reduced by 18.6%, 50.1%, and 37.2%, and by 4 weeks, recovery of larvae had been reduced by 65.4%, 66.5%, and 96.2% in samples stored at 5, -5, and -18 degrees C, respectively. Infectivity results (measured as reproductive capacity index (RCI)) from mice inoculated with larvae recovered from non-frozen meat samples at day 0 was 23.5. Following storage at -18 degrees C for one and two days, the RCIs were 2.09 and 0.99, respectively. Small numbers of infective larvae were still present in meat samples stored at -18 degrees C for 4 weeks. The RCI of ML recovered from meat samples stored at -5 degrees C was 14.99 and 6.36 at 2 weeks and 4 weeks respectively; the RCI of samples stored at 5 degrees C was 23.1 at 8 weeks, and fell rapidly thereafter (12 week RCI 1.33; 0 at 24 weeks). These data demonstrate that infective T. spiralis, a non-freeze tolerant species, can survive for at least 4 weeks in horse tissue frozen at -5 or -18 degrees C, and that the numbers of infective larvae decrease substantially by day 2 at -18 degrees C and by week 4 at -5 degrees C.
Publication Date: 2007-04-05 PubMed ID: 17418492DOI: 10.1016/j.vetpar.2007.02.001Google Scholar: Lookup
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Summary
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The research paper presents a study on the impact of freezing conditions on the survival of the Trichinella spiralis parasite in horse tissue. The results demonstrate that the parasites can survive in horse meat that is frozen at -5 or -18 degrees Celsius for at least four weeks, but the number of live parasites gradually reduces.
Overview of the Study:
- The purpose of this study was to understand the freeze tolerance of Trichinella spiralis, a type of worm, in horse meat stored at various temperatures ranging from 5 to -18 degrees Celsius over a period of 1 day to 24 weeks.
- The study was prompted by a current lack of understanding on the survival of Trichinella species in horse muscle.
Key Findings:
- The results from the study showed a consistent decrease in the number of live muscle larvae (ML) recovered from the frozen meat samples as the freezing time increased.
- After the first day, the recovery of live larvae had fallen by 18.6% for meat stored at 5 degrees Celsius, 50.1% at -5 degrees Celsius, and 37.2% at -18 degrees Celsius.
- By 4 weeks, these reductions were 65.4%, 66.5% and 96.2% respectively.
Impact on Infectivity:
- In addition to measuring the survival rates of the larvae, the study also assessed their infectivity after being frozen. This was determined by calculating the reproductive capacity index (RCI) of the larvae from meat samples.
- On the first day without freezing, the RCI was measured at 23.5, indicating high infectivity. This significantly dropped to an RCI of 2.09 after one day, and 0.99 after two days at -18 degrees Celsius.
- Even after four weeks at -18 degrees Celsius, some infective larvae were still present in the samples.
- The RCI was 14.99 and 6.36 after two and four weeks respectively at -5 degrees Celsius; at 5 degrees Celsius, the RCI was still 23.1 after 8 weeks but rapidly decreased afterward.
Conclusion of the Study:
- The study concluded that Trichinella spiralis, even though it is not freeze-tolerant, can survive in horse tissue frozen at -5 or -18 degrees Celsius for at least four weeks.
- However, the number of infective larvae substantially decreases by the second day at a freezing temperature of -18 degrees Celsius, and by the fourth week at -5 degrees Celsius.
Cite This Article
APA
Hill DE, Forbes L, Gajadhar AA, Gamble HR.
(2007).
Viability and infectivity of Trichinella spiralis muscle larvae in frozen horse tissue.
Vet Parasitol, 146(1-2), 102-106.
https://doi.org/10.1016/j.vetpar.2007.02.001 Publication
Researcher Affiliations
- United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, BARC-East Beltsville, MD 20705, USA. dhill@anri.barc.usda.gov
MeSH Terms
- Animals
- Female
- Freezing
- Horse Diseases / parasitology
- Horses
- Larva / physiology
- Male
- Meat / parasitology
- Mice
- Muscle, Skeletal / parasitology
- Trichinella spiralis / isolation & purification
- Trichinella spiralis / physiology
- Trichinellosis / parasitology
- Trichinellosis / veterinary
Citations
This article has been cited 8 times.- Koutsoumanis K, Allende A, Alvarez-Ordóñez A, Bolton D, Bover-Cid S, Chemaly M, Davies R, De Cesare A, Herman L, Lindqvist R, Nauta M, Peixe L, Ru G, Simmons M, Skandamis P, Suffredini E, Sánchez JÁ, Blagojevic B, Fürst P, Garin-Bastuji B, Jensen HE, Paulsen P, Baert K, Barrucci F, Broglia A, Georgiadis M, Hempen M, Hilbert F. Evaluation of public and animal health risks in case of a delayed post-mortem inspection in ungulates. EFSA J 2020 Dec;18(12):e06307.
- Yang Y, Cai YN, Tong MW, Sun N, Xuan YH, Kang YJ, Vallée I, Boireau P, Cheng SP, Liu MY. Serological tools for detection of Trichinella infection in animals and humans. One Health 2016 Dec;2:25-30.
- Riva E, Steffan P, Guzmán M, Fiel C. Persistence of Trichinella spiralis muscle larvae in natural decaying mice. Parasitol Res 2012 Jul;111(1):249-55.
- Gottstein B, Pozio E, Nöckler K. Epidemiology, diagnosis, treatment, and control of trichinellosis. Clin Microbiol Rev 2009 Jan;22(1):127-45, Table of Contents.
- Medina-Lerena MS, Ramirez-Alvarez A, Kühne M, Gómez-Priego A, de-la-Rosa JL. Influence of different processing procedures on the reproductive capacity of Trichinella spiralis in pork meat. Trop Anim Health Prod 2009 Apr;41(4):437-42.
- Iacob OC, Paşca AS, Olariu LA, Ivănescu LM, Mareş M. Controlled freezing inactivates Trichinella britovi in wild boar meat: Insights from a murine infection model and multiplex polymerase chain reaction. Vet World 2025 Jun;18(6):1667-1674.
- Bessi C, Ercole ME, Fariña FA, Montalvo F, Fassa V, Acerbo M, Ribicich MM, Pasqualetti MI. Survival of Trichinella spiralis and T. pseudospiralis in Experimentally Infected Wild Boar Muscle Tissue under Freezing and Environmental Conditions. Iran J Parasitol 2024 Oct-Dec;19(4):457-464.
- Dubey JP, Thompson PC, Fournet V, Hill DE, Zarlenga D, Gamble HR, Rosenthal BM. Over a century of progress on Trichinella research in pigs at the United States Department of Agriculture: Challenges and solutions. Food Waterborne Parasitol 2024 Sep;36:e00239.
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