SESSION TITLE: Infectious Disease Cases II
SESSION TYPE: Affiliate Case Report Slide
PRESENTED ON: Wednesday, October 28, 2015 at 11:00 AM - 12:15 PM
INTRODUCTION: Trichinellosis is a parasitic roundworm zoonosis from infected raw or undercooked meat. Trichinella infection occurs in two-phases—enteral then parenteral phase. The enteral phase is characterized by intestinal invasion and a gastrointestinal illness. The parenteral phase is the migration of the parasite to striated muscle including the diaphragm. Classically, trichinellosis symptoms develop during the parenteral phase with fever, facial edema, and myalgia.
CASE PRESENTATION: A 47-year-old man without prior medical history presented with one week of worsening fevers, edema, and myalgia. Despite initial empiric anti-microbials and supportive-care, his symptoms worsened. Bacterial and viral etiologies were not identified. He progressed to hypercapnic respiratory failure with pH 7.31 and PaCO2 51 necessitating transfer to the ICU and non-invasive positive pressure ventilation (NIPPV). Chest x-ray showed decreasing lung volumes and diaphragmatic ultrasound showed decreased bilateral excursion. Further history revealed that he was a hunter, who three weeks prior caught and ate a wild bear. Complete blood count showed a profound leukocytosis of 29,000 with 40% bandemia and 24% eosinophilia. Parasitic evaluation ultimately revealed Trichinella antibodies and he was subsequently initiated on albendazole and prednisone for Trichinellosis. After two-weeks of treatment, his symptoms and diaphragmatic excursion slowly improved with eventual liberation from NIPPV. Samples of the ingested bear meat were later confirmed by microscopy and PCR as T. spirialis.
DISCUSSION: In animal studies, Trichinella infection is associated with reductions in diaphragmatic function related to number of larvae, duration of infection, and inflammatory response to the infection. Recovery of muscular function can be slow taking months to years. Evolutionarily, Trichinella’s preference for striated muscle may be beneficial in weakening the host to promote capture and subsequent parasitic transmission.
CONCLUSIONS: Although Trichinellosis is a rare parasitic infection, the parasite’s predilection for striated muscles can lead to profound weakness including life-threatening respiratory failure, which may evolutionarily beneficial.
Reference #1: Gottstein B et al. Epidemiology, Diagnosis, Treatment, and Control of Trichinellosis. Clin Microbiol Rev. 2009 Jan;22(1):127-45
Reference #2: Harwood CL et al. The effect of Trichinella spiralis infection on the mechanical properties of the mammalian diaphragm. Parasitology. 1996 Dec;113 (Pt 6):535-43
DISCLOSURE: The following authors have nothing to disclose: Jason Lee, Sarah Waldman, George Thompson, Nicholas Kenyon
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