Human trichinosis: report of four cases, with emphasis on central nervous system involvement, and a survey of 500 consecutive autopsies at the Ottawa Civic Hospital.

In 1963, acute trichinosis was recognized in four patients at the Ottawa Civic Hospital. One presented with cavernous sinus thrombosis and sixth nerve palsy. A second had a severe systemic infection with myocarditis; the signs of myocarditis appeared in the third week. Electrocardiographic abnormalities included T-wave flattening, prolongation of PR interval and QRS complex, and non-specific changes in 25%. Central nervous system involvement occurred in the second week with general symptoms (headache, delirium and psychotic behaviour), followed in the third week by focal signs (nerve palsy, convulsion, pareses and coma).The incidence of trichinosis in the U.S.A. fell from 15.9% before 1948 to 4.5% in the period 1948-1963. The Canadian incidence in the period from 1940 to 1943 was 5.6%. In a survey in Ottawa using the Baermann digestion and compression methods, four positive cases were found out of 500 diaphragms examined. These figures indicate the success of the public health regulations aimed at controlling trichinosis. A gastrocnemius muscle biopsy is still an invaluable diagnostic tool, especially in critically ill patients with negative skin tests and no eosinophilia.